im trying to see witch one is a better set up. should i go with 2x 38mm tial wastegate or 1x 60mm tial wastegate on a Greddy T88. going for 30 to 35 psi. can anyone please help me out.

 

Why make it more complicated if one can handle your needs?

 

Well, the higher the boost you plan to run, the less work the wastegate has to do. You'll be absolutely fine with one. Two leads to plumbing nightmares.

 

Talk to Steve Kan over at gothamracing.com he's been fabricating dual WG manifold setups for along time. I'm sure he can answer your questions about the dual WG setup, and if you'll need 2 WGs for your setup...

 

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.

 

Running higher boost pressure you will only need one. Why would you need two to bleed off at higher boost pressures? Now if you were running lower boost you might want two wastegates to regulate the pressure. Get the gist?