I got my 97 Corvette tuned at Vengeance a couple of weeks ago. I have an LS2 402 built by AMS Racing in Louisianna. The cam is a T-rex. The heads are 59cc Patriot ls6 stage 3s. I have a ported FAST 90/90, ASP pulley, Breathless 1 7/8 longtubes with no cats, and a spec 3 clutch w/ an aluminum fidanza flywheel. The car is an M6 with 4.10 gears. I also have 42 lb. injectors and a racetronix fuel kit. My compression is 11.5:1. I put down 476rwhp and 469 rwtq. I was somewhat disappointed. Are these #'s that low? I would love to get to the 500 mark. Ron told me that with AFRs or TFSs I would be much higher with that compression ratio. Should I go with 205s, 215s, or 225s? My car also idles like ****. Mike and Ron said they worked on it for hours, but since it was a 97, that was the best that could be done. The car won't idle down to 1000 rpms. It wants to idle at 2000 rpms most of the time. I can press the clutch while cruising and the rpms will just stay the same. Is there anything that can be done? Are the 97 ECMs that bad?

 

A better can selection may of helped also.
I don't know if I would spend the $ to get another 25 or so HP for the better heads.

 

find a better tuner perhaps....

 

sounds like a tuning issue bigtime!

 

my car does the same thing... because its not tuned

 

I've got a 98 C5 403 L92/L76 build that makes 501RWHP with heavy wheels, all belts, 3.90's, stock WP, etc. It idles at 850rpm and drives like stock. I don't think there is any difference in the PCM's on those years. I run an open loop/MAF tune. Tuned by Ed Hutchings in Chesapeake, VA.

My $.02

 

There are cams out there that are bigger but run better. T-rex's would not be my 1st choice, also with the head selection I wouldnt put a patriot head on my car even it was given away free and was offered free install. A nice set of ETP's would make a huge diff and with the limitations on the 97/98 pcms, they wont tune as well as a 01-02 cars.

I am currently working with a car that has a Eastside Perf. 402, a decent but not rediculious hyd cam, 13 to 1 comp (he runs race gas), on a th400 w/ 5500 stall, and moser 12 bolt putting down 470's rwhp last time I recall, if a 6 speed was still in the car it be easily making over 500 to the tire.

Long story short it seems to be a mixed bag of H/C selection, Comp ratio and tuning (97/98 PCM's, not the tuner). I bet if you ponied up for some BS3, it would respond very well alone

 

Thanks for the help everyone. Some guys have told me that I should go with speed density tuning and the car would drive like stock. That I would lose a few HP but I would be able to drive the car around town and not have to worry about the thing cutting off on me at red lights. Wouldn't I lose a few top end horses with a speed density tune? I have heard great things about the tuning at Vengeance Racing. Why would my tune be any different?

 

The guys at Vengeance have made around 550 RWHP with 402's many times with the TFS 225 heads, so I would think you have more than 25 HP to gain with a good set of heads. A speed density tune may be in order also.

 

That would be me!
So, I'll spew my .02.
Budget heads make budget HP. Period. I know somebody on here is gonna post up that they made a gazillion HP with some patriots or something, but for the most part the CNCed GM heads make budget numbers.
Pony up for some ETPs, AFRs, or TFSs.
As for the idle problem, theres ways to tune even the 97/98s to act right. They by no means are "untuneable". If thats even a word.

 

I'm with him.....we both use the same tuner and have had 0 issues.

 

The T-Rex was designed for stock heads and stock cubes. The heads you have are OK, but there are so many other better heads on the market these days. I still feel 500 is possible with those heads. Just don't expect to be at 525+ with them. Do some research and find a cam more specifit to your set-up.

 

It sounds like your car is a mishmash of mods that weren't really pieced together too well. All I've heard about Patriot heads is to avoid like the plague if you are looking for a higher performance car and high performance numbers. A TRex is a beefy cam, but it should make the car lopey, not run like poo. See if you can sell your Patriots and pick up some TFS heads (or AFRs or ETPs) so it's not a total loser deal. Talk to your tuner and see what he suggests as far as heads go, and maybe consider swapping out to a '99 ECM.

Good luck!

 

VERY educated response.

 

The T-rex cam was chosen to be used with a stock shortblock but the block had an issue. So I figured I would try the cam in a 402. What cam would anyone recommend for this setup? I know I need better heads. Patriot Heads are terrible. If I could go back, trust me, I would.

 

I would have to agree that your set-up will never give you the numbers or running ability that you want. It is not the tuner/tune. With all the cars that come out of Vengeance running perfectly and putting out good #'s, it would be safe to put the blame elsewhere. That cam is not designed for a 402, and the heads are a poor quality. Computers are also cheap, why not buy one that has more parameters which allow proper tuning. Listen to Mike and Ron, they will NEVER steer you wrong.

Just give them a call. They will help you with what you want.

 

I agree with most people here, mismatched parts ect. I'm guessing the parts made it hard to tune.97 Vette's are hard but not impossible.

 

Don’t believe all the hype. Better heads will net you better results, Is the money worth it? Only you can decide that for yourself. I don’t see you swapping heads and coming up 75 hp better. I just don’t see it, unless you change a few other things and go with their whole package. Cam, rockers, heads you name it, you are in for a whole new package to get 75hp more than what you have now. That I can guarantee. Will who's ever head you buy guaranty you net 75 with just heads as suggested previous in the thread? money back guaranty?? I don’t think so... take it from someone with experience in this matter. Throwing down 3k for another 20-35hp? If you budget is ok then I say go for it and then you’ll never have any questions about it. You’ll have piece of mind that you’ve spent top dollar and are getting the best your money can do for you. But it isn’t going to be 75 hp from just 225 TFS heads. Vengeance has had great results with their package, but it doesn’t include a t-rex cam. It’s their cam and their formula for results. You’ll have to go for the whole package not just pieces of it to get similar results.

 

I don't see where anyone said he'd get 75 HP from heads-- I said sell the Patriots, use that money towards the new heads, so it won't cost him 3K. I think it comes down to how well he'd like the car to run, and how strong he'd like it to be. He'd probably help that ported FAST out with some great flowing heads!

 

A certain comment points towards it. You didnt make the comment. I wanted to set the record straight that just because Vengeance gets 550 using TFS 225's that this guy wont see that by simply switching heads.