PhineasFellOff

The technology has been tried before on piston engines. This fall, Honda will introduce an Accord Hybrid (with a supplementary electric assist motor) that will also have VCM (variable cylinder management), which will shut off one bank of three cylinders during hwy cruising to increase gas mileage.

Is it possible for the two-rotor Wankel to cruise on one rotor only? Could one rotor cruise efficiently and thus get greater mileage?

flatso

you can get that already on the new Chrysler 300 hemi

waldo

Gains are minimal. YTou have to figure that the now smaller engine has to work harder, using more gas. GM is gnning to use it in most of their vehicles soon, and projected savings are 15%. You can save much more than that by not driving so agressive.

jtimbck2

I remember when I was a kid we had a 1976 Chevy Caprice station wagon -- it had a 4-barrel carburetor that would cut back to 2 barrels for cruising.

Sue Esponte

Cadillac used to have a v4-6-8...horrible failure of an engine but the newer piston shut down technologies are supposed to be a vast improvement over the past. It seems like a neat idea but in the long run I wonder how much of it is really worth while in terms of fuel savings.

-Eric

GiN

My 1981 Coupe DeVille had that 4/6/8 thing. It didn't help diddlysquat. :D

Gigolo Jason

The rotary engine works like a pump. It is constantly moving and sucking and blowing. I supose it could be done iwth indipendant throttle bodies, controld systems, and fuel systems for each rotor, but not as it stands now.

I would also argue that this would increase wear on the rotor that is shut off and not allow the engine to balance itself properly while running.

Senseny

Wouldn't the engine need two separate e shafts that are independent of the other for that to even be a possibility.

mamccubbin

I had a Datsun 210 that only had three of its four cylinders working. Does that count?

Doctorr

Like Gigolo Jason says the rotary is basically a pump, if you shut off fuel and spark, it would still be using energy 'pumping'. If you shut the throttles, it would get worse, trying to pump a vacuum.

The piston versions worked by leaving the valves shut all the time, causing an 'air-spring effect'. The piston would compress the air, then be pushed down by it, with little net loss.
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ricks8

Actually, Internal Combustion Engines are most efficient when operating at full throttle. Sounds counterintuitive, but thats why a flogged econbox gets better milage then a muscle care limped along.

See this article

http://www.caranddriver.com/article....&page_number=1

IKnowNot'ing

Exact and the system works by entrapping combusted gases (instead of fresh air) into the chamber in order to keep it warmed-up.

cas2themoe

I heard of that last year, their were testing it out in Chevy trucks

zoom44

we had this discussion some time ago in this thread and as mentioned- you dont need to shut off one whole rotor just skip a cycle per rotor. but this question on our urging was also put to Mazda by rotarynews.com and they answered "No". i think they are working more towards hybrid and hydrogen to increase fuel economy and decrease emissions

88gt

No it's not feasible. The e-shaft won't allow it.

Gigolo Jason

They are most efficient when at full throttle and at full RPM, yes, but they are not designed to run continuously at this pace. Most piston auto engines are designed to run at 30% of there rated power continuously. The opposite end if piston aircraft engines that are designed to run at 75%-80% of there rated power continuously.

The currect e-shaft won't allow it but double e-shafts have been produced in the past. The 20B had a two piece e-shaft.