Educate Me - Why have rotary engines never really taken off?

Makhaira

Makhaira

Makhaira

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As per title really, rotary engines have intrigued me, and whilst some (namely ****el designs) have made it into some vehicles like the RX-8 and predecessors, these never seem to have really taken off in the car industry. What's the catch with them that I'm not aware of? They're lighter and smaller, not to mention less complicated. As with all engines, I'm aware that they're not suited to all applications, but they seem to be less common than I would have expected even taking that in to consideration.

Educate me!
 
I think we need to ask why some manufacturers still bother with them.

Not particularly powerful, very thirsty, not reliable and high oil consumption.
 
[TW]Fox;17667759 said:
I think we need to ask why some manufacturers still bother with them.

Not particularly powerful, very thirsty, not reliable and high oil consumption.
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Light weight, high power, high revs, plus they have the novelty factor.
 
Firestar_3x said:
It is when you look at its displacement.
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Even though it is a 1.3, doesn't it actually count as a 2.6 because the engine fires twice per rotation or something?

My 1.4 has 180bhp so I'm only 12bhp the RX-8, with much better fuel and oil consumption.

Smaller turbocharged engines are the future.
 
The swept volume equates to 1.3 liters, I’d say 231bhp out of a 1.3 liter engine puts it in the high power stakes.

I've not once stated the engine is of an efficient design, I’m objecting to the fact that the above classed it as a low power unit.

Yes the MPG is directly proportional to how efficient the design is, but to use this as a power benchmark is wrong, with this in mind is a Ferrari or Lamborghini which only get 12mpg low power?
 
Peerzy said:
Even though it is a 1.3, doesn't it actually count as a 2.6 because the engine fires twice per rotation or something?

My 1.4 has 180bhp so I'm only 12bhp the RX-8, with much better fuel and oil consumption.

Smaller turbocharged engines are the future.
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If you're comparing a turbocharged car with an RX-8 it's a little unfair, try comparing it with an RX-7..... ;)
 
Bar the RX7 and early RX8s, they aren't really that unreliable - they just require a little more maintenance.

Oil consumption isn't as bad as some would have you believe, and it isn't nearly expensive as you'd think either, seeing as they don't require synthetic oils. There are many BMW and Honda engines that consume oil as well, yet this is never a consideration when buying such a car.

They aren't massively powerful in NA form, but will make (and take!) silly power under FI as proven by just about any single turbo RX7 you look at. Not that 230BHP (or 250BHP JDM) is particularly bad out of the RX8 - not different to the kind of power that say E46 330s of the time were making, so I'm not sure how people deduce they aren't particularly powerful.

High fuel consumption is a problem, and many of your average punter isn't willing to run a car averaging 16MPG. Lots and lots of RX8 owners do though, its a price worth paying for such an awesome engine IMO :)

Their pros are an awesomely linear power delivery in NA form, which is great for actual performance, but not so great for your 'butt dyno'. Their size allows them to be mounted further back and lower down than your traditional piston engine - lower centre of mavity and having the engine closer to the middle of the car is only ever going to be a good thing and is partly what the RX7 and 8 owes its poise and such balanced handling to.

Oh, and the high revs are awesome. A standard RX8 revs to something like 9500RPM, and will happily rev to ~14000RPM reliably (although would require a bit of work to make power there!)

They aren't really that light at all though.

I guess what it boils down to for manufacturers is an engine technology that is expensive to develop and has limited demand.
 
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They can be made to make epic amounts of power but for daily car engines they suffer from the points mentioned above.
 
They are good fun to drive though, it just keeps going and going.

Shame they are so expensive to run, but then the RX8 is an amazing buy because of that.
 
MikeHiow said:
Bar the RX7 and early RX8s, they aren't really that unreliable - they just require a little more maintenance.
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What other rotary cars/engines are there? Those are the only two I can think of and you've said 1 and 1/2 of those 2 cars is unreliable and they've only just sorted it after how long of using the engine?
 
Peerzy said:
What other rotary cars/engines are there? Those are the only two I can think of and you've said 1 and 1/2 of those 2 cars is unreliable and they've only just sorted it after how long of using the engine?
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He has basically just said 'car the two made in the last two decades'.

Amusing eh :D
 
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