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:. Miscellaneous - FAQ .:

Last Updated: 2004/04/24

I've tried to put together a list of questions that come up all the time on the Corvette Forum and elsewhere. The information is as accurate as I know it to be, but please correct any misinformation or omissions you see by sending me e-mail (link at top.). Most questions currently have some incompleteness, or perhaps errors, since the FAQ is not currently complete, so USE THIS FOR INFORMATIONAL PURPOSES ONLY, AND I AM NOT RESPONSIBLE FOR THINGS YOU DO TO YOUR CAR

That unpleasantness aside, I hope this helps you get to know your C5 and the aftermarket better!

Question Index:

1.) Engine

1.1.) What Exhaust systems are available for the C5?
1.2.) What headers are available for the C5? Are shorties worth it?
1.3.) What X-pipes are available for the C5? Will I gain horsepower?
1.4.) What intakes are available for the C5?
1.5.) What intake manifolds are available for the C5?
1.6.) What are the specs of my cam?
1.7.) What software is available to tune or datalog my engine?
1.8.) Which cam is right for me? How do I select a cam?
1.9.) Who makes upgraded or ported cylinder heads?
1.10.)What compression can I run on pump gas? How do I change it? How does it help?
1.11.)What combustion chamber volume is equivalent to what compression ratio on a stock LS1?
1.12.)Is the LS6 cam worth the upgrade? What do I need?
1.13.)Do I need programming for cam 'X'?
1.14.)Will a cam affect my gas mileage?
1.15.)I want more inches. (don't we all) What bore/stroke motor combinations are there?
1.16.)How tough are Corvettes? When to engine and driveline parts start breaking?
1.17.)What else should I do while installing heads/cam? 1.18.)What should my oil pressures be?

2.) Suspension

2.1.) What are the differences between the C5 Suspensions? Can I swap them?
2.2.) What aftermarket shocks are available?
2.3.) Who makes aftermarket swaybars for C5's? Are there any downsides?
2.4.) Do I need to get an alignment after I lower my car?
2.4.) What are the various spring rates in C5 suspension packages?

3.) Drivetrain, Brakes, & Accessories

3.1.) What gears should I get? What RPM is it at 'X' speed on the highway? Do I need to break them in?
3.2.)
3.3.) How is the M12 (Z06) gearing different from the MN6 (C5) gearing?
3.4.) Do I need to balance my GM or Aftermarket clutch/flywheel before installing it?
3.5.) What aftermarket clutches are available? Which one should I get? What do I need?
3.6.) Who makes short shifters for C5's? Are there any problems?
3.7.) Who makes aftermarket flywheels for C5's? How much weight will I save? Will it hurt my launches?
3.8.) What brake pads should I use?
3.9.) What is the clutch drill mod? Why should/shouldn't I do it?

4.) Body And Exterior

4.1.) Can I install Z06 brake ducts?
4.2.) Can I install Z06 style cold-air screens?
4.3.) How wide wheels and tires can I fit on my car? Can I go wider?
4.4.) My headlights suck! What are my options to fix this?

5.) Interior

5.1.) Why does my seat rock? Can I fix it?
5.2.) The leather is wearing out on my seats. What can I do?
5.3.) What aftermarket seats fit in a C5?
5.4.) Who makes brackets to put seats in a C5?
5.5.) Can I install a HUD on a non-HUD equipped C5? Even if it's before they even offered it?
5.6.) My vanity lights don't work (and neither does my underhood light) How do I fix it?

6.) Racing your Corvette

6.1.) What do I need to go Autocrossing?
6.2.) What do I need to go road racing?
6.3.) Who makes harness bars for C5's? What are the concerns?
6.4.) Who makes rollbars for C5's? What are the concerns?
6.5.) What kind of alignment should I have for autocrossing?
6.6.) What SCCA classes do C5's run in?
6.7.) Who makes oil coolers for C5's? Where can I get more info?
6.8.) Who makes larger radiators for C5's?

7.) Forced Induction

7.1.) Head/Cam or SuperCharger? What are the pros and cons?
7.2.) Will FI affect reliability?
7.3.) What kits are available?
7.4.) What are the pros and cons of various FI types?
7.5.) Why can I run more boost on a lower compression engine?
7.6.) are 6.0L/LQ9 heads a good idea? what do they lower compression to?
7.7.) What do Superchargers sound like?
7.8.) What is "Pinning the crank" for a Supercharger?
7.9.) How can I decide between the ATI and Vortech units?
7.10.)What is an 8-rib setup, and why do I need one?

8.) Electronics, PCM, and tuning

8.1.) How do I check the codes stored on my car? What do they mean?

9.) Common Problems and Fixes

9.1.) I keep getting the message "Active Handling Warming up." What does it mean? Is anything wrong?
9.2.) My seat rocks back and forth. How can I fix it?
9.3.) My Fuel gauge doesn't work right - how can I fix it?
9.4.) My battery seems to be leaking? Can this cause any problems? What is the fix?
9.5.) Something is leaking oil from the rear of my car - what is it?
9.6.) I'm getting a vibration and/or squeal from my car, what could it be?
9.7.) I have some belt squeal, what is causing it?
9.8.) What is the intermittent "Service ABS" and "Service Traction Control" light mean?
9.9.) My passenger window quit working. Why?
9.10.) My reverse lights stopped working. Why?
9.11.) My steering wheel won't unlock, and the car dies when I try to move it. Help!
9.12.) My headlight motor is stuck up/down/etc.
9.13.) Sometimes after driving my car hard, the clutch pedal sticks to the floor.
9.14.) There is a whining noise coming from behind me in my '97-98 car. What is it?

10.) Audio

10.1.) Can I hook up an aftermarket CD Changer to my stock head unit?
10.2.) Can I use my stock Bose speakers with an aftermarket head unit?

X.) Miscellanous

X.1.) What are the various Model Year differences?
X.2.) How well do high-mileage vettes hold up?

Answers:

1.) Engine

1.1.) What Exhaust systems are available for the C5?

Here is a short list of commonly used exhaust systems on C5's. It is generally held that they're not worth more than about 10hp or so at the outside, so if you upgrade, it should be mostly for the inrease in sound. I've tried to list them in approximate order of loudness, and left out the hyperexpensive aftermarket Ti systems that nobody seems to buy:

Exhaust Cost Material Lbs per Side Notes
Corsa Touring ?
Stock Z06 ~$500 used Titanium 17 lightweight, no resonance, 4-tips.
Magnaflow ?
Stainless Works 3" ?
Bassani Exhaust $800 Stainless ? various tip styles available
B&B PRT's $800 19 various tip styles available
Corsa Indy's ~$850 ? various tip styles at varying costs
Borla Stingers (2-tip) $600 19 most popular. Some have reported resonance around 2000RPM
Borla Stingers (4-tip) $600 22 most popular. Some have reported resonance around 2000RPM
GHL Magnum(2-tip) $600 ?
GHL Bullet (4-tip) $700 ?
GHL Bullet ?
Borla XR-1 $800 ?
Borla Straight Pipe $300 ?




1.2.) What headers are available for the C5? Are shorties worth it?

Here is a short list of the commonly available c5 headers out there. Short-tube headers will provide almost no gain over the stock manifolds. The mid and long-tube headers (top 4 below) will provide substantial gains. Most are 1 3/4", as that seems to be the generally agreed ideal size for stock LS1's.

Header Material X-pipe? Cats? Cost (est) Notes
Kooks Headers Stainless Yes Optional - $200 $1,350 Available in many combinations, including 1 7/8" for cars with FI, or big plans. This author's personal favorite bang/buck choice, and folks claim to have done back-to-back tests where they made the most power (for what that's worth without dyno charts...). (Further disclaimer of bias: they're what I've got on my car) Mild-Steel x-pipe.
LG Motorsports Stainless Yes Optional - $400 $1,600 Requires removal of intake manifold on 97-00 for AIR tube fitment. Longest primaries on market. Require O2 sims even with cats due to length
Stainless Works C5 Headers Stainless No, but available Cats? $950 Lifetime warranty
FLP (Finish Line Performance Ceramic coated Mild Steel Yes Yes? $1,600 Swappable off road pipes included.
TPIS Mild steel (coating opt.) No No $850 Coating optional. Comes with H conversion to fit to your existing H-pipe ass'y, requires some welding.
Dynatech SuperMaxx Stainless yes yes - opt $??? LGM header "clone", but a solid product, for less money.
--
Belanger         v
TTS         1 5/8's size, versus 1 3/4".


And, a bit of info, for those seekign some comparative numbers: As of this writing, the two kings of the hill are Kooks and LGM headers. Dyno graphs have been posted to Z06Vette.com showing Kooks making more power than TPIS, Dynamaxx, and Stainless works headers. Similarly, graphs have been posted showing LGM headers creating more power than the FLP's.

It also bears mentioning that no matter what header you get for your C5, they are all good products, and you will be happy with them, so when you do shop, pick one, and be happy with the choice. You can see my writeup, impressions, and install of the Kooks in my projects section, and many testimonials to all brands of headers have been posted on Corvette Forum and Z06Vette.com.




1.3.) What X-Pipes are available for the C5? Will I gain horsepower?

An X-pipe will smooth out the sound of your car and reduce the 'motorboat' sound some folks report. Also, it should eliminte the 'popping' sound some cars experience on deceleration, which some folks find unpleasant.

You may gain 5ish horsepower, but this also is mostly a sound mod, or as part of a header system.

X-Pipe Material Bolt-On? Cats? Cost (est) Notes
Bassani Stainless Yes No $270 lifetime warranty, slip fit front, flanges rear - no welding req'd
Corsa Stainless Yes No $250 Required cutting of stock H, clamp on front, flanges rear.
Flowmaster N/A Yes No N/A Required cutting of stock H, clamp on front, flanges rear.
MagnaFlow Stainless No - welding No $250 Required cutting of stock H, welding on
Random Technology Stainless Yes Yes $700 Complete repalacement from header flange to exhaust flange. Available w/ front flange or slip-fit for headers (TPIS, etc)




1.4.) What intakes are available for the C5?

There are many intakes available on the market, from the simple, reasonably priced, to expensive, gorgeous intakes. Do your own research, and decide where the right fit is for you. Here is a short list:
Intake Cost (est) Notes/Desc
Blackwing $200 replacement airbox + filter. Easy install. Good filtration, good gains, good sound
Breathless Vortex Rammer $250 uses a cut in the radiator shroud to take cold air from radiator. Can throw codes on wet days.
Vararam VR1-B ~$320 uses foglight cutouts for 'ram air' effect. Poor filtration quality with their filter. Commonly on special for $310-$330 shipped from TByrne and Exit28 MS
Halltech TRAP $630 Gorgeous carbon-fiber. Relocates large filter under bumper, behind license plate. good cold-air, greate torque, good filtration. Does not work on early C5's due to airbag sensor under bumper.



1.5.) What intake manifolds are available for the C5?
There are not many intakes available to fit the LSx series of engine, since the factory ones are quite good. Aside from the standard LS1 intake on the earlier (97-2000) cars, there is the factory LS6 intake, which is good for a few horsepower, mostly on modified cars. To install the LS6 intake on a later car, in addition to the intake gaskets, you will need (1) #88894339 LS6 Intake, (1) #12568478 Coolant Pipe, and (2) #12563325 Plugs. It usually runs around $400.

A company called FAST is making what they call the "LSx" intake, which is now in testing. It is closer to $800, and is available in small and large throttle body sizes. It has shown decent gains over the LS6 intake.

Lastly, TPIS makes a modified LS6 intake that uses an oval inlet, and an accompanying oval throttle body. dyno graphs have been posted showing the FAST LSx intake making a bit more power than this one, and for less money. Information is scarce, however, so do your homework.

Holley makes an intake, but the LS6 has surpassed its performance, and is no longer in common use.


1.6.) What are the specs of my cam?
Published specs for Corvette cams are as follows:

'97-00 LS1: 0.472/0.479, 202/210 on 117
'01+ LS1:  0.500/0.500, 198/208 on 115.5
'01 LS6:   0.551/0.547, 204/218 on 117.5
'02+ LS6: 0.551/0.547, 204/218 on 117.5



1.7.) What software is available to tune and datalog my LS1?

Software Logger? Tuner? Cost URL Notes
LS1 Edit        
AutoTap        
EFI Live        
Predator        
Hypertech  
Tech II        




1.8.) Which cam is right for me? How do I select a cam?

This is a very complex question, and a very subjective one. Selecting a cam has to be due to lots of research, listening to a lot of folks cars, and then getting in the right ballpark. A few degrees here and there won't matter a whole lot, so the important thing is to get in the right general area with some good research.

jmX has a good writeup on cam selection on his ls1howto.com site, here.

He brings up most of the good points, but here are a few others. It is important to talk to tuners and get a good combination of parts, since that will get you the best results.

Cam Lift: Lift, along with the lobe profile of the cam, will have a big impact on spring longevity. You can compromise by going with less lift, but that can cost power. Valvesprings are relatively cheap, so perhaps lift is not the area to compromise - you will have to decide. Second, regarding lift, if you plan on staying with stock heads, high lift may not make much sense, since the heads will not flow as well at high lifts. With ported heads, most keep doing better and better as lift goes up, so you can see significant gains from a higher lift cam. Most aftermarket cams are in the 0.550-0.600 range.

Duration: Duration, as quoted usually on the 'net, is how long the valve stays at or above 0.050" of lift. The larger the duration, the choppier your idle, and the powerband tends to move upwards in the rev range. Stock cams are right around 200, 'mild' cams are in the 216-220 range, 224 is average or so, and most cams over 227 are considered quite large on stock 346ci engines.

LSA: Or, 'Lobe Separation Angle' - this is the difference between the intake and exhaust lobe centerlines. Larger numbers (wider) will idle better, and be cleaner on emissions. Powerband is effected somewhat by different lobe centers, but frankly, there seems to be no agreement on how, on the 'net. Stockers are in the 115-117 range, 114 is still nice idle, most of the time, and 112 and lower is noticably choppy.




1.9.) Who makes upgraded or ported cylinder heads?

Mfr URL? Costs? Notes
Absolute Speed www.absolutespeedls1.net/ $1,000 - $1,900. $300 LS1 Core, $1200 LS6 core Very nice, high performing heads.
Cartek www.cartek.net ~$3,000 + LS6 core Currently the benchmark. LS6 and LS1 versions
LG Motorsports www.lgmotorsports.com ~$3,000 + LS6 Core Also very good.
MTI www.motorsporttech.com
Patriot Performance www.patriot-performance.com $1,100-$2,000 LS1, 5.3L, and LS6 style castings. No core charges for LS6 heads, incredible bang-for-the-buck.



1.10.) What compression can I run on pump gas? How do I change it? How does it help?

Factory LS1 compression is 10.1:1. LS6 Compression is 10.5:1. Most folks seem to agree that right around 11.0:1 is where you want to be for worry-free operation on pump gas, with most cams. Folks have gone as high as 12.2:1 with high overlap cams, that reduce cylinder pressures a bit.

Higher compression raises cylinder pressure, so you get more torque and horsepower, basically for free. As well, higher compression can help smooth out your idle on larger cams. You can change compression one of three ways:

1.) Milling the cylinder heads: - this takes material off the deck of the head, thereby reducing combustion chamber volume. This has the downside of reducing piston-to-valve clearance, which may limit how much lift and duration you can run on your cam.

2.) Welded combustion chambers - Some companies, like Patriot, add material to the combustion chambers and then CNC it back out to reduce combustion chamber volume without causing P/V clearance reduction.

3.) Rebuilt bottom end with different pistons - Naturally, any new motor you have built can have pistons with their own compression ratio specified.


1.11.) What combustion chamber volume is equivalent to what compression ratio on a stock LS1?
Here is a table, built from various posts, assuming a 0.056 thickness head gasket on a stock motor.

68cc = 10.1 CR (stock LS1 head spec)
65cc = 10.5 CR (stock LS6 head spec)
59cc = 11.1 CR



1.12.) Is the LS6 cam worth the upgrade? What do I need?

It is up to you to decide if the effort of the swap is 'worth it', but the cam is worth about 20hp on an otherwise untouched LS1. jmX from ls1howto.com installed it on a mostly stock F-body, and saw almost exactly 20hp, and nearly all the gains above around 5000 RPM.

See threads: a (CF) b (LS1Tech)


1.13.) Do I need programming for cam 'X'

If you ask "should I", then the answer is yes. If the question is "do I need to", then the answer is maybe. Most cams up to around 224 duration will idle with a little help, without any PCM tuning. You may required a decent sized hole in the throttle body blade to get the car to idle up enough to keep running, and to avoid stalling.

That said, just because the car is running does not mean you have an optimum state. With the engine's VE changed as drastically as a cam change will change it, your factory tune just went right out the window. At best, you will be running too rich, and at worst, you can be running very lean, and detonating badly.

Do yourself a favor and have the car tuned properly. The idle will improve, there will be zero, or minimal stalling and surging, and you can wring the most out of your car's mods and know that it is safe doing it.


1.14.) Will a head/cam upgrade affect my gas mileage?

Yes, but mostly for the better! Folks usually report that their mileage stays the same, or even goes up a few ticks when they get a head/cam package. Note that raising compression will naturally improve your gas mileage as well, due to more efficient combustion. Of course, it will be hard to keep your boot off the gas with your newfound power!


1.15.) I want more inches. (don't we all) What bore/stroke motor combinations are there?

Here is a list of common bore and stroke sizes, and their results on LS1's: Stock 346ci
bore 3.898"-3.900"
stroke 3.622"

LS1/LS6 382ci - 388ci
bore 3.905" (4.1000"-4.125")
stroke 4.000" (3.622")

LS1/LS6 396ci
bore 3.905"
stroke 4.125"

LS1/LS6 409ci
bore 4.060"
stroke 4.000"

LS1/LS6 422ci-428ci
bore 4.100"-4.130" (4.100") <-Diff. ways to reach the same goal.
stroke 4.000" (4.040")

LS1/LS6 436ci
bore 4.100"
stroke 4.125"

LS1/LS6 448ci (all you need is another 6ci to get to the magic 454 of the orginal LS6 )(uncommon)
bore 4.155"
stroke 4.250"



1.16.)How tough are Corvettes? When to engine and driveline parts start breaking?

Corvettes are admirably strong. So far, nobody seems to have made more power than a stock block can handle staying naturally aspirated. Only mistakes such as running lean seem to do the LS1 in. Forced Induction cars seem to be happy until around 550whp, beyond which things can get a bit sketchy.

As far as the rest of the driveline, the clutch is the weak link from the factory, which is fine. Once that is strengthened, the driver's side output shaft in the differential is notoriously weak. When you have your 3.90 or 4.10's put in, have a stronger shaft installed for another $300 or so.

Beyond that, using full slicks at the track can break tranny and diff casings, and some folks have even snapped torque tubes. But, that is with hard launches, lots of horsepower, and extremely sticky tires. Other than needing a stronger clutch, without heaping slicks and 6000RPM clutch dumps on your car, it should be fine even at obscene power levels. Heck - even some of the Lingenfelter turbo cars use nothing more beefy than a Z06 clutch!


1.17.) What else should I do while installing heads/cam?

There are a few items you have good access to when doing a head/cam job on your Corvette. When installing the cam, it is a good idea to replace your oil pump if you have a high-ish mileage car. For older vettes, the new style LS6 oil pump is a bit beefier and will give you better pressure. Either one from GM, or a modified version from Thunder, SLP, Katech, or others will likely be just fine.

Second, you might take the opportunity to install a new water pump. Although their service life is quite long, there's no harm in preventative maintenance.

As well, while the timing gear is off, it is a good idea to replace your timing chain, either with a stocker, which is perfectly fine, a JWIS single chain, or one of the heavy-duty double rollers that some folks favor.

If you are installing a cam that is much more than a stock replacement, you will need valvesprings to keep your valves from floating, and Ti retainers are cheap enough to be considered a required upgrade too. Replacing your pushrods is advisable as well, since aftermarket ones will be stronger, and chances of having a bent stocker are not small enough to ignore.




1.18) What should my oil pressures be?
With 5W-30 Mobil 1, the 2000 manual lists hot oil minimum specs at:
 ·6 psi at 1,000 engine RPM
 ·18 psig at 2,000 engine RPM
 ·24 psig at 4,000 engine RPM

So, if you are above those numbers, you are still just fine.

Oil filter you use can have an effect on presures somewhat - Mobil 1 filters are known to reduce pressure a bit versus the GM factory PF44 and PF46 filters.




2.) Suspension

2.1.) What are the differences between the C5 Suspensions? Can I swap them?

Five C5 suspension packages exist:

  • Base (FE1)
  • Z51 (FE3)
  • Z06 (FE4)
  • Adjustable (F45)
  • Magnetic/Adjustable (F55)


From GM, each of the five options has its own shocks, springs, and swaybars, all of which are interchangable to make the combination you want.

Sway Bar sizes:
Of the non-adjustable shocks, the only ones worth upgrading to are the '04 Z06 shocks, which have improved rebound damping over previous years. Unless you have the F55 shocks and want to keep them, consider upgrading to these, Konis, or some other aftermarket shock.

Sway Bar sizes:
Sway bars help reduce the amount of body roll your car has in corners. They have a small impact on straight line ride quality as well, but less so than stiffer springs. Larger diameter bars provide more roll resistance.

See FAQ 2-3 for a list of swaybar sizes for C5's.
Upgraded Z06 bars can be had for about $250 shipped from various sources, with bushings and endlinks.

Springs and rates:
Springs keep the car off the ground, and reduce dive/squat during acceleration and braking, as well as controlling body roll. The stiffness goes Base/FE1 < Z51/FE3 < Z06/FE4.

Here are some Spring P/N's, in case you are looking to upgrade:
- Z06 Front spring: 22178729
- Z06 Rear spring: 22188038
- Z51 Front spring: 22178729 (note: same as Z06)
- Z51 Rear spring: 22179020
- Base Front Spring: 22178728
- Base Rear Spring: 22179019

The Z06 rear spring is about 10% stiffer than the Z51 rear - numbers are not 100% known, since the information was not made easily available by GM. Z51 springs are a bit stiffer than F55 springs, which are, in turn, a bit stiffer than base C5 springs.

Please see jmX's c5howto.com for swap instructions.


2.2.) What aftermarket shocks are available?

Several upgrades are available to improve the handling of your C5. For installation help, you can try http://www.ls1howto.com, or this link.

Shock Est. Cost Adjustable? Notes
Bilstein Sports ? No slightly shorter for lowered cars. Stock valving too soft, not ideal for competition.
'04 Z06 Shock $350 No GM's latest revision. Good handling and ride, and great bang/buck
Koni Sports (orange) $800 Yes - rebound These are a good bang/buck adjustable shock. 3/4" shorter than stock for slightly lowered cars.
Penske Single Adjustable $1,900 (Ankeny Racing) Yes - rebound, nitrogen pressure Fantastic shock, for competition folks only.
Penske Double Adjustable $2,800 (Ankeny Racing) Yes - rebound, compression, nitrogen pressure As above.
HA1's $??? ?? Drag oriented shock




2.3.) Who makes aftermarket swaybars for C5's? Are there any downsides? What do I need?
There aren't a huge number of them out there, see the table below, listed approximately in order of size/aggressiveness:
Bars Front Dia. Rear Dia. Thickness Cost Notes
Base / FE1 23 mm 19.1 3.81mm/2.0mm $-- --
Z51 / FE3 - '97-'99 25.4 mm 21.7 ??  $-- --
Z51 / FE3 - '00-'04 28.6 mm 23.6 4.15mm/3mm $-- note rear same as Z06 rear, and both updated from earlier Z51 bars.
Z06 / FE4 30.0 mm 23.6 4.5mm/3.5mm $250 shipped - Fichtner, etc. Fantastic for good street driving, and good for autocrossing.
ADDCO/BMR 31? mm 21? mm ?? ?? Not much known, as you can see!
Hotchkis 31.75 mm 25.4 mm 4mm/4mm $495 (LAPD e-mail Shawn) Supply new heim jointed endlinks that are adjustable *and* quiet
GM T1 38.4 mm 27.5 mm 6.35/6.35 $600 Much stiffer ride. Works with stock endlinks if you want to.


Note that if you have an older '97-'99 C5 with plastic swaybar endlinks, you will need to go to the GM aluminum endlinks for the larger bars (GM PN:10435298, ~$60/set), as the old-style plastic ones can snap with the force from the stronger bars. Fichtner includes these in a Z06 bar order, along with the new rubber bushings for the larger bars.

If you're seeking input on which to go with, let me offer my input, based on having owned stock early Z51 bars, Z06 bars, T1 bars, and Hotchkis bars, in that order: Anything smaller than the Z06 swaybars is a waste of time, in my opinion. The Z06 bars offer outstanding handling, at virtually no ride penalty over a FE1 or FE3 car.

The T1 bars make for absolutely 100% flat cornering, but are, again, in my opinion, brutal on rough roads. They take all compliance out of the suspension on anything but smooth pavement. Even turning the rebound on my shocks down to *nothing* made no change.

I went back to the Z06 bars after that, but was still having a small amount of rubbing trouble, so I have since installed the Hotchkis bars to see if it will be enough to keep the car off the fenders in long sweepers when autocrossing. The new endlinks Hotchkis supplies make no noise at all, look beautiful, and installation was the same as with the other bars. Ride quality made no perceptible change over the Z06 bars, and the cornering is definitely flatter. Turning up the rebound on the shocks has a far worse impact on ride quality than these bars did. I will be keeping these swaybars.

As an extra data point, I talked to SCCA Solo II champ Gary Thomason about his car, and he said that he tried the T1's, and that the car understeered horribly, and that the front bar was simply too big. He said he was going back to an all Hotchkiss swaybar setup to complement his 900# VB&P front spring, which he added since winning on just the Hotchkis bars the year before. Hope that helps to hear input from somebody other than me! ;-)


2.4.) Do I need to get an alignment after I lower my car?
Yes.

Lowering your car changes the camber, which in turn changes the toe settings. Both will cause increased tire wear, so you should have them adjusted to account for this.


2.5.) What are the various spring rates in C5 suspension packages?
GM Offered several different spring packages from the factory, but was pretty tight-lipped about what rates those springs actually are. I'll fill in this table as I find more information:
Spring Package Front Rear Cost Notes
Base (FE1) -- -- --  
F45 Electronic -- -- --  
F55 Magnetic -- -- --  
Z51 (FE3) 650# 620# (est) --  
Z06 (FE4) 650# 680# --  
GM T1 Racing -- -- $??  
Danny Popp's ASP Setup 1,000# 680# ~$1,100 ASP National champ Danny Popp's autox setup on his Z06.
GM T1 Racing -- -- $??  
As GM never did publish specs for the suspension springrates, there is some disagreement. An alternate table is published here, based on numbers from a Car & Driver article on C5 suspensions:




3.) Drivetrain + Accessories

3.1.) What gears should I get? What RPM is it at 'X' speed on the highway? Do I need to break them in?

I will give you my opinion: If you own a MN6 car, you should get 4.10's, no question. I have 3.90's, and my mileage is as good as ever, the car lopes along at about 2000 RPM at 80MPH, and accelerates amazingly well. Incredible bang for the buck, without the thing feeling like it will run out of gear at 110mph!

The Z06 fellows, with their shorter gearing, seem to favor 3.73 and 3.90's, if they change them at all. Drag racers go to 4.10 almost universally. Lou Gigliotti recommends that for road racing, you should probably stick with 3.42's if you have a Z06, which would make 3.90's an equivalent choice for a coupe/MN6 car.

Auto cars seem to vary between 3.15's, 3.42's, and the more extreme folks will do 3.73's. 3.42's are fairly commonly available from manual transmission cars upgrading to higher ratios.

Here are some great URL's for calculating your speeds, gear ratios, and things like that:

Shag Finger's ratio page
Gear/Speed/Ratio Calculator
Accelration Simulator


IMPORTANT: gears do need break in. The initial 500 or so miles in your diff is what heat treats the gears. If you go out and bang on them initially, you can end up with gears that will whine under load, under decel, or both. If you take it easy for 500 miles or so, then bang on them, then you will have whisper quiet operation for the rest of their life, but if you don't, you're gambling. I would know - I had to have a set warranteed for that exact reason.


3.3.) How is the M12 (Z06) gearing different from the MN6 (C5) gearing?

Z06 gearing is shorter than a C5's. Both Z06 and C5 have 3.42 rear end gears, but the Z06 has different transmisison ratios.

In short, the Z06's 1-2-3 are much shorter, and almost identically match a C5 with 3.90 rear-end gears. For more numeric comparison, look at This FAQ.


3.4.) Do I need to balance my GM or Aftermarket clutch/flywheel before installing it?

This has been problematic for folks, and a lot of information is available on the forums. I have not yet had to do an aftermarket clutch install on my car, so this information is secondhand - definitely read on the forums, and talk to vendors to get the latest information before putting a clutch in your car.

That said, the short answer is YES. The best way to do this is to have the flywheel zero balanced, and then the clutch/pressure plate zero balanced. This way, if you replace the clutch and keep the same flywheel, the unit can remain balanced.

There is some debate about the presence (and occaisional absence?) of balancing pins in the stock flywheel, which are purported to help balance the engine, much like the pins on your stock crank pulley. However, I haven't been able to clean much of a consensus from reading on the forums, so I'll simply stop at making you aware of the flywheel balance-pin issue.


3.5.) What aftermarket clutches are available? Which one should I get? What do I need?

Here is a short (and incomplete) list of the clutches commonly used by C5'ers.

Note that with any of these upgrades, you should replace the slave cylinder, and should also probably replace the master cylinder. the GM Parts are about $100 apeice, and McLeod makes an adjustable master cylinder for a bit more, which is required with some of the stronger clutches, like the RAM, and Spec Stage II and higher.
There have been spotty reliability issues with all of these except the Z06 and Exedy clutches, so unless you will be drag racing often or launching the car, or are making a LOT of torque, the Z06 clutch might be sufficient for your needs.

Supposedly, even the LPE Stage I TT cars use the Z06 clutch, so that is a pretty strong endorsement, and several forum members report over 100 drag passes at around 450whp with no problems. As with all mods, call around and get advice from tuners before making your final decision.

Clutch Cost Rating Est
rw tq.
Description
Exedy Single Disk N/A N/A Some increase in pedal effort. 36.7lbs.
Exedy Dual Disk $1,500+ 600+ The most expensive, but the most reliable, and most user friendly of all of the clutches capable of holding a LOT of power. Some increase in pedal effort. 38.4lbs
McLeod Single Disk N/A N/A Supposedly much harsher to drive around the street?
McLeod Dual Disk N/A N/A Supposedly much harsher to drive around the street. Extra torque-tube noise due to bearing configuration
Spec Stage II ~$450 ~475 Feels almost stock, clamps well, no chatter. Customer service issues.
Spec Stage II/III Hybrid ~$420 525+? Stage III pressure plate, with Stage II Friction material, to reduce chatter. Customer service issues.
Spec Stage III ~$450 600+ Very stiff, known to chatter. Customer service issues.
RAM 402/6100 N/A N/A N/A
RAM 980 N/A N/A Stronger than 6100, Comparable to a Spec III - known to chatter.
Z06 stock $300 450+ Comes with new flywheel ass'y balanced to it. Clutch ass'y 42.8lbs




3.6.) Who makes aftermarket shifters for C5's? Are there any problems?

There are just a few short shifters out there:
Shifter Cost Description
Hurst $230 The Hurst shifter seems to be the most popular.... It does get some associated vibration or rattle that folks have cured in various ways - some with chopped off tennis balls, others by installing a heavier shift-knob to help absorb the vibration.
B&M Ripper Folks seem to not like this one as much - too much effort.
Breathless (BPP) Shifter $230 Adjustable many different ways for angle/direction. Wedge included to tilt towards driver. Seems as well- liked as the Hurst.
Mallet Shifter $???
Kirban Shifter $???




3.7.) Who makes aftermarket flywheels for C5's? How much weight will I save? Will it hurt my launches?

Aluminum Flywheels on a C5 are a win-win situation, no matter what you're doing. I have had them on several of my vehicles, and never have found downsides. For any car with enough torque to pull the skin off pudding, (i.e. not a Honda) will not have any appreciable detrement from a lighter flywheel.

Some of the fastest drag racers are using Fidanza's flywheel and cutting 1.4 times, so you should have little worry about it hurting your launch. Similarly, all of the national level ASP Corvettes use lightened flywheels for their Solo II cars, and the benefit is there for road racing cars as well.

Be sure to have your flywheel balanced in accordance to your clutch and engine assembly!

Here are some comparison weights, courtesy of DynoTech Engineering:

 ·O.E. iron flywheel weight- 23.3 lbs.
 ·Total O.E. flywheel/clutch assy. rotating weight- 44.8 lbs.

 ·Fidanza aluminum flywheel weight-12.4 lbs.
 ·Total Fidanza w/ SPEC clutch assy. rotating weight- 33.9 lbs.


Below is a table of some aftermarket C5 flywheels, although it is currently woefully incomplete:

Flywheel Cost Material Notes
Fidanza $300+ Aluminum Most commonly used aluminum flywheel.
SPEC $300+ Steel Steel flywheel to go with SPEC clutches - perhaps others too.




3.8.) What brake pads should I use?

Almost everybody has their own opinions on this. I'll just list some common options:
Pad Cost For Notes
Z06 Factory ? Street/AutoX Quiet, grippy, slightly dusty.
Hawk HP+ ? Street/AutoX/light Track Squeaky, but a decent all-around pad.
PFC 01/99 $330/set Track Extremely grippy when warm, great wear. Easy on rotors. Dusty. Worth the price (IMO)



3.9.) What is the clutch drill mod? Why should/shouldn't I do it?
The "drill mod" is drilling out the restrictor that is in the output line of the stock clutch master cylinder. Supposedly it is there from the factory to help reduce 'shock' to clutch components and the rest of the system. Some folks like to get rid of it, to make clutch takeup more positive. If you have no issue with the action/feel of your clutch system, then you can leave it - it's not a big deal.

Some folks say that it helps to improve lazy/stuck clutch pedal syndrome, (FAQ) so that might be a low-buck attempt to solve that problem, if you don't want to pull the car apart to change clutches and slave cylinders.




4.) Body And Exterior

4.1.) Can I install Z06 brake ducts?

Absolutely - I've installed them on my coupe. A set of instructions, with pictures, is listed Here at Corvette Forum. The internal ducting fastens in the same place as on the Z06, and looks 100% factory.


4.2.) Can I install Z06 style cold-air screens?

Absolutely! They are only insert pieces that fit into your foglight openings. On a Z06, they are fastened in place with screws, but most folks install them with velcro or double-sided tape in C5's. I found it easiest to install them well by completely removing the stock blockoffs, and installing the Z06 vents in place. Some images of me doing it on my car are available Here.

The screens are available for around $100 from various places, including Fichtner.


4.3.) How wide wheels and tires can I fit on my car? Can I go wider?

The absolute answer to this depends a bit on your shock and spring selections, as well as how low your car is.

most folks can run with Hoosier 305/30-18 on all four corners, with the car's ride heights set at around 14"/14.5" (measured from top of fender to hub center), and have no rubbing. Brad Neff (subdriver) reports that he runs 315/35-17's, and has minor rubbing on the rear brake ducts of his Z06, but he also runs T1 bars and springs on this T1 racecar, which adds stiffness (and therefore, less rubbing due to compression)

If the ducting is not a concern, or removed, then as large as 335 on 18 can be fit in the rear, although some fender interference may occur if the car is not run high enough to avoid contact.

Lingenfelter and others offer a "mini-tub" kit whereby you cut into the area of your trunk, and gain enough room to comfortably fit a 345 width tire, but the cost is pretty high ($1,500+).


4.4.) My headlights suck! What are my options to fix this?

The stock headlights on a C5 are terrible.

Fortunately, several paths exist to upgrade them.

The first option is brighter bulbs in the stock housings.

Another option is to replace the factory foglights with driving lights. Contact Tuan Le on Corvette Forum for a good deal on PIAA lights that directly replace the factory foglights, and look great, for about $140 or so.

It is also possible to retrofit ture HID headlights to your Corvette.


5.) Interior

5.3.) What aftermarket seats fit in a C5?

The C5 has a notoriously thin tunnel for the seats to fit in, so it takes a relatively narrow seat to fit. Here is a list of seats that fit well, fit with some mods, and are known *not* to fit:
Fit Well Fit tight, or with slight mods Do not fit
  • Caravaggio 'race' seat
  • Sparco EVO
  • Sparco Roadster
  • Sparco Pro-2000
  • Recaro Pro-Racer
  • Most Recaros
  • OMP RS
  • Sparco EVO II
  • Corbeau A4
  • Corbeau Forza
  • Recaro SRD
  • Recaro SP-G




5.4.) Who makes brackets to put seats in a C5?

There are two companies I am aware of. By far the most popular is Hard Bar. their mounts are aluminum, and are fixed (once installed). SpeedWare motorsports makes a base that uses Recaro sliders with Sparco side mounts to provide sliding adjustability to a seat.


5.5.) Can I install a HUD on a non-HUD equipped C5? What if it's before they even offered it?

Absolutely! You do need a few parts though, and they aren't super cheap.
...wiring harness, button difference, etc.


5.6.) My vanity lights don't work (and neither does my underhood light). How do I fix it?

Check fuse #2 in the passenger footwell box, it is probably blown. If your underhood light *does* work, then your visors may have become unplugged at some point, and you'll have to halfway remove them to find the plug and double-check.

6.) Racing your Corvette

6.1.) What do I need to go Autocrossing? What classes will I be in?

The C5 comes already wonderfully equipped to go autocrossing. All you truly need to go and have some fun is an approved helmet, which is usually an "M2000" or the better (but more expensive) Snell "SA2000" rated.

As you get more competitive, other details such as a competition alignment, tires, and many other mods will help you go faster, but other than a helmet, a stock Corvette provides a great base for learning to go fast!

As far as classes, in the SCCA, things look like this:

  • Super Stock - cars that are stock, other than cat-backs, shocks, and a few other small things.
  • A-Street Prepared - Allowed mods are larger than factory wheels, rear swaybar changes, spring changes, flyhweels, intake, intake manifold, headers, misc else
  • Street Modified 2 - cars with heads/cam, coilovers, etc.
  • E-Mod (?) - Forced induction (SC/Turbo) Vettes
  • Open-Street Prepared - optional regional class for SC/Turbo vettes



6.2.) What do I need to go road racing?

Upping the speed ups the risk ante a bit when you decide to go road racing, so a few more things are advisable to make sure that the day ends happily, rather than with a bent up car, or worse, a bent up driver!

The C5 comes already equipped with plenty of power, brakes, and handling to go have fun at the track, its weaknesses are in keeping its various systems cool enough to do their job.

First and foremost is some preparation for the driver: First, get a good helmet. As the saying goes, get a $10 helmet for a $10 head. Me, I bought a nice full-face Simpson helmet. Bell and Bieffe are other good ones.

As well, be sure to bring extra distilled water, Dexcool, and oil for your car, in case you need it during the day. Make sure to top off your oil (maybe even a little high, to help combat oil starvation), and give all your hoses a once-over. Most folks bring a toolkit to the track and even some spare parts, just to be prepared.

For the car, you should absolutely bleed your brakes with good, high quality brake fluid, like Motul or ATE Super Blue (there are others) beforehand. The last thing you want coming up to a 90* corner at 100mph is for the pedal to go to the floor. Believe me.

Those two things are enough to go out and have fun at a low level. However, if you run the car hard or long, the oil and water temperatures will begin to climb beyond the 280* mark, which is bad news. To keep oil temps under control, buy an oil cooler. Similarly, a larger radiator is required to keep water temps down. After doing the research, I finally gave in and bought Doug Rippie's oil cooler/radiator combo.

Now that the radiator will let the car run for longer periods, your next problem will be the brakes again. They don't get much air under the car, despite the factory brake duct "tire sidewall coolers", so you must complete the ducting to the rotor. I went the easy way and bought Doug Rippie's brake ducts, which have worked fantastically. Other folks have made custom ducting using dryer hose and cut up Mobil1 oil cans - whatever works for your DIY desires and budget is up to you.

However, stock brake pads will still not hold up to the temperatures, so you will need to get some pads for the track, that have more heat tolerance. My personal opinion is that having two sets of pads is the nicer way to do things - get some nice quiet, dust-free pads for the street, and some badass grippy pads for the track. I run Z06 pads for street/AutoX, and PFC's on track. Hawk pads are popular as a halfway measure, and there are countless other choices out there that you can research if you so choose.

I went with Performance Friction 01/99 pads from Behler racing, and they have been great. Easy on rotors, great wear, so worth the cost, in my opinion. Make a habit of swapping them before you race, and bleeding the brakes at the same time.

The items above:
  • Good helmet
  • Good brake fluid
  • DRM Radiator
  • DRM Ducts
  • PFC 01/99 pads
have allowed me to run full 20 minute sessions nonstop, running as hard as I can (against a friend of mine in a very fast turbo Eclipse) without any problems whatsoever. Second Creek raceway is notoriously hard on brakes due to the tight course, high altitude, and hot temperatures, so if I can run OK with this setup, then you almost assuredly can too.

As a quick warning, the next problems you'll run into are transmission and rear differential overtemps (which you can only be sure of in a Z06...), and again, more brake ducting via LGM's spindle ducts will even out your rotor and pad wear, and give you more margin for keeping the brakes cool.


6.3.) Who makes harness bars for C5's? What are the concerns?

Many companies make 'harness' bars for C5's. Harness bars run from each seatbelt mounting point to provide a good place to mount racing harnesses.

Harness bars have one sticky safety issue, in that they allow you to use a harness (duh). The downside of this is that they provide no rollover protection, so in a rollover, there are no hoops over your head to keep the roof from crushing inwards, and your head becomes the high point of the car. This is bad anyway, but if you are strapped in with a harness, you do not have the ability to move or get pushed out of the way, and that can be a Very Bad Thing(tm).

For this reason, harness bars are considered fine for autocrossing, but a little bit risky for using without a rollbar when road racing. Yes, Corvettes are hard to flip, but anything can happen, and you only get one shot at this life... Here is a list of manufacturers, which I'll update as I find/research more:

Bar Cost Notes
Brey-Krause $$$! ... down-tubes connect to floor?
Hardbar $280? Very well engineered bar. Available in variety of materials. My choice :-)
many others...    



6.4.) who makes rollbars for C5's? What are the concerns?

There are several vendors that build pre-built cages/bars for Corvettes. As well, there may be a cage builder in your area who can build a very nice cage to your specifications. But, if like some of us, you live in a smaller town without many good fabricators, the commonly available production rollbars are all quite good.

Here is a table with some results from some research I've done on 4-point bars. Considerations change somewhat for 6-points, and for a full competition rollcage, you should have one custom built for your car.

Manufacturer Cost Tubing Top Fits? Feet Mounting Minitub OK? Notes
R-D Racing $535 1.75 x .120 DOM MS Yes Bulkhead Yes Built to SCCA GCR, all angles legal (30* on rear braces). Foot plates shaped to match bulkhead floor. FANTASTIC support and response. Nutsert/Bolt or Weld in
Kirk Racing $??? 2.00x.180 DOM MS No Bulkhead ?? SCCA GCR Legal. Thicker tubing is heavier. Responsive e-mail support.
Autopower Industries $270-$405 (options) 1.750x.120 DOM MS No Bulkhead ? Optional removable X-brace and harness bar. Good support. SCCA GCR Legal.
Doug Rippie MS $545 ? Yes Bulkhead Yes Not much known. Cross brace from driver's head to RR footmount.
Wolfe Racecraft $475 1.750 x .134 DOM MS Yes Floor Yes Bent (unsafe, IMO) or straight rear bars. Feet mount to floor. Good support response. Not SCCA legal with either rear bar configuration, and no X-brace.(can be special ordered running to trunk though)
Wolfe Racecraft $750 1.750 x 0.95 Chromoly Yes Floor Yes Bent (unsafe, IMO) or straight rear bars. Feet mount to floor. Good support response. Chromoly no longer SCCA legal.
LG Motorsports $1,000 1.750 x .120 DOM MS ? Bulkhead ? Not much known. No cross brace, so not SCCA Legal.


There are a few things to think about when buying a rollbar for your vette:
  • What sanctioning body must it be legal for? SCCA? NHRA?
  • What material do you want? (Chromoly is lighter, but not always legal, and more $$)
  • Do you want bulkhead feet mounts or floor mount? (arguments vary)
  • Do you want (or need) to fit a Coupe targa top on its mounting pegs?
  • Do you have need to be able to fit a minitub around your bar



6.5.) What kind of alignment should I have for autocrossing?

What you will actually end up doing is up to you, your driving style, and your car's setup, but here are the guideliness that should get you close:

Camber: -2.5* front, max rear (up to -1.5* if you can get it, most are closer to -1.0 to -1.2)
Caster: Max after camber set Toe: varies - 1/8" toe out front, 1/8" toe-in rear is common.

Note that these are 'race' settings, and will be murderous to tires on the street. I got about 10K out of my Kumho MX's with these settings (including 4 track days), including flipping them on the rims at about 6K to even out the camber wear.

The camber/caster settings above are almost exactly the same as I have been told from nearly every national level autocrosser I have talked to, including John Ames and Gary Thomason. Toe settings depend on driver preference. Some drivers run the car straight up (zero toe), and some run as muhc as 1/2" toe in in the rear to help stabilize it. Certainly you'll develop your own ideas as you learn to drive, and learn your car, but those should be a reasonable starting point.

I'm running 1/16" toe out in front as a tire-wear compromise (the car turns in just fine), and 1/8" toe in in the rear to help keep the car pointed straight ahead on corner exit. But, I'm not much of an expert, so dial your settings as you choose.

When in doubt, run the car with zero toe if you have no preferenc otherwise, your tires will thank you.

If you have trouble getting a lot of camber in the rear, as I did, you might try Hardbar's camber shim product - it got me another 0.3* on my car.


6.6.) what SCCA Classes do C5's run in?

an SCCA rulebook is your best friend for this, or you can try moutons.org, but for a VERY abbreviated list to give you an idea, check out This FAQ.


6.7.) Who makes oil coolers for C5's? Where can I get more info?

Oil coolers are not hard to come by for the C5, as there are a few different solutions. One thing to note is to ask about the outlet directions/locations, to ensure that headers will fit with the oil cooler (if you want to install headers). Some combinations don't end up working for header clearance. If it helps, DRM's adapter and Kooks headers do work with no problems ;-)
Manufacturer Cost Notes
GM ? T1 approved oil cooler. Mounts in front of A/C condensor. rubberized lines.
Doug Rippie Motorsports ? standalone oil cooler, mounts in front of A/C condensor. AN lines.
Doug Rippie Motorsports $1,200 Integrated radiator/oil cooler

Here are some URL's to help you find more information on your own. By no means are they an exhaustive list!

http://forums.corvetteforum.com/zerothread?id=688522




7.) Forced Induction

7.1.) Head/Cam or SuperCharger/Turboss? What are the pros and cons?
Both are good ways to make horsepower, and each side has its pros and cons. There are probably more than I listed below, but this is a decent list to help you consider:

  Pros Cons
Heads/Cam
  • Simplicity - no new parts are added over a factory configuration
  • Reliability - H/C setups are generally more reliable than FI setups (look at what road racers are running!)
  • Drivability - as power levels increase, drivability due to large camshafts decreases
  • Limits to power gains - There are definite ceilings to how much power can be made with a given displacement, without getting horribly radical.
  • Civility - Head/Cam packages result in bumpier cams that may shake the car, valvesprings that make noise, and other general loss of 'refinement', again, depending on how radical you go.
Forced Induction
  • Drivability - FI cars can be indistringuishable from stock cars until the go pedal is nailed
  • Potential - the sky is the limit on horsepower potential with forced induction
  • Torque - FI systems, especially Roots superchargers and turbos, make fantastic torque numbers, which feels *great* on teh street
  • Complexity - Adding components adds failure points in your system
  • Reliability - In addition, worries of belt slippage, breakage, or jumping on S/C systems is a problem. Also, engine failure due to heat/detonation is much more likely than with H/C setups
  • Competition Rulesets - depending on your competition venues, Forced Induction may put you in strange classes (SCCA in particular)
  • Quarter mile times - For whatever reason, at comparable HP levels, FI cars don't seem to put up the quarter mile times that H/C cars do.
  • Weight - Any FI system adds 75-100lbs to the front of the car (about the same as adding an iron block to your car...)



7.2.) Will (Forced Induction) FI affect reliability?
The short answer is "yes".

The real question is "How much?". Even head/cam setups have a higher failure rate than stock cars, mostly due to valvespring problems. Superchargers bring with them belt tension, wear, noise, slippage, and alignment problems. Turbos bring with them immense heat and packaging issues. Either brings increased intake temperatures that increase the likelihood of detonation, which is the biggest cause of engine failure on forced induction engines.

However, the single most important factor of long engine service in a FI motor is to get a good, safe tune. 13:1 on a FI engine is NOT SAFE, they must run richer/cooler to stay in one piece.

When it's all said and done, they can be made as reliable as a good H/C setup, but it takes a lot more time and work to get them there. Because of the added components, you will also have more maintenance to keep track of.

Prevailing opinion seems to be that for the street, FI is fantastic. For drag racing, belt problems are an Achilles heel of superchargers, but if you can keep the belt planted, they are just fine. Turbos are fantastic. For autocrossing, the progressive response of superchargers is nice, whereas the sudden hit of turbos can make the car very difficult to drive. For road racing, it is a similar situation, but it is worth mentioning that most road racers and autocrossers stick to the simplicity and drivability of N/A engines for a reason...


7.3.) What kits are available?
New systems are coming out every day, but here is a short list to help get you up to speed before reading a bit on CorvetteForum's C5 FI list.

System Type HP/TQ Levels
(Mostly stock car)
Cost Notes
ATI Technologies Centrifugal Supercharger 475ish/450ish $5,000 The only ATI system worth getting is from A&A Corvettes - the ATI stock system is quite poor. Andy's setup is great. ATI's have a noticable screech at idle. LOTS of room to grow, 500+ easily attainable. D1SC head unit makes more power as well.
Magnacharger (non IC) Roots Supercharger 400ish/400ish $~4500 (on special commonly)s Great torque, fantastic reliability. More limited top-end. 500rwhp is about the max due to smaller MP119 blower.s
Magnacharger (intercooled) Roots Supercharger 450ish/450 ~$5,400 (on special commonly) IC adds a measure of safety to the non IC'd system, and more hp/torque. Top-end still limited to around 500hp.
Vortech Centrifugal Supercharger 450ish/425 ~$5,500 (on special commonly) Similar to ATI, but uses air/water intercooler. SQ head units make virtually no noise.
Turbo Technology, Inc. Twin turbos 450ish/500tq $7,500 Pricey, and not much of a DIY kit. Note that no headers are required on a turbo car, since they're included! Injectors and tuning also not included, which add additional cost.
Lingenfelter Turbos (various stages) Twin Turbos 500/500 and up $21,000 and up If you can afford these, then you don't have much need to be reading this FAQ, now do you?!
Extremely pricey,but 100% proven, and the Lingenfelter name is worth something on resale.



7.4.) What are the pros and cons of various FI types?
So if you've chosen to build a forced induction car, the next question is to decide what characteristics you're looking for that will give you a car that you're happy with. Each type of FI has slightly different characteristics, and it's up to you to do a bit of homework to decide which you'd like.

  Pros Cons
Centrifugal Supercharger
(Vortech, ATI)
  • Top-End - Centrifugals have great top-end from 3500+ RPM
  • Room-To-Grow - With many head units available, the sky is the limit for HP levels with centrifugals.
  • Cost - Centrifugals HP/Dollar is unbeatable.
  • Low-End Torque - Centrifugals produce boost as the square of the compressor speed, meaning below 3000 RPM, they produce little, if any boost, meaning no extra grin-inducing torque. Note this can be a positive on traction-limited cars like the C5.
  • Reliability - of all the FI types, Centrifugals still have the most trouble with belt alignment, pulley issues, and such. Most are small detail issues, however.
  • Noise (ATI) - ATI's make quite a racket at idle. Again, this can be a positive for those that like it.
  • Trailing throttle heat buildup - at high revs and low throttle angles, the blower is still producing boost that must be vented, and thus heat builds up in the system. This is a con for road racing, where heat management is an issue.
  • Engine Servicability - Particularly with the Vortech, there is now a lot of junk hanging off the front of the motor that can make some maintenance items a much bigger production.
Roots Superchargers (Magnacharger)
  • Low-End Torque - Roots superchargers make power just off idle until around 5,500 RPM or so in the Magnacharger.
  • Simplicity - The Magnacharger simply replaces your intake manifold, and thus has the fewest additional lines, changes and packing issues.
  • Reliability - the Magnacharger has a fantastic reliability record.
  • Hood fitment - The Maggie requires a hood change to fit in a C5, which is a dealbreaker for some.
  • Room to grow - due to its size/CFM capabilities, the Maggie is limited to around 500rwhp at peak output.
  • High cost/hp - the HP/Dollar is much higher with the Magnacharger than with the Centrifugals. This is reflected in the quality/reliability somewhat, but there ya go...
Turbos
  • Powerband - turbos share the great top-end and low-end benefits of both supercharger types. On most systems, they give up a little down low (<2200) and some up high (>6000), but can be sized for any desires you may have for your car. This flexibility is the main argument towards turbochargers. Nothing has the feel of turbos planting you in your seat!
  • Flexibility/Room to grow - as with Centrifugals, the sky is the limit on HP levels with turbos. With large displacement V8's like the LS1, turbo lag is a nonissue.
  • Wow factor - nothing beats a pair of turbos under your hood!
  • Muffling effect - Turbos act as giant mufflers which quiet down your car significantly. (this is a negative to some, but nothing some straight pipes can't solve!)
  • Complexity - Plumbing and all the associated details for two turbos makes for a much more complex system than a simple supercharger install
  • Cost - TT systems are much more expensive than comparable supercharger systems
  • DIY-ability - There are currently no TT systems that are recommended to be installed by your average shadetree wrench-turner, which adds to costs.
  • Drivability - due to the nature of turbos which "spool up" when throttle is applied, the sudden, massive rush of torque can make it hard to keep the car pointed in the right direction - particularly if autox/road racing.



7.5.) Why can I run more boost on a lower compression engine?
I'm sure there is a more detailed (and correct!) explanation than this, but basically it works out to something similar to this:

When the air/fuel mixture goes into your cylinders, it is compressed by the piston. Being compressed causes the mixture to heat up. The more you compress it, the more it heats up as a result, even before a spark is fired. If it gets too hot, it will ignite on its own, which is known as detonation. You'll hear it as a 'marbles in a can' sound coming from your motor under heavy acceleration.

when you lower the compression ratio of your engine, the same amount of air/fuel is compressed less, and less heat is thereby introduced. The cooler charge is less likely to detonate. Therefore, you can raise the boost to increase the amount of air going into the motor, and more power is the result.

To set the record straight, the contention that you can make more power in lower compression engines "because there is a larger combustion chamber volume" is totally false.


7.6.) are 6.0L/LQ9 heads a good idea? what do they lower compression to?
For FI motors, a popular upgrade is to run heads from a GM "LQ9" 6.0L motor. The motor is 6.0L because of the larger 4.0" bore, versus our 3.9" bore. They have a larger combustion chamber than our stock LS1/LS6 heads, and just drop the CR to around 9.4, I believe.

Some folks dislike the use of the LQ9 head because the larger combustion chamber diamter (4") on a stock bore makes for an odd 'ridge'. In practice, it seems to work quite well for a lot of people.

Note that some 6.0L engine heads are made of iron, and aren't ones you'd want to use on a C5. I believe these might be "LQ4" heads, but I am not sure - do your homework before buying a set of 6.0 heads to put on your FI engine.


7.7.) What do Superchargers sound like?
It depends on the type. Centrifugals give off a high-pitched whistle at idle. Vortechs are a lot quieter than ATI's, especially the SQ series. At wide-open throttle, they take on a whooshing/jet sound, just like turbos.

Roots blowers make hardly any noise at all at idle. Under full throttle, they give a high pitched 'eeeeeee' whine, that can trip sound meters at over 100dB!

For a directory listing with all the clips I've found of supercharger/turbo sounds try This link.


7.8.) What is "Pinning the crank" for a Supercharger?
The stock crank pulley is held in place on the crank with nothing more than a LOT of torque and friction of its fitment.

When you add the power of a supercharger, and the resultant pulls on the crank pulley, the forces can add up to be enough to cause the crank pulley to spin on the crank itself, which is a Bad Thing(tm).

Pinning the crank means drilling through the pulley, into the crank, and adding a small metal "pin" that goes through both, so that they will always spin together. This makes sure that the crank pulley will not spin on the crank.

See this image..


7.9.) How can I decide between the ATI and Vortech units?
Both are centrifugal type superchargers, and both make comparable horsepower numbers for a roughly comparable cost.

The primary differences among the systems are:
  • Oil supply
  • Intercooling setup
  • Head unit noise

Oil Supply - Vortech superchargers take their oil from the engine's oil supply. The kit includes an adapter to get oil from the filter housing, and you must drill a hole in the oil pan to act as a return line. By contrast, the ATI uses its own oil supply, which must be changed separately from engine oil.

Intercooling setup - Vortech superchargers use an Air/Water setup they call an "aftercooler." The aftercooler is placed on the front of the engine, and uses a small bilge pump to move water, and a heat exchanger that sits in front of the A/C condensor to cool the water. The ATI uses air/air intercoolers. In the 'stock' ATI system, it uses a pair of twin intercoolers mounted in the brake duct area. Andy's A&A system uses a large FMIC mounted in front of the A/C condensor.

Head-Unit-Noise - The Vortech SQ units are virtually silent. ATI head units emit a rather loud squeal/screech that some folks like. It sounds similar to a seizing pulley (and is often mistaken for that). Whether or not you want that sound will decide which system you wish to go with.


7.10.) What is an 8-rib setup, and why do I need one?
...




8.) Electronics, PCM, and tuning

8.1.) How do I check the codes on my car? What do they mean?

Sometimes in the course of driving, your car will notice problems with itself, and store a flag in it's computer. This is known as "throwing a code". You can extract these codes from your computer using the DIC (text at the bottom of your gauge pod), with a few keystrokes.

For details on how to do this, and what they mean click Here. There are several other lists out there on the web, this is just the first one that came up on Google. If you arm yourself with these codes, it will be much easier for your CorvetteForum brethren to help you out when you ask questions about what might be going on.


9.) Common Problems And Fixes

9.1.) I keep getting the message "Active Handling Warming up" - what does it mean? Is anything wrong?

The Active Handling Warming Up message comes on under 2 'normal' conditions. Usually, it will be because it is cold out and the IAT is reading below 15F.

Another reason you might see this message is because you had your wheels turned when you started driving. The steering position sensor needs to calibrate itself by going straight for a brief period of time during the first 30 seconds of driving. Autocrossers commonly see this when they start their engines at the line and the course immediately goes into a turn.

If neither of these are true, then check the IAT connection. A loose wire will give a false reading and cause the message. If these don't fix it, then check the codes. It may be a bad sensor or other loose wiring."




9.2.) My seat rocks back and forth. How can I fix it?






9.3.) My Fuel gauge doesn't work right - how can I fix it?






9.4.) My battery seems to be leaking? Can this cause any problems? What is the fix?






9.5.) Something is leaking oil from the rear of my car - what is it?






9.6.) I'm getting a vibration and/or squeal from my car, what could it be?

There are a few common causes, but I'll list the first two here, and add more as I see them on the forums:

The first, and simplest, is a tire that's out of balance. You'll notice the sound change with speed, or it may have a harmonic period to it. The solution to that is simply to have your tires balanced, or replaced, if it's getting to that time.

The second possibility is a wheel bearing going bad. They are more of an issue on Corvettes than on other cars, for one reason or another. A bad bearing might manifest itself as a vibration or sound that goes away when making a turn in one direction, and gets worse when you turn the other direction. It may be a grumbling or a squealing as well. If you need to replace the bearings, dont' worry, it's not a bad job. Links to instructions that a fellow sent me a while back can be found in the Misc section of the website.


9.7.) I am having a lot of belt squeal noise - how can I fix it?

First, there is a TSB (Service Bulletin) out on Corvettes for an idler pulley that can cause a squeal if improperly tightened down. The part is very cheap, and is replacable in about 10 minutes with only two wrenches.

Second, your belts could simply be getting old. Try buying new GM replacements. Folks from CorvetteForum seem to favor the Gatorback belts as well, so you can try those. Some folks have been able to quiet squeaky belts by rubbing soap on them.

Your tensioner may be getting old and giving up the ghost, so replacing that may solve your problem.

For Automatic cars, another TSB exists for a 'grumble' sound, that is related to a clutch on the altnernator, or something like that. Check and see if it has been performed, as that may be the problem.

If you have tried the above, you can remove the belts from your car completely, and drive it for a few blocks. If the squeal persists, then the sound you're hearing is not belt related. There have been some reported cases of the PCV system causing sounds that can sound much like belt slippage. In my case, playing with the PCV system solved a problem that I had thought was caused by the belts. (thanks rwj383!)


9.8.) What is the intermittent "Service ABS" and "Service Traction Control" light mean?

This has a number of causes, which you will have to investigate, or have the dealer do. This is not a complete list either, since new causes have come up and gone in the past that I can't seem to re-find. The basic reason is that the ABS computer can't read the wheel-speed sensors properly, which disables the ABS, which in turn disables the traction control/active handling. (if equipped).
  • Bad connection between various ABS sensor wiring harnesses
  • Failing ABS Wheel speed sensor (requires replacing wheel bearing)
  • Bad connection for ABS fuse in fusebox
  • Malfunctioning ABS computer ("EBTCM")
  • Malfunctioning Body control module ("BCM") - under passenger footwell
  • Failing/Misaligned/Problematic steering sensor (Active Handling cars only)
  • Evil spirits (apparently the cause of mine :-( )



9.9.) My passenger window quit working. Why?

It is relatively common for the passenger side motor to die. The only fix is to replace the motor. The Part Number may vary by year, so consult your local parts fellow for the part number.

Replacement is easy to do with simple hand tools and the factory manuals in your garage at home.


9.10.) My reverse lights stopped working. Why?

It is relatively common for the reverse switch on the transmission to die. The only fix is to replace the switch, which lives on your transmission, under the rear of the car.

The Part Number may vary by year, so consult your local parts fellow for the part number.

Replacement is easy to do with simple hand tools and the factory manuals in your garage at home.


9.11.) My steering wheel won't unlock, and the car dies when I try to move it. Help! (Also a code 1286?)

This is the infamous Column Lock problem that has plagued C5's. Not all of them get it.

There is now a recall out by GM to fix this problem, so if you have not received a notice, call your local dealer to have the service performed.

If your car throws a 1286 code, then the column lock mechanism is not working, which can actually be a good thing if it stays unlocked, but you'll want to have it corrected to have the code removed from your computer, and ensure that it doesn't get stuck in the locked position.

This is known to have locked up and stranded folks, but there are no confirmed cases of the column locking with the vehicle in motion, so your safety is not at risk driving the car.

An aftermarket product is available to remove the column lock mechanism altogether. The CLB-Column Lock Bypass is an aftermarket product, costing between $50-$100, that when installed will disable the column locking mechanism, while allowing the car's computer to believe that everything is working normally. It is faily simple to install. Installation instructions are at this link on jmX's excellent LS1HowTo site.


9.12.) My headlight motor is stuck up/down/etc.

The motors which control the raising/lowering of your headlights have a plastic gear in them which can strip out if something blocks it, or simply by many raisings/lowerings over time.

A nice writeup on replacement of the relevant parts has been done Here on Corvette Forum by pewter99.


9.13.) Sometimes after driving my car hard, the clutch pedal sticks to the floor.

The sticky clutch pedal problem is due to a design flaw in the slave cylinder of your clutch system. The slave cylinder is what pushes on the fingers of the clutch to make it release. In the flawed part, when the clutch gets hot, the heat is transferred to the slave cylinder, causing the piston inside the slave to expand, and it binds in its bore, causing the clutch pedal not to be able to come back up.

Depending on the severity of the problem (I have had it happen once), the solution is to have the slave cylinder replaced, preferably at the same time as a new clutch and flywheel.


9.14) There is a whining noise coming from behind me in my '97-98 car. What is it?
On '97 and early '98 C5's, the fuel pump was particularly noisy, so this is probably what the sound is. You may notice that it gets worse when the car is cold, hot from a long drive, or when the tank is getting low on fuel. As well, you'll probably hear the whine alternate in pitch when your turn signal is on, as voltage to the pump changes slightly.

In mid '98 (I believe) the pump was redesigned to be a bit quieter, although they still do make some noise.

The noise is not necessarily an indication of malfunction, although you can have it replaced if you wish. However, it is not a cheap replacement, so you might consider upgrading to a Racetronix pump (or similar) instead, to support any future modification plans you may have.


10.) Audio

10.1.) Can I hook up an aftermarket CD Changer to my stock head unit?

Yes!

There is an adapter that exists, made by a company called "PIE", that is called the GM10-AUX adapter. It plugs in to the factory CD Changer cable, or if you do not have that, you can buy the cable "COR-HAR" from PIE. The GM10-AUX adapter provides RCA Pins that an aftermarket CD Changer can interface to. I found Logjam Electronics a good place to deal with for my parts.

A further helpful quote from one of the CF Threads below: "The PIE GM-AUX10 adapter that gives you RCA L/R inputs has the same connectors as the factory CD changer. It WILL NOT plug into the footwell harness as the connectors are different there than what they are at the CD changer end. Granted, one could trace out the electrical connection paths of the second harness and try to wire the PIE GM-AUX10 adapter directly into the footwell harness; but it would be a lot of work. Seems to be much easier to just buy the rear changer harness and coil it up somewhere up front (or run it to the center console as the above poster mentioned)."

"If one wishes for L/R audio inputs on their Bose headunit - then there is no way to avoid buying the PIE GM-AUX10 adapter and the rear CD changer harness"

The PIE X3-GM9 adapter will not work in the vette.

Here are a few useful URL's:



10.2.) Can I use my stock Bose speakers with an aftermarket head unit?

Yes!

It is, however, a little tricky due to the oddball nature of the Bose speakers, and the way GM wires them from the factory. The 8" subs in your doors are separately amplified, and aftermarket units aren't expecting this goofy configuration when you install them, so they will not work unless you take special considerations.

While one option is expensive and time-consuming re-wiring of the Bose speakers, the cheaper option for non audio-phile such as myself (who simply want the functionality!) is to find the right adapter to make them work off of your new head unit.

Thanks to the help of the guys on Corvette Forum, I found the GMCRV1 adapter harness by SoundGate, which I got at Log Jam. This allows you to install any aftermarket head unit and get your Bose speakers to function as well as they did with your stock receiver.


X.) Miscellaneous

X.1) What are the various Model Year differences?
Why, I'm glad you asked, and I've put most of it here.


X.2) How well do high mileage vettes hold up?
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