220/250d twin turbo, 350d single turbo

[Markssl]

Just wondering why the 4 pot Diesel engines get twin turbos and the V6 gets a single.
My first experience of a 3.0 litre diesel was a 2003 530d. It had a great take off but narrow power band. My next car was a 535d with twin turbos. This drove way better with power available across the whole rev range. My E350CDi seems to have a wide power band and behaves more like my old 535d. Anybody an expert on this care to explain?
Thanks


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[geraldrobins]

You don't say how old your E350CDI is but engine technology has moved on in over 10 years.

 

[grober]

Variable vane turbo technology /better intercooler---- could be anything|? I believe emisssions did for the OM651 twin turbo setup

 

[Andyfkettle]

I believe the C250d twin turbo has one small turbo to reduce lag and a bigger one to give it the beans! I’m guessing the 350 has enough get up and go to only need the one, also as above no doubt aids emissions.

 

[Turbo1]

The turbo sits within the V of the om642. I doubt there’s room for two.

The 535d was never that big a seller compared to the 530d etc - it perhaps wasn’t worthwhile re-engineering an engine for sales.

I believe the predecessor to the OM642 was a straight six and Mercedes moved to the V to fit the engine to Vans and possible transverse mounting applications


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[Markssl]

You don't say how old your E350CDI is but engine technology has moved on in over 10 years.

Mines registered 20/12/10. It’s the 265hp.


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[Markssl]

I believe the C250d twin turbo has one small turbo to reduce lag and a bigger one to give it the beans! I’m guessing the 350 has enough get up and go to only need the one, also as above no doubt aids emissions.

There’s no noticeable lag with the 350.


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[grober]

Green Car Congress: Mercedes-Benz introducing new diesel family in E 220 d this spring; new OM 654 with 13% lower fuel consumption; diesel “indispensable”
this article shows the raft of engine improvements with the OM651 4cylinder replacement the OM654.
The eagle eyed will notice a slightly reduced power and torque bandwidth at slightly higher RPM's but couple this to an auto box with many more ratios and you can still keep it in the appropriate rev band??
Mercedes havn't abandoned the twin turbo concept because the new straight 6 cylinder petrol has two turbos the difference being the small first turbo is electrically driven.

 

[Andyfkettle]

Robbed off Wikipedia referencing the 220-250
Although all engines have the same 2,143 cc swept volume, engines with various power outputs are produced ranging from 120 ps (badged x180) through 170 ps (badged x220) to 204 ps (badged x250). The 170 ps and 204 ps versions employ a twin-turbo charger with a small, high pressure turbo providing quick boost at low RPM and a large, lower pressure turbo providing increased performance at higher RPM. The 100kW lower output version has only a single turbocharger.

 

[Mr Filipov]

The 350 runs a variable geometry turbo. It has vains inside which are vacuum operated. At lower rpms they will be shut and act as a small turbo (thus reducing lag). As you get higher up in the range the vains open and the turbo is then in full force. If you have had a look it is not a small turbo by any means.

 

[Markssl]

The 350 runs a variable geometry turbo. It has vains inside which are vacuum operated. At lower rpms they will be shut and act as a small turbo (thus reducing lag). As you get higher up in the range the vains open and the turbo is then in full force. If you have had a look it is not a small turbo by any means.

So that’s why it’s completely different to the single turbo cars I’ve had previously and hence why it keeps pulling all the way through the rev range.
Great, thanks for the post


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[Mr Filipov]

So that’s why it’s completely different to the single turbo cars I’ve had previously and hence why it keeps pulling all the way through the rev range.
Great, thanks for the post


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Technology has moved on since then. Obviously the bigger the turbo, the more top end you will have. Other than that you have all sorts of systems and management code in the ecu to make sure everything is done precisely etc.
There are many reasons. I am not a guru, nor am I claiming to be, but diesels have come a long way since 2005. A gearbox in a car make a big difference as well.

 

[Markssl]

Technology has moved on since then. Obviously the bigger the turbo, the more top end you will have. Other than that you have all sorts of systems and management code in the ecu to make sure everything is done precisely etc.
There are many reasons. I am not a guru, nor am I claiming to be, but diesels have come a long way since 2005. A gearbox in a car make a big difference as well.

I assume my 08 330cdi would have had similar 2 in 1 turbo technology too as it also pulled like a train right across the range.


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[Turbo1]

Technology has moved on since then. Obviously the bigger the turbo, the more top end you will have. Other than that you have all sorts of systems and management code in the ecu to make sure everything is done precisely etc.
There are many reasons. I am not a guru, nor am I claiming to be, but diesels have come a long way since 2005. A gearbox in a car make a big difference as well.

Yes. The newer 9 speed boxes are incredible.

The w213 e350cdi cracks 60mph in 5.5 seconds with just 254bhp. My car with the 7 speed takes 6.9 with 231bhp.



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