*Keith: Thank you for your series of informative presentations. One correction though: For NA engines, it is Atmospheric Pressure pushing the air mass towards intake vacuum, not Gravity. Gravity has zero useful effect on intake air flow.*

I started using these in my VWs in 1970. RIMCO had them. The top rings worked great for me but I did discover the need for more gap. I also really appreciated being able to buy just the top rings instead of a set. It was definitely an affordable benefit back then.

Thanks. I was wondering about those issues, and you answered them perfectly. At the time in 2007, I asked the question why not top ring, and one of your reps suggested that i can wind up getting ring flutter so its best for 2nd ring kit. I purchased my 2nd Gap ring Kit in 2007 X2667 (3.917 1.2 4CYL) WRX 2.5 Still as strong ! and its now 2019 : )

can you run both ? top and 2nd rings gapless !

Would you dare run both top and second gapless rings in a normally aspirated engine? or, would that "oil starve" the top ring? I'm also interested in this concept for air compressors, to minimize oil into compressed air.

I have been recommending gapless rings for years in turbo motors. However, getting people to listen here on this, instead of just running a bigger ring gap on the top ring is not easy...

A interesting Video. Does it make sense to install in a natural aspirated engine a gapless top and 2nd ring? What about the vacuum the engine produce when you lift up the pedal at high rpms? I guess the gapless ring produce more vacuum in the crankcase. Does anything Need to be considered to avoid unexpected issues?

So on like the Subaru NA Ej25 daily driver, the top rings would be the ideal choice?

Can't we use both of the Top and second Gappless Rings in a street driven Turbo charged application and do we need special pistons to accommodate these Gappless cylinder Rings?

but they wear faster than reg ring in street motor

Air does not get "sucked in" on the intake stroke, air is rushed in by Atmospheric Preassure.