Well as far as twin turbos go, there are a couple of different ways to set them up. one is to have two turbos feeding into the intake theby making more boost than a single turbo, or you can use a small turbo to provide boot to a bigger turbo to help it spool up faster, and using the boost from the big turbo to feed the intake. I believe the second method is the best way to go since putting two turbos on a single exhaust manifold would essentially cut the airflow to each on in half. if you had a V6 or V8 then the first method would be too bad, but you could also aply the second method twice, and end up with quad turbo.
Accually, if I was gonna TT a car, I would put a smaller turbo for quick spool, because a big turbo has mondo turbo lag, you have a smaller turbo to spool up first, then, about the time the small turbo quits pushing, the big turbo kicks in, thus giving even more power. Would be awsome to see a TT Escort, but dont think it could happen without spending alot of money
Thats called a sequential Twin turbo, cars like the Subaru Legacy, including the Wagon use sequential TTs to give the heavier car more grunt and low rpms. Even though the Legacy Wagons have 2.0L Flat fours, (aka boxer engines) I bet if you could find a Legacy wagon TT in the junk yard you could rip them out and find a way to stuff them on the EGT. All you´d have to do is find some custom piping and re-chip the ECU.
Okay, hate to be the pessimist, but (you know the J-Lo sized one too) Its a hell of a lot more work then you think it is. Finding room under the hood to do would be a nightmare. Using a method of dividing the turbos to two cylinders ISNT really a good idea. Realize that your cutting the exhaust flow down, so you´ll get BAD lag, and re working the intake manifold is more then a ecu reprogram. I think the worst part of seperating the turbo´s is sequencing. Remember the GT fires 1,3,4,2 (I think) Either way its not going to obtain a desirable flowrate.
A sequential turbo set up would be more efficient with low displacement, however, once again finding room under the hood wouldn´t be fun. Even if you used a really small T25 (motorcycle turbo) to spool like a T3/T4 hybrid, you´re still not going to hit the sweet spot in terms of rpms of the turbine without a ton of work. A T3/T4 hybrid is most efficient (thinking of a Garrett) like around 18-26psi. I´m not saying you couldn´t find a great mate between too turbo´s, but I am saying that I really dont think its worth the work. If you used a VJ23 ballbearing turbo and built the scort able to push 14-20psi most of us would be too scared to drive the thing.
I´ve got to agree with Jason on this one. trying to shoehorn in two turbos is not worth the time and effort. Besides if you really need to spool things up faster at the strip just add a shot of nitrous. lots easier. To answer the question about the subaru legacy - no not many were made with a turbo.
It wasn´t just the legacy´s that were made with twin turbos, I just couldn´t remember the name of the other car, but i do now! Let me tell ya before I forget again, it´s the B4 RSK, sedan and wagon versions. Not sure how many were made with TTs but I know some were. If you play Gran Turismo 2 for PS1 you can buy twin turbo´d B4 RSKs, they´re pretty slick for being such heavy cars.
Never heard of a TT Dodge Shadow, my sister owns the 4 banger sedan version, and a good friend of mine owns the 6 banger coupe version of it, didn´t know they came as TTs, unless that was what the owner had done in his spare time....
hmmm.. talked to the guy.. apparently only single turbo... and i looked at the car.. i swore i saw twinturbo... or esle where did i see it to make me think of it.. anyways.. yup dodge shadow.. single turbo