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-   -   Stall rpn vs cruise rpm (https://forums.maxperformanceinc.com/forums/showthread.php?t=853749)

Rar_421 10-06-2021 05:50 PM

Stall rpn vs cruise rpm
 
What's the rule of thumb on how much higher your cruise rpm should be over stated stall Rpm? Heard every thing from 100 Rpm to 500 Rpm

steve25 10-06-2021 06:55 PM

A lot depends on your cars rear gear ratio and how much excess torque your motor makes to sustain a given mph on level ground.

What cid motor are we talking about here?

Rar_421 10-06-2021 07:02 PM

350,17 heads, removed the st300 and rebuilt a th350 and found a deal on a Hughes 2000 stall,I have to determine my gear ratio when I can get to garage this weekend,but it's likely it has the standard 2.56 ratio,had planned on 3.36 gears this summer but work got in the way

Jay S 10-07-2021 08:28 AM

The difference in the flash and cruising couple depends a lot on the pedigree of the converter. The Hughes converters are pretty loose, they slip quite a bit very far (400+) under the stall. But a 2000 should work with what ever gear you want, it is basically stock. I would tend to agree with the 400-500 under for cruising though on a Hughes. A better more efficient converter can run 2000 under. I have a 4200 in one car that is coupled up by 2000, but open throttle it flashes to 4200, more efficient design than a Hughes, also much more $$$$. I have a 5400 race convert for Pro tree racing (very loose!). even it would hook good enough to pull the car 400under the flash. 100 rpm under sounds like something for a commuter bus…

67Fbird 10-07-2021 08:46 AM

as stated there is a big difference in convertor efficiency per maker. Best suggestion would be contact HUGHES. Not a BIG deal with only a 2000 converter and as usual instal with ANY automatic...add an PLATE type trans cooler!!

Half-Inch Stud 10-07-2021 09:25 AM

13" has the least slip and mush. Stock 60-70s Big Car thru GTO, tight as you know.
For some reason the 4L80 stocker for gasoline engines has a nice stall but plays tight on cruise, where is not worth locking it up.

12" Hughes "2500?" ought to play well. Great balance on low-slip, low mush with highway gears, nice flash on a 455.

11"-10" better seek ATI or other spendy, proven converter.

NeighborsComplaint 10-07-2021 10:56 AM

You're fine, You're in stock convertor territory at a stall speed of 2,000. It's not going to slip or overheat.


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