Thread: Single wastegate on Twinscroll Manifold

Got a Holsett and I'm in the process of fab'ing a Twinscroll manifold....

I know ideally I want 2 wastegates OR 2 wastegate exits merged into one.
However... How badly would performance be affected if I were to install the wastegate flange with the opening reading from each half of the twin scroll?

(|) <--- That's how I imagine the wastegate flange being installed...

I know the wastegate placement is important to prevent boost creep and I know the twinscroll is designed to increase spool efficiency (without going too much into the other benefits of each)...

Thoughts?

That is perfectly acceptable, as long as you continue the separation of the pulse sides all the way up to the wastegate valve. So when looking into the flange it still looks like this:

its not a matter of how performance would be affected. Its a matter whether or not the one wastegate only dumping off two cylinders will keep the boost under control. Its been done before without issues for people wanting to run higher boost levels. You might not be able to keep the boost from climbing thats the only thing. Depends on the size turbo really and what your goals are. I dont have experience doing it but from what ive read you will get boost creep up top and depending on how much you want to run that is not necessarily a bad thing.

Im more of an open turbine housing guy. Not as quick of a spool but way better topend.

i concur, top end is better with open scroll. I may actually try an open housing to see how it does in comparison to the 1.06 ts housing I have now.