Twin turbos with non compound exhaust, but with compound intake ?

[parkland]

Hi all,

I wanted to know what you guys think, and if this has been done before.
So far I know of compound turbos, where the exhaust manifold is channeled into a single conductor pipe, and travels through 1 turbo, then the other. And on the air side, same thing; air travels through 1 turbo, then the other, then to the intake. This is compounding.
And then, more commonly seen on gas v8's, I see there are twin turbo setups, where each header has it's own turbo, and 2 pipes traveling to the air intake.

What I'm wondering, is what about a 2 turbocharger system, where the fresh air is compounded, but the exhaust side is setup like twins?
If we pretended we were turbocharging an 8 liter v8, common sense tells me that a good twin setup could use 2 turbochargers from around a 4 liter engine, both feeding into the intake, and sharing the work.
If you compound the intake side though, a turbo made for 4 liter engines probably wouldn't flow enough for the 8 liter engine.

Is this where someone would have to spend huge money, and use tiny exhaust housings (roughly for a 4 liter engine), and larger compressor housings (roughly for an 8 liter engine) ?

But then the question comes up, this doesn't seem like it should work, as the tiny exhaust turbines would have trouble spinning the larger compressor turbines.... ??

It seems like someone must have tried this before, but maybe it's just cost prohibitive ?

:blahblah1:

 

[nwpadmax]

Won't work as you describe it. Small turbines will not make enough power to drive compressors that are much larger than the normal size ratios you see available from the OEMs.

 

[parkland]

Won't work as you describe it. Small turbines will not make enough power to drive compressors that are much larger than the normal size ratios you see available from the OEMs.

Thanks,
Thats sort of what I thought, and it makes sense, but it did seem like it could be possible somehow.

 

[Hurley]

the key consideration is that with a turbo you have shaft work (or horsepower) in from turbine, and you've got shaft work out from the compressor, which is always slightly less than the input due to losses from bearings, heat, etc. you can plumb the setup as described, but in the proposed scenario, there's not enough power available from the turbine side to run the compressor on the high pressure stage.