Aron9000

Rotary engines are great in race cars, they don't really work in road cars. You can rev the **** out of them all day long and they don't break on a race track. Mazda won the 24 Hours of LeMans in a 4 rotor prototype car. That car made 900hp naturally aspirated out of 2.6 liters of displacement. They then banned rotary engines the next year.

The thing is they don't like the type of use a street car gets put through. They never could figure out how to keep the apex seals together on street cars(think of it as the piston rings on a normal engine). The engines use a lot of oil(by design), so that is another reason they fail, people don't check the oil. The apex seals can also fail from excessive carbon buildup, this is caused by sedate driving and not revving the **** out of it. There are a number of other ways to break them as well, including a clogged cat converter.

Sulu

There is, in fact, such a thing as a rotary piston engine, but because of its large frontal area, it was not used in automobiles (that I know of). It featured a odd number of cylinders arranged in a circle around the central crankshaft but the strange thing was that the crankshaft remained stationary and the whole crankcase and the cylinders spun around it.

mmarshall

Rotary engines also get poor gas mileage, mainly due to the fact that the rotors, as they spin, have more spark-plug-firings per rotation than you find in typical four-stroke piston engines. Lousy gas mileage will work against you in racing, as you obviously can't make time on the track if you're constantly in the pits refueling.

They burn oil because the small lubricating film of oil on the apex tip-seals constantly burns off and gets replaced as the seals whirl around during each rotation and are exposed for a split-second as the spark plugs light off in the combustion chambers. That's why constant oil pressure (and oil-supply) in a rotary is even more critical than for a piston engine. The small amount of (normal) oil smoke, of course, is usually burned up in the catalytic converter after it warms up...but that's why rotary-engined cars need strong efficient converters.

mmarshall

Rotary aircraft engines, which spun around their own crankshafts, were installed in a few early aircraft dating up through World War I, but were almost never used after that. They were horrendous for early pilots, because the aircraft had to contend with not only propeller-torque from the spinning prop-mass, but also the huge torque from the spinning engine-mass as well. This naturally made the plane want to do constant banks and rolls in one direction, unless corrected by strong aileron and rudder action...especially at low airspeeds when the flight-controls were less effective. It also made the plane highly unstable in some handling maneuvers, and prone to vicious stall/spin characteristics.

Aron9000

I think you hit the nail on the head as to why we will never see another rotary engine in a production car. With current regulations, they use too much gas and pollute too much. Cat converter failures on the Mazda RX-8 are common, and can lead to increased exhaust gas temperatures, which once again can lead to apex seal failures on the rotary engine.

geko29

Ah, I must have missed the word piston in the question. Thanks for pointing that out.

Lil4X

Except for the steam engine questions I think I had this quiz in 8th grade shop.

30/30 in bed, half asleep. Maybe that's the formula.

mmarshall

I agree it wasn't particularly difficult (the majority of posters here got all or almost all of them), but the really difficult tests don't seem to published on-line.

Byprodrive

iTrader: (1)

Designed by some guy named Ferdinand Porsche, I wonder what he did after the war?

mmarshall

Though it is not particularly well-known except among auto-historians, Dr. Porsche actually used an earlier Czech vehicle-design called the Tatra as a reference for the first VW Beetle. The Tatra was also rear-engined, air-cooled, with a swing-axle.



Dr. Porsche died in 1951, so he wasn't really around that long after the war. He was spared what probably would have been great sorrow for him to see the famous young actor James Dean get killed in a Porsche Speedster. In 1955, a Ford sedan pulled out right of an intersection in front of him, and Dean couldn't stop in time, even with the Porsche's good (for the time) brakes That, of course, was before the era of seat belts for most street cars.