i am trying to figure out if i should go with 2x 38mm tial wastegates or 1x 60mm tial wastegate. what is better for a greddy T88 going for 30 to 35 psi. anyone with info please help

 

Well, two wastegates should give you a very little better boost response in the 1,000-2,000rpm range from what I have experienced due to the manifold being completely pulse divided.

Of course, this assumes a full divided turbo as well.

A single wastegate with proper tubing will flow better because you have a collector and equal length primary tubes before the restriction/acoustic reflector of the wastegate thus providing scavenging just as in an exhaust header.

Much more important than single or dual wastegates would be the overall design of the manifold and wastegate runners intersection, tube size, bends and lengths, turbo selection and engine porting.

 

Run one gate. We had 2 on a low 8 sec Cobalt and for some reason we couldn't boost past 40 psi falling to 36 by the end of the track even though the turbo should have been good for about 48. We switch to one and the boost stayed at about 40 and picked up 2 tenths up top, this is now the trend in hot rod and pro fwd. I understand these were ecotec motors on meth though and not rotories so this post is probably completely useless to you lol. IMO tho 2 gates are better for response and one for accuracy. My 35red streetported streetcar has 2 v44's.