904 vs 727?

80fbody said

Is there a "rule of thumb" concerning how much would be picked up by going with a 904 instead of a 727? It would only be behind a 400hp smallblock in a dart. Likely a 12 sec. package (for now).

I've got to build a tranny either way as most of my stuff is 4 speed right now.

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Back in the '70's Chrysler and Turbo Action did a series of tests between a 904 and 727. The conclusion was that if both transmissions and corresponding converters are built to the same level, the 904 will be approx. .15 faster than a 727. This was behind small block SS cars of that day, which aren't near as fast as the same ones today Not sure if the did the test using Stockers also. But it wasn't legal to put a 904 behing an engine that came with a 727 from the factory back then.

I have a 904 in mine built by JW transmissions with a 2.71 low gear and the usual good bands, clutches, manual valve body, etc. Nothing "trick". I have run 11.22 at 3,540 lbs. without any problems. Regular servicing and a deep pan help as well as a good fluid. JW says to keep using whatever fuid I'm using in the trans about my Amsoil Supershift when I do bring it in to freshen every several years.