PPC for Auto Tranny - Clarified [Archive] - SaabCentral Forums

: PPC for Auto Tranny - Clarified


saabvec
31-03-04, 08:36 PM
Here is the reply I got from Engstrom about upgrading an auto tranny for those interested:

Q: I have a 2003 Saab 93ss 2.0T Vector with 5 speed automatic transmission. I'm considering of purchasing the PPC upgrade and just need a question clarified before I decide. Would the overall performance gain be the same in an automatic transmission and that of a manual? Thanks for your time in answering my question.

A: There are extra torque limiting in place on automatic car so the torque around shift points are often 10-15% lower than on manual cars. That will still be there after the upgrade but peak hp is normally the same in both cases.

Regards,
Bo Engstrom

Saba
31-03-04, 09:25 PM
The argument is whether the torque limiting contraints are constant or proportional to the gains. The popular view is that they are constant. The torque losses are due to additional loads on the drivetrain due to frictional forces and inertia in the auto box. As these remain the same regardless of the PPC (the PPC does not add any hardware to the drivetrain) the expected gains should come through in full or close to it. However it is not as simple as that as there are probably other forces and feedback that come into play when increase stress is placed on the drivetrain.

ie. If stock torque is 300Nm on a manual then stock torque on a auto will be about 255Nm (-45Nn constant or 15% proportional). If the software upgrade boosts torque to 400Nm on the manual, the argument is whether the auto will have 355Nm (-45Nm constant) or 340 Nm (-15% proportional).

Since no additional friction or inertia was placed on the drivetrain, then the loss should be constant and not proportional. But its probably somewhere in between.

I would feel robbed if I had an auto. :cheesy:

jcancio
01-04-04, 02:32 AM
This confuses me too. How do you get almost 280 ft.lbs of torque
while stock is only 221 ft.lbs of torque. That's one heck of an
increase. It's amazing how much extra torque we get from the PPC. I guess it's not a 1-1 ratio for the upgrade, huh?
Anybody here can teach me a little bit more about this?
The only thing I know is that torque moves the car while
you need hp's to keep the car moving. Is this true?

Thanks.

Saba
01-04-04, 06:47 AM
This confuses me too. How do you get almost 280 ft.lbs of torque
while stock is only 221 ft.lbs of torque. That's one heck of an
increase. It's amazing how much extra torque we get from the PPC. I guess it's not a 1-1 ratio for the upgrade, huh?
Anybody here can teach me a little bit more about this?
The only thing I know is that torque moves the car while
you need hp's to keep the car moving. Is this true?

Thanks.My torque figures were not real figures. I just used them to make the example easier to follow. The PPC doesn't give those torque increase (it would be great if it did :D )

Here's any easy to read article about torque and HP.

http://www.canadiandriver.com/articles/jk/020327.htm