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-   -   Twin Turbo? (http://legacygt.com/forums/showthread.php?t=116201)

rockle3 07-11-2009 10:19 PM

Twin Turbo?
 
alright my flame suit is on
i have searched but not come across much


During a bbq today at my local shop, i came across a crazy idea. As the title suggests, I was wondering if a twin turbo set up was feasible with my 09 Spec B. Before we talk about getting custom exhaust manifolds etc etc etc. I had an idea of using one of the older Twin Turbo legacy exhaust manifolds or an aftermarket version of one for that year. I dont know about the fitment exactly but the boxer motor has not changed much over the years. Another problem is if there is enough room to fit the two turbos and two downpipes.

The older Twin Turbo model came with a 2.0 motor and with my upgraded displacement, I have no doubt that if I can fit the old turbos, manifolds, etc, I can push more than 300 hp with little to no lag.

Another thing I'm worried about is if the engine can handle the power. Will I need to build the motor? Will I need upgraded cams, pistons, etc etc.

Sorry for so many questions, but I also need to know, what kinda turbos do you guys thing i can upgrade to? obviously the car wont be able to handle two fp greens or more extreme, fp reds. What would be the max set up?

This build is just a thought. Although I am highly excited for answers, this build will probably start in half a year to a year after I have enough finances and have put in enough thought.
Thanks for putting in your time
Thanks in Advance LGT for your imput
-Elijah

MGV101 07-11-2009 10:44 PM

I know quite a few twin turbo users and they absolutely hated their twin turbo setup and envy our single turbo Legacy.

The low rpm performance with the smaller turbo wasn't exactly spectacular.
During the transition period where the second turbo is about to turn on there is actually a slight hesitation in acceleration as exhaust gas is being diverted to the second turbo while it has yet to spin up.

I have know an owner of a previous generation Legacy who had gone as far as converting their car to a single turbo system from a WRX since they hated the twin turbo system so much.

Subaru ditched their sequential twin turbo system on their newer Legacy for a reason. Still, I guess there might be a slight chance that you can come up with a system that is better than Subaru.

Aczwild 07-11-2009 10:51 PM

Dont do it, I have a friend who has swapped his '98GT to the TT setup, it just isnt worth it at all

terrangama 07-11-2009 10:52 PM

what about doing parallel twin turbo?

Darkness of Death 07-11-2009 11:12 PM

you mean one right behind another?
that is actually called a sequential turbo
as opposed to a twin turbo setup that is split like the older LGT

NSFW 07-11-2009 11:21 PM

Quote:

Originally Posted by Darkness of Death (Post 2533857)
you mean one right behind another?
that is actually called a sequential turbo
as opposed to a twin turbo setup that is split like the older LGT

:confused:

MGV101 07-11-2009 11:23 PM

Quote:

Originally Posted by Darkness of Death (Post 2533857)
you mean one right behind another?
that is actually called a sequential turbo
as opposed to a twin turbo setup that is split like the older LGT

Turbo on the older LGTs are sequential not split.
The full name is actually Sequential Twin Turbo.

Darkness of Death 07-11-2009 11:24 PM

2 Attachment(s)
actually i just looked that up
they are split
one on each side of the engine
but it's still called a sequential twin turbo setup.

i was thinking sequential twin turbo more of the one turbo in front of the other. i've seen pictures of them before.
not really like the first pic but the second one.

Richard B. 07-12-2009 12:23 AM

Quote:

Originally Posted by terrangama (Post 2533843)
what about doing parallel twin turbo?

i think the b5 s4 has that kind of setup.

monster power when modded.

MGV101 07-12-2009 12:31 AM

Quote:

Originally Posted by Darkness of Death (Post 2533873)
actually i just looked that up
they are split
one on each side of the engine
but it's still called a sequential twin turbo setup.

i was thinking sequential twin turbo more of the one turbo in front of the other. i've seen pictures of them before.
not really like the first pic but the second one.

Ah, so the confusion was simply due to the different understanding of terms used between us.

Sequential for me is where the turbo are being turned on in sequence according to the RPM.

When I read split, I though you were referring to two cylinder powering one turbo and another pair of cylinder powering another or at least the exhaust gas would be split and powering two turbos at the same time with no sequential activation. (or simply, a parallel design)

Planetary 07-12-2009 12:37 AM

Quote:

Originally Posted by MGV101 (Post 2533838)
I know quite a few twin turbo users and they absolutely hated their twin turbo setup and envy our single turbo Legacy.

The low rpm performance with the smaller turbo wasn't exactly spectacular.
During the transition period where the second turbo is about to turn on there is actually a slight hesitation in acceleration as exhaust gas is being diverted to the second turbo while it has yet to spin up.

This.

Over the course of my time in NZ I had 3 twin turbo legacys (94 auto saloon, 94 manual saloon and 96 manual estate) and always wished I had a single and enjoy my 09 far more than the others. The single turbo gives a nice kick at a lower rpm range.

The smaller turbo on the sequential diddn't give the omgboost feeling I love so much and although the second turbo was quite a kick in the pants, it diddn't kick into so high of an rpm that I diddn't really get to enjoy it often in everyday driving.

Maybe that could have been helped with a tune, but I wasn't even aware that was possible until I discovered this place.

MGV101 07-12-2009 12:37 AM

A really good article on the Subaru twin turbo:
http://autospeed.com/cms/title_B4-an...1/article.html

MGV101 07-12-2009 12:40 AM

Quote:

Originally Posted by Planetary (Post 2533911)
This.

Over the course of my time in NZ I had 3 twin turbo legacys (94 auto saloon, 94 manual saloon and 96 manual estate) and always wished I had a single and enjoy my 09 far more than the others. The single turbo gives a nice kick at a lower rpm range.

The smaller turbo on the sequential diddn't give the omgboost feeling I love so much and although the second turbo was quite a kick in the pants, it diddn't kick into so high of an rpm that I diddn't really get to enjoy it often in everyday driving.

Maybe that could have been helped with a tune, but I wasn't even aware that was possible until I discovered this place.

There are actually sequential controllers that could be installed to modify when the larger turbo would kick in.

However it is still a pain to set up as having the larger turbo kick in earlier doesn't always mean better. You need enough exhaust to spin it!!

Richard B. 07-12-2009 12:44 AM

you guys are thinkign to start with an ultra small turbo. i say let stock be the small turbo and a gt35r be the upper end turbo.

Verwilderd 07-12-2009 01:07 AM

I think fotment would be tough with that. But would be awesome to see that actually happen.


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