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To be fair they also said they could crack 700whp with a vacuum pump and a more dyno friendly trans. Cam only LS7's can make 560 which is spitting distance to this 468 making 580. I am in NO way knock OP as I know him, I'm just saying that I think something is holding it back.
No, I agree overall power is down - but it shouldn't just be looked at a problem with rpm as that wouldn't really address what is being seen between the two pulls. Something is happening from 4800-6500. It is down 40 ft lb at 6000 rpm despite peak power and the shape of the power curve staying more or less the same.
If you look at the two dynos the shape of the curve are really overlaid, even the humps in the torque curve down 3000-4500rpm. At 4800 both dynos are reading 550 ft lb. Somehow at 5000rpm the previous dyno peaked torque at 583, and the new dynojet pull flatlined at 550 and fell from there.
So I guess we should be trying to figure out what causes that. Semi-restricted cats does kind of make sense. Might want to do basic things like check the plugs. Doesn't look like a valvetrain thing at all. Knock is usually jagged or a sharp drop in the torque curve so that doesn't make sense.
Initially I wanted to chalk most of that up to a difference in dynos, but my experience with dynapaks around this power level is that they read very close to a dynojet. Many stock c6z dynos ~460whp on a dynapak I've been on. Intake, headers, and tune c6z's are 490-510whp range. Add into that the power/torque below 4800rpm is near overlaid..something very well might be up.
Specs:
WCCH heads
Im not sure if HPR likes to keep their cams a secret or not, so i have a 25x/26x 0.650/0.650 grind
mamo msd intake
1-7/8 arh headers, cats, oem catback
mpss tires @31psi
3.90 gears
baseline was 580/536 with wavy afr and some KR sprinkled in. Once we cleaned up the fuel table and added a little timing up top i got 587/551 but it picked up everywhere as much as 11hp and 15tq.
honestly im a little disappointed in the absolute number but i suspect (hope) the cats are plugged up considering the car dynoed 631 in california on 91 octane and 3.42 gears before i bought it. Ive put about 6k miles on it and havent replaced plugs or done anything else except gears and oil changes.
I couldnt help but compare to the graph fnbadaz06 posted and i made like 25 more tq at 4500 but way less horsepower once things started spinning.
California graph:
Here is mine from yesterday, Blue is baseline, red is last pull
anyway, this is my first time chasing dynos in a car, so roast away
What changed on the car in between the run on the Dynapack and the run on the Dynojet?
this thread fell off my radar until now, which i regret.
the only change is cali 91 and stock gears to florida 93 and 3.90s.
also the tires were really old MPSS that spun easy. not sure it was doing that, if i can tell in a datalog? once i put new MP4S tires on it was a new animal.
heres the efilive datalog from the last pull, red line in graph
after the dyno i took the cats off and gutted them but never messed with it other that driving it a lot. car runs excellent and always has. with gutted cats now it probably would benefit from some more dyno time and polishing up the tune a little.
That can be left to the next owner, since im selling the car, which is why this thread got my renewed attention.
it was actually a fun afternoon cause it was on Cal's dyno and each run we would go over the data together and work through what to change. i have a lot of experience but nowhere near his so it was cool seeing some of his tricks, and i havent had a chance to hang out at his place in almost a decade so it was nice catching up.
it was actually a fun afternoon cause it was on Cal's dyno and each run we would go over the data together and work through what to change. i have a lot of experience but nowhere near his so it was cool seeing some of his tricks, and i havent had a chance to hang out at his place in almost a decade so it was nice catching up.
Should have hit me up! Would loved to have watched it on the Dyno and see how someone else tunes in person. Glad it was a good experience!
08-03-2020, 06:14 AM
