fendamonky

iTrader: (6)

This entire exchange sounds like a classic example of the Dunning Kruger effect in action...

jts749

its looking like it

how do you intend the air forced in from the SIDE intake ports to push on the rotor?

mr2peak

Just to make conversation, a few supercharged rotaries have been run in E Modified. However that's a very specific use case

Slides

So where does the drive power for the supercharger come from? You are attempting to describe a perpetual motion machine. The compression isn't a free lunch. Final compression efficiency/work for charge density in a late close intake setup with intercooling can be better than rotor/piston alone but you aren't "making" torque on the intake stroke. That would require greater than 100% total efficiency, not even 100% adiabatic so like 200% on theoretical.

VE for the same MAP will be higher than just a turbocharger with positive pressure differential across the motor but if you are talking less than 3 bar boost with well matched modern turbo, the system efficiency of turbo alone will still be better in terms of delivered power for available air/fuel. Twincharging or use of a supercharger really is only about boost threshold rpm or very specific use cases.

pedantic_but_friendly

It’s a matter of pressure: as far as the exhaust can flow relatively unrestricted and the overlap doesn’t allow the intake charge to flow out of the exhaust ports, there will be torque generated. I don’t know the term in English, but it’s known as “pompaggio positivo” in Italian (the phenomenon has been observed in engines since the 1930s).

Cheers, blokes!

pedantic_but_friendly

Thanks for the insult, chap! It’s not very nice of yours, but feel free to think I’m uneducated on the matter. If I may say so, you may learn something from both of us if you listen carefully enough…

Cheers!

pedantic_but_friendly

That’s a fair point! Personally, I believe there hasn’t yet been enough research on supercharging. That may be because everybody sees the high exhaust flow as a resource to exploit, even though it’s rather inefficient. However, 2 stroke engines are theoretically more inefficient, but they go “BANG” twice as much… similarly, rotaries are a bit… weird… but there’s lots of power “stroke”.

Cheers, blokes!

jts749

That's the thing, there is going to be a power stroke happening on the adjacent rotor while you are trying to push this rotor with boost. The force generated would be negligible to the other forces happening in the engine.

pedantic_but_friendly

I’m very aware the torque generated by the intake charge wouldn’t be the main source of torque of the engine, I’m not a moron. All I’m saying is: if you want high power on a rotary, you need to spend a ton of money to get poor efficiency and usability out of an engine which (on paper) is close to perfect. The main role of that force is to recuperate a bit, not much, of the power used to drive the supercharger and to smooth out the torque delivery even more, which would SLIGHTLY (you all correct me thinking I’m talking about big gains here) increase torque at low rpm and would make the torque curve A BIT flatter. Once again, it’s not going to be much, but nothing great has ever been created without meticulous attention to detail. The Lancia Rally 037 (supercharged) is a good example, it didn’t have 4WD, but it still won (slightly against the rules) against the AUDI quattro (turbo), because it was overall a better car. The Lancia experienced the phenomenon I talked about, the AUDI didn’t. Again, it wasn’t the main thing, but it was a piece of the puzzle.

I assume everybody here knows that no engine will ever be perfect, but you can get as close as possible. The set-up I believe would take the most out of a 4 rotor rotary engine would be: peripheral port (as big as possible), mechanically driven (to withstand the zippy nature of the engine) supercharging (there’s lots of cases of supercharged rotary jet boats loosing their supercharger due to the pulley slipping off (NEVER trust a pulley)), variable geometry intake ducts, partial direct fuel (and oil) injection, twin spark plugs and some good structural integrity, plus excellent cooling. This would obviously be very expensive, but it would, I believe, prove to be the overall best set-up (when Mercedes tried to make the rotary engine a bit better they thought of direct injection and (only for few instants) of supercharging (plus individual throttle bodies)).

Again, we all know about the 1000 hip turbo engines out there (and all the other magnificently powerful machines), we all know about the tricky bits of making rotaries work. I just wanted to share a new idea of what I think would prove a more balanced set-up.

I was negatively surprised by the amount of scepticism in this thread and by the rudeness of some. I know I might sound a bit pretentious by selling (accidentally) supercharging as a big gain in power efficiency and drivability, but it would be a change from everything we’ve already seen for years.

Anyhow… Cheers, blokes!

pedantic_but_friendly

Quote:
“You are attempting to describe a perpetual motion machine. The compression isn't a free lunch. Final compression efficiency/work for charge density in a late close intake setup with intercooling can be better than rotor/piston alone but you aren't "making" torque on the intake stroke. That would require greater than 100% total efficiency, not even 100% adiabatic so like 200% on theoretical.”

Why does everyone here think I’m a blithering idiot?

I’m obviously not describing a perpetual motion machine, I’m not 5?! Yes, you are “making” torque on the intake stroke, that torque is partially making up for the power used to drive the supercharger itself. The reason why you are making torque on the intake stroke is the same why you make torque on the power stroke: there’s gases at pressure trying to expand. You could theoretically blow with your lungs on the rotors to make torque if you made enough flow (I’m obviously exaggerating).

I chose my name because I was told in other threads that I was excessively pedantic, but of respectable insight. However, it seems that here I’m the least pedantic and definitely the least rude.

Anyway… Cheers, blokes!

pedantic_but_friendly

I’m genuinely curious. Could you explain to me why you think supercharging wouldn’t make sense? Please be thorough, as you seem very knowledgable on the matter and as I’m confident I will understand.

After you’ve explained to me I’ll try to point out why I believe it would make sense.

Cheers, mate!