Turbo/super charging a 2 stroke.

[DanMan1]

How about trading in the cost, weight, bulk, and complexity of a turbo saw engine for simply more CC's?? I know, I know... that's no fun.

 

[Al Smith]

How about trading in the cost, weight, bulk, and complexity of a turbo saw engine for simply more CC's?? I know, I know... that's no fun.

I think you are on to something.

 

[ErrolC]

How about trading in the cost, weight, bulk, and complexity of a turbo saw engine for simply more CC's?? I know, I know... that's no fun.

Thats a bit radical..maybe a motorcycle motor...maybe a smal GP engine..say 125..or even a 500mx..or even a V8 ..baby!

Horsepower=heat..pac more into a smaller package and things get hotter..anyone tried shielding the hot bits from the hot stuff..say, ceramics could work..or is my thinking twisted

A point to account for in small turbos is the smaller they get, the faster they have to spin to get comparable boost..everyone remember the CX500 Honda..2" turbo impeller (200k rpm full boost)..bearings and oils begin to have a problem at these speeds and thats with 250cc cylinders feeding..perhaps ceramics again!! Then again I've been out of the picture for a while, playing catch up.

 

[average joe]

You could do it with a direct injector. Long intake port with a tough reed on the intake. Stuff air with the blower after the piston clears the exhaust on the up stroke,inject before top dead center,hope for the best.It's all theory,who knows.I haven't quite figured out how to oil the lower end. You would have to have a real high volume blower with a fast acting waste gate.Any thing is possible,however it may not be practical.

The Krauts beat you to the punch, AL. They had a aircraft engine of simualr design in the 30's.
In regards to pison shapes for DI, 2 stroke engines. The one that I have seen has a small bowl with a cone shaped device in it design to take the injection plume and diffuse it. As for lubrication. These no DI 2 stroke outboard engines use a injector type sytem that has lines or ports so as to direct the lube directly to the bearings, and pistons, etc. The use much less oil than usual because there is no fuel dillution and the oil is directed to the exact areas needed.

 

[drmiller100]

The principle of turbocharging is to make the engine "believe" that it lives in denser air with a pressure of, say, a couple of atmospheres. The engine sees a thicker air on the inlet side and at the exhaust ports. Because of the thicker atmosphere, you can burn, say, twice as much fuel in the same cylinder.

resurrecting an old thread, the above exactly describes why a turbocharger cna work very effectivelyl on a 2 stroke, and why a supercharger has such a very hard time.

I built a supercharger for a 2 stroke snowmobile. I learned a LOT doing it. I believe I am one of the very few to ever add a supercharger to a 2 stroke and have it end up making more horsepower when done. But when all done, it was very incremental gain. The secret was to plug the exhaust to build boost, counterintuitive at first.

Turbos by definition build back pressure as a function of front pressure, which is circular logic, and brings us back to t_anderson's excellent description of how to think about it.

Also, on sleds, you need to think big. stock 800cc's is 150 horsepower. If you want to add a turbo to one of these, the Holset turbo off of a dodge cummins is a good size to start with.
all that being said, turbo or supercharging a saw seems pretty counter intuitive.

-doug

 

[blis]

resurrecting an old thread, the above exactly describes why a turbocharger cna work very effectivelyl on a 2 stroke, and why a supercharger has such a very hard time.

I built a supercharger for a 2 stroke snowmobile. I learned a LOT doing it. I believe I am one of the very few to ever add a supercharger to a 2 stroke and have it end up making more horsepower when done. But when all done, it was very incremental gain. The secret was to plug the exhaust to build boost, counterintuitive at first.

Turbos by definition build back pressure as a function of front pressure, which is circular logic, and brings us back to t_anderson's excellent description of how to think about it.

Also, on sleds, you need to think big. stock 800cc's is 150 horsepower. If you want to add a turbo to one of these, the Holset turbo off of a dodge cummins is a good size to start with.
all that being said, turbo or supercharging a saw seems pretty counter intuitive.

-doug

Just that the biggest problem with turbo´ng chainsaw is that they are too small for almost any kind of turbo to kick-in and even with turbo small enough to work, it still would need oil circulation etc... and in the end it would weight too darn much to be usable... hotsaws are different thing thou...

off-topic, how much hp´s you got out of your sled with turbo?? i´ve myself seen a rotax kart with 500 or 600 engine turboed, man, it was fun thing around ~150hp and tons of burnt rubber :hmm3grin2orange: