Originally Posted by
Seagull 170
A couple of years ago I gave a lot of thought to building a 3 cylinder axial flow turbo 2 stroke, the idea was to use a commercial 2 stroke block with replacable liners, the head was to have 2 desmodromic inlet valves with 2 plugs & a single overhead camshaft.
the breathing was to be turbo,single carb into the 3 crankcases, out into a common inlet gallery somewhere where it could lube the little ends & cool the pistons, then out & up to the head.
The exhaust would be low & very wide more than 180 degrees wide, giving a longer trapped stroke, exhaust ports either side of cylinder block feeding into a turbo that was offset way over on one side in the hope of damping 6 smaller pulses rather than 3 big ones.
The hopes were that the high scavenging efficiency coupled with the longer trapped power stroke & the higher cylinder pressure when the valves closed (dependant on the boost pressure) would raise the torque enough to cover the slightly lower max revs.
Because of the lower bore/stroke ratio required the piston speed would have to be balanced with the valve speed until they were both civilised.
The problems that I never answered were, where to put the crankcase outlet ports (in a block with 3 cylinders that almost touch each other) so they could do some usefull piston cooling, & how was I to lube the camshaft & everything at that end. I did consider putting the camshaft into the inlet gallery.
Fuel consumption was allways going to be poor when you have to clean & cool the piston with that much of the fresh charge.
I must be getting old when most of my waking thoughts are about 2 stroke motors.
Bookmarks