I am somewhat familiar with how to tune a naturally aspirated piston engine exhaust runners and total length and the calculations that go into it.

I haven't been able to find any information on exhaust tuning on rotary motors and turboed piston and rotary motors and within that, what changes if anything when you move to a PP or BP or larger SP housing.

Any books, SAE papers, websites, or general knowledge and experience that any of you would divulge would be very helpful.

I'm trying to learn more, but finding a lot of closed doors due to people making a living off of knowing such tuning information while the rest of the population is left wondering or having to experiment on their own.

Thanks,

-Nic

 

mazdatrix and racing beat catalog speak on the importance of exhaust on rotary engine

If your speaking on the new housing design (rx8) the only thing I can think that would change would be back preasure (which will affect HP torque)

 

I agree Nic. I too am looking into the same things right now in the interested of building my own manifold. I have read several theories ranging from making the runners as short as possible, between 9" and 11", 12" to 14" and then the longer the better... basically the whole range.

I've posted this before but this site has some interesting info:

http://www.vishnutuning.com/exhaust101.htm

It's more on the exhaust after the turbo, but he does comment that shorter is better. I would be intersted to see any formula or whatnot though. Otherwise I'm trying to decide how much $$$'s I want to spend experimenting with runner length and diameter.

 

Have you found anything specific to rotaries or turboed piston/rotary engines? thanks for the link - i'll check it out.

i understand all of the fluid dynamics behind different diamaters of the runners and how that will affect the velocity of the gases and also how that size relates to high end HP or low end torque gains depending on which way you go on the spectrum.

What I dont know is if the turbo is treated as the "free/dead air" which would be at the end of the piping on a N/A engine.
What has me really thinking though is how the tuning would go on a rotary. I mean, you want to tune the length so that at a certain reflective value the gases would be going out the pipe as the next exhaust pulse is coming out of the engine port to suck that next exhaust pulse's gases out.
you would get an exhaust pulse once every 2 revolutions of the crankshaft on a piston engine, but this occurs 3 times for every revolution on a rotary engine. SO...wouldn't you want to make things much much shorter???

can someone tell me if i'm really off base here?

if someone can help me out, and/or just doesnt want to confirm or deny the validity of my thoughts or this information publicly, please just PM or email me.
c03nicholas.morris@usafa.af.mil

hmm....actually typing this out brings some new ideas to mind - guess i'll try running some calcs and see if i get anything that makes sense (i.e. similar lengths to the manifolds that i have seen made).

Thanks,

 

Unfortunately i haven't found anything really on this subject matter. I am very intersted in these things as well. I was tempted to contact the guy at Garrett (if I can find him) just to see what his thoughts are. He may not have rotary specific info, but any general info could be good.

Let me know if you come up with anything.