twin turbos...

is it at all possible to twin turbocharge a 4 banger? is there a minimum size it would have to be or what? and if you have to ask, im interested because i like the idea of twin turbos and nobody else has done it bfore, though tha t might be for a reason, i dont care, just is it possible or not.

there are tt 4 bangers i belive but can't think of them right now, but i am postive it has been done . and fyi this would go in the forced induction section not the trivia one.

there are tt 4 bangers i belive but can't think of them right now, but i am postive it has been done . and fyi this would go in the forced induction section not the trivia one.
sorry, couldnt find the forced induction section...

Most cars that are TT's have at least a V6, and for a reason. Each bank of cylinders push's a turbo to get the most out of the turbo.


If you used 2 Cyl for each turbo you could turn the turbine, but it wouldn't turn it very efficiently and you wouldn't get nearly as much boost as you would like. Plus there would be a lot of custom piping to make it work. If you wanted to TT a 4 Cyl. a sequential TT system may be your best bet.

It's just not done much anymore but it is possable.

I would stick with a single turbo, unless you are really looking for a novelty item to talk about. Performance wise... Stick with a single you'll get more bang for the buck!

Most cars that are TT's have at least a V6, and for a reason. Each bank of cylinders push's a turbo to get the most out of the turbo.


If you used 2 Cyl for each turbo you could turn the turbine, but it wouldn't turn it very efficiently and you wouldn't get nearly as much boost as you would like. Plus there would be a lot of custom piping to make it work. If you wanted to TT a 4 Cyl. a sequential TT system may be your best bet.

It's just not done much anymore but it is possable.

I would stick with a single turbo, unless you are really looking for a novelty item to talk about. Performance wise... Stick with a single you'll get more bang for the buck!
not that i have the money for the twin turbos or the piping anyway, but thanks for the useful info.

the thing is that it's just useless on an i4 engine. the reason people do it on v engines is becuausi it's easier to plumb everything. i think single turbos are slightly more efficient, not completely sure, but many people with supras swap out their twins for a larger single turbo.

the only reason i could see for doing a twin setup on an inline engine would be the wow factor. nobody does it so it would look different, but it would probably be a little heavier and less efficient.

there is one reason to go with twins on a 4 cylinder, and thats being a cheap bastard :icon16:

If your goal is 400 HP, for example, it COULD be cheaper to find two 200hp capable turbo's out of a junk yard vs finding/buying a single that would make 400hp by itself.

But thats the only reason I would ever bother. It'll be heavier, it'll have space issues under the hood with unnecessary extra piping, and it would perform the same as a single.

The ONLY reason to ever go for a twin setup, is if your engine config and engine bay make a single more difficult than a twin setup. There is no performance gains.

This is all assuming that we're talking about turbo's in parallel of course.

quick question:
turbos in parallel, this means that you have two turbo's, one on each side, coming from seperate cylinders?
sequential turbos means that one turbo "feeds" another?

if i'm confused, feel free to correct me.

in series means one feeds the others. In parallel means that they are independant, either they are fed off a common log, or they are ran from independant cylinders.

Sequential means you have 2 different sized turbo's that are fed through a log, but you have flappers or valves that isolate one turbo from the other, so that they are only engaged individually (if desired) for a portion of the RPM/throttle

im interested because i like the idea of twin turbos and nobody else has done it bfore

Have you not heard of a turbo subaru legacy?
They've been doing twin turbo four cylinders for around a decade. But they're boxer engines, not inline.

Do a search for: subaru RSKB4, subaru GTB, Subaru GT or Subaru RS.

I think they've gone back to a single turbo with twin entry for their latest versions though.

turbo's are now cheap and efficient enough that it would not be worth the time & effort on a 4cyl, like they said it could be done but not worth it at all. it just sounds cool to some people to hear twin turbo. most inline 6's with twins from the factory, when modified are switched to one more efficient power, that all depends on power levels and goals

turbo's are now cheap and efficient enough that it would not be worth the time & effort on a 4cyl, like they said it could be done but not worth it at all. it just sounds cool to some people to hear twin turbo. most inline 6's with twins from the factory, when modified are switched to one more efficient power, that all depends on power levels and goals
The twin 6's, i would keep a twin for, hopefully, faster spool on one or the other for a larger powerband, correct me if im wrong because i really dont want to screw up a 6 with twins from the factory

v6, yes i would keep them, i said inline i would go single

the smaller turbo in a sequential setup will restrict exhaust flow and become less efficent at higher rpm's, you are right about a broader powerband but less power.