This is a twin turbo F-body that makes 555RWHP with the converter locked on the dyno. It has a stock trans with a transgo shift kit and a 3600 vigilante converter.

While it feels like it shifts great on the street it was a different story when we got it to the track. It trapped a best of 99.6mph which to me in a F-body would equate to about 490-500rwhp

It seems to complete the 1-2 shift quickly but the RPM doesn't drop very much (stretching converter?) It also seems to complete the 2-3 quickly but it has a very odd flare... It really looks like when someone shifts a manual car without getting out of the gas and being slow on the clutch. It seems to hit 3rd nice but its got a quick little flare up between the 2-3 shift. (trans problem?) RPM also doesn't drop much after going into 3rd.


We plan on getting a built trans from FLT or RPM but we are not sure if we need to send the converter off also.

 

BTW in that log the second little shift is the 1-2 and the little peak is the 2-3.


Trans temp is going from 170 before run to a stabilized 197 after the run. Some quick scribbling on some paper tells me theres about 75HP into taking 14 quarts of oil 27 degrees hotter in 7 seconds. I'm not sure how many quarts a trans has in it total i'm thinking its actually about 10 quarts but regardless theres a bunch of power being dumped somehwere

 

A loose converter or one with a low efficency could acount for the power loss and the very low RPM drop in a shift. Its hard to say about the flare theres a big jump in gearing from 2-3 and with the converter being loose since the PCM only measures engine RPM verse output speed to determine when the shift occurs a loose converter could make it look like a flare on a graph. I would be looking at the converter myself.It would explain every thing from the feel. power loss and the heat generation.

 

Log your trans input shaft and output shaft speeds and you
can tell easily whether it's flare or stretch by comparing the
(in/out) ratio to the trans nominal ratio for current gear.

 

Feel free to give me a call in order to discuss this. We work with guys at the track weekly. As a matter of fact one of our clients was here last night after hours reviewing logs with me from his passes this past weekend. It is only part of how we support our customers' racing programs.

I would be very suspicious of th 3/4 clutches. If there are no modifications to the 2/3 hydraulic circuit then indeed you are seeing a flare IMHO.

But, like I said... give me a call and we might be able to pin it down for you. Do you hae any other graphs that illustrate similar passes?

g