C4 modifications?
Please advise....chip...exhaust...mod? what?
Thanks
I have topped my c4 out 2 times and it has stopped on 155 is this because of a GM computer setting?
Because the engine won't pull the car any faster
What revs / gear were you in?

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Do you want to go faster? Quicker? Handle better? Louder?
I've not heard of a governer on the Corvette's and I believe the LT1 cars were once tested by one of the car mags with a top of around 162 or such. Read it along time ago, so...
But there is no one magic trick for noticeable gains. It is when a variety of mods are done that compliment eachother, that the real seat of the pants results are found. Like cam+rockers/heads+exhaust. Each one, alone may give a little more, but it's when these things are planned out to work in concert, that the goal is achieved.
So, what you are really asking, is "where do I start?"
A bad optispark will cause the engine to bog down under load in high gear. (Uphills, with the wind resistance of a top speed run, etc.)
When mine was bad I would hit say.... 115 MPH and then it would feel like you just hit a brick wall. It would not go any faster.
Last edited by dizwiz24; Dec 1, 2012 at 09:42 AM.
Please advise....chip...exhaust...mod? what?
Thanks
I have topped my c4 out 2 times and it has stopped on 155 is this because of a GM computer setting?
there is no 'single mod' that is going to provide you a noticeable improvement.
I would say heads/ cam / tune / long tube headers...is what you want to do. I did these all at once (made 353 rwhp/ 355 rwtq) and felt a difference in top end pull.
IMHO... dont waste money on the exhaust. its already a free-flowing setup.
As far as a top speed, 155 is not that bad depending on the trans and diff gear ratio. And I assume you are talking about hitting these speeds on a closed course
Talking about driving at high speeds on the street may wind up having a Mod locking your threads. 
So what is the car configuration? Auto trans coupe? Manual trans car? A manual trans C4 will make its top speed in 5th gear, not in 6th. For either trans, you can expect a top speed in the 155-160 range as that was the speeds that various car mags came up with when the tested the later C4's when they were new.
As far as a top speed, 155 is not that bad depending on the trans and diff gear ratio. And I assume you are talking about hitting these speeds on a closed course
Talking about driving at high speeds on the street may wind up having a Mod locking your threads. 
So what is the car configuration? Auto trans coupe? Manual trans car? A manual trans C4 will make its top speed in 5th gear, not in 6th. For either trans, you can expect a top speed in the 155-160 range as that was the speeds that various car mags came up with when the tested the later C4's when they were new.
The 1992 c4 lt1 6spd ran 172 MPH in perfect conditions (no winds, flat desert road, low altitude) conditions. Averaged out 2 ways to cancel any minor effect of wind or grade. No, this is not the zr-1, but the lt-1 that ran that speed.
Though I will agree on certain conditions (headwind, grade of the road, altitude, etc.) could make 155 the top speed
Last edited by dizwiz24; Dec 1, 2012 at 10:36 AM.
Do you have a garage, tools, knowledge, service manuals, know-how to turn a wrench on this car?
If the answer is 'no', then torch's advice is pretty good.
Now, if the answer is 'yes'... then prepare to spend lots of money and invest lots of time (more time/money than you would to soup up a c5/6) to make the c4 run. Also plan on lots of downtime (time not driving the car). C4 mod's take time, patience. Not plug-n-play solutions. Rather 'find this guy and get him to weld/mod this part', 'find another guy who knows how to do this'.
Im just in it to prove a point. I will spend lots of money to do so. In the end, will probably be a slightly slower car than a similarly mod'd c5/6 that someone spent less money (than me) to mod and more time enjoying their car by driving it.
However, I like the c4 just that much more than the c5/6. Or maybe its the owners.
C5/6 guys Ive met seem to snicker and look down at me (as a c4 guy). I dont get on off-topic anymore as I got tired of people (who disagreed with a non-car viewpoint of mine) would look into my profile and bring up the fact that I have a c4. Its irrelevant. Those people SUCK.
Its reasons like this that I continue to mod the c4.





Just kidding, guys!
I have had three (3) C4s. All new. I only sold the previous one to buy the next one.
In January '96, there was as much or more secrecy concerning the all new C5. I thought I would buy a 96 CE and wait to see if I liked the C5 enough to move up in a year or two.
Still waiting..............
I did like the C6 a little more.
BUT, there is NOTHING to compare sitting in the "Fighter Cockpit" of a C4!
Ordered my CE w/LT4 in March '96. I picked up my Vette up in April '96. I did my first mod in June. Oh well, I guess I do not qualify for NCRS!
There are so many tricks and mods that can be done to ANY C4. Some do more than others as far as HP and/for torque. There is also the question of customizing the interior/exterior.
The list goes on and on..........
Did I mention I really LOVE C4s?














