Cylinder leakage test

[Cglrcng]

Originally Posted by Kirk Morgan

Will a gas ported piston and ring package leak the same as a conventional piston and ring package?

Am no expert here (call Ed Ercis at Ross, or anyone at Total Seal and they will explain it in simple terms)...But logic says the gas ported piston ring package is a historically recent modification beyond the normal piston/ring usage (though now widely used), and using a tiny bit of cylinder pressure on the way up, and the same in exhaust gasses on the way down (to expand the top or top 2 rings outward against the cylinder walls for better compression ring to cylinder wall sealing, has to without a
doubt in my mind also allow a certain amount of those gasses/pressure to bypass the compression rings and escape to the pan due to the gaps below, unless maybe in the use of a gap less ringset (don't know, and my logical mind says that is also a further modification that may change the equation).

Now add in that a leak test is usually done static (without piston and ringset movement in the up/down directions so it (the air pressure, that you are introducing during the leakdown testing process would still be pushing the compression ringsets against the cylinder walls, but some leakage is bound to be present, just not in the
same exact manner as actual running of the engine uses it.

Who was it long ago that was actually knurling the piston skirts? It was beyond a novel concept and gave birth I think I read many years later to the gas ported piston/ringset idea.

My bet is the Guys in Lake Havasu City at EFI University having a Spintron machine, probably have tested the exact question you posed in a non-static (and an actual engine spinning but not actuallt running condition). The Spintron is an expensive yet amazing test machine. They have done testing there as a learning institution that nobody has ever attempted (like running an engine on the dyno full throttle open plenum intake without a throttle body or carb, just to see what happens)...it ran...wide open w/zero restrictions. A super crazy test for sure. No throttle blades to close off airflow. Ever seen a runaway diesel on a dyno explosion? Think ok it runs perfectly...Now how do we shut it off without intentionally going full lean by simply shutting off the fuel flow? Will the clipboard in his hand be big enough to choke off that airflow, and who would be crazy enough to enter a dyno room and approach that engine at full throttle....all on camera and uploaded to YouTube for our viewing pleasure.

Pose the question to them, my bet is they know the answer.