Hot Saw Parts

[sedanman]

Wayne, Each flat of the lobe is only 1/2 of a combustion chamber, the other 1/2 is the portion of the engine case where the spark plugs are. Easy to see why rotarys are so hottly debated.

 

[ccicora]

So what would be the best two stroke oil to use on then??? Are they piston ported or valved controled??? I do know that the engines take well to turbo charching and NOS. Now I did see a mini one used on a chainsaw (Don't remeber were I saw the clip). Could you make one that you could cold start and race??? Would it be EPA complyant?

Do you think this snow ball is growing yet? :Eye:

 

[sedanman]

Piston ported, no valvetrain. Dolmar built a production Wankel engine chainsaw. Sachs made Wankel snowmobile engines and a lawnmower engine.

 

[stihltech]

stihlman

Chris needs some sleep.

 

[WRW]

Wayne, Each flat of the lobe is only 1/2 of a combustion chamber, the other 1/2 is the portion of the engine case where the spark plugs are. Easy to see why rotarys are so hottly debated.

Shouldn't that be "Each leading flat of the lobe" ,or half of the flats of the lobes?

 

[sedanman]

Bill, Debatable as combustion pressure acts on the whole flat side of the lobe. Pressure in a vessel is equal everywhere with in the vessel.

 

[Lawn Masters]

This is confusing. The only problem I can see with a turbocharger on a chainsaw is the need for an intercooler to cool the oil that keeps the turbos bearings cooled. that alone would add somewhere around 10-20+ pounds to the saw. though if one were to invent a supercharger that is driven by the flywheel, that would be interesting, but still require an intercooler for the bearings.
Complex stuff isnt it?

 

[spacemule]

A 90° vee twin with a single crank throw is the only twin capable of perfect primary balance (every ¼ turn) in all planes.  All other configurations will produce a rocking couple along the axis of the crank in one or more planes.  Counterbalance shafts can alleviate the imbalances only to a certain extent, not entirely, and at a cost of weight, complexity, and (as mentioned) power.

Even an inline 4 is buzzy because of those rocking couples.

Glen

How about a simultaneous firing, 180° opposed two-stroke twin with two crank throws 180° apart? Will this configuration not display near perfect balance?

 

[glens]

In one respect, yes; at 0° and 180°.  Think about what the crank counterweights are doing at 90° and 270° though, with nothing to oppose them.  There will be relatively severe vibration in the vertical plane if the jugs are oriented horizontally.

In the 90° vee twin with common throw (or multiples of such twins on a common shaft) the counterweights are working against a mass which directly absorbs their energy every 90° of crank rotation, instead of only every 180° as in the boxer.

I just did a google search for "engine primary balance" and http://www.prime-mover.org/Engines/GArticles/BALANCE.Lyc looks like it'll be a good read.

Glen

 

[WRW]

Bill, Debatable as combustion pressure acts on the whole flat side of the lobe.

You're right. The second thing to go is memory.

Pressure in a vessel is equal everywhere with in the vessel.

Well...I think there can be some variations in pressure, if we're talking gasses.