Exhaust Valve on PP Engine
03-03-2020, 01:58 AM
#1
Exhaust Valve on PP Engine
How’s it going guys,
I’ve been been thinking a lot about hybrid Renny builds lately, and 13b builds in general. I’m no guru on any of it, building a rotary engine and such, but do have a good understanding of port timing and overlap and it’s effect on power range and what not. I don’t have the money available to undertake any of my thoughts, at the moment anyway, so this is all hypothetical. But coming from a racing 2 stroke background, and 2 strokes having their power affected by port timing changes and such, has a peripheral and side port (I’m assuming that’s hybrid) engine been developed before, with an rpm/load/etc controlled peripheral exhaust valve, much like any old two stroke would have, hence increasing drivability in lower rpm, allowing larger pp size and more potential power? Our 125 GP bikes could make around 40hp without an exhaust valve, and 50-55 with, so obviously there’s a whole lot to be gained in being able to vary the size of the port or even having the port fully closed.
Thanks for your time
I’ve been been thinking a lot about hybrid Renny builds lately, and 13b builds in general. I’m no guru on any of it, building a rotary engine and such, but do have a good understanding of port timing and overlap and it’s effect on power range and what not. I don’t have the money available to undertake any of my thoughts, at the moment anyway, so this is all hypothetical. But coming from a racing 2 stroke background, and 2 strokes having their power affected by port timing changes and such, has a peripheral and side port (I’m assuming that’s hybrid) engine been developed before, with an rpm/load/etc controlled peripheral exhaust valve, much like any old two stroke would have, hence increasing drivability in lower rpm, allowing larger pp size and more potential power? Our 125 GP bikes could make around 40hp without an exhaust valve, and 50-55 with, so obviously there’s a whole lot to be gained in being able to vary the size of the port or even having the port fully closed.
Thanks for your time
03-03-2020, 08:59 AM
#2
Smoking turbo yay
Assuming the theory works, how to implement this will be a whole other monster.
Rotary exhaust is very hot, you'd be lucky to have any mechanism survive that long under that level of temperature.
Rotary exhaust is very hot, you'd be lucky to have any mechanism survive that long under that level of temperature.
03-03-2020, 04:15 PM
#4
Yeah, the heat had me concerned and what you could get to work for it, ideally, a valve/flap that completely closed off the exhaust and/or intake peripheral port would be ideal to minimalise loss of flow. Servos could be mounted far enough away from exhaust to negate heat, along with using whatever metal needed that’s withstands heat for the mechanisms.
I haven’t seen a setup like that before Brettus, that’s extremely interesting. Has that engine been run?
I haven’t seen a setup like that before Brettus, that’s extremely interesting. Has that engine been run?
03-04-2020, 10:23 AM
#6
Smoking turbo yay
Yeah, the heat had me concerned and what you could get to work for it, ideally, a valve/flap that completely closed off the exhaust and/or intake peripheral port would be ideal to minimalise loss of flow. Servos could be mounted far enough away from exhaust to negate heat, along with using whatever metal needed that’s withstands heat for the mechanisms.
I haven’t seen a setup like that before Brettus, that’s extremely interesting. Has that engine been run?
I haven’t seen a setup like that before Brettus, that’s extremely interesting. Has that engine been run?
The theory is pretty sound since it makes flow velocity higher, but yeah, I'd be curious on the implementation as heat will definitely be a challenge, or at least a challenge with a reasonable cost.
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