MAGK944

It's been done by Mercedes F1 for some time now but I'm curious why this hasn't been taken up by any other manufacturers on a regular basis. Splitting the turbine from the compressor seems like an easy way to run cooler intake temps and gain more power. Thoughts?

V2Rocket

this thread is the first I've heard of this.
sounds like they just make the center shaft linking the "wheels" a bunch longer?
good idea for heat and packaging (you could put the turbine behind the engine say above the bellhousing and the compressor up front like a centrifugal supercharger)

as to why not picked up more..."regular" cars aren't constrained by the level of packaging and aerodynamics that the F1 stuff is, and making such a turbo is probably fairly expensive vs a run of the mill "traditional" garrett or mitsubishi unit

rellim

jet engines do it , but the turbine becomes the hottest part

odonnell

Just spitballing, but having them remote from each other puts a lot of mass into the shaft - mass that must be accelerated rotationally during spool. Not a big deal for a high budget R&D racing team, but possibly a hang-up for "pedestrian" turbo setups. That and physically installing/removing the turbo would be a way bigger deal.

MAGK944

I cannot see how it could be that much more expensive, you are simply inserting a longer shaft between the turbine and the compressor wheels. It just makes sense to separate the hot and cold sides. If you imagine in our cars the turbine would sit where it is now and the compressor would sit where the alternator sits.

Northern_aqs

Packaging aside, overcoming the inertia while building boost would be an issue. More lag on a street car that may not be an issue for an F1 package where revs and air flow never drop to comparable levels. I compare it to a low mass flywheel in between the two ends.

For compound boosting, using an electric motor to spin that shaft, its a great concept and already on the drawing board I understand.

Voith

Also material of the shaft is gamma ti which is much lighter than the inconel used in most stabdard turbos.

rlm328

I would like to know how much heat in the compressed air is from conduction from the turbine to the compressor side vs the actual compression of the air. I am going to take a wild guess and say the compression process is the major contributor.

MAGK944

I am wanting to agree but have my doubts. I understand that quickly compressing air will cause quite a lot of heat in itself and that heat transfer is a relatively slower process, however isn't there a point where heat soak from the turbine will prevail? Also, if that was the case why would Mercedes even bother to develop a split system AND at the same time run smaller intercoolers, there must be a significant cooling effect somewhere.

Voith

Like in refrigerator, AC or any other heat pump, gas when compressed releases heat. Turbine split from compressor is not a good turbo design that's why its not been used anywhere. Mercedes achieved very tight engine package with it so that's why they use it.

Interestingly, the solution came from mercedes truck development division.

mikey_audiogeek

+1

Mike

Laust Pedersen

It is actually shown in the video from 1:52 to 1:57 and in full use in F1 racing.

If you look at this video from 1:50 to 1:55 you will see another explanation for the separation, namely the need for a rather long electric (3-phase AC) motor. The concept also known as "torque-fill".


I have temperature sensors on the compressor outlet of my turbocharger and just after the throttle body (mainly to evaluate the characteristics of the intercooler). At cruising speed both temperatures are approximately the same, namely about 70 F in the winter time and 100 F in the summer time (Southern, CA weather).
Under short heavy boost compressor air temperature goes up to about 300 F, while the after throttle temperature has barely changed from the cruising temperature.

Laust

mel_t_vin

Laust, is the factory IC still responsible for this observed ~200*F delta between compressor outlet and manifold inlet, or are you using an aftermarket setup?

Laust Pedersen

This is the factory IC setup.

In my case the full boost is 25 psi, but typically for no more than 3 seconds. For that brief period the aluminum IC acts as a heat sink. In my opinion the factory IC, its placement and shrouding are well-engineered.
On the track, with a much higher boost duty cycle, the temperature may creep up, but I would still question the value of installing a large IC, which increases spool-up time.

mel_t_vin

Factory IC...impressive. Thanks for your observations.


Agree.