Driveline loss 4T60E vs. 284

[Kevwood]

Okay guys, I forgot to post these results. For a long time there has been a lot of speculation as to what the drivetrain losses of the 4T60E and Getrag 284 are. I have these numbers for you;

Engine in my red car with the 4T60E -> 225 WHP
Engine in my white car with 284 -> 240 WHP (before additional tunning and u/d pulley)

This was taken out of the red car and dropped right into the white car, NO CHANGES WHATSOEVER.

So, 15 WHP difference. I was told by a few GM tech's, two different tranny rebuilders and a tuner of these w-body cars that the 4T60E has a drivetrain loss of about 25% & the Getrag 284 has a loss of about 18%. Michael at FFP also uses the 18% loss to calculate his WHP (265 - 18% = 217.3 or 218 WHP) I believe these numbers to be true, look at this;

240-225=15 OR 225/240=93%, a 7% difference.
25% 4T60E loss - 18% 284 loss = 7% difference.

So, there is no question that there is 7% difference between the transmissions. One 'mystery' down, lot's to go...

P.S. The FFP pulley was exactly 5 WHP, virtually no difference in voltage and no difference in operating temp! Great bang for the buck!

[OldSkoolGP]

That's about what I figured for a 284. However, I have found one issue with the UD pulley. I have a 160 amp alternator. I don't know if that makes a difference, but if my lights are all on and the cooling fans are both running, my alternator can't keep up. If I have it wound out to 1200-1300 RPMs, it's running at full capacity again. And since Ben retuned my chip and the fans are always on in city driving, this gets to be a bit of a problem at night. Hopefully some creative electrical rerouting to reduce losses will keep this from happening.

[RacerX11]

Most hi-output alternators trade low-rpm charging capcity for the higher current rating when spun faster. It sounds like your alternator and the UD pulley are not a good match.

Marty

[timg]

I was calculating 21-22% (44 hp) loss for the 4T60e tranny. Here were my calcs.
205 hp - 161 whp - 44 hp delta - 21.5%
210 hp - 166 whp - 44 hp delta - 21%

Tim

[Kevwood]

Most hi-output alternators trade low-rpm charging capcity for the higher current rating when spun faster. It sounds like your alternator and the UD pulley are not a good match.

Marty

I agree, I had a high output alternator in my red Z34 to run all my audio gear - it sucked ass at an idle, 1,200rpm it was fine. I chose not to run that alternator in this car, the stock one is just fine with an Optima battery to run all my electronic goodies on the way.