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8" convertor stall change?

Posted By: cudadon

8" convertor stall change? - 03/11/18 09:42 PM

I'm looking at an 8" convertor that came out of a car with about 100 hp and 90 lb ft of torque more than my engine.

What would this convertor do in my car?

How would the launch/stall be in comparison?

Thanks, Don
Posted By: Al_Alguire

Re: 8" convertor stall change? - 03/11/18 09:49 PM

Were they both on the same dyno? If not those numbers likely will be different. It would be tighter, less stall and more drop on the shift in your combination than in one with more power.
Posted By: cudadon

Re: 8" convertor stall change? - 03/11/18 10:00 PM

Originally Posted By Al_Alguire
Were they both on the same dyno? If not those numbers likely will be different. It would be tighter, less stall and more drop on the shift in your combination than in one with more power.


Thanks for your reply Al.

Yes same dyno. When you say "tighter" what does that mean?

I could use more rpm drop on the shifts from my current 8" (700 rpm)

Thanks, Don
Posted By: cudadon

Re: 8" convertor stall change? - 03/11/18 10:02 PM

Sorry Al. tighter means less stall, and more rpm drop. Correct?

I didn't read your reply and let it sink in! DUH.

Don
Posted By: CMcAllister

Re: 8" convertor stall change? - 03/12/18 12:40 AM

It will be tighter. How much all depends on combinations, if it was set up correctly for the original car, engine stroke, weight, gear ratios, etc. 100HP less is a big deal if it's a 400HP piece, not so much if it's 1400HP.
Posted By: cudadon

Re: 8" convertor stall change? - 03/12/18 01:45 AM

Thanks.
Posted By: Leigh

Re: 8" convertor stall change? - 03/12/18 02:21 AM

I've always wondered why there isn't a hydraulic converter attachment for dynos. Seems long over due. Added cost: Sure. Last I knew ONLY B&M has a converter dyno. Ridiculous, I think. Sorry to go off topic.
Posted By: Sport440

Re: 8" convertor stall change? - 03/12/18 05:32 AM

Originally Posted By cudadon
I'm looking at an 8" convertor that came out of a car with about 100 hp and 90 lb ft of torque more than my engine.

What would this convertor do in my car?

How would the launch/stall be in comparison?

Thanks, Don



No one can answer this without knowing the weight and hp/torque of your car as is, And his cars weight. up Could stall higher or lower, but with a 8" vert. your in the 4500 to 5500 range depending on how its built.

If all else is equal, weight wise it will be tighter and stall a few hundred rpm earlier.
Posted By: Cab_Burge

Re: 8" convertor stall change? - 03/12/18 07:02 AM

Originally Posted By cudadon
Originally Posted By Al_Alguire
Were they both on the same dyno? If not those numbers likely will be different. It would be tighter, less stall and more drop on the shift in your combination than in one with more power.


Thanks for your reply Al.

Yes same dyno. When you say "tighter" what does that mean?

I could use more rpm drop on the shifts from my current 8" (700 rpm)

Thanks, Don

Have you tried revving the motor higher before the gear shift to get more RPM drop on the shift? If not maybe it will help you scope twocents
Posted By: A727Tflite

Re: 8" convertor stall change? - 03/12/18 09:04 PM

There is an very close calculation for stall speed if you know (from dyno testing) the toque of an engine. Horsepower means nothing, just torque in this calculation.



What is your exact torque in your engine?
Posted By: Anonymous

Re: 8" convertor stall change? - 03/12/18 11:46 PM

Converters are like rubber bands
I have had about as good a luck buying one at the swap--running it then getting adjusted
I would say if it was in a Mopar do it some Chevy 8 in units can be crazy loose but sounds to me like you will be fine
Converter builders get it more or less on try #1
After you get to know a converter guy and how his stuff works relative to what he says then you can do pretty good from that spot forward-- brand new builds are crap shoot without a good dyno sheet( and that is no promise if car info is off)--folks always say they have a 3,55 gear when i ask then they say they are "planning" on one in the future--so converter builders get a half dozen inputs like that so no wonder they struggle to Nail it
I say drop that unit in and have fun--should work great
should be tighter than in the other car but it really depends on tire diameter , gear, Car weight, etc
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