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Old 03-15-2019, 12:01 PM   #1
Makinchips
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Default Torque converter slippage

What percentage does an 8" a/sa or b/sa converter slip approx.

I'm considering upping the rear gear in my bracket car which runs low 10s presently but am unsure of the rpm gain from converter slip.
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Old 03-16-2019, 09:28 AM   #2
Alan Roehrich
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Default Re: Torque converter slippage

We get 4%-6% with an 8" ATI.
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Old 03-17-2019, 02:12 PM   #3
Dan Fahey
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Default Re: Torque converter slippage

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Originally Posted by Alan Roehrich View Post
We get 4%-6% with an 8" ATI.
How about 10 inch? I need a stall of 5000 - 5600 for my Impala SS
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Old 03-17-2019, 03:27 PM   #4
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Default Re: Torque converter slippage

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Originally Posted by Dan Fahey View Post
How about 10 inch? I need a stall of 5000 - 5600 for my Impala SS
How are you going to get that stall from a 10" converter with low hp?. gsa612
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Old 03-17-2019, 08:20 PM   #5
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Default Re: Torque converter slippage

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Originally Posted by Dan Fahey View Post
How about 10 inch? I need a stall of 5000 - 5600 for my Impala SS
you would be hard pressed to get that from a 9"
8" is the area ,, tune the converter from there
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Old 03-17-2019, 08:41 PM   #6
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Default Re: Torque converter slippage

ATI told me as much as 9% for a PG 8" 5800 rpm 1.76 first gear 3200 lb. 509 BBC 800 hp was not uncommon.

Last edited by STK1217; 03-17-2019 at 08:46 PM.
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Old 03-17-2019, 10:50 PM   #7
Dan Fahey
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Default Re: Torque converter slippage

Quote:
Originally Posted by gmonde View Post
you would be hard pressed to get that from a 9"
8" is the area ,, tune the converter from there
Thanks...my car is a 1995 Impala SS LT1.
Weight 4150 lbs, stock rods, limited to about 7000 rpm.
Trying to understand the latest generation of converters.

Determining best gear to chose for top end.
5% slippage more gear, 8% slippage less gear.

D
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Old 03-18-2019, 01:50 PM   #8
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Default Re: Torque converter slippage

Quote:
Originally Posted by Dan Fahey View Post
Thanks...my car is a 1995 Impala SS LT1.
Weight 4150 lbs, stock rods, limited to about 7000 rpm.
Trying to understand the latest generation of converters.

Determining best gear to chose for top end.
5% slippage more gear, 8% slippage less gear.

D
Dan
The more gear that you have in the car the less the converter will slip. Talk to ATI about your combo and they will get you in the ballpark on the first try. Then you can make some changes as you move forward and test the car. Talk to Charlie at ATI. He is real familiar with the class racing stuff. You really can’t go wrong with them.
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Old 03-18-2019, 09:58 PM   #9
Mike Rietow
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Default Re: Torque converter slippage

Quote:
Originally Posted by Makinchips View Post
What percentage does an 8" a/sa or b/sa converter slip approx.

I'm considering upping the rear gear in my bracket car which runs low 10s presently but am unsure of the rpm gain from converter slip.
There is an equation. Need this info.

Tire size + observed roll out? + bias or radial?

Current gear

New gear

The current rpm and mph at the stripe.

It'll tell exactly what rpm you'll cross with the new gear , as well, as converter slip percentage with the current and new gear.
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