Converter Slippage at top end

[Jim Hanig]

Originally Posted by Dan Fahey

Currently using a 10 inch Yank 4400PT Locking converter.
Calculated a 12% slip based on Wallace Racing Calculator

What is a typical converter slippage on Racing Converters.

Trying to determine best gear ration for my 95 Impala SS for Stock

Dan

should be 4 to 7%

[Jeff Stout]

Going through this right now. I was at 13% and tested using John Deere Hydraulic oil and dropped 300 RPM. I think I'm at 9% now. It was just an experiment and now will remove converter to tighten up top end and hopefully keep starting line rpm the same. Debating on what to get converter set at because I race from 2000ft to 6500ft of air throughout the year and don't want to change converters.

[Tom Goldman]

The PT converter is a lockup so you should have ZERO slippage .
If you are using it as a non lock up of course your slippage will be higher than a real purpose built Stock Eliminator converter .

[Dan Fahey]

Originally Posted by Tom Goldman

The PT converter is a lockup so you should have ZERO slippage .
If you are using it as a non lock up of course your slippage will be higher than a real purpose built Stock Eliminator converter .

Have not used the lock up !!

YET !!

Dan

[Jeff Stout]

Originally Posted by Dan Fahey

Have not used the lock up !!

YET !!

Dan

Any reason why you haven't tried lock up?

[Dan Fahey]

Originally Posted by Jeff Stout

Any reason why you haven't tried lock up?

Thought of it.
No need with current 4.56's and 28 inch tires.

The Yank was designed with an extra large clutch.
Have calculated adding more gear and using existing Converter.
Sure would launch hard with 5.38's.

Would ET closer to the K-L/SA Index with the current Blueprinted cam.
Mostly cool weather near sea level tracks.
Thinking if the car used the Stocker cam would not need so much converter.

D

[ss3011]

4L60 has a 3.06 first gear and a huge ratio change from 1gear to 2nd gear . Might want to checkout the Sonnax gearset that reduces 1st gear into the 2.8 range . Are you planning on using 4th gear ?
Back in the mid 80's I ran a Olds Cutlass with a 307 and a 200-4R with a 2.74 first gear , 5.57 rearend gear , and a 28" bias tire . The problem with all that ratio is the engine can't rev up that fast . Much of the engine power was trying to accelerate the drivetrain , and not the car . Ran better with a 5.38 ratio , and swapped in a different overdrive ratio (.72) and that helped a bunch . Converter clutch was worth 2 mph !

[Dan Fahey]

Originally Posted by Jeff Stout

Going through this right now. I was at 13% and tested using John Deere Hydraulic oil and dropped 300 RPM. I think I'm at 9% now. It was just an experiment and now will remove converter to tighten up top end and hopefully keep starting line rpm the same. Debating on what to get converter set at because I race from 2000ft to 6500ft of air throughout the year and don't want to change converters.

This is interesting

I use Amsoil for racing