Originally Posted by fyrstormer

Yes, I know bolt-on superchargers for nitro engines don't work, at least not well enough to justify the extra complexity. I'm just pondering something.

Nitro engines are designed so the exhaust port opens before the transfer ports do, to release exhaust pressure so exhaust doesn't blow down through the transfer ports and block inflow of fresh air and fuel. The side-effect of this is the exhaust port also closes after the transfer ports do, reducing the engine's compression, even with a tuned pipe on the exhaust to "bounce" the escaping fuel and air back into the cylinder before the ascending piston seals off the exhaust port.

But what if you engineered a nitro engine specifically to work as well as possible with a supercharger? If the crankcase were sufficiently pressurized by a supercharger, you wouldn't have to worry as much about exhaust blowing down through the transfer ports, so you could have an exhaust port that opens at the same time as the transfer ports, or even opens *later* than the transfer ports. (the exhaust port could be made wider to compensate for not being as tall, so it would still have the same flow-rate.) That would mean the transfer ports could stay open after the exhaust port closes, and the intake valve on the crankshaft could be adjusted to stay open for longer while the transfer ports are open, which would allow the supercharger to actually pressurize the combustion chamber properly.

Thoughts?