Turbo 2-stroke

[CanadianCarGuy]

What about using the mixed gas intake charge? There's oil enough for the bottom end bearings, why not a turbo shaft? The turbo only needs enough oil to leave a film on the shaft. The aerocharger only uses a couple misters to lubricate itself with aircraft turbine oil. Tap into the crankcase plumb thru the turbo then back into the crank case. I think that there 4 stroke lawnmowers that use mix gas for lubrication and have no engine oil.

 

[huskydave]

I would see two problems with that one fire hazard and two what would that do to the crankcase pressure would it be all over the map? I would prefer to have an oil only setup even if you had to use an electric pump they can be run off arctic model saws . I think the big saws would turn a small turbo good and if piped back the turbo could be mounted close to the intake track. If you used this on a bikesaw the yamaha seca turbo would be ideal.

 

[CanadianCarGuy]

Yeah you are probably right about the fire hazard, plus the boost from the turbo and crankcase (yes crankcase would be pressurized from the intake side no matter what you) would blow the seals in the turbo. I think I will just seal off the middle bearing housing and fill it with aircraft turbine oil.

Also the world's fastest 125cc two stroke motorcycle is powered by a similar sized IHI Ball bearing turbo.

 

[glenn31792]

HuskyD
I understand your concern but... this guy got 45 horsepower from a 12 horse engine!


It does not matter how many hp he got from a 12 horse motor. What matters is how
many hp he gets per ci or cc. About 5 years ago Honda was getting 6.75 hp per ci out
of a 2st race motor. They could have gotten more but they wanted to have a wider
powerband. That power per cc would give a 50 cc saw around 20 hp.

 

[huskydave]

The only rules for hotsaw is one cyl no size or horsepower restrictions with the bikesaw class. I am thinking about building a 250cc bikesaw but fist sending the engine to a bike builder to get ported low compression piston bored 44mm carb and make a pipe for it. I have curtis sparks in mind for building the engine/pipe. I would then like to try to get a turbo to work. I don't have the money at the moment but it's nice to dream.

 

[glenn31792]

Sounds cool. I bet a new 250 bike saw would spin at least 45 hp.
Would love to see pics!

 

[husky hustler]

We have to get away from a typical turbo. A turbo that works like an automotive turbo wouldn't work. Think more along the lines of a supercharger. its drive will be gear directly out of the crankshaft. Now place it between the carb and engine. Now what we have is a vacuum from the carb pulling air and fuel straight through it. No inter cooler needed as it is pulling cool air from a source away from the engine. Plus most of you guys mix so rich that turbine will never have a chance to attract friction! Plus this type of design will step away from the lag that is associated with turbo engines, giving a more direct throttle response. This is important because at wot the engine might flood out as the turbo hasn't allowed its potential rpm's!

 

[drmiller100]

btdt.

read my posts earlier in this thread.

 

[Wortown Mick]

old CR 500

No powervalves to cater to low and midrange torque, Im talking pree, maybe 88-89.. older mid eighties ones. Its a high RPM screamer type motor.

Alot of HP.
70-80 anyways. Could prob get more with radical porting. The real old ones are air cooled. Cut the back half of the cases off, voila 80 hp powerhead.

Turboing that would be a conservative 100-120 hp.

 

[romeo]

I don't think a turbo is the way to go on a race saw. You are going to have two strikes against you; turbo lag and weight. HP in the cut means little when the slowest section of your time in a race is the operator.

Even in a 30" single cut hot start west cost race, can that turbo spin up quick enough to matter, when Cahoon's 500's are already breaking 2 seconds.


As far as the power valve motors go, I find them preferable.

 

[huskydave]

This guy seems to get enough power from his turbo on his banshee.

http://www.trickracing1.com/home.html


The turbolag can be eliminated if you tune it right and use a lot of boost.

I was just toying around the idea because I thought it could work. I am abandoning the idea because I think it would end up being too heavy and not gain much time compared to a traditional bikesaw.

 

[cdog]

How about a miniature detroit diesel??
Cdog.