Seems like the reason most OEM does not use TotalSeal ring is here:
http://www.team-integra.net/forum/displa...ng+Common+Topic
Quote:
The style ring you use will depend largely on
- the type of engine (NA or FI)
and the extent of the modifications. :
- Gas-porting (on your pistons) [gas ported pistons have holes on the side of them to allow air to push the rings against the cylinder wall when the piston goes up & down for better ring sealing: usually used on a race only piston and not a street piston)]
- piston diameter above the top ring,
- engine rebuild frequency [do you plan to rebuild the engine in 1 week like the race engines or at 30-50K miles for modified street performance engine rebuilds ?]
- honing capabilities [do you have access to a good engine machine shop with honing machines that can bore and hone perfectly straight and round cylinders or does the shop do it by hand which is worst ?]
(These all) dictate ring shape and material selection.
Oil ring tension can obviously be reduced if you're able to exert a vacuum on the crankcase. [i.e. There's more suck from below the piston in the crankcase , if your engine block PCV (positive Crankcase Ventilation) system can vent the crankcase's gases better like on an oil catch can setup or in dry sump engines with block vacuum pumps which are race only]
HISTORY OF GAPLESS RINGS
Childs & Albert pioneered the "gapless" rings back in the early 1970's. They found a lot of racers willing and waiting for a better way of sealing the gasses effectively in the cylinders. The rings were moderately successful, with most of the people running them in the old Jr. Stock classes, where rules were very strict and prohibitive. As more conventional rings received more and more attention, with all sorts of different alloys and ring face configurations, the gapless rings lost favor.
Total Seal jumped on the gapless bandwagon about the time the "fad" faded out, but as I've mentioned before, they became the first (and only) manufacturer to make metric sized rings, so their gapless designs were often the only rings available for folks rebuilding "foreign" engines. This original "niche" market turned into quite a large movement as the popularity of "import racing" rose to the heights it's currently enjoying....and with a lot of advertising, Total Seal has capitalized on it.
I've experimented with some of their rings in engines we've built but I've never seen power that we can achieve with our more conventional Nippon rings.
I believe that the reason behind it is due to the fact that the (gapless) rings aren't as stable in the (piston's) ring grooves in applications where the ring width is 1mm or less. It's a lot more difficult to achieve a tight fit in the groove with two rings as opposed to one.
With individual rings this thin, they have to be made from HARD material just to stand up, and this causes problems too, with many stock and aftermarket cylinder liners. I'd say that the cylinders (walls) would have to be prepared pretty coarsely to seat them in a reasonable time period and once seated, I seriously doubt that they'd actually "leak" any better than properly gapped conventional rings...assuming you're leaking the cylinders near operating temperature.
We try to configure ring end gaps to when the engine's at maximum operating temperature, the ends will come very, very close to touching each other, without actually butting and scoring the cylinders, so any leakage would be minimal at best. When you think about the tiny bit of gap that gasses must pass through, and the amount of time per stroke this has to occur, going gapless makes even less sense.
Ring stability is, on the other hand, extremely important, and this is where conventional rings are better by a fairly wide margin.
Many domestic ProStock teams are currently having Total Seal make rings for them with special coatings (on the ring sides) and they lap them to achieve the minimum ring to groove clearances they're after. It's interesting to note that none of these rings are of the gapless variety. Being a relatively small company (compared to some of the more prominant OE ring suppliers), Total Seal can, and does make a lot of small-batch "special" rings that work pretty well, but these are a long way from what they're selling over the counter to import racers.
The Total Seal rings that are custom-made for some race teams are not the same pieces you have access to either.
Gapless rings have end gaps too, but they overlap in such a way as to be described (and marketed) as gapless.
When you push too much fuel between the rings, it'll finally "explode" if there's any detonation in the chamber, blowing the ring lands out. This happens frequently on engines using gapless second rings.....
Zero end-gap ring designs are constructed where the ends of the ring are cut to half thickness. When installed in the piston, the half-thickness sections of the ring overlap. When the engine is running, the ring heats and expands. The ends of the zero end gap ring slide across each other, which in turn, leaves no gap for the gases to escape. In a more conventional high-performance ring combination, the gaps actually close when the engine is running. Very little pressure actually escapes through this opening. Because of this, the tradeoffs in ring weight (a conventional ring is typically lighter than a zero end-gap design), and sealing capability (a conventional, thin high-performance ring incorporates a barrel shape; a zero end-gap ring doesn’t) simply aren’t worth it. The bottom line: a conventional ring will outperform a zero end-gap ring. The only exception would be in alcohol-fueled applications. Alcohol fuels are not compatible with motor oil, and any residual alcohol that may be in the combustion chambers after the engine is shut off can drain through the ring gap and contaminate the oil. In this case, a zero end-gap ring can prevent this from occurring.
