What are the advantages and disadvantages of running parallel (non-sequential) twin turbos on the same cylinder bank?

 

I'm not a very good technical person when it comes down to it, but dosn't it have to do with having the car make more power without the turbo lag. So basically one turbo spools at low RPM, while the other spools at a higher RPM. It makes the cars more driveable from the factory, while still putting out bigger numbers than one smaller turbo.

 

disadvantages: twice as many oil/coolant lines, intake/exhaust sections, heat sources.

Are we talking about a parallel setup (GT-R) or a sequential (3rd gen RX7) style?

 

less exhaust to equal size turbos

can be good if the turbos are small, bad if they are large.

unless you're talking sequential, thats a whole nother story

 

Whoops, clarified. I meant parallel.

Fritchard, don't really get what you're saying about less exhaust or bad if they're large.

 

can you clarify this a little more? you arent saying they are on the same exhaust manifold are you?

 

It also depends on how many cylinders are in your "bank". Are we talking 1/2 of a V8 here? Does one I6 count as a bank? I also assume that you're talking about equal total flow between setups? (ie. 2x 25lb/min turbos versus 1x 50lb/min turbo)

There is incresed exhaust flow efficiency by having fewer runners per turbo. This is the idea behind twin-scroll technology. That is one thing going for a twin setup over one single-scroll turbo. The other idea I've heard tossed around is that twin smaller turbos have lower total inertia than a big single, which helps them spool faster (assuming both setups support equal flow). This argument was countered with accusations that the inertia difference only applied to older turbos, and that newer turbos are designed with a lot less inertia per flow.

 

Disadvantage:

Having twice as much crap to go wrong... (2 Wastegates, 2 turbos)
Having less space two work with twice the crap of a single...

My $.02

 

only thing i could think of is that two would spool fast casue the each turbo only has to do half the work like instead of 20 psi on one turbo but 10 psi on each turbo but im probley wrong im not that great when it comes to shit like this but yes twice the headache

 

What I mean is instead of having (for simplicity sake, use a 4cyl) 4cyls feeding one large turbo, you'd have 2cyls feeding each turbo. Not such a bad thing if the turbos are the right size (smaller) but a big problem if they are larger. You need a lot of exhaust flow to spool larger turbos.

See what I'm sayin?