04-17-2009, 11:57 PM
I think he is confusing this with the Super Turbine 400 transmission that Buick used back in the '60s in the full sized cars. It has a variable pitch stator in the torque converter. it launches in high stall to give greater torque multiplication, and above a certain RPM/engine load (or a micro switch on the carb linkage) it would drop back to low RPM stall speed for greater fuel economy and less slippage.
I put one in my GSX, and it launches with a 3500 rpm stall converter, but drops back to a 1300 rpm stall converter driving down the freeway or around town. It is effectively like a 6 speed transmission. This is the transmission that the Turbo Hydramatic 400 transmission is based on. The 4L80E is the 4 speed overdrive version of the TH400, but lacks the mounting bosses and blocked passages in the casting to allow you to convert and make it into a dual stall overdrive 4 speed automatic. Its a shame, as a stock one is good for an 800 lb/ft engine, and way beyond that if modified properly.
I put one in my GSX, and it launches with a 3500 rpm stall converter, but drops back to a 1300 rpm stall converter driving down the freeway or around town. It is effectively like a 6 speed transmission. This is the transmission that the Turbo Hydramatic 400 transmission is based on. The 4L80E is the 4 speed overdrive version of the TH400, but lacks the mounting bosses and blocked passages in the casting to allow you to convert and make it into a dual stall overdrive 4 speed automatic. Its a shame, as a stock one is good for an 800 lb/ft engine, and way beyond that if modified properly.