1QwkSport2.5r

A roots type blower works just a teeny bit differently than an exhaust driven turbocharger, and a 4-stroke lends itself to having forced induction work significantly better and easier than a 2-stroke engine.

Bax

My Feedback: (11)

The O.S. Max FS-1.20 Surpass SP (supercharged) used a Roots-type blower and did produce a lot of power. It was designed for the FAI Pattern airplanes of the time. It could be temperamental at times, and would usually need to have about 5 gallons of fuel run through it before it really "came in" and began to handle well. I knew several flyers who loved them. There was one group that used them in 1/4-scale pylon racing and were quite disappointed when O.S. ceased production of the engine.

Sport_Pilot

Supercharging doesn't work well with two strokes because both the exhaust and intake ports are open for most of their periods. So the gas cannot be compressed, or not very well. About all it will do is compensate for friction loss and volumetric efficiency.

1QwkSport2.5r

A turbocharger will work in theory, but only because the turbo charger creates back pressure at the exhaust port. They have been turbocharging 2-cycle snowmobiles for some years now. I think on a large scale engine such as a snowmobile, power gains can be realized. On a small scale engine such as a glow engine, I doubt any gains would be realized. Tachometer readings under natural aspiration and under forced induction would likely detail some improvement, but at what expense? If the parts cost is high to gain a small amount of power, one would be better off buying a higher performing engine in reality, or at the very least adding a tuned pipe and adding more nitro.

I agree a supercharger would be a fruitless endeavor on a 2-stroke engine without any way of restricting the exhaust to prevent pressure loss.

Snake0311

yes im tracking, i doubt there will be much of a performance gain, but if what you said was true about the exhaust hole, the turbocharger that i used on my super tigre is only approximately 1/4" in diameter give or take a 1/32", its made by tks. they threw me some parts to build the turbos and said go nuts in hopes that i could figure out how to put together a kit to market, and for the most part i have, but id love to prove that this is more than just an eye candy kit, if yall have any ideas, please share, but heres some pictures of the hotside's inlet hole.

1QwkSport2.5r

If it were me doing it, I'd mount the engine on a test stand with a good fuel tank/plumbing and take a video running the engine normally and show with a tach what the peak rpm is on whatever prop you're using. Then fit the turbocharger and run it up again on the same prop and fuel and show the peak rpm from the tach. This way you have a bit of an edge in credibility towards the guys that say it can't be done. I think it can, but not everyone does and many folks will say you did this or that wrong, so don't be surprised.

Snake0311

sounds good to me, prolly just leave the engine on the bird and install the oem muffler first and test that, but how do i test the rpm??

1QwkSport2.5r

Leaving it on the plane can create problems due to the harmonics created in the airframe. Bubbling fuel, prop vibration, etc. using a test stand means you're on a solid platform with an isolated fuel tank and problems are better diagnosed. It is really the best way to have more repeatable results IMHO.

If you want to have a more scientific test, test run with no muffler at all, with OEM muffler, and lastly with turbocharger fitted. Running without the muffler will give you the real world power the engine is capable of. The OEM muffler oftentimes robs some power and doesn't give a good indication of what power the engine is capable of producing. Any rpm gain above open faced exhaust (no muffler) is in effect a tuned system and means whatever "extras" that are connected to the engine are in fact adding power.

A tachometer measures RPM. http://www.hobbico.com/fieldequip/hcap0401.html

Snake0311

sounds like a plan to me.

Snake0311

due to some concerns i had about the heat that the exhaust will put off, i decide to upgrade the exhaust tube to stainless

Snake0311

1QwkSport2.5r

Okay, 4 threads. Seriously...?

Snake0311

hey, i could use all the help i can get, for all us ground pounders out there, stuff gets confusing sometimes lol

1QwkSport2.5r

You usually won't get much help posting about an airplane engine in the car forums and about a car engine in the airplane forums. Not trying to be a downer, just making a suggestion. Posting the same stuff in several threads all over the forum isn't going to motivate anyone to offer suggestions.

Until we see the engine running and having some rpm data to go off of, there isn't much to be said other than it looks cool and the skeptics saying "that isn't gonna work". As I suggested before, run the engine in a controlled environment with a few different exhaust configurations and post the data you collect. Note the fuel, glow plug, and prop used as well as what the engine is and what rpm it ran in each configuration. A video showing the runs is always nice too for us glow heads that like to see something 'new'.

Snake0311

sounds great, waiting on the latest model of the turbo in the mail