The Fixer

OK, so what's the advantage of two turbo's over one? I understand that two can flow twice as much air as one but what about lag? Surely double the back pressure would be very laggy?

Any Impreza's out there 2.0 litre or bigger running two turbos?

Is there enough room for two under the bonnet?

Nissan skylines use them to good effect on 2.6 litres?


Oh! Oh! I'm on one of my mad ideas again.....

David_Wallis

two.. exhaust is complicated on the flat 4..

can be done.. plenty of room.. legacy twin turbo manifold would do it...

Hard to control..

then its how you run.. sequential / staged etc..

David

Ive595

I'm looking into this at the moment, but have more questions than answers!

How does the legacy turbo run its turbo's Staged?
Does it have 2 boost solonoids?
Are the headers linked like a WRX or does each side run its own turbo?

Advise would be appreciated

Ivan

M0NEY

Shanes wrx in Australia is a 2.5 twin turbo with 400bhp atw and does 10.7 on the 1/4 mile.

Spoke to the guys who built it and they said they prefer single big turbo compared to 2

The Fixer

I would assume that both staged and sequential make good use of electronic wastegates and that the controller wastes all exhaust gases to the non required turbo up until the point the second turbo is required???? Then the wastegate is closed and "voila" second turbo on line???? Or something like that?

David, exactly which year legacey turbo manifold would I need????



Helter skelter he we go?

Cord

Sequential or staged turbo's are a no-no. They are just simpley to complicated to manufacture all the turbo and inlet manifolds. Twin turbo's are a very real possibility I have been looking into them for my 2.2
The advantage's of twins are decreased lag and masses of torque. But you have to have linked exhaust manifolds (to prevent shuffle) and also all the extra piping for your inlet and oil/water feed. Contorlling them isn't a big problem (but I have the advantage that I spend all my time working on skylines, so I know a thing or 2 about twin set ups)

The Fixer

Cord, how can there be decreased lag when there are two them to spool up? Surely theres more back pressure in the exhaust manifold/combined up-pipes?

Cord

Lag is decreased because the small turbo's have a lower rotating mass, due to their small wheels. So they (even tho recieving less exhaust gas) spin up quicker.

A single turbo skyline running a T78 came on boost around 5500-6000 rpm and produced about 650bhp, the exact same car when converted to a pair of 2835's came on boost 1000rpm sooner and made similar if not maybe 30bhp ish more. The power delivery was a lot more linear, and also carries on further into the revs when using twins. Twins are definately the way to go. But expensive to fit to a car that doesn't have them as standard.

The Fixer

That sounds good Cord m8, when you've done all the pipework, jig it and sell me a set...

Now then where did I put that pair of MD321 turbo's I had lieing around.

lol

Conrad

P20SPD

iTrader: (1)

Conrad, behave

Cord

Cheers i'll get right on it!!
Seroiusly has anybody got some pictures of a legacy twin turbo engine bay? Or an exhaust manifold?

LB4

Some-one did put up on here a while back a line diagram of a Legacy engine specifically showing the inlet / exhaust pipes ... if i can find it i'll add it.

Gary

hypoluxa

SYMS used to make a twin turbo manifold which paired 1&2 to turbo A and 3&4 to turbo B.

The Fixer

Marvelous! Things are developing nicely.....

Steven, It's not in my nature LOL

David_Wallis

any of the twin turbo legacys.. i believe it was on 22b when discussing the porsche etc.. think carlos posted it.