Missing power?
10-15-2010, 10:09 PM
#1
Missing power? So I just got my swap completed. Car is a 1989 Porsche 944.
Engine is from an '02 Camaro SS with 65k miles on it.
Here's how it's set up, stock heads, bottom end, LS6 intake manifold and throttle body. Comp Cams 224 cam with matching valve springs and pushrods. 1 7/8" primary shorty headers leading into a dual 2.5" exhaust with high flow cats and an X pipe and a tune.
It dynoed 338rwhp and 337 ft lbs. I was expecting more like 370-380rwhp, unless I'm off base?
What should I be looking for? I'm thinking the cam timing is off a tooth, probably retarded, but what else?
TIA!
Engine is from an '02 Camaro SS with 65k miles on it.
Here's how it's set up, stock heads, bottom end, LS6 intake manifold and throttle body. Comp Cams 224 cam with matching valve springs and pushrods. 1 7/8" primary shorty headers leading into a dual 2.5" exhaust with high flow cats and an X pipe and a tune.
It dynoed 338rwhp and 337 ft lbs. I was expecting more like 370-380rwhp, unless I'm off base?
What should I be looking for? I'm thinking the cam timing is off a tooth, probably retarded, but what else?
TIA!
10-15-2010, 10:53 PM
#2
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Exact same thing happened to me this week. I dynoed a few HP less after my cam swap than I did as a bolt-on car. Took the valve covers off & measured my pushrods & they were too long. My preload was somewhere around .120" & apparently my I & E valves were both staying open & I wasn't building any compression.
I got the shorter pushrods installed & am going back on the dyno next Thursday, so I'll be sure & report my results. I'm about 99% sure this was my reason, so we'll see. Yours could be something else for sure, but definitely make sure on pushrod length!
PS My car ran & sounded just fine. Probably never would have known if I didn't get it on the dyno & find out.
I got the shorter pushrods installed & am going back on the dyno next Thursday, so I'll be sure & report my results. I'm about 99% sure this was my reason, so we'll see. Yours could be something else for sure, but definitely make sure on pushrod length!
PS My car ran & sounded just fine. Probably never would have known if I didn't get it on the dyno & find out.
10-16-2010, 10:22 AM
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You will need right around 7.4" pushrods. I used 7.425" at first because of the smaller base circle on my cam (& I measured, but didn't really take my time to double check. 7.425 is kind of what I was expecting), but ended up those were way too long. I guess my car is a bit different than normal. After taking them out & measuring, I ended up needing 7.375".
Anyway, you will need right around that range, but definitely need to measure!
Anyway, you will need right around that range, but definitely need to measure!
10-16-2010, 10:24 AM
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7.400" pushrods should be fine with that cam and stock heads.
What drivetrain you running behind that motor? I'm guessing you don't have any numbers before the cam swap.
What drivetrain you running behind that motor? I'm guessing you don't have any numbers before the cam swap.
