Looking twice as big the Simonini exhaust system is only ~2 kg heavier than the old one.
Here is the short version (for the long version Google “tuned exhaust system”...):
The exhaust, forming a wave, start by going down the pipe and then - during the same cycle - bounces on the back wall and goes backwards pushing fresh mixture back into the cylinder.
To get maximum benefit from this wave movement the exhaust system need to be “tuned” in terms of volume, length and shape.
Forget cutting a bit and adding another bend to squeeze in the exhaust system under the hood. Doing that will inevitably reduce performance.
The exhaust, forming a wave, start by going down the pipe and then - during the same cycle - bounces on the back wall and goes backwards pushing fresh mixture back into the cylinder.
Click the picture to see the animation
(Source http://www.southernskies.net/page_info/runningtwostrokeengine.html)
I.e. each cylinder need an individual exhaust system and anything looking like a “Y” should be banned...(Source http://www.southernskies.net/page_info/runningtwostrokeengine.html)
To get maximum benefit from this wave movement the exhaust system need to be “tuned” in terms of volume, length and shape.
Forget cutting a bit and adding another bend to squeeze in the exhaust system under the hood. Doing that will inevitably reduce performance.
hi,
ReplyDeletegood luck with the Simonini install. I used to fly ultralights/ LSA when the biggest rotax you could get was the 503. I'm glad to see someone try something different.
I am looking at a simonini engine for a paramotor.
Thanks Pete!
ReplyDeleteSimonini has a good reputation in paramotors over here. If you go for one, let us know what you think about it.
I used to make and shape 2-stroke exhausts professionally and as long as you keep the bends smooth, a tuned exhaust will work fine - especially in the relatively low RPM ranges that 2-Stroke aircraft engines operate. Have a look at off-road motorcycle pipes (google 'cone pipes) and you'll get a feel for what's possible.
ReplyDeleteRC San Diego UL pilot
hello, i have hovercraft witch ROTAX 503. I made amateur tuned exhaust damaged pistons :-(
ReplyDeleteI need new tuned exhaust. Can you send me producer this tuned exhaus system or some plans to making. Thanks Hejna (I am from Czech rep.)
hejna@ausys.cz
Hi Hejna,
ReplyDeleteThe tuned exhaust system is made by Simonini and is delivered with the engine. They have a few different models depending on your planned installation. I don't know if there is anyone making tuned systems for Rotax.
Regards
Fred
Hello I,am Anatoly.Need Rotax 582 exhaust mufflerwith delivery.How mutch?I,am from Latvia
ReplyDeletekrasan@inbox.lv
Hi Anatolijs,
ReplyDeleteI'm sorry I do not have the 582 exhaust muffler available to sell.
Regards,
Fred