Quote:
Originally Posted by Ecky
This is peripheral to your idea, Logic, but Mazda is using the rotary again in nearly the exact way described - as part of a serial hybrid. Rotaries have many of the same characteristics (and drawbacks) of two strokes, and even have similar power density.
Best I recall, Mazda managed to greatly improve the rotary efficiency and emissions by coupling the rotor to a small motor, which actually slows down and speeds up the rotor during small parts of its revolution, to achieve different combustion chamber characteristics. One could similarly do this with a reciprocating piston engine, for example changing the dwell time or speeding the piston up as it approaches TDC.
I don't see why a two stroke could not be made extremely clean or efficient as long as it did not need to operate in a wide range of conditions. It's just a matter of implementation. However it would almost certainly need to be paired with a relatively large battery, given that the compromises of running outside its ideal conditions would be much more severe, and extra buffer would be needed to prevent that.
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Thx Ecky.
Yep I have been looking at rotaries for power density and wondering about their efficiencies etc at constant rpm.
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Mazda Iconic SP is both a beautiful car and interesting in that the plan is use a 2 rotor in a PHEV.
It looks to be pretty aero too!
NB the different left and right, mirrored mags that look like they suck some air out from under the car.
I NB that any engine designed and optimized for constant rpm is not only more efficient but a hell of a lot cheaper!
ie: A carburetor and old school ignition, properly tuned, is fine for constant rpm.
(Then tuned length intake and exhaust plumbing is always optimal and cuts down on emissions)
I have not looked into how large the battery needs to be to avoid varying loads on the 'genset' as the trend seems to be to make them large enough to cover the average trip distance with the engine off and a wall charge and that looks to be more than enough to avoid varying engine loads.
If one were to also use ram air to help induction and the vacuum behind vehicles to help extract exhaust and fill the vacuum, airspeed is the only variable, but a decrease in pumping losses should only require a decrease in fuel (leaning out) to keep keep rpm constant.