EDIT: It is the inlet port, not the exhaust port !!

Anyway, could it be doable around an exhaust port ??

On the following picture,

http://www.curareracing.com/mediac/400_0/m...6;20004.111.jpg

you can see 2 channels fed by lateral holes in a SS180 piston modified for a GS160 conversion.

Obviously, it improves lubrification and even help cooling a little bit the upper part of the exhaust port. (oups)

To my understanding, it may also improve the engine overall output by acting as a "4th port" (exactly in front of the 3rd port). Indeed, when the piston is going down, mixture is also going to be "rushed" through this port, counter-acting the effect of the 3rd port, and helping the fresh mixture to be more "centered" and not escaping through the exhaust port...

source: http://www.curareracing.com/51601.html

To my knowledge, modern 2Strokes engine doesn't have such things....

What do you think of this ? Pro/cons ?

Bearbeitet 10. Mai 200719 Jr. von KTy

reminds me of this:

(Quelle: MB Developments)

but I think that theese ports don't really work like the boostports that we know today. They maybe angled to the exhaust port to push out the burned gasses, or maybe angled to to support the transfers but expecially on the GS barrel the "boost" won't be strong enought to do so.

Bearbeitet 10. Mai 200719 Jr. von Blue Baron

AFAIK the main "effect" [i.e. better torque, some more (over)rev] results from improved "flow area" and thus better flow rate. The standard transfers are just too small (and gas velocity was a bit overestimated those days).

These carvings are not around the exhaust port but around the inlet port!

BOOST PORTS

These improve lubrification and also sligthly increase power