I know David Vizard is a big proponent of them, but the debate on SpeedTalk has never been resolved to anyone's satisfaction.
Some folks say they see small power gains.
Others say there's no power benefit, but the engines "stay fresh" longer.
And others, like RAMM, have reported oiling issues; he's NOT the only one to have raised this issue, for anyone who thinks he's an outlier on this subject.
I don't have an R&D budget to prove/disprove their benefits to myself. Since my own limited findings have been inconclusive, I'm using a more traditional ring pack now.
To the person who asked if I liked Napier 2nd rings, I don't have any miles (only dyno time) on the engine to see how the oil consumption is. What I do know is that GM switched from the old 2nd ring design to Napier 2nds as part of their "fix" (or mitigation?) of high oil consumption with certain LS engines.
Like I've said, I've personally used so many sets of these rings and not had a single issue that I find it hard to believe everyone can't get them to seal. It's a freaking ring. It doesn't know it's gapless.
I finish all my bores with a 400 finish and hit it with a brush for 8 strokes. Without having the honing book in front of me I can't give you the exact values of the finish but IMO it's not that hard to achieve.
I also know other builders using them and I called one yesterday and he says he's not having issues either. BTW and FWIW I developed my honing procedure way back in 1995 through several phone calls with Earl Garte and several more with Smokey Yunik, since I read an article in Circle Track magazine where Smokey worked with Peterson Machine Tool (IIRC) to develop soft hone brushes.
I've used that finish on everything from tool steel to plain cast iron that were new old stock from 1954 and never had any issues with ring seal.
I also spent many hours on the dyno with the first 3-4 engines that I personally used them in to measure actual blow by under load. The rings every single time showed a massive improvement in blow by reduction.
The first engine was a 400 Chevy done by another shop. It was an oil burner. You knew it had no ring seal because you couldn't keep oil in the engine. It would build crankcase pressure and blow oil out wherever it could. When it was sealed up, it would blow the dipstick out.
It was .060 and the owner wanted a new block. I talked him into letting me use gapless top rings to test them and if it didn't work he didn't have to pay for it.
I ran into him earlier this year. It's still going. Doesn't use oil. Runs as good now as the day it came off the dyno.
The moral of the story is if you can't get a ring to seal that's on you. Most rings are pre-seated before they even go into the box. Cheap rings used to be belt lapped and the better rings were barrel lapped, although there may be a better method now.
There is no excuse for bad ring seal in this day and age. No excuse. To blame the rings is like a machinist blaming his tools for piss poor work.
I never base how I build engines on what OEM's do.
