Piston Gas Porting

Piston gas porting, does it work or not? I would like to hear some opinions.............Or perhaps some benifits?

gas ported pistons are needed for today's low tension piston rings in high compression race motors, cylinder pressures are so high that if you use light wieght low tension rings with out gas porting you can get serious ring flutter and the rings wont keep there shape and they can allow excessive combustion gas blow by. that being said they will cause excess wear of the cylinder and and ring set so i wouldn't recommend there use on a street motor. unless it was a turbo or blower motor or maybe one that used fairly big loads of nitrous from time to time if you do use this kind of piston and ring pack be prepared to replace them more frequently than standard type pistons and rings

Please explain what piston gas porting is.

What are gas ports and when should they be used?

Vertical gas ports are primarily used in drag race applications. Lateral gas ports are more often used in circle-track and road-race applications where carbon build up can occur. When gas ports are used, pressure is directed to build up behind the compression ring and seal it against the cylinder wall. This helps prevent ring flutter and extends the power curve upward in the RPM range. Vertical gas ports have the holes drilled from the deck of the piston into the top ring groove and behind the ring. Lateral gas ports are drilled through the bottom side of the top land and extend to the back wall of the ring groove.

Lateral Gas port.

The real advantage is that you can run a ring package with lower static tension than a stock ring. This gives you less friction and frees up horsepower. Without the gas ports the low tension rings wouldn't seal against the cylinder very well, but allowing extra combustion pressure to force the ring against the cylinder makes up for this. In effect you get a variable-tension ring. It's high tension when needed for sealing, low tension for reduced friction the rest of the time.

The engines I've built have all been short-run use (tractor pulling) so I can't confirm or deny about the increased wear phenomenon, but it does make sense.

ArthurGoVroom wrote:

The real advantage is that you can run a ring package with lower static tension than a stock ring. This gives you less friction and frees up horsepower. Without the gas ports the low tension rings wouldn't seal against the cylinder very well, but allowing extra combustion pressure to force the ring against the cylinder makes up for this. In effect you get a variable-tension ring. It's high tension when needed for sealing, low tension for reduced friction the rest of the time.

The engines I've built have all been short-run use (tractor pulling) so I can't confirm or deny about the increased wear phenomenon, but it does make sense.

What is the lowest compression ratio, you have seen them used with? The lowest I have seen is 10:1 ratio.

i've seen them used in some low compression blower or turbo motors 8-1 or less. it all depends on how much boost was being used

interesting I've never heard of that before. It makes sense but does sound like something you would want to use in a race bike rather than a street bike

All good and fine John. But what color will your bike be ?

thompsonmx100 wrote:

interesting I've never heard of that before. It makes sense but does sound like something you would want to use in a race bike rather than a street bike

and this all means what to the 99.8% of us who run on the street...?:laugh:

absolutely nothing unless you want to be changing pistons and rings on a regular basis.