I straped my car on the dyno today. I was expecting around 380rwhp, but only got 342rwhp. All the pulls were done in 4th gear. Is that the correct gear or should they have been done in 3rd gear? What would be the difference? What gear should be used?

My car has the APS TT with the 93 maps. Nothing else, stock exhaust.

Thanks!

 

5th gear is closest to 1:1 I think

 

How much boost were you seeing?

 

5th gear is the one but not everyone likes to do it since you are spinning the wheels over 130 mph and 4th really doesn't make too much of a difference maybe 10 hp at those levels

 

On those pulls, only 6.9psi. I usually see up to 7.6 on the streets. I beleive that the APS TT kit was made for 7.5-8psi. Maybe I have a small leak somewhere... It was really hot and humid too, over 100 degrees.

 

The dyno did not apply enough load to the motor. Let me guess inertia dyno.

The way I can tell this is you stated that the boost level you saw during the dyno pull was less than what you see while on the street. Boost levels will drop or trail offf on a dyno if there is not enough load on the motor, creating increased cylinder pressures, that are lower than WOT on the street. This lowered cylinder pressure do not have enough energy to generate the force needed to spin the turbo to genereate the same amount of inlet pressure you see on the street. Hence the lower boost level, hence less rwhp.

They could/should have run the vehicle in a higher gear to "effectivly" apply more load to the motor. This would have resulted in a more realistic boost curve and rwhp measurement. If this was done on an eddy curent dyno the operator needed to increase the load and need to go back to dyno mfg for more training.

If you had been able to hit and hold 7.6psi you would have seen ~358hp.

 

Interesting... I'll talk to him and see what he has to say.

Thanks a lot!

 

If the dyno operator knows what he's doing, it's not really important. 4th and 5th are both good

the important is that you always dyno on that gear afterward