Why Rotary Engines Kinda Suck

The RX-7, the RX-8 and the 787B race car all have something in common - the rotary engine. The famous spinny ‘Dorito’ holds a special place in any petrolhead’s heart as a key part of JDM car culture.

So, why is it so popular when it’s so damn flawed? They’re terrible on fuel, even worse on oil, they can be expensive to fix AND their torque figures are pretty weak.

Let’s take a look at why rotary engines kinda suck and why they might actually be making a comeback.

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Japanese performance cars are hugely popular, with the used car market for ‘90s JDM icons absolutely booming at the moment. And that’s because, if you want a rotary - you have no choice but to go used - as no current new cars use them.

Anyway, the Supra, the Skyline, the Evo and the Impreza are just a few examples of the Rising Sun’s offering of attainable performance cars.
These were turbocharged, often motorsport-derived saloons and sports cars that offered a hell of a bang for your buck. Cars like the R34 GT-R and MK4 Supra gained a reputation for being giant killers with huge tuning potential.

However, they've all got something in common - they’ve all got old-fashioned piston engines. Want to stand out from the crowd? The RX-7 is the one for you.

Sure, it wasn’t the first rotary-powered Mazda, in fact there were a fair few before it. There was the Cosmo Sport, the RX-3, the RX500 as well as the world’s first and only rotary-engined pickup - the REPU (Rotary Engine Pick Up) among many others. The RX-7, however, was part of a golden era of Japanese performance cars that really made it desirable.

#RotaryEngines #RX7 #Wankel

[Mr.Takahash]

Rotary engines:
Displacement of a 4 cylinder
Power of a 6 cylinder
And fuel economy of a 8 cylinder

[namenamename]

"10 years ago, Audi tested a Rotary engine"
Huh, I didn't know Audi did that in the early 2000s... Wait, 10 years ago was 2011. Damn.

[martinantelo]

I think the reliability problems could have been fixed, and where I live, rebuilding a rotary is far cheaper than rebuilding a piston engine, because there are so few parts. Granted, it's more prone to failure due to the issues we all know (sealing failures and such) but I think that overall, that could have been fixed. After all, most dedicated rotary owners have third-party solutions installed to fix those reliability issues.

Problem is fuel efficiency & emissions. A RX8 can eat like a supercar going presto even at normal city speeds. Like 15l per 100km. That's a lot in a world in which efficient, full combustion cars can go as low as 5l, and a Porsche 911 can do 7-10.

And there's emissions. They burn oil by design. Inherently, they pollute a lot more.

[terrybaird]

I absolutely loved my RX-7 convertible. People probably thought I was crazy, because sometimes I just laughed out loud while driving it. It was that much fun.

[kizmetmars]

Rotaries sound fantastic. 787b all the way.

[montlejohnbojangles]

I think that no matter how you slice it, Mazda has just always had weirdness going for it. I'll always love that unique style, and I'll always hope to have an SA-22 in the garage. Too cool.

[orangensaft]

"That's cheap RX8 isn't looking like a deal anymore" What? For a weekend car it's an absolute bargain. The car I'd compare it to is the S2000 and the RX8 has slightly better handling and is way easier to drift. Even with a very expensive rebuild of 5k$ you can get an RX8, a full rebuild with bridgeport making it go BRAP, 5 years worth of fuel and it will still cost you like 1/4 the price of the S2000.

[TheInnerParty]

Interesting video. Thank you.
My greatest automotive regret was selling my RX8.
Everything you say is true, but you left something out. They are absolutely delightfully fun to drive. The rotary engine finds itself at relatively high RPM. And when I say high I mean HIGH! 😱
For instance, entering a cloverleaf and accelerating through it.. downshift one or two gears to 7000 RPMs and accelerate. You can easily go to 10, 000 RPM on an RX8 — something most cars would drop fragments of pistons on the road as the engine blew.

So it’s not a muscle car dragster, but it finds itself on curvy highways. I much prefer it to the Porsche I have now.
The weight distribution was just perfect. The major reason for it being discontinued, was emission regulations. Rotary engines by definition burn oil.

[philipjamesparsons]

I've had my RX8 for 11 years. It has been a generally good car. Well, until a few weeks back when it blew a seal on a track day, with 76k on it. I would rebuild it but there are so many Friday, afternoon rebuilds. Even if it is rebuilt well, it's 20mpg (10 on track) and £600 UK tax. They are fun cars that, to be honest you are better off avoiding.

[grayaj]

I've heard that for smaller light-duty engines, there have been some substantial improvements -- but this is in the 1/4 to 4hp range. I love mazdas, and am sticking a toe into the crossover market, so the MX30 is very appealing.

When I was a kid, a neighbor had an RX3 that rev'd over 10K and sounded amazing. Of course, it was up on blocks a lot waiting for parts a lot.

And I still remember Mazda's jingle from the 70's "Piston engine goes boing boing boing boing boing but a Mazda goes

[dachanist]

My household had 3 first gens and 2 second gens. Rotary cars are very special, but today I drive a 50k mile BRZ/FRS/GT86 as I really don't want to be on automotive forums 24/7 trying to diagnose and fix my sportscar on life support. No regrets, not even the 85 where I changed the gearbox oil and had to do synchros and bearings right after. No regrets, not even lightly drifting at over 100mph on lakeshore in Saskatoon in the 91. No Regrets on the 82 that I bought for $1200 in 95 and wrote off for $3k in 96. No Regrets for the 82 that I power shifted until the clutch disappeared. No regrets drifting the bridge loop at work every day in 100hp car. These cars were simple enough that a kid could learn how cars work and how to diagnose car problems. These cars changed my life... but today I choose an FRS. Its still lightweight, low CG, better suspension, killer in the corners - but its good on gas, doesn't break and will last twice as long... maybe more. Here's to the car and the engine that taught me how cars work and how to drive them. RX7/8.

[vrswp]

The Mazda dealer I turned wrenches for had a grip of dead RX7's and 8's sitting abandoned behind the shop. We called it The Field of Broken Dreams.

[THEBOZZ]

yes, all RX7´s and RX8´s are considered as mid-engined cars, due to the engine being placed behinde the front and infront of the rear axle. They are called front-mid-engined (like an SLS or a Corvette)

[Adogsmate]

You most certainly don't need to be a specialist to rebuild a rotary engine. I built my own 13b monster bridge port in our shed on our farm with the help of just a book. This was mid 1970s, in those days, nothing could touch them bang for buck. My completed built in those days was 2000 folding. That includes lightened, balanced rotors and new housings and new everything else including the clutch. She could drop 225hp at the wheels after a few hours on a dyno. That car had a 4 barrel Holly and inlet manifold with a beautiful air cleaner with the velocity trumpet in it from Rotor motion on it, that was a very cool piece of kit. That may not sound like much of a big deal, but I'm from NZ, so it was at the time. My old rx2, what a fun car that was.

[arboris]

Better not let Rob Dahm read that title 👀

[LearningFast]

A Wankel engine is just about the worst engine you could use for an electric generator. They call it a 1.3 liter engine but it actually fires each cylinder more times per output shaft rotation than a traditional 4 stroke reciprocating engine. That means it acts more like a 2.6 liter engine. If you compare the fuel economy of a 2.5 liter Nissan Altima 4 cylinder to the RX8 you will see that the Altima has vastly better efficiency. It even produces similar Torque to the RX8 and weighs slightly more. Yes the RX8 has more power. However, if you compare the turbocharged 2.0 liter Altima to the RX8 you will see that the Altima surpasses the Wankel engine in the RX8 for Horsepower and Torque all while having vastly superior fuel economy in a heavier vehicle. The Wankel engine is SPECTACULARLY inefficient no matter what you do to it.

[sriharidesai]

787b and efini rx7 pretty much defined rotary engines. Honorable menations: Mazda Cosmos, RX3 etc :o

[driftertank]

So, the 1.3L rating of the 13B was based on the displacement of a single chamber of the rotor...
But as far as mass flow over RPM, the 13B is actually comparable to a 2.6L engine.
This is a pedantic little detail, but the 1.3L designation was a great boon for advertising, since they could claim 200hp+ from a "1.3L engine, " but makes their fuel consumption/displacement sound abysmal. If you think of them in terms of actually being equivalent to a 2.6L 6-cylinder, their power and fuel consumption make a lot more sense.

They DO still have the advantage of small size and weight for displacement. That oil consumption, though...

[icemanxidkp]

1998 to 2002 rx7's would make around 300hp stock with the waste gate limiter removed as all auto manufacturers in japan had a agreement that none of the sports cars would make over 275 Hp

[bygonebebygones]

I remember owning the 2004 RX8 high power, it was lots of fun, the sound was great. My main issue was the rear wheels slipping way too often though, I moved from bridgemoans to conti's and that mostly solved the issue. The oil top ups was annoying but the 18 MPG on average was pretty dire but I bought it for the smiles per gallon anyways :)