Let us not count out the two stroke.

[mep]

These piston and cylinder are really interesting.
Can someone explain why there is so a strange configuration
of the inlet and outlet ports and what are those boost ports doing?
Even the piston itself has a lot of these holes.
I wonder how they work together with the ones in the cylinder.

[safeaschuck]

Don't know if this an urban myth but I'm sure I've been told the Ford Ka was originally going to use a 2 stroke engine. That would have been 15 plus years ago now. A shame because the engine they gave it instead was absolutely dreadful, the worst thing about an otherwise great little car.

[Belatti]

Don't know if this an urban myth but I'm sure I've been told the Ford Ka was originally going to use a 2 stroke engine. That would have been 15 plus years ago now. A shame because the engine they gave it instead was absolutely dreadful, the worst thing about an otherwise great little car.

Indeed, a thirsty and underpowered piece of crap.

[flynfrog]

These piston and cylinder are really interesting.
Can someone explain why there is so a strange configuration
of the inlet and outlet ports and what are those boost ports doing?
Even the piston itself has a lot of these holes.
I wonder how they work together with the ones in the cylinder.

The boost ports are to get more fuel and air into the chamber. The holes in the piston are to create more crank case volume (in a two stroke the crank case acts as part of the intake track of the engine). But the short answer is it has all of the holes to flow massive amounts of fuel and air. Similar to adding bigger valves to a 4 stroke motor

[aterren]

What work of art engine are those pictures from?

[flynfrog]

What work of art engine are those pictures from?

http://www.twostrokeshop.com/TSS1100GP.htm

[mep]

The boost ports are to get more fuel and air into the chamber. The holes in the piston are to create more crank case volume (in a two stroke the crank case acts as part of the intake track of the engine). But the short answer is it has all of the holes to flow massive amounts of fuel and air. Similar to adding bigger valves to a 4 stroke motor

Sorry I can't really believe that because they increase the volume just by a margin.
To avoid misunderstanding I am talking about the holes in the skirt of the piston.
They are drilled in very thin metal so they have a small volume.
I rather have the impression that they have something to do with the steering times. But I don't really see how it is working. With so many holes in the cylinder I guess you want the piston skirt closed.

[Flummo]

The big windows far down on the intake side are there to connect the intake to the crankcase all the time = the reedvalve gets complete control of intake timing.

Smaller windows higher up: most likely for feeding the two ports above the inlets (commonly called boost ports, but not on that pic). Added bonus: air flow through there cools the piston and the small end of the conrod, and also brings additional oil to that bearing.

Holes above the piston pin: As far as I know, only meant to keep the weight down. On some occations cylinders have holes, connecting those holes to the scavenge ports.



Work of art? Perhaps. But these days tuning cylinders for mopeds look more or less like that and can pump out 20+hp from around 70cc...