golf porting

[michael faszcza]

Anyone ever try golf balling a zenoeh intake port .after seeing some before and after dyno numbers on a bike motor .I'm very impressed

 

[Dennis Somers]

There are two types of intake flow, depending on the fuel delivery system. Our very small boat 2 strokes use "wet flow". Oil is the heaviest component, gas is next heaviest, and air of course, being the lightest. Having all the components well atomized right up to ignition will make good power. The surface of a wet flow port should not be very smooth or mirrored, but rather have a slight texture, so the heavier components don't separate due to surface tension of the liquids. The "golf ball" surface is doing that on your picture, albeit a very exaggerated surface. With our small size intake ports, slightly roughened surfaces does fine to the same end.

So yes; it's been done for decades, and continues to work well. It's not unlike breaking the water surface tension on the bottom of a glossy hull, by putting a very slight "texture" on the running surface. "Dry flow" ( you're only moving air or exhaust gas ) does well on a mirror surface.

 

[Patrick Mulvany]

I Golf Ball my pistons below the ring to retain oil and reduce friction but not the Ports??

Later!!

Pat

 

[Charles Perdue]

I Golf Ball my pistons below the ring to retain oil and reduce friction but not the Ports??

Later!!

Pat

Just curious...did you notice any difference in RPM or performance after dimpling the piston skirt? If so, how did you measure this change?

The reason that I ask is I tried this before on a nitro engine and measured a small decrease in RPM's,.

After thinking about this, I concluded that since the piston skirt is sliding on an oil film, like a boat hydroplaning on the water, rather than the assumed metal to metal, when you put the dimples in the piston skirt you break up this lubricating oil film causing more friction between the piston skirt and the cylinder liner.

Charles

 

[Jim Allen]

Charles,

I found the same thing to be true in larger displacement engines (15 to 30 cc). This applies to both gas & nitro engines. I was unable to find a pattern that would make the tested engines run faster. I tested different patterns & depths using an internal expanding collet to hold the pistons for machining. As far as golf balling transfer walls, I can't see how this would increase the laminar flow through the transfers. However, it would probably increase the turbulent flow. Lots of information on the internet about which is best for a high performance two cycle engine.

JA

 

[Patrick Mulvany]

Charles,

During testing I use the SenDec Tach and haven't found a difference in RPM?? I feel it just lubricates the piston and jug a little better for longer life. Along with routing out the inside of the piston it takes just a bit more weight away which I have found it increases accelleraration in my opinion.

Later!!

Pat