i didnt know that, i was speaking purely from a physical point of view. thanks for the correction though, you wanna help me on my physics exam tomorrow? lol

 

That's mostly because a manual trans has a generally fixed (linear) loss due to friction. If that auto isn't locked up, it's slipping (duh) and throwing the extra power away as heat. Hence the need for tranny coolers. I've seen a similar thing happen on a Dynojet with a slightly slipping clutch. Numbers would come back 10hp low, 20hp high, etc. Then you pull up the rpms vs mph plot and it ain't straight!

 

the black coupe is clean dude

 

Well, lockup generally happens in 4th gear in an automatic. Some programs for the 4L60e can force the lockup clutch in the converter to engage (when it ordinarily would not) for dyno runs but this is not a common modification. Stall speed is determined by several factors, including the distance between the impeller and the turbine and the design of the stator. It is not a matter of "throwing the extra power away as heat." If you think of the design of a stall converter as two fans facing one another with a fluid transfer rather than an air transfer, you're getting the idea. Going further, the angle of said blades are what determines the stall or what manual transmission guys would say is the "point of engagement."

That being said, it is not a heat-loss transfer issue, it is a controlled engagement point. Granted, I can see why you'd think it was throwing away the extra power due to heat because the friction of the fluid moving through the converter and throughout the transmission itself causes heat. This also occurs in every automatic transmission on the planet which is why you'll never see an automatic without a heat exchanger.

I'll quit now, I'm no longer a transmission guy...that was a former life.

 

Thanks! Sorry for the shitty picture, was too greasy to get the real camera, had to settle for my uberphone PDA POS.

 

Lots of good info in there! I honestly don't know too much about auto trannys. Only that they work on magic and elves (not the cookie kind). The impeller/turbine/fluid arrangement is what I had envisioned. Just to be picky, air IS a fluid.

The basic formula I'm going on is work in = work out. If the motor is measuring N horsepower and the motor is really putting out N+10 hp, then that 10hp is going somewhere. That work is either not going in or is coming out the side as heat. If you find an extremely long, boring link on the math behind it, let me know. I'm pretty sure you're working the efficiency angle and I'm missing the boat here somehow.

 

swapped out the Fujitsubo cat back for a new HKS unit that is a lot more sleeper, as well as a lot less noisey.

 

^pics?

 

Noise is for slow cars. Sometimes you just want to hear the damn radio!

 

I actually had a formula but it was not a blanket one. It's also important to note that a torque converter acts to multiply torque over a given range depending on converter diameter (if memory serves). Most highly stalled automatics will dyno low on horsepower and very high on torque.

Before I worked in a transmission shop, I too thought automatics worked on some sort of voodoo magic.