the truth hurts
not makeing excuses but but here go's..the guy that owned the dyno told me before we started that it was 9rwhp lower than everybody elses..the motor only has about 100-150 miles so when it get a little more broke in I should gain a few. now for the big killers I have a moser 9" w/4.10s and a th350 w/4000 stall
it did 429rwhp and 400rwtq

I was gonna post it but I cant figure out how
We had a 402/ETP/TH400/12 bolt 4.10 combo that had poor numbers too. The customer has some garbage converter in th car.
416 rwhp
100% full weight Z/28
11.0 @ 123 ... on the limiter thru the traps due a 26" ET Radial & 4.10
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I did a 408 for a guy with the same exact cam as yours, fast 90 setup, all bolt ons, etc. We used a set of heads VERY comparable to the ones you are running. The car was a 6 speed with 4.10 gears. It made right at 500rwhp/470rwtq. I don't like to guess at ****, but if I were guessing.. I would say his drivetrain is ATLEAST 10% more efficient than yours... maybe even more. So going by that ASSumption, 10% of 500 is 50 and add that back to your 430 and your there at 480. His 500 was done on the "good" dyno I use and not the one you used.
About 6 months after doing his car, he saved up some money and we changed out the other heads for a set of ETP 245's, cometic .040 gaskets, longer pushrods for the ETPS, and morel lifters. Besides those mods, we changed the rear gear from a 4.10 to a 4.30. Went back to the dyno and it made over 530rwhp. That's the highest dynoing 408 I've ever witnessed.
A few weeks ago I did a 402 LS2 based car on the same dyno with a 4L80 conversion and unlocked big stall... similar head/cam/intake combo as you.. but he had a stock rear.. 430rwhp.
I guess what I'm getting at is, don't sweat the dyno stuff.. .I think the car is making what it should for the heads and drivetrain setup. It should turn a good number at the track.
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gomer you are the man!!
You dont need no stinkin mileage!!We've dynoed cars with less than 100 miles on the motor.
A couple heat cycles and make sure shes good to go, no leaks, cooling system working good, let er eat!!
And, all of our motors are tuned spot on as far as part throttle, before we start makin pulls.
Sorry bout hijackin this guys thread BTW.
We had a 402/ETP/TH400/12 bolt 4.10 combo that had poor numbers too. The customer has some garbage converter in th car.
416 rwhp
100% full weight Z/28
11.0 @ 123 ... on the limiter thru the traps due a 26" ET Radial & 4.10
I can echo this nearly exactly...
I did a 402/AFR225s/12 bolt 3.73s ... had a built 4l60e with a crappy loose non-name stall that would not lock (well it wouldn't stay locked) on the dyno..
419rwhp
100% full weight+some T/A with all factory power options
11.0 @ 124.5 first pass

The funny thing was.... this was a girl's car. She bought it to compete with her boyfriend. His car at the time was an M6, stock engine with an ls6 intake , headers, and a powerdyne supercharger at about 7psi, and his car put down 434rwhp on the same dyno and same day. That same night at the track where her car trapped 124.5 with her 419rwhp, his car trapped 117.5 with his 434rwhp/M6.





