Rotary engine Vs. Piston engine (1 Viewer)

[hefa13bt]

just thought id add this thread up, see how it goes

 

[seremify007]

I doubt many people here really understand the differences between the two.

But in all honesty, I think Mazda is only sticking with Rotary just to be "unique" and they'd probably be better off devoting those resources elsewhere.

 

[luscious-llama]

It's a shame the Rotary engine (well the wankel one that Mazda uses in its cars) isn't too crash hot on fuel economy... stupid oil prices *shakes fist*

 

[Jiga]

How does a rotary powered engine work? I know the very basics, but thats it. I was suprised at how something like the RX8 with a rotary powered engine is only 1.3L yet has something like 180kw!

 

[bowman]

rotary engines IMO have the fucking maddest sound when done up
a 13B. fuck they sound off there head.

one of my dream cars is a Mazda RX3 coupe, with a worked off its head 13B turbo.

i know it will never happen but i can dream

 

[seremify007]

How does a rotary powered engine work? I know the very basics, but thats it. I was suprised at how something like the RX8 with a rotary powered engine is only 1.3L yet has something like 180kw!

From memory there's a pretty good explanation somewhere on howstuffworks.com

 

[petar13]

Rotary vs. Piston

Positive:
High Revvability
High power per litre ratio
All are RWD (pos or neg, either way)
Fuel consumption better than piston engines of similar power

Negative:
Short lifespan - seals don't last long
Hard to service
Small aftermarket // Have to buy genuine parts

There's probably more, but that's all I have at the moment.

 

[DaddyK]

If you go here and then scroll down you will see a diagram which shows exactly how they work.
http://auto.howstuffworks.com/rotary-engine1.htm

The reason why rotary engines rev so high is because they have an intake, combustion and exhaust stroke every 120 degree's. Compared to a usual 4 stroke piston engine where the crankshaft completes 2 full revolutions for the 4 stroke cycle to be completed.

 

[pottsy44]

rotary's are not worth your time unless u know what ur doing, good for club racers or dragers, not an everyday car really.

 

[Zozo6969]

Another bad thing about rotarys is that they don't generate as much torque as a normal piston engine and are nowhere near a diesel engine.

 

[petar13]

Hmmm...

The amount of torque a 1.3l rotary develops is far more than a 1.3l piston. I suppose what you meant is that a 1.3l rotary develops less torque than a piston engine with equivalent kWs. Considering in most cases this piston engine would be a big block v8 or a turbocharged affair, then it really isn't that surprising.

Anyways, there is nothing in the vicinity of a diesel in respect to Nms. Except for a blown diesel.

 

[loquasagacious]

I'd say the biggest downside on performance ones is the need for very regular rebuilds. eg in a racing app they will be rebuilt between every race.

Another negative is that they use lots of oil.

And finally that to get more power you do some radical porting jobs which gets enormous power but completely destroys streetability.

 

[bowman]

the noise that a rotar makes is insane.
make the hair stand up on the back of my neck.

they are pure power. a dirty rasping engine noise is awesome

 

[jackm]

I'd say the biggest downside on performance ones is the need for very regular rebuilds. eg in a racing app they will be rebuilt between every race.

Another negative is that they use lots of oil.

And finally that to get more power you do some radical porting jobs which gets enormous power but completely destroys streetability.

re: them havin to be rebuilt every race....
not so true, i worked on a team that was running 2 rx7's and rebuilding motors seasonally. they blew a couple on the dyno testing limits etc first though.
sure the high hp race motors have to be rebuilt everyrace, but dont the top fuel pistons dragsters do that aswell? im sure there are alot of rebuilds everyrace in high budget teams.
dont get me wrong, i hate rotors ahah
but yeah the oil seals in them tend to farck up alot... the big hp ones are a joke, i met a bloke who had been to the track 3 times with his 450hp 13b rx3 and hadnt completed a run due to blown motors, whats the point...

yes they use lots of oil

they sound shit

they attract white adidas caps

alot of the blokes that drive them are tools

 

[DaddyK]

they attract white adidas caps

hahaha.

So very true....funny, and true.

 

[dem2gtu]

rotary engines..

they are not made for torque, they are made for pure speed

u see them on the track running 7s,8s,9s easily with such a small

basic engine.. fuel efficient? get over it its part of the fun and sound

you find a legal street car that can launch on the back two wheels

Without spending much on the engine.. come talk to me

rotary power baby

high revs high speeds
big ports
low 8s

 

[Azamakumar]

rotary engines..

they are not made for torque, they are made for pure speed

u see them on the track running 7s,8s,9s easily with such a small

basic engine.. fuel efficient? get over it its part of the fun and sound

you find a legal street car that can launch on the back two wheels

Without spending much on the engine.. come talk to me

rotary power baby

high revs high speeds
big ports
low 8s

Um, it's torque that puts the 1/4 mile in such low figures?

And I was under the impression that they had flatter torque curves than piston engines, ie they hit peak torque in the mid range and stick it out til redline, unlike most piston engines (esp turboes?) that drop off after reaching peak 2/3 of the way to the redline.


EDIT: making a rotary's torque curve more desirable?

 

[F2001]

Um, it's torque that puts the 1/4 mile in such low figures?

And I was under the impression that they had flatter torque curves than piston engines, ie they hit peak torque in the mid range and stick it out til redline, unlike most piston engines (esp turboes?) that drop off after reaching peak 2/3 of the way to the redline.


EDIT: making a rotary's torque curve more desirable?

torque is great for the take off/launch, once you get going/momentum, its hp.

 

[Riet]

Rotaries tend to have shit amounts of torque (compared to a piston engine) relative to their horsepower because they are usually about 1/3 the displacement.

 

[Riet]

rotary engines..

they are not made for torque, they are made for pure speed

u see them on the track running 7s,8s,9s easily with such a small

basic engine.. fuel efficient? get over it its part of the fun and sound

you find a legal street car that can launch on the back two wheels

Without spending much on the engine.. come talk to me

rotary power baby

high revs high speeds
big ports
low 8s

YouTube - Steve's 9 Second Cuda Doing a Big Wheelstand

You realise its just torque and weight balance that makes a car wheelie though, right?