Where is all my HP
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Joined: Nov 2001
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From: Bridgewater,Ma
Where is all my HP Just got back from the dyno and I'm lost.A history of the car.
309hp/320tq stock with 800 miles.
340hp/351tq w FLP's,Corsa
362hp/359tq with TR220 cam
382hp/370tq with mild ported Heads
372hp/365tq with 12 bolt(3.73's)
390hp/385tq with TR224 Cam,ported TB and tuning.
412hp/397tq with edit tuning
All at the same dyno,I've done over 60 pulls there.
Now today I went with 4.11's gears installed,ported LS6 Heads(11.2-1 comp,2.02/1.60 valves)Denny's steel nitrous DS and tuned it in with Edit with 28 degree's total timing and A/F tuned to 13-1 across the board with 0 knock and ended up with 408hp/391tq.I did start with 390hp/375tq and A/F at 12-1.
The temp was around 95 degrees and engine temp was 180-190 each run.I really think there should be highers #'s for my setup??? Could I be missing something??
Another H/C car was pushing 405hp after tuning that should be with the 420-430hp club.This is on a dynojet dyno.Could the correction factor be off?
My M6 car traps at 117mph in the 1/4 with 3700lb race weight if that helps.
309hp/320tq stock with 800 miles.
340hp/351tq w FLP's,Corsa
362hp/359tq with TR220 cam
382hp/370tq with mild ported Heads
372hp/365tq with 12 bolt(3.73's)
390hp/385tq with TR224 Cam,ported TB and tuning.
412hp/397tq with edit tuning
All at the same dyno,I've done over 60 pulls there.
Now today I went with 4.11's gears installed,ported LS6 Heads(11.2-1 comp,2.02/1.60 valves)Denny's steel nitrous DS and tuned it in with Edit with 28 degree's total timing and A/F tuned to 13-1 across the board with 0 knock and ended up with 408hp/391tq.I did start with 390hp/375tq and A/F at 12-1.
The temp was around 95 degrees and engine temp was 180-190 each run.I really think there should be highers #'s for my setup??? Could I be missing something??
Another H/C car was pushing 405hp after tuning that should be with the 420-430hp club.This is on a dynojet dyno.Could the correction factor be off?
My M6 car traps at 117mph in the 1/4 with 3700lb race weight if that helps.
Re: Where is all my HP The 4.10's are worth about -8 to -20 hp (I've seen people lose 8-20 ph with them). How much heavier is the new driveshaft than your old one? AN increase in rotating weight will hurt dynojet permormance numbers. It takes HP to accelerate that driveshaft, the heavier it is, the more power it will "absorb". Just my thoughts...
Thread Starter
LS1Tech Sponsor
iTrader: (12)
Joined: Nov 2001
Posts: 14,865
Likes: 6
From: Bridgewater,Ma
Re: Where is all my HP The DS is at least twice as heavy.I was just wondering how all these high HP cars are doing it?I must run on the wrong dyno.We'll see tomorrow at the track on how the tuning does.
Re: Where is all my HP Honestly, I'd expect your car to run higher than 117 trap speeds. Have you dyno'd through a cutout at all? Also, when you're ready to get rid of that 224 let me know 
Re: Where is all my HP Spending some of it "stirring up the mud"
in the rear end, for sure. Rotating mass
contribution to horsepower loss depends on
how fast you run up through the RPM; if you
have the option of making this happen slower
then you could get another reading and get
to an extrapolated constant-RPM horsepower
(not that that would be a very interesting
thing, race-wise, but it would give you
some idea of how much the heavier DS etc.
might have played into the back-sliding).
Any "correction factor" is a balled-up set
of assumptions and somebody else's data. The
less your particulars resemble that, the more
out-of-line the correction will be. I think
the way gears let you run up the load drum
speed differently relative to engine RPM
probably gets into that, big time.
in the rear end, for sure. Rotating mass
contribution to horsepower loss depends on
how fast you run up through the RPM; if you
have the option of making this happen slower
then you could get another reading and get
to an extrapolated constant-RPM horsepower
(not that that would be a very interesting
thing, race-wise, but it would give you
some idea of how much the heavier DS etc.
might have played into the back-sliding).
Any "correction factor" is a balled-up set
of assumptions and somebody else's data. The
less your particulars resemble that, the more
out-of-line the correction will be. I think
the way gears let you run up the load drum
speed differently relative to engine RPM
probably gets into that, big time.
Re: Where is all my HP The best way to get data that is "free of the RPM factor" is to find a "brake style" dyno. One that loads the motor until it can't accelerate at each rpm (usually 500 rpm steps), it just adds load until the motor is "held" there). But that dosen't simulate a real launch like a dynojet....
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