Suby Club

Just found some of the below information around - hopefully it helps some one out!

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With Subaru 2-stage turbo system. When it comes time to spool up the secondary turbo, exhaust must be diverted from the primary turbo. This is just like opening the wastegate - boost pressure and torque drop. Eventually the secondary turbo is producing the same boost pressure as the primary and it's put online and things are good.

There are some headers on the market that will allow you to run a parallel setup, however I have not heard of many people performing this mod to standard 2L B4's or GT's / GTB's in the Gen2's.



Here's an official description of how the last iteration of Subaru's 2-stage turbo system works:
 63749.pdf   394.86KB   21 downloads

And here's a description of an earlier version:
http://web.archive.o...Engine_spec.htm

what happens when the primary is getting a butt load of boost at 7000rpm? what happens when the secondry is getting FCUK ALL at 6000rpm?

Mate, not sure of the specifics, theory or results of any of this - I am not a TT expert, nor do I claim to be. I just hoped that this information would be of some assistance to TT owners!

That description pretty much sums up what I used to feel..

The parralell setup would be fantastic.. IF, both turbines were the same size..

having each turbo a different size, and different max RPM just wouldn't work as meant to..

The 2nd turb would lag on one side, while the smaller was firing up, and then at top rev the smaller would die and the larger would keep pushing.. hence why they are sequential..

but then again I ain't no engineer.. i'm working off what I think would happen..

But having 2 VF32's would be the hum-dinger.. or.. having 1 Garrett T03 High flowed would be even better!!

(Maybe even a T76 if you have a 14,000 rpm Boxer motor.. lol)

This is a T76 - http://www.mjmturbos.../images/T76.jpg

ahh screw it buy a V8, eh Brendan .

Can you not remap the ECU to open the exhaust gas vaulve sooner and stop venting boooost from the 2nd turbo ?

Fairly sure its a mechanical valve man, not a solenoid. Could be wrong though! Fairly sure its a mechanical valve man, not a solenoid. Could be wrong though!

Fairly sure its a mechanical valve man, not a solenoid. Could be wrong though!

Fairly sure its a mechanical valve man, not a solenoid. Could be wrong though!

its a mechanical valve thats operated by an electronic solenoid.

FYI, i am now running a 2.2 with parallel equal sized turbos, basically drives like a single. made 217kw @17psi on stock untuned ecu.

What turbos are you running Billsy?

What turbos are you running Billsy?

im running ported vf26/27 at the mo, the 26 has a modified secondary housing from a vf19 and im running en external wastegate
this is a temporary setup, ive got a garrett GT17 and a truck turbo to bolt on to it