A really efficient 60 turning a top heavy 91 or even the right 94 would work great IMO

 

Agreed. I could go t3 if I used a really big wastegate. The idea here is quick spool and low as possible back pressure with out running out of compressor.

 

T3 on the small side, t6 on the atmosphere turbo.

 

The big turbo will be the easy choice. The smaller one will be the most difficult to spec so it doesn't become a restriction... But in a setup like this, the small one will be come a restriction a some point anyway. It's just finding the right one that doesn't choke you out as soon as that big boy actually gets to work.

 

Just need one with a very good flowing housing. Maybe a big a/r on the compressor. The more atmosphere the little one "sees" the more efficient it should act. This way I should be able to have 15-20psi in the manifold with out over spinning the little guy.

 

subscribed,, looking to do a compound myself , haven't experimented much though,, keep us posted

 

You're going to end up needing a massive wastegate to route exhaust around the small turbo. They do the same thing on diesels but they run more boost and turn less rpm...so the small turbo on your setup will be more likely to overspin. Factor in $500 for that 60mm JGS...

 

You could run 2 smaller waste gates as well. Running different rates on each one would give even greater fine tuning ability by adding another variable.

 

Is it done yet?

 

this is what i have thought about doing. having one open before the other so it can regulate pressure better. if a big one opens too soon or fast it could loose boost before the big one can apply itself. with two smaller ones you can have the first one open on manifold pressure and the other one's reference hooked to the charge pipe between the two chargers. that way it would open as the big charger took over so to speak and of course one for the big charger itself.