Over the winter I decided to make the jump away from the C4 track car. It served me well, but it was time to move on. I have compiled a list about 50 pages long of positives and negatives about the car but here were some of the most valuable and or interesting lessons learned:

1. The LT4 is capable of RELIABLY making 500hp. The engine was a 383 LT4 with an Eagle rotating assy, stock heads (with some basic work done), a Quick Fuel R/R carb, crank trigger MSD ignition system with Digital 7 box and Pro Power II coil, Meziere electric water pump, and some other goodies. It showed right around 500hp on the dyno with a conservative tune. It got pushed harder than about 99.999% of the Corvettes in the World, saw a LOT of RPM and simply put, it just didn't quit.



2. C4 Corvette brakes... well... suck. If you are going to be hurling yourself down a track at ludicrous speed it is a good idea to be able to stop at the end of a long straight. Doing this even with J55 calipers with stainless pistons and lines as well as the best pads and rotors out there has a pucker factor that is off the charts. Do yourself a favor, spend a little $$ and go at LEAST with a Wilwood SL6 setup. It's relatively cheap, easy to maintain, and actually stops the car consistently. While we're on it... be sure to add some brake cooling.



3. The C4 suspension was great... for its time. When compared to other cars of the era, the C4 handles like a champ. On paper, with the big skid pad numbers, it looks like it compares to the modern cars very favorably. Unfortunately, the real World has a few more factors. The C4 suspension geometry doesn't compare favorably to the later generation Vettes. Everything from turn-in to stability to power down on exit is lacking in comparison. Don't get me wrong, you can get up on the wheel and make a C4 run right with the C5/C6 but what it takes white knuckles and a very finely calibrated *** to do in the C4 is done with ease in the later cars. It becomes VERY evident through high speed corners or in corners that aren't entirely smooth. The massive low end torque of the 383 kept me in line with the C5/C6 in terms of total lap times but even with big 315s all around they just walked away in corners and under braking. I will add that the braking loss was due to the overall stability of the car itself under the heavy front load, not the actual brakes. A big camber brace makes a HUGE amount of difference in the front end, especially under braking.

4. The factory cooling systems on the C4 are not adequate to withstand abuse. If you want to keep it reliable, you need no less than a power steering cooler as well as an external oil cooler. Ideally, I would have a diff cooler as well if you are running above stock power with big sticky tires. The water system itself is pretty decent. Even with the big 383 that put off a massive amount of heat, the stock system kept everything in check using distilled water AND WATER WETTER. The weak link in the system is the pump itself. The LTX driveshaft design does not seem to like sustained 6,500+ RPM. At that speed, even a slight cavitation makes the internals turn to shrapnel. With the Mezziere electric pump, all was well. If you do go with a mechanical make 100% sure that you are using a GMPP pump. The auto store pumps are not even remotely close to the same. They have less bearing packs, the internals are cheap stamped crap, and the shaft itself is some low grade steel.

5. The C4 is a very fun car to drive If your goal is to go feel like superman on a track, the C4 is a great car. It gives great feedback, is somewhat predictable, and responds well to pretty much all driver input. The most interesting part of the "feel" of the C4 is how well it responds to throttle input through corners. With even small inputs you can do everything from setting the nose on entry to making it rotate through the center. On the flip side of the response to inputs is the fact that if you get it wrong, it can go bad in a big hurry. It will reward you for doing it right, but is VERY unforgiving if you screw it up. If you are reactionary rather than proactive with your inputs, it is going to be a long day.

As I said at the beginning, as with any car, there is a near infinite list of things to be said but these were the first few that came to mind.

Most importantly, if you want to take a C4 to the track, you better have at least a decent amount of mechanical knowledge because something WILL break. Another in general comment is that if you plan on doing HPDE, build it how you want and go for it. Focus on reliability first and speed second. If you want to compete, build to a specific class. The biggest issue with this car is that it was impossible to class. With the modifications, it was put up against cars that it had absolutely no chance against. It was fun to drive, but in the end, I want to be competative.

Some HPDE fun:

 

A preview of what's to come...

 

Thanks!, for the write up. Also, nice video. I'm jealous. Can't wait to see your next ride in action. Now I really can't wait to drive my vette on the track. My ride's currently in the garage for too many mods and repairs.

 

Thanks for the honest write up. Did you sell it?

 

There aren't many surprises here with this write up. These cars that we own are old with old technology, even with upgraded parts, expecting them to keep up with(or be faster than in your case) modern technology is unrealistic, imagine how hard it would have been in a C1-C3. I always liked your C4, good luck with the new to you C5, but I'm sure in time you will find yourself once again looking for a change to keep up with the big boys, it's just a natural progression.

 

Nice writeup. Forget the C5. Go to a C6Z!

 

Cool thread Bryan.

 

 

You've got mad skills!!!!!!!!!

 

I've had the 02Z for quite a while. It was my daily driver for years.

I though about getting a C6Z but when it came down to it, there wasn't much to be gained considering the price swing. The only thing not easily overcome is the aluminum frame vs. the steel. The geometry is the same, the brakes aren't going to be stock either way so that's no big deal, you can easily make power out of the LS6, etc. My goal in building this car is reliability first, consistency second, and speed last. The C4 had speed but lacked severely on the other 2. With those goals in mind, the C5Z is every bit as (if not more) capable than the C6Z. Time has proven the LS6 to be about as bulletproof as it gets on a track. The LS7 doesn't seem to fare quite as well.

The C6Z might be faster in stock form simply because of the power but when it comes right down to it, the C5Z is every bit as good a track car, if not better. It also is a WAY easier car to class for competition.


The C5 will have some tricks thrown up it's sleeve...

 

Still was a damn fine looking C4

 

100% My all time favorite track car.

 

If you weren't busy pulling cars off of trash heaps it could be yours.


I will certainly miss the "wow" factor of the C4. It was a safe bet that there wasn't going to be another like it at a track and I do have to admit that there was a certain amount of satisfaction in being able to pass C5s and C6s.

 

Nothing really surprising here, especially suspension. Even stock I can feel the wheels trying to break loose during mundane cornering when the road isn't perfectly smooth. I wonder if coil-overs would help alleviate that issue. Very interesting read, thanks for sharing!

What's going to happen to that C4?

 

WHOA, those are some serious wheel studs.

Here's to many years of reliable track time with the C5Z

 

It's actually back in the hands of the people who owned it before me and will no doubt continue to terrorize the Eastern US.



SKF racing hubs (and ARP studs) are no joke.

Compared to stock:

 

It was all VetteBrakes suspension with Bilstein custom valved shocks, stiffer springs, etc. Pretty much everything possible had been changed/upgraded short of actually going to a coilover setup.

Not sure how much difference I could have made going that route but was always curious. The only reason I didn't was the simple fact that I didn't want to dump any more $$ in it knowing that it was pretty much stuck being a HPDE car because of the difficulty of getting it comfortably in a specific class.

 

Before you create a track car out of your C5 (if you didn't already), have you considered something like Formula Fords? Trust me when I say that the handling capability is miles beyond any street based platform (and I mean ANY street platform - exotics included). You will never lack for competition and if you set the car up right you can be very competitive.

 

The C5 is going to be an intermediate step. I'm not dumping a bunch of money into it. I have a friend who does the cages for a few World Challenge and American Iron cars doing some work as a favor and with the exception of hubs and seats, every part on it from the brakes to the sways and coils has been bought used at a serious discount. Everything in the driveline is staying 100% stock. I'm really using this as a challenge to myself and as a learning tool to see what I can do from the finesse and handling side rather than the brute force perspective that the C4 had. I'm putting this car together so that pretty much everything other than the rollbar can be easilly undone. It is going to be used for TT, HPDE, and Auto-X so it isn't even going to be getting a full cage.

My eventual plan is to go to a specific race platform instead of starting with something made for the street. I'm still learning these things and doing it on a thin dime and even less time it makes it a difficult jump into a full W2W situation. I am going to be limited on events as is and the schedule shrinks even farther if you take away those that don't allow open wheel.

I'm seriously considering going into something like a Radical when I finally do make the jump out of TT and into W2W. The Formula Fords are most definitely on the list as well. I think the deciding factor is going to be looking around to see what gives me the most schedule flexibility and opportunities to get on track. So far I have stuck to my long term plan pretty well. Right now, I'm planning on the C5 being about a 3 year run to get as much seat time and as much setup and tuning time as possible as well as getting myself where I need to be with licenses. From there... W2W.

 

Thanks for the insights

Did you have any big offs? Any caught on camera? I learned a lot about cars I was in on trackdays by going beyond their limits

It does seem to make sense to go straight to a C5Z for trackdays rather than dump $$ into my C4. Would love some nice Wilwoods tho