How does back pressure and rotaries coinside??

 

Sorry but you asked for this answer:

The same as You and backpressure coinside... Stuff a cork in yor *** and see how fast you run

seriously, less is better for rotaries, no valves to burn ya know!

kenn

 

I tried to look it up; proxy errors for the last week. Learned a way aroud it. Thanks.

 

You never want exhaust backpressure. It is never good for making power regardless of what rpm it is at. So many people get confused and think that you need backpressrue at lower rpms to make low end power. Not true. What you do need it exhaust velocity to help scavenge. This is the key that is so confusing. A smaller pipe doesn't make more low end because it ultimately flows less than a larger one. It doens't need to anyways. What it does do is to keep gas flow moving quickly to aid in scavenging. You only want a larger pipe when you need a larger pipe. this is no different between rotaries or piston engines. This gets even more critical the more port overlap you have such as in bridge or peripheral port engines.

 

I dont want to hear that BS about piston engines, the valves will burn out? WTF? I hate myths. Oh yea and for rule of thumb, you dont gain anything when you replace the connecting pipe that goes to the muffler if you go up in size, unless turbo. Racing Beat actually has results for this. The only good that would do is help find a muffler if you decide to make custom exuast. 2.5'' is plenty big for the N/A.

 

Thanks, great info.


Got on the topic at the last drag race I attended w/ a fellow motor head.

Never heard/read anything involving backpressure/rotary engines, always been told that it's needed on piston engines because if it's not there the colder atmosphere will cause burnt valves. wondered because rotarys don't have valves.

So, in reality, you could run a rotary without the manifold and, in theory, it won't cause damage??


You say N/A, does that include street/bridge ported engines??

 

Street port will take a better flowing exaust ,but Racing beat still only uses 2'' exaust on the way back. Bridport, I asume, will act the same way, though I hear they dont like back pressure at all. I wish I could search, but cant now.

 

I see my thread posting work-around is working...

I'll just stick with getting RB exhaust! :P

 

Its my understanding that backpressure is needed to prevent excessive scavenging which can burn exhaust valves among other things. It has to do with how the valve timing and overlap is set up. I'd assume it worked the same way with piston engines and port overlap.

 

Sure you can run it with no exhaust, but I prefer headers to a 3" dump :P Without headers youll burn up the engine bay heh, but it is possible and its apparently one of the loudest most aggrivating sounds ever.

 

Don't plan on running that setup just was a question of burning up an engine without b.p Thanks.

I'll stick to an RB header and custom 2.5" from there on out.

 

^^^ haha most underestimate how loud these little engines are. I tryed a racingbeat header to presilencer straightback, was way too loud for my tastes. No joke 30 minutes later I had the powerpulse muffler ordered. But it all depends on what your tolerance is and how much you want your neighbors to hate you...

 

My neighbor ownd an 80' GS with a, gulp, 383 Chevrolet along with a 68' Camaro, so noise ain't an issue;

there's three dragracers within 300 yards of each other, on any given day you can hear mazda, chevy, ford, or dodge.

 

That sounds like a good place to live
If I found some good ear plugs and a neighborhood that didnt care, I would run header only :P Awesome sound hehe.