Two Stage Turbo

[Lextreme II]

I found this article doing research on Dodge Sprinter Van:

New Sprinter introduces two stage turbocharged diesels
Mercedes recently introduced regulated two stage (R2S) turbocharging on the four cylinder diesels of the new Sprinter vans. R2S turbocharging was developed in cooperation with Borg Warner Turbo Systems in Kirchheimbolanden. To meet the growing demands regarding power output and emissions, it solves the conflict of optimum output and high boost from low rpm with two sequential large and small turbos. The four cylinder diesels probably wont make it to the USA, though. And the six cylinder OM642 in the new Sprinter uses variable nozzle turbine (VNT) turbocharging instead. Earlier Shelby offered VNT already on the '89 CSX-VNT. However it proved unreliable due to the high exhaust temperatures encountered in gas engines.

 

[Tomasberkut]

Good for diesels, wont work in a gasoline engine properly beacause of high backpressure.

 

[XR8tt]

Diesels like pressure ... Gas engines work different..

 

[mshawari1]

see the new Ford 6.4 L diessele engine with two turbo in serial .... one of them is VNT

 

[XR8tt]

In series.... As apposed to parallel as in some Japanese engines...
The VNT does a great job. We have some Hino's, Mitsi and Isuzu trucks at work..EPV's [cherry pickers] The new direct injection etc helps also...Way better than previous models...

 

[Anaema]

what is on the diagram would work just fine for a gasoline engine. it wouldn't be practical though. i've looked up compound charging(what is in the diagram), it is really only good for racing on gasoline engines. and when they aren't running on pump gasoline.

 

[XR8tt]

Mazda's RX7 turbo was similar with its sequential twin turbo ...But realy a GOOD single will do the job...If they can get VNT to work on gas engines ? It would be far less complicated...

 

[Tomasberkut]

If you want to have really high boost pressures look at turbos with secondary guide vanes on the compressor side. Holset if one of those producers, i dont want to lie but i think boost up to 3.5 bar is within reach.

Still the question is: what one wants to achieve. I really cant find compound charging practical on a gasoline engine. It would have a chance of working as a 2 stage compression but parrarel turbine setup with a throttle body on the bigger turbo. Is anyone planning on 5 bar of boost ?