What do you think about Wankel?

Question

(the engine)

Answer 1

The Wankel has a lowly beginning in Germany, first fielded in a commerically available car called the NSU. However, the rotor tips in the NSU had very low durability and often wore out in 10,000 miles. Later it was liscensed to Mazda who greatly improved the tips, and put it in various cars in the early 1970s, the RX2, the RX3, the RX4 and the Cosmopolitan, among others. By then the durability had reached about 60-70,000 miles, but Mazda offset the still relatively low mileage failures by offering very inexpensive long blocks. ABout the same time Mercedes built a C-111 prototype that was Wankel powered, but was extraordinarily expensive to produce and was never marketed.

Mazda discontinued US sales of Wankel powered cars after 1976, as I recall, until it reintroduced one in 1979 in the RX7. Mostly, this hiatus appears to have been a function of the engine's pollution problems, as the rotors chasing the fuel/air mix around the sort of figure eight shaped combustion chamber do not acheive sufficient compression to fully burn the fuel, and at least back then Mazda was attaching a ceramic-lined chamber outside the exhaust ports to burn off the 30 percent or so of unburned fuel that the engine emitted.

Gradually Madza made all sorts of improvements in ignition and exhaust systems that increased the engine's efficiency and horsepower output, peaking, at least in the RX7 models with a twin-turbo version that was extremely fast. The RX8, as I understand, has still more improvements.

Generally speaking the advantages of the Wankel engine are incredibly high redlines and a relatively flat torque curve. They also put out an enormous amount of horsepower for such a small block, although there is some controversy within the automotive community as to precisely how the volume of the combustion chambers should be calculated.

The disadvantages are that for such a small engine it certainly consumes a great deal of fuel, and the pollution problems associated with the design require a lot of engineering to overcome.

Still, I owned one of the old RX7's and had some friends who raced Wankel engines up at a short track at Summit Point, Maryland quite successfully. I got to take a ride in their race-prepared RX3 and was amazed at how much horsepower they had extracted from a 1.3 liter engine. All in all, I think the Wankel-engined Mazdas are pretty good cars, and a lot of fun to drive.

Answer 2

I would say the rotary is an interesting idea but it contains an inheirt design flaw that allows large amounts of unburned hydrocarbons to escape into the exhuast.

It does give a ton of power for its size but once they get some miles on them they are the dirtiest engine out there. Hard to pass emission tests without rebuilding the engine.

Its a little light weight power plant well suited for a small sports car. Which is why so many people are emotionally attached to the Wankle... they LOVE their RX-7 / 8. But if the engine really is so superior one must ask themselves, "Why doesn't Mazda use it for all their cars?"

Answer 3

It's a great invention. It has improved quite a bit since the first rotary engine militar "jeeps" were manufactured. Pistons waste energy that can be felt as vibration. The rotary rocks.

Answer 4

I have no prob with it. As long as the owner does do scheduled maintenance. For instance in the RX8 u will lose about a quart of oil for every oil change. The reason being, as the rotary spins it takes oil in with the fuel mixture, which is normal.

Answer 5

rotary engines are for suckers

Answer 6

Never heard of it.

Answer 7

Don't do it or you'll go blind!