How does this sound? That’s a great question as this new Mercedes-AMG SL 43 roadster uses an electric exhaust gas turbocharger derived directly from Formula 1. Say what?
That’s right, Mercedes-AMG said the technology has been used successfully by the Mercedes-AMG Petronas F1 Team.
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In reply to J.A. Ackley :
Oof....hope it works how they want it to work.
I assume that it works like a generator when they want to curtail boost.
375hp... weren't they getting 425hp+ from the two liter already?
In reply to Pete. (l33t FS) :
Thing is... it's a lot more efficient to 1) put the electrical power directly to the crankshaft and 2) take electrical power directly from the crankshaft.
If they are doing e-boost, then it's highly likely that it's a 48V system, which means you have the system to run a good mild hybrid alternator.
I wish them luck but there are good reasons eboost isn't likely to be used widely AND why it's being taken out of F1.
In reply to alfadriver :
48v per article, yes.
I do wonder how much extra power they get from the engine via rapid boost response, vs. how much power it takes to get the turbo started.
I am assuming, here, that they still rely on exhaust flow to do the heavy lifting and the electric portion is just for transients. The heavy heat shielding suggests this is the case, else they would not need to mount the turbo there.
In reply to Pete. (l33t FS) :
I had that argument at work. The time lag for the e-boost is 1) how long it takes to build pressure 2) how long it takes for that new air to get into the combustion chamber, 3) how long it takes to combust that. Compare that to just the time to put electrical power to the crank. The transient holes are so much better filled by direct drive. So much better that you can oversize the turbo a little to not worry too much about lag.
(BTW, a 48v starter/generator that does a little hybrid work is an MHEV (Mild hybrid). Which by legal definition of CA is an EV)
In reply to alfadriver :
Reading between the lines, it sounds like they are prespooling the turbo when off throttle so that there is 20psi or whatever of pressure at the throttle body, ready for explosive throttle response.
I will trust your experience in this field, to be sure. I wonder how much is Mercedes wanting a certain driving impression, beyond actual performance.
I am somewhat reminded of the guy who mounted a jet engine in his hillclimb car, and fed his BDA engine a constant 30psi or so boost from the turbine's compression stage. Highly inefficient, but no possibility of turbo lag!
In reply to Pete. (l33t FS) :
There are a lot of cool and fun ways to use the e-turbo- no question about that. But they don't come for free. For some cars, that's an acceptable trade off. But for the gross majority of future cars, with CO2 rules, it's not- you have to best use what energy you have and can get.
That last part is one thing that has bothered me about other projects I worked on, where the desire for a ton of power resulted in lots and lots of boost that only could be dealt with via very retarded spark. Which is to say that the power was incredibly inefficient- hardly a good idea when that kind of power would regularly be used in a pick up that towed a 5000lb trailer.
Ever see an early Evo with a stock tune on track? They ran ignition timing borderline ATDC and so much fuel that they had visible exhaust smoke like an overtuned Diesel.
Meanwhile, Mercedes is rather proud of their high tumble combustion chamber geometry (or whatever the latest thing is) with something like 2.5 times as much as a traditional engine, allowing them to make 200hp/l turbo engines on pump gas.
I still vividly remember being shocked when I opened the hood of a full sized Sprinter van that I'd just driven and found that it had a 2l gasoline engine. Felt just like the 3l turbodiesel, except quieter.
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