An expansion chamber works by improving volumetric efficiency. Shock waves help empty the cylinder of spent gases, literally sucking them out, then keep the fresh charge in the cylinder untill the exhaust port closes.
Now back to the original premise. You guys got me thinking and it IS THEORETICALLY possible,
though not practical.
Here's how it COULD work. Take a 4-stroke engine, like a Raptor 660 for instance. To turn it into a 2-stroke the first thing you'd have to do is speed up the camshaft so it turns the same speed as the crank, by reducing the cam sprocket by half ( impractial #1, this is going to be hard on the valve train and will cut potential rpm in half) Now you've lost your intake stroke, and crankcase compression, so a supercharger would be a must. Obviously valve timing becomes critical, though with a double overhead cam you have more room to experiment than with a single cam. An engine with high rpm potential like a Raptor, would be a good starting point ( Don't! I repeat, Don't try this! This is purely academic) Its' multiple lightweight valves
may be designed for 10,000 rpm, which means they can only go 5,000 rpm in this engine.
So now we've cut rpm in half, and added the weight and expense of a supercharger just to make it work. We've decreased efficiency because of overlapping intake and exhaust cycles, like a 2-stroke.
But it would run. Certainly not as well as a regular 2-stroke or 4-stroke. It would combine the weight of the 4-stroke with the inefficiency of a 2-stroke. The expense of a high rpm valvetrain and a supercharger would be lost to just making it run. Keep it as a science project. But keep thinking.

 

I have a friend that is a Toyota Tech and he got a free trip to Japan and seen what they are working on in there high performance indy engines, Try ditching the entire valve train and replacing the valves with Fuel injector type high temp cyilanoids that are computer controlled to alter the timing anywhere in the powerband and also allow unlimited RPM with no rolling valve train mass. The engine he seen was a 2,000cc (2L) V16 oval piston engine with 4 cyliaonid type valves per cylinder that made 700HP and 50FTLB torque The engine redlined at 25,000RPM and sounded like nothing he has ever herd. Now that can be cannonade's next engine!

 

The reason the 2 cycle diesels worked is by the nature of diesel engines. By nature, gas engines would be much harder to do this on. The 2 stroke diesels used a supercharger to pressurize intake air. It blew the exhaust out and filled the cylinder with a fresh charge of air. Because there is no fuel mixed in a diesel intake, there was no worry of unburned fuel going out the exhaust (emissions alone wouldn't allow that anymore). The diesel then injected a shot of fuel directly into the combustion chamber, where it ignited, producing power. I think the limiting factor would be figuring out a way to direct-inject gasoline into the cylinder. Then, you coult theoretically get by with intake/exhaust ports (no valve train) and use a supercharger to blow the air in and exhaust out. The supercharger would be fairly heavy, but would allow very high RPMs.
How about a turbine engine on an ATV? Or maybe a rotary???

 

Yeah Baby, Now that's entertainment!!!

 

just yesterday i was thinkin about a turbine engine in a quad. They are said to be more powerful and efficient. On the other hand, can you see an engine in a quad capable of 50,000+ RPM? that is a bit much. Those engines cost an extreme amount of money. they are pretty sweet though. you can get them to run on gas, kerosene, diesel and probably alot of other fuels, I bet they would be a pain to maintain. I don't even want to think of the cost for a rebuild.

 

Crystler made turbin powerd cars and trucks between 1950 and 1975 as research and development only. MY dad had a nebor that had one as he was picked as a demo driver back in the 60's when he lived in fairbanks while in the airforce. It was a 3 speed auto and gutless below 20MPH but would smoke the tires at 60 and rocket to 100 even on a 6% hill. We have old 8mm movie of it as it was well before my time. And about the Direct Injecton, its common use on gasoline engine in Europe but not compatabe with our fuel as it requires a min of 100 octane. Just another drawback to our junk fuel in the states

 

Im only 13 and don't know much
but could you have 2 stroke with
the exsaust components of a 4 stroke
for less emisions