2-4 stroke

[BoatBuoy]

A previous post about gearboxes brought a question to my mind that I've been wondering about (not about gearboxes). Has anyone experimented with a 2-stroke hybrid. One that burned gas only (no oil) but an otherwise 2-stroke fuel system, and used a lubrication system like 4-strokes? Just another one of my dumb ideas.

 

[JB]

Re: 2-4 stroke

Several of the oil injected engines put the oil directly into the crankcase, BB.<br /><br />All of the DFI 2 strokes do the same.<br /><br />Because air is pumped through the crankcase of all 2 strokes, it is unlikely that a circulating lubricating system like all 4 strokes use, would be possible. Oil would still get pumped into the cylinders and be burned.

 

[jim dozier]

Re: 2-4 stroke

Detroit Diesels are supercharged 2-stroke diesels (I believe) with an oil bathed crankcase like a four stroke. I think (never had one apart somebody here probably has) they use intake ports like a 2-stroke and overhead exhaust valves like a 4-stroke. The supercharger is necessary because there isn't any crankcase pressurized fuel mixture to inject the fuel charge into the cylinder. They are limited in rpm because the valves are opening every stroke for the exhaust. With a modern double overhead cam valve train I don't see why you couldn't get a similar desinged gasoline engine to operate up to about 5,000 rpm. My guess is that some of the benefits of the 2-stroke would be lost (simplicity and cost) and the current 4-strokes would probably get better fuel economy and emissions. I wonder how the diesel desribed above compares to the standard 4-stroke diesel?

 

[BoatBuoy]

Re: 2-4 stroke

I remember hearing that some diesels are 2-stroke and the trained ear can hear the difference. thanks for the replies.