What Killed The Rotary Engine?

What killed the rotary engine? Wankel engines have struggled to compete with piston cylinder engines, despite their many benefits and overall simplicity. Rotary engines have a long, growing combustion chamber as the rotor spins, making complete combustion difficult - not great for fuel economy. They’re also difficult to seal, and since you have multiple chambers at different stages of combustion, proper seals between chambers is critical. To help promote a good seal, oil is sprayed directly into the combustion chamber. All of this results in an inefficient engine with terrible emissions. You might think that because all of these negative factors exist, it's done for good, but Mazda actually brought back the rotary engine in the MX-30, acting as a single-rotor range extender!

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[dannytu]

Great engine for a race car, terrible engine for a daily vehicle.

[iannordin]

Their critical flaw is that the same part of the engine that's supposed to make the seal is also the same part of the engine that is constantly being worn down via friction. Rotary engines literally destroy themselves as a consequence of their own operating principles.

[charliechristie]

I worked as a Mazda dealership tech in the early 70’s. I rebuilt over 300 of those little suckers. The biggest problem was the inner neoprene seal that ran around the rotor housing would fail from the combustion heat around the bottom between the spark and exhaust port. First they were round, then square, then we got a factory bulletin that came with super thin stainless steel “ seal protector” that we slipped between the seals and housing. That burned, too. The engine would act just like a head gasket with hard starting, running rough for a few seconds, blowing the coolant into the overflow. Mazda gave up and fazed the rotary out. It was very sad !!

[rkidy]

I like how in both the animated model and the physical model, the apex seals didn’t hold in either. Kinda shows the main weakness of the engine if you can’t even make a model that works lol

[noelmartin]

What killed the rotary engine?
Ans: Itself 😅

[RikAindow]

The rotary engine is probably the sole reason you can pick up an RX8 very cheaply. The cost of rebuilding the engine is very high.

[turnerjazz]

I used to sell Mazdas back when the RX8 was new. I loved test driving them and they were a blast as long as you drove them aggressively. I remember we had one come back with a blown engine after about 4 months because the buyer tried to drive it gently and keep it under 3000 rpm. The mechanics at the dealership said you have to drive them at high RPM for the engines to last. That makes them fun but that's a hard dynamic for the average consumer to get and be willing to live with.

[danielescobar]

They don't like being driven reasonably. Kept under load they last longer, mile for mile, than being grannied around in regular traffic

[chrish]

The issue we encountered is if you let off the key before it starts, the fuel washes the oil off of the seals. It was $1500 usd before we found you could pour a quart of oil down the intake to fix it.

[ohmygosh]

I have never seen a company trying this hard to convince us that engine design is good. Even if it means burning oil like gas. Simply amazing

[ImTHATguy...]

I've owned 12 RX-7s, my brother and friends have owned every rotary car/truck there is (yes, including a cosmo) and what really didn't help the rotary engine is NOBODY WANTS TO WORK ON THEM

[andrewedis]

I have an old RX7 and I love the way is sounds. It also loves reving really high but you gotta be careful getting it too hot.

[texaswunderkind]

My dad had a 1989 RX-7 convertible. The fit and finish on that car was amazing. It drove really nicely, and the automatic top sealed perfectly. In the frozen tundra of the north, however, it sat in the garage for four months while the snow melted, and blew blue smoke when he finally fired it up again.

[Connor_Streetmann]

I love the fact that you probably wrote off that bag of Doritos as business expense

[CristobalWatsonHernandez]

"What killed the rotary engine?"
It's design...

[cliffyknight]

I had an 80 something RX7. I loved it on the freeway. It felt like you could never redline. Fun stuff.

[DreamFSAE]

nobody followed the owner’s manual: after warmup, bring car to redline… fill oil regularly… (not in the manual: premix your gas)

[ShaneAgain]

What killed the market was the people who were used to driving and working on piston engines got rotarys, not knowing how to maintain them, blew them up, and conplained about it. While the rotary mechanics had minimal issues.

[kevriley]

I used to rebuild these wankels regularly back in the rx3/4 days. Always the apex seals. Rotor housing seals were equivalent to a blown head gasket really. Super smooth, quiet & high revving, but very thirsty on both fuel and oil.

[noname-sddt]

The rotary is like fireworks.
Bad for the environment
Loud
Annoying to others
Short lived
Expensive
But fireworks, although pointless are fun and always bring on a smile.