need help w/ heads and cam issue...
Thread Starter
Staging Lane
Joined: Aug 2002
Posts: 96
Likes: 0
From: centreville, va
need help w/ heads and cam issue... here's the details:
car: '02 ws6 t/a, 6 speed
mods: thunder racing stage II heads w/ dual coil springs, tr224 w/ 114 lsa cam. FLP longtubes, corsa cat-back, lid w/ k&n filter, GM 4:10 gears, ported/ polished t-body.
problem: car won't make any power above 6,100 rpm on the dyno, and is low on the numbers as well (393 rwhp, 367 tq.)
i was told by the folks at thunder that that cam and head package should make power up to at least 6500 or 6600 rpm. so of course they say something is wrong. i've tried orp's and that only gave me a 5 rwhp increase. my a/f ratio is perfect (13.1), timing is good, no knock retard, runs great 'till it hits 6100 rpm and the power curve just starts to "rollover" and go back down. it's gradual "rollover" not a massive drop off. basically, short of tearing the car back apart, we can't find anything wrong w/ the car! it runs great, normal drivebility is awsome. it even blew like a new untouched on our emissions machine! that part has me scratching my head. shouldn't it barley pass w/ that cam? anyway any ideas would be great...
car: '02 ws6 t/a, 6 speed
mods: thunder racing stage II heads w/ dual coil springs, tr224 w/ 114 lsa cam. FLP longtubes, corsa cat-back, lid w/ k&n filter, GM 4:10 gears, ported/ polished t-body.
problem: car won't make any power above 6,100 rpm on the dyno, and is low on the numbers as well (393 rwhp, 367 tq.)
i was told by the folks at thunder that that cam and head package should make power up to at least 6500 or 6600 rpm. so of course they say something is wrong. i've tried orp's and that only gave me a 5 rwhp increase. my a/f ratio is perfect (13.1), timing is good, no knock retard, runs great 'till it hits 6100 rpm and the power curve just starts to "rollover" and go back down. it's gradual "rollover" not a massive drop off. basically, short of tearing the car back apart, we can't find anything wrong w/ the car! it runs great, normal drivebility is awsome. it even blew like a new untouched on our emissions machine! that part has me scratching my head. shouldn't it barley pass w/ that cam? anyway any ideas would be great...
11 Second Club
Joined: Aug 2003
Posts: 1,541
Likes: 1
From: Boring Green, Kentucky
Re: need help w/ heads and cam issue... Your HP doesn't sound too far off. But I would be concerned over the drop @6100. You have long tubes, so your not choking....hmmm. Rev limiter has been bumped.
All I can say is get a serious tune and analysis. Good luck, keep us posted.
All I can say is get a serious tune and analysis. Good luck, keep us posted.
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Re: need help w/ heads and cam issue... Was the cam checked on a cam doctor before it went it? The results sound more like a TR-220. How much advance? If it's installed at 4 degrees advance, it will probably peak lower than if installed at 2, or straight up.
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Re: need help w/ heads and cam issue... well I got alot more in mods them him and my tr230 is falling on its face at 6kish as well. I was told valve float because of the rev duals and I switched to the new crane doubles. I even put on a whole new valve train. guess waht same results.I have really good flowing heads as well and I still make nothing. I mean 40-50 less then others have posted and it runs out of steam at 6k
Thread Starter
Staging Lane
Joined: Aug 2002
Posts: 96
Likes: 0
From: centreville, va
Re: need help w/ heads and cam issue... the pcm was "mail order" tuned by the guys at thunder. timing bumped to 28 or 29 degrees, rev limiter bumped to 6800 rpm, reset fuel enrichment tables. no a/f ratio was done at this time. when i took the car to get tuned by a local guy who has a dyno and ls1 edit, we found that nothing needed to be adjusted. the A/F ratio was right on the money. teh car ran great on the dyno, so valve float wasn't an issue, plus it didn't drop off rapidly like if it were floating valves. it was a gradual "rollover" at 6100 rpm.
i installed the cam "straight up" dot to dot. i'm a mechanic at a pontiac dealer, so i like to think i know what i'm doing, lol. the horsepower isn't THAT far off the mark, it's the torque numbers (367) and the fact that it quits making power at 6100.
i installed the cam "straight up" dot to dot. i'm a mechanic at a pontiac dealer, so i like to think i know what i'm doing, lol. the horsepower isn't THAT far off the mark, it's the torque numbers (367) and the fact that it quits making power at 6100.
Thread Starter
Staging Lane
Joined: Aug 2002
Posts: 96
Likes: 0
From: centreville, va
Re: need help w/ heads and cam issue... the cam was supposedly checked on a cam doctor before shipping, they sent me the little sheet w/ the numbers. i'm curious about the other guy that is having the same issue as me, what did thunder tell you?
Teching In
Joined: Aug 2003
Posts: 15
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Re: need help w/ heads and cam issue... I had a similar problem with the TR224 cam. I lost power and torque all the way to 4000RPMs and didn't gain power until after 4700RPMs vs. the stock cam. The TR224 also peaked just shy of 6000RPMs. I talked to the vendor that sold me the H/C package and after they talked to the shop that did the LS1 edit tuning, they were convinced the cam was ground wrong. Instead of risking it and going with the TR224 again, I went with a 228/228 .588/.588 114 cam. I am much happier with it. It seems a lot of people have luck with the TR224 cam, but I was not one of them.
TECH Resident
Joined: Nov 2001
Posts: 917
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From: Chattanooga,Tn
Re: need help w/ heads and cam issue... make sure you have no exhaust leaks by your O2 sensors. I have seen even minor leaks affect power a lot!
It should make power higher than that. do you have a cutout?
It should make power higher than that. do you have a cutout?
Thread Starter
Staging Lane
Joined: Aug 2002
Posts: 96
Likes: 0
From: centreville, va
Re: need help w/ heads and cam issue... no exhaust leaks, no cut-out. the guys at thunder have been very helpful- in thier defense-and offered anything i can think of to help the situation. if i'm gonna pull the cam i'd rather put a differant one in. any suggestions? i'd like to keep my drivebility. the 114 is a nice lsa, never driven one w/ 112 lsa. let me know what you guys use and how you like it...
Re: need help w/ heads and cam issue... Have you done a compression check?
A buddy of mine thought he too was down on power. He thought he'd installed 7.35" pushrods, but it turns out they were 7.40", and they were hanging the valves open slightly. A compression check was 140-150 PSI with 7.40" pushrods, 180-190 with 7.35". Yes, that much difference.
He dyno'd 402 RWHP with the 7.40's. He hasn't redyno'd, but I'd bet he's in the 430 range now. I base this on his trap speeds at the track - he's right even with me, and I dyno upper 430's.
What length pushrods did you use? Do a compression check.
Andrew
A buddy of mine thought he too was down on power. He thought he'd installed 7.35" pushrods, but it turns out they were 7.40", and they were hanging the valves open slightly. A compression check was 140-150 PSI with 7.40" pushrods, 180-190 with 7.35". Yes, that much difference.
He dyno'd 402 RWHP with the 7.40's. He hasn't redyno'd, but I'd bet he's in the 430 range now. I base this on his trap speeds at the track - he's right even with me, and I dyno upper 430's.
What length pushrods did you use? Do a compression check.
Andrew
11 Second Club
Joined: Aug 2003
Posts: 1,541
Likes: 1
From: Boring Green, Kentucky
Re: need help w/ heads and cam issue...
I had a similar problem with the TR224 cam. I lost power and torque all the way to 4000RPMs and didn't gain power until after 4700RPMs vs. the stock cam. The TR224 also peaked just shy of 6000RPMs. I talked to the vendor that sold me the H/C package and after they talked to the shop that did the LS1 edit tuning, they were convinced the cam was ground wrong. Instead of risking it and going with the TR224 again, I went with a 228/228 .588/.588 114 cam. I am much happier with it. It seems a lot of people have luck with the TR224 cam, but I was not one of them.
