Converter Slippage at top end
 

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

Re: Converter Slippage at top end
 

should be 4 to 7%

Re: Converter Slippage at top end
 

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.

Re: Converter Slippage at top end
 

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 .

Re: Converter Slippage at top end
 

Have not used the lock up !!

YET !!

Dan

Re: Converter Slippage at top end
 

This is interesting

I use Amsoil for racing

Re: Converter Slippage at top end
 

Not sure why you included this info, but if you're going to use a T200 and an 8" converter, there are plenty of people here who can figure what gear you'll need. You won't have to figure a thing.
Only question would be: Will you have enough steam to run a second under, or are you just looking to run the index?

Re: Converter Slippage at top end
 

Hopefully Mark will back me up on this , since he has a lot of converter experience . A 10" converter is an odd choice in stock . Example , To make a big converter stall up at 5000 rpm will trade efficiency and make it slip a high percentage through the traps It is much better to have a 8" converter configured to stall at 5000 rpm , and gain back the overall efficiency through the traps . A bonus of the smaller converter is the coupling point of the converter (the point that converter multiplication goes to 1 ) will be at a higher rpm . A big converter will get to 1 to 1 at a lower rpm , so the car will not accelerate as quickly while the converter gets through this in-efficient part of the converter curve .

Re: Converter Slippage at top end
 

Staying with 4L60E..
If it breaks PerformaBuilt will rebuild.
Far less expensive than a built Th200-r4 and much stronger.
Don’t have to make a new Cross member or Size a new drive shaft.
More first gear for weight of car
8 inch Converter is being built.

Re: Converter Slippage at top end
 

So you're using an o/d - lock up trans, but not using either ?
Gearing it tight in 3rd for a big duration Stocker cam?
Oh.

Re: Converter Slippage at top end
 

Any reason why you haven't tried lock up?

Re: Converter Slippage at top end
 

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

Re: Converter Slippage at top end
 

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 !

Re: Converter Slippage at top end
 

Depending on what I do...
5.38 will work with existing PS cam with OD or Locking Yank 4400PT..
In fact would be good with Stocker Cam holding rpm below 7000rpm. Preferably 6800 rpm with existing 28 inch slick.

Want keep the rpm 7000 or under.
Speaking to Don Compolito their J/SA crosses at 7500 rpm
Car would need better rods for that rpm.