Everything that I have read says that you can get more flow on a 4 bolt. No experience though. My 4 bolt on the Nissan is a puny T-28, but it is suppesed to make 350 horsepower (flywheel).
After talking to a John Craig, the 3 bolt housing is a pretty big restriction. A 4 bolt housing will out flow a 3 bolt by a large margin. The Buick setup is pretty restrictive.
Originally posted by Taffy After talking to a John Craig, the 3 bolt housing is a pretty big restriction. A 4 bolt housing will out flow a 3 bolt by a large margin. The Buick setup is pretty restrictive.
For what its worth, my buddy has the 4 bolt version of the PT 61 and I have the 3 bolt version and spool up is the same. We have em on a 2.0 DOHC 4 popper.