Ambitious newby

**blackburn mark** · 30-06-2012

i assumed expansion chambers would do all the work and "suck" the next charge in

**Robin Hewitt** · 30-06-2012

Originally Posted by blackburn mark

i assumed expansion chambers would do all the work and "suck" the next charge in

Did you miss the 2 stroke part? There is no suck unless you do something really clever with the exhaust pipe geometry.

To pep up a 2 stroke you put a clack valve between the carburettor and the air inlet, it stops it blowing back through the carb when the piston starts it's down stroke. (They call them "reed valves" but they are really clacks).

A turbo charged 2 stroke is interesting. Of course you can't increase the cylinder pressure because the exhaust valve is still open when the inlet cracks, but 2 stroke power is all about flushing the exhaust from the cylinder. With fuel injection you wouldn't be blowing unburnt fuel down the exhaust if you over-cooked it.

OTOH what do beer swilling morons like me know about designing engines?