588 rwhp 523 rwtq Is that right?

[QKRNYRS]

We took my friend Brian's car to a Dyno Day today. I guess that I was expecting more. We only made two clean runs.

The last one was 588 hp and 523 tq.

Here is the combo:

109 block, JE piston/girdle/stock crank.
224/224 roller cam
ported champion aluminum's
PTE frontmount
ATR headers ATR DP w/ ATR gate.
Turbo is an older PT76
FAST engine Management.
Trans is a TH400
Rear is stock gears with spool
Afr set to 11.0/correcting <3%
timing is 26.5°
injectors are 83 lb and the FAST shows them at ~90%
fuel pump is an ATR double pumper w/ stock lines
I think I got all the important stuff

Boost was at 29.5 psi on that run. Air fuel according to the FAST was ~11.1, according to the dyno's AFR it was ~12.5.
He ran the car up to 6400 according to the recorded data, however, the dyno showed like 8500 RPM. The guy running the dyno (it's a dynojet, btw) said that it is normal with a high stall converters.

The car in the same basic configuration but at 26.5 psi went 10.33 at 132 on a 1.53 60'

The run prior was at that 26.5 psi. and made 545hp at the wheels

Why is the torque so low? And Horsepower? Should it be higher for the combo? Is the converter too loose? Maybe 29.5 psi is too low of boost

Thanks for any comments.

 

[wbrophy]

Track times sound about right for mods. Mine ran 130 mph at 23 pounds of boost, it touch 24 pounds in the traps (back in 2000). My set up is close except I used stock exhaust, p-trim 70 turbo, no fast system, 200 trans, 24 degrees in chip and a 4 pound launch

 

[Ed Valvo]

Something sounds fishy. RPM should have been the same or close. Not 8500! I have done research on GN dyno runs with different cams and the larger cams had less TQ, probably typical for most engines, but the HP was better. Did the power peak out before 6000 RPM? Is your car lightened at all?

 

[QKRNYRS]

It peaked at the 6400 RPM when he shut it down.

The car only has a "glass" front bumber. Weight is 3700 w/driver

 

[Chuck Leeper]

Not uncommon

It's not uncommon for the Dynojet tach signal pickup to not work properly w/ the DIS ign on the TR's.
If that happens, then the torque readings are fubar.
We use a new, DJ, and will have to go to a strobe pickup off the balancer in order to get consistent readings when running the TR's.....
Also could be, if the 8500 showed up consistantly, on all pulls, it could be the operator had the setup wrong....

 

[ijames]

If the torque readings are wrong, and the rpm reading is wrong, then the calculated hp pretty much has to be wrong too, right, Chuck? 132 mph is a 10.27 on average so the 10.33 is right in line with that and 3700 lbs and 10.27 sec gives 673 average rwhp so something is definitely off.

 

[Drac0nic]

Re: Not uncommon

Originally posted by Chuck Leeper
It's not uncommon for the Dynojet tach signal pickup to not work properly w/ the DIS ign on the TR's.
If that happens, then the torque readings are fubar.
We use a new, DJ, and will have to go to a strobe pickup off the balancer in order to get consistent readings when running the TR's.....
Also could be, if the 8500 showed up consistantly, on all pulls, it could be the operator had the setup wrong....

I think you're on the right track, but I think the HP's off. HP=TQ*RPM/5252 or whatever it is, so chances are the dyno's thinking the set TQ is at a higher RPM then it is, thereby increasing the HP. This is why ricers can have 600 HP and 75 foot pounds torque, it's all at 12,000 RPM. =)

 

[QKRNYRS]

After visiting a couple of sites with hp calculators and they all show hp in the 660 to 670 range at the wheels. So something was obviously not correct. Yes, Chuck, it does have an MSD DIS 4 on it. So that could have been a problem. They spent 10 minutes just trying to get a good tach signal.

On a brighter note, he did win the dyno contest. The next highest was a F-body with NOS @508 hp.

Thanks

Pat

 

[Otto J]

My car made 547 last year and went 10.47 at 131.84 and it weighed 3700 with driver at 30#s

Although my new setup made 625HP and 735 TQ with 25#s this year, Dyno could not load the car enough to make any more boost
and the convertor also shot right to 6600!!! I found out it stalled to high with that much boost

So i am putting in another convertor this week

 

[Mike Licht]

You are putting in enough fuel to make over 800HP so the wideband stuff sounds wrong as well. The fast wideband is pretty close. The RPM stuff really changes the reading since is part of the Dynojet calculation. Go to another dyno that has an eddy current dyno that can properly load the car. Livernois MotorSport has a Mustang (my old dyno) that will do it.
Mike

 

[ULUZ2A6]

Mike... You say there is enough fuel for 800HP. What is the weak link then? Is the FAST's claim of 90% duty cylce on the injectors accurate?

What kind of duty cycles are you guys with simular combos seeing?

 

[EightSecV6]

For the RPM to be that much different, the operator may have not set the computer to 90deg, that is where it needs to be for the inductive pickup. Alot of times on the Buicks, you have to change from engine RPM readings to speed, the roller speed HP will be accurate but the TQ will not be correct if there is an ignition problem. The optical pickup is the best way to go on some of these cars that give you alot of grief with the inductive pickup...

 

[Dusty Bradford]

Your post says you have the stock fuel lines. Those DC% numbers sound right for those injectors and stock lines. Put a 8an line on it and your DC will drop. We saw a 14% drop from stock lines to a 8an with a double pumper intank setup.

 

[Robert Walton]

A loose converter will skew the readings too because it's not as efficient. I may be wrong though