Dyno’ed this morning on a DynoJet. I try not to get hung up on dyno numbers, but I will admit I do not like what my graphs indicate. My car specs are listed below.

98 TA
M6
SLP lid
P/P TB
LS6 intake manifold
Stock fuel pump
FMS 42lb injectors
Patriot ported LS6 heads (2.00”/1.55” & 64cc)
Patriot Gold Springs
LS7 lifters
7.35” hardened PR’s
Cometic .045” gaskets
226/230 .57x/.58x 111+2 (224/228 .581/.588 110 nominal advanced 2 on install)
UD pulley
QTP 1-3/4” headers
Magnaflow 3” Metallic-Cat converters
Bassani 2.5” dual exhaust
Stock clutch, driveshaft, and rear differential
Wait4me mail-order tune tweaked by SspdDmon (thanks )

I advanced the cam ~2 degrees on install with a Cloyes Hex-A-Just timing set. I did not degree; just torqued the cam plate down with the bushing on the +2 degree dot. I am not going to whine because I did not hit my mark, but I do wonder why my peak numbers are so low. I also wonder what is up with the wide trough in the torque curve between 3100 and 4800RPM. The AFR graph results are ~1 point higher than we saw on the street with SspdDmon’s LM1.

This is a scan of the WinPep7 (DynoJet) graphs of my second pull.


I re-plotted the power data points using Excel to provide a better picture.

 

Something is wrong for sure you have a good set of mods your car should make 420rwhp you also have good boltons.

Good luck man and keep usposted.

 

Your peak numbers do look surprisingly low... but your curve isn't too bad, you make some pretty decent numbers across the spectrum... do you know what your numbers were before the mods?

 

i hope you figure it out bro-somethings out of wack. i hate dyno's im always hoping to see 50rwhp more than i always get

 

I do not.

 

That is odd. Something is off. Good luck.

 

get a real tune

 

also maby try a cut out that 2.5" cat back might be holding you back a lil but not 50hp

 

I think SspdDmon knows his stuff and a 2.5" dual exhaust w/ 3" high flow cats and a superb crossover is not holding any car back that makes less than 500hp. I still appreciate you taking time to read and respond. Thanks.

 

did he tweak the tune when you where at the dyno or?
a h/c car with a mail order tune to me don't go together.
2.5" true duals? i thought you ment the cat back was 2.5" with dual tips

 

I may have a freak but my car with that cam made 424 rwhp and 408rwtq(-4.10 gears-) with the LS6 intake and 452rwhp 408rwtq with a ported fast. I have milled and ported 241 heads. I also made these numbers with a 12 bolt with 4.30 gears and a heavy Denny's nitrous ready driveshaft. I think there is more to be had out of your set up. When the car made 424 rwhp it had SLP headers and a factory firehawk catback.

 

i agree with everyone else. that is low numbers with stock heads with your mods. you should be in the 410-420 range with around 390-400 rwtq.

 

Do you have a stock rear? what gears? what driveshaft?

 

The mail order tune was just to get the car on the road. After that a little tuning has been done on the street. SspdDmon had the AFR dialed right in at 12.6 – 12.8 based on the LM1 plugged into the RH bank. I know the tune is not perfect, but I suspect it is not the limiting factor here. I could be wrong. A lot of people claim to have put down 400 or 410+ with “similar” setups. We can try to dial it in better, but I should make sure there are no other problems before I drag him back out to help me w/ the tuning. Like I said previously, I am always suspect of dyno HP/torque numbers, but mine are low enough to concern me.

As listed in the OP, stock, so 3.42.

 

 

I think something is wrong. Cause with the stock drivetrain you should have hit 400 with no problem. My numbers I mentioned are real, no dyno tricks and was done on a dyno that reads lower than most.

 

The dip in the torque curve and the fact that that cam is making peak power at 5700 rpm indicate where the issue is. Peak torque at 4700 and peak hp at 5700? Advancing a cam with a tight LSA like that is going to lower the power peak, and your going to sacrifice some of the ponies you'd find up higher.

I'm going to lean toward the cam timing being your issue. I'd move it to straight up and degree it to make sure everything is where it's supposed to be. But, as you know, there are plenty of other possiblities ... installed height on the valvesprings being off, poor port job on the heads, tune being way off (though with wait4me and SSpdmon involved, it should be close to dailed in).

 

Mine peaked much higher with just the 224/228 581 112 cam. You might be running out of fuel up top?

 

thats def something to be concerned about easily IMO u should have 420 RWHP no problem with all them mods... i say change the fuel pump if i had to guess something looking at ur mods big injectors and stock fuel pump def a problem... id go with a racetronix just my .02

 

Looks to me like the motor is starting to fall off about the 5400 rpm mark. For some reason you are running out of air. Like was stated above it could be the cam timing. Your cam most likely came with 4 degrees advance built in.

Adding the 2 degrees advance would not help your cause in the higher rpm range. Just a hypothetical but the tolerance stack could be 1 or 2 degrees advanced from straight up. Now you are 3 or 4 degrees further advanced than from straight up. Without degreeing the cam you will won't know.

This is just one of the reasons when building a motor there can be a 40 to 50 horsepower difference using the same parts.