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Well im plannin on punching out my 350 to a 383 and reaching around 425 horse. My question is how much does my stock automatic transmission hold. I do understand i will need change out my converter since i will be goin on a pretty heavy cam between 480 and 510.. Please advise with any ideas or how i should proceed and information on that transmission!
 

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which transmission are you talking about useing ?
and are you willing to upgrade your current trans,or swap transmissions

both the stock th350 and 700r4 are designed for a 350ft lbs tq, limit and under 5500rpm shifts ,both can be upgraded to handle about 450ft lbs with the correct parts but youll be far better off with an upgraded TH400 or 4L80E, a good heavy duty trans cooler, a 3000-3500rpm stall speed converter and a 3.73-4.56 rear gear, if your beating the hell out of the car, and expect it to preform.
don,t be mislead by transmission adds that say the trans holds 500hp-700hp etc, its heat and tq that kills transmissions, not hp

keep in mind the formula for hp is torque times rpm divided by 5252=horsepower

so 350 ft lbs at 5000rpm =333hp
250ft lbs at 7000rpm = 333 hp
350 ft lbs at 7000rpm= 400hp
450 ft lbs at 3500rpm =299hp
but I can assure you that the lower hp, higher tq will kill the trans first in many cases

a well designed N/A 383 can exceed 500 ft lbs of tq, and twist up parts easily add a healthy nitrous kit to that 383 and 700-800 ft lbs of tq are possiable


http://www.transmissioncenter.net/4L80E.htm
 

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A 350 will take a surprising amount of (ab)use. I built one 10 years ago for a 67 GTO that's raced every weekend and it's still in there. Use the 34 element sprag, take all the wave plates out and replace with flat steels and use red clutches. THat and a trans-go kit setup for hd-performance. Set all the clutch packs up at the low end of the specs, (minimum clearances) and go.

Pretty much the same stuff for a TH400, except use clutchs and steels for a 4L80E.

IT takes about 25 horsepower MORE to run a 400 than it does a 350, just because of the additional mass.

:cheers:
 

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The ONE thing that amazes me is, you saying 25 hp differance in trannies....I find that freekish.....25x746= 18kw.....that's more than all 4 burners on your electric stove at once....talk about a COOLING problem....dissipate THAT amount of heat take a freeking waterfall to cool it...NIAGRA.....

good thing we don't do that on the street very often, or it would last about 2 minits, or less....

no matter what....
 
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