Which is stronger TH350 or 700R4?

[SSedan64]

The TH350 can be built to handle 600HP/TQ fairly cheap, above there it gets more expensive and a TH400 could be used & built cheaper.
Most of the Pro Builders shy away from the TH700R4/4L60 above 500-550 HP/TQ, a few claim theirs can handle 700 HP/TQ. The TH2004R can handle 800 HP/TQ reliably if properly built with some 4340 Billet parts, above that power level a 4L80E should be used.
For the 700R4 or 2004R Trans to be reliable & last at high power levels they should be built by someone who specializes in them. There're a lot of little tricks that make a big difference.
87-93 700R4/4L60's have the most Factory/OEM upgrades, many newer parts from the 4L65E/70E can also be used in the 4L60, 5-Pinion Planetaries, Drums, Output Shaft etc... Same with the 2004R Trans, 87-90, the newer the better.
Most any Shop can build a stout & reliable TH350 or TH400.

 

[DOUG213XRJ]

Any Transmission can be built to handle a lot of horsepower & torque, Even the 200 4R with the right hard parts. lol



Doug

 

[Pete@Hughes]

A TH350 can be built to reliably handle up to 850 flywheel horsepower and 700 - 750 ft./lbs. of torque.

A 700R-4 can be built to reliably handle up to 650 flywheel horsepower and 550 - 600 ft./lbs. of torque.

Vehicle weight, intended use of the vehicle, traction coefficient, and power adder use will all have an affect on max HP/torque ratings for these as well as any automatic transmission. Some builders make claims of building the 700R-4 for 800+ HP capability. While you may get limited use out of a 700R-4 at this power level, it will inevitably fail. A properly built TH350 will actually take the occasional blast above 850 FWHP, but long-term durability will become an issue.

Some builders claim 1,000 FWHP capability with the 200-4R. While we do not offer a 200-4R compatible with that kind of power, it is a good overdrive transmission design for higher-HP use with the appropriate upgrades.

The 4L80E is the best choice for a bulletproof overdrive. We have 4L80E units with 1,500+ FWHP capability.

 

[allisontech]

I agree the 700R4 even with Zpak ,Beast shell,5 pinion planetary,and sleeved input drum will not live long in a 3000 lb 700 hp car. I have them behind 500 hp Big blocks and the output shaft if stock, will still crack at the lube holes eventually if the car hooks hard. The 350 upgraded with a 34 element sprag on the direct drum will last much longer.