Wankels, why only 1.3's?

[300bhp/ton]

Something I've just been pondering. But is there a limit to making a wankle engine bigger displacement?

The RX-8 manages 231bhp from 1.3 litres (even if the mpg suffers) thats an impressive 177.7bhp/litre n/a. But how hard would it be to make it 2.0+ and see over 300hp? Would it affect fuel economy even more or is there some other limiting factor?

Cheers.

[reggie82]

It's not really a 1.3 though is it?

[300bhp/ton]

reggie82 said:

It's not really a 1.3 though is it?

Is it not? I know a rotary is totally different to a piston engine. And I think the first RX-7's where 1.0 or 1.1's. I just wondered why over the past 32 years Mazda have never increased it's displacement further.

Edited by 300bhp/ton on Saturday 22 January 20:48

[randlemarcus]

Having driven an RX8, 1.3 is quote enough, thankyouverymuch. Taxed as a 2.6 and drinks like a 6 litre

[CraigyMc]

300bhp/ton said:

Something I've just been pondering. But is there a limit to making a wankle engine bigger displacement?

The RX-8 manages 231bhp from 1.3 litres (even if the mpg suffers) thats an impressive 177.7bhp/litre n/a. But how hard would it be to make it 2.0+ and see over 300hp? Would it affect fuel economy even more or is there some other limiting factor?

Cheers.

Instead of increasing the capacity by making the rotor bigger, the usual way to get more power is to add more rotors (similar to how nobody builds a 6 litre 4-pot piston engine, but there are loads of V8/V12 cars that size). Either that or forced aspiration.

C

[TheArchitect]

not sure why but the rotary in mazdas' are actually an equivalent of 2.6.

[conrodgti]

its two 1.3 chambers bolted together, i asked about it once and apparantly its to do with the balance and centrifugal forces?

[reggie82]

300bhp/ton said:

reggie82 said:

It's not really a 1.3 though is it?

Is it not? I know a rotary is totally different to a piston engine. And I think the first RX-7's where 1.0 or 1.1's. I just wondered why over the past 32 years Mazda have never increased it's displacement further.

Edited by 300bhp/ton on Saturday 22 January 20:48

People always say it's a 1.3, but as other's have said, my understanding is that it's more realistically a 2.6.

I think it's because each chamber is 1.3 litres, but two chambers are being used at the same time (one for induction, one for exhaust). I may be totally wrong on that though, dont fully undertand rotary engines!

[wackojacko]

This is one of the most ongoing debates in History to do with cars.

wankels cannot be compared to normal Piston combustion engines because they're obviously different.

A wankel engine capacity can be increased by simply adding more rotors e.g triple rotor set ups, in theory it's not possible to be accurate calculating Cubic capacity for a rotary engine as piston size is obviously not measurable nor is compression to piston drag ratio nor can the cubic capacity be measured by the good old 'centi-litre draw'method.

Saying a regular wankel is a 1.3 is only for people who really love the fact that it's so powerful for such a small engine, technically it's not that's why it's put
in the same classes as Straight 6's and V6's.

[saaby93]

Is there an economical version?

[pacman1]

saaby93 said:

Is there an economical version?

Nope, always been the same.

http://en.wikipedia.org/wiki/NSU_Ro_80

[BlueMR2]

300bhp/ton said:

reggie82 said:

It's not really a 1.3 though is it?

Is it not? I know a rotary is totally different to a piston engine. And I think the first RX-7's where 1.0 or 1.1's. I just wondered why over the past 32 years Mazda have never increased it's displacement further.

Edited by 300bhp/ton on Saturday 22 January 20:48

You need a mazda cosmo triple rotor 20b engine if you want the extra grunt.

[deveng]

Why not just buy a car with torque and good fuel consumption. Nice 6 cylinder petrol engine.

No, not a diesel. Especially not if it's remapped.

[300bhp/ton]

wackojacko said:

This is one of the most ongoing debates in History to do with cars.

wankels cannot be compared to normal Piston combustion engines because they're obviously different.

A wankel engine capacity can be increased by simply adding more rotors e.g triple rotor set ups, in theory it's not possible to be accurate calculating Cubic capacity for a rotary engine as piston size is obviously not measurable nor is compression to piston drag ratio nor can the cubic capacity be measured by the good old 'centi-litre draw'method.

Saying a regular wankel is a 1.3 is only for people who really love the fact that it's so powerful for such a small engine, technically it's not that's why it's put
in the same classes as Straight 6's and V6's.

Cheers for the reply. That wasn't quite my angle though. I don't car if its 600cc or 8 litre. I was just curious 'if' you could increase the displacement, the 'affect' of doing so. And possible depending on these answer why they haven't.

Forced induction is also fine, but again not really my question.

[300bhp/ton]

conrodgti said:

its two 1.3 chambers bolted together, i asked about it once and apparantly its to do with the balance and centrifugal forces?

Ta.

[300bhp/ton]

deveng said:

Why not just buy a car with torque and good fuel consumption. Nice 6 cylinder petrol engine.

No, not a diesel. Especially not if it's remapped.

That would be great - if it's what I asked. Maybe try reading the OP again?

[JonnyFive]

300bhp/ton said:

wackojacko said:

This is one of the most ongoing debates in History to do with cars.

wankels cannot be compared to normal Piston combustion engines because they're obviously different.

A wankel engine capacity can be increased by simply adding more rotors e.g triple rotor set ups, in theory it's not possible to be accurate calculating Cubic capacity for a rotary engine as piston size is obviously not measurable nor is compression to piston drag ratio nor can the cubic capacity be measured by the good old 'centi-litre draw'method.

Saying a regular wankel is a 1.3 is only for people who really love the fact that it's so powerful for such a small engine, technically it's not that's why it's put
in the same classes as Straight 6's and V6's.

Cheers for the reply. That wasn't quite my angle though. I don't car if its 600cc or 8 litre. I was just curious 'if' you could increase the displacement, the 'affect' of doing so. And possible depending on these answer why they haven't.

Forced induction is also fine, but again not really my question.

As above, just add another rotor on then. The Furai is triple rotor, YouTube "Furai" and listen to the engine.. Brilliant!

[EDLT]

pacman1 said:

saaby93 said:

Is there an economical version?

Nope, always been the same.

http://en.wikipedia.org/wiki/NSU_Ro_80

There is always a blue one of those parked outside a hairdressers near here, the owner must have a thing for unreliable cars because there has been a string of Alfas there before it.

[thewildblue]

Dont forget how smooth they are as well...smoothest engine you can get as its just spinning.

There are some ace 4 rotor RX7s out there, youtube them they sound ace and do 10sec quarters.

[wackojacko]

300bhp/ton said:

wackojacko said:

This is one of the most ongoing debates in History to do with cars.

wankels cannot be compared to normal Piston combustion engines because they're obviously different.

A wankel engine capacity can be increased by simply adding more rotors e.g triple rotor set ups, in theory it's not possible to be accurate calculating Cubic capacity for a rotary engine as piston size is obviously not measurable nor is compression to piston drag ratio nor can the cubic capacity be measured by the good old 'centi-litre draw'method.

Saying a regular wankel is a 1.3 is only for people who really love the fact that it's so powerful for such a small engine, technically it's not that's why it's put
in the same classes as Straight 6's and V6's.

Cheers for the reply. That wasn't quite my angle though. I don't car if its 600cc or 8 litre. I was just curious 'if' you could increase the displacement, the 'affect' of doing so. And possible depending on these answer why they haven't.

Forced induction is also fine, but again not really my question.

o right ok sorry chap , I was just explaining the common mis-conceptions.
The answer to your question would be yes you can increase the displacement by simply adding more Rotors, the most I've seen is a quad rotor system in a Mazda Concept, why they don't do this is because the fuel consumption is simply horrendous ! also to do with emissions, aftermarket tuners do often use a triple rotor set up with Forced air induction to great resault but then again fuel consumption and emissions are truely epic.

If you built a rotary engine from scratch you could design bigger rotors but this would then affect how high the engine revs to (due to the increased energy and inertia) it's sort of swings and round abouts when weighing up the advantages and dis-advantages but the common middle ground is 2 rotors and a turbo or two.

Hope this helps chap

Jacko