So I finally went to get the car tuned with the AEM on Wenesday. Everything seemed to be fine except that the hp was falling off after 8k rpms.
We managed to pull 388hp and 281ft/lbs at +-14.5psi on the inline pro setup with an sc61 turbo and full 3 inch catless with a 3mm hg.

I am loving the high torque number she pulls hard. I am just curious why power would be falling off at 8k+???
We regapped some new plugs just incase they were getting blown out at .028" but it didn't seem to help.

Any ideas??

 

the power band. You max power should be anywhere between 6000-7500. How is your tune?

 

max power is there but the hp line should be linear and not fall off up top

 

I'm not that familiar with the SC61 turbo, but it may just be running out of steam. How much boost are you getting at redline?

 

I suspect that if you look at a graph of the torque vs boost, you will see them dropping off in the upper rpms. Do you have any graph printouts?

 

A/Rs of that turbo?

 

What are the specs of the turbo?

With my GT35 .6 A/R I don't drop in power till about 9100rpms

 

I have a print out but I can't get it to load quite yet. Torque starts falling at around 7300 but thats normal. horsepower is steady til 8000 when it starts to fall off.
its a .69 trim cold side but I forget what the hot side is.
The first time I had it tuned I didn't have this problem, although it was on an emanage.
The turbo is rated to 680hp it is similar in size to the gt35 only it is not water cooled.

 

your running out of fuel! - what is fuel pressure at those rpms? (have to have gauge and do a pull on dyno and watch fuel pressure)

 

Log manifold, restrictive exhaust, restrictive turbine housing, etc. can all cause power to fall off at high rpm.

Tim