stall speed question

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stall speed question

#1 Post by JohnDougherty » Fri Nov 11, 2005 5:46 pm

Does anyone have a graph like Beyonds "engine rpm/ driveline rpm/ acceleration graph" from the other post which shows an engine "on the convertor" after a shift. What I am trying to find out is, when the car shift from 1st to 2nd gear (th350) does too high a stall speed hurt acceleration?
Example: I have a 5000 stallspeed and shift 1-2 at 6500. This should drop my rpms to 3900 or so. But having a 5000 stall convertor puts me at 5000 rpms. Does acceleration suffer until the convertor locks up?

I asked the same question over at, and most people say run the high stall speed.


#2 Post by Guest » Sat Nov 12, 2005 10:51 am


Obviously, the purpose of the high stall converter is to keep the engine in the best power range throughout the run. Where your stall needs to be can be determined from the dyno sheets for your engine. For the best ET, a combination with a normally aspirated engine (with no nitrous) typically wants to stall between peak torque and peak HP. Exactly where, depends on how wide the power band is.

If yours is a typical race engine, and 6500 is the correct shift point, it probably makes substantially less power at 3900 than it does at 5000. If you pulled it back to 3900 at shift, you would slow down.


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#3 Post by hsutton » Sun Jun 10, 2007 12:45 am

In a engine that shifts at 6500 the peak torque is probably somewhere in the neighborhood of 4500 so he probably isn't hurting his E.T's much, if at all. Changing gears, converters or shift points will tell you for sure. A data logger and a knowledgeable person like Randy to decipher the logger's information would be even better. Later this year i'm going to get one of his units for my son's car.

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