CAR NEWS: "Hell freezes over, BMW releases M Performance Diesels (w/ video)"

**ghosthunter** · February 1st, 2012 11:22 PM

Hell freezes over, BMW releases M Performance Diesels (w/ video)
Words by Niky Tamayo | Photos courtesy of BMW Group

BMW's M Performance division has made a name for itself developing hardcore versions of its regular road cars. While Mercedes-Benz's similar AMG's are more like road-going locomotives, cars bearing the M badge have always had a reputation as razor-sharp race cars for the road. But in recent years, BMW's definition of M-cars has become somewhat more liberal.

Take the case of the BMW 1M Coupe, which was as hardcore as an M gets, but it had... gasp... turbochargers. And now, BMW is straying even further from the original M ethos with the M550d sedan, M550d touring, X5 M50d, and X6 M50d....

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**niky** · February 2nd, 2012 11:55 AM

Now if they would only put that motor in a 3-series and bring it here... No need for a 400 hp M3 any longer.

Hmmm....

Perhaps that's the reason why they didn't put the motor in a 3 series...

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When I wrote this, I'd forgotten that I had an old Autocar magazine which featured Mercedes' own tri-turbo diesel engine... the CDI 320. It was pretty cool for the time, with nearly 300 hp... but BMW's twin-turbo 35d motor has already surpassed that... and this one leaves it in the dust.

Rumors are Mercedes is mulling a 525 hp diesel for AMG...

**Ry_Tower** · February 2nd, 2012 12:00 PM

^ Kudos to BMW M for doing this. Just pushing the boundaries of auto tech to new heights for their cars!

**cripple_rooster** · February 2nd, 2012 12:44 PM

Originally Posted by niky

When I wrote this, I'd forgotten that I had an old Autocar magazine which featured Mercedes' own tri-turbo diesel engine... the CDI 320. It was pretty cool for the time, with nearly 300 hp... but BMW's twin-turbo 35d motor has already surpassed that... and this one leaves it in the dust.

Actually the tri-turbo setup is not really needed, even with a single turbo these power levels can be achieved, altough the turbo lag would turn into a severe issue to overcome. About the tri-turbo, it works as a twin-stage setup, with one turbo blowing hard since a lower RPM band with pressure from all the cylinders while the other ones blow each one from 3 cylinders but could be easily replaced by a single larger one. In the SLK-based Mercedes-Benz prototype presented with this setup, it was chosen because the twin-turbo setup in a V-shaped engine is usually preferred because it's reported to allow a better exhaust flow.

Rumors are Mercedes is mulling a 525 hp diesel for AMG...

That would be great. But would it be a V8?

**niky** · February 2nd, 2012 06:16 PM

It's strange that they went tri-turbo considering it's a straight six, but it's likely they have two smaller turbos attached to each bank for very quick spool up, and the third turbo is the high rpm one. Yes, you could do it with just two or even one turbo, but having driven a single turbo dual-scroll set-up that's only half as aggressive, I think that nobody will like the driveability characteristics of such a schizophrenic set-up. The turbo ramp-up would be ridiculous.

BMW already has severe ramp-up with the twin turbo 35d. It's possible this would reach Ferrari F40 levels of uncontrollable if they stayed with that set-up for the 50d.

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Rumors are a V8 diesel... but Mercedes denies such a system would go into their AMG program.

**cripple_rooster** · February 3rd, 2012 08:10 AM

Originally Posted by niky

It's strange that they went tri-turbo considering it's a straight six, but it's likely they have two smaller turbos attached to each bank for very quick spool up, and the third turbo is the high rpm one.

A single turbo would receive more exhaust "pulses", then spinning faster from a lower RPM band. And the other 2 for each 3 cylinders can actually have the same size of the 1st-stage turbo.