I'm building a twin-GT45 502; I currently have a 50mm, 6psi wastegate right at the collector on each side. The bypass is 50mm, or close to 2", on each, and shortcuts around the turbo right to the exhaust.

Should I expect to have any trouble controlling boost? Each of those is bigger than the factory exhaust pipe on my old Pontiac MarkIV 427, but you never know...

Thanks!
Dave

 

As long as the placement is good, I would say you're fine.

 

Here's the setup, as you can imagine it's duplicated on each side of course. This is just for the dyno, if I put it in-car I'd be a little more attentive to angles and flow, but... #ad

 

90* angle to flow isn't very good placement. But they are large enough it might not matter. Give it a shot. Ideally the turbo and the WG should trade places.

 

The glaring issue is not the wastegate placement or size (although it could be better, it isn't terrible); it is the angle of your turbos. They look to be nearly 45 degrees from horizontal. Your turbos will not drain properly, and you will have oil leaking into the turbine housing. There will be additional load on the thrust bearings. I really recommend reworking the headers and turbine flange to place the turbos horizontal.

 

Must be a visual illusion from the photo -they're maybe 15 degrees off plane. Thanks for the input though, if I wind up mounting them in a car or similar I'll take greater care to get them even.

I will measure though to make sure I'm not underestimating.