Thoughts on 1.0/1.0/2.0 mm ring package, pure street 60s engine

[bigfoot584]

Thanks for the replies

I have another question. Is a single oil ring on a 2.0 mm oil ring pack significantly thinner than a single oil ring on a 3.0 mm pack, or for that matter are both significantly thinner than single oil ring on a 3/16 pack?

I have heard concerns about oil control with 2.0 mm, and have also heard that the spreaders have reduced tension as they go thinner, but I am having a hard time comprehending how thin the individual oil rings can get and still stay stable. Seems hard to believe that an individual oil ring in a 2.0 mm pack is that much thinner than a 3.0 mm ring pack. At some point you'd have something that would not be easily supported I would think.

Or is the reduced tension because the 2nd ring works better at 1.0mm so it allows less tension with a 2.0 pack versus a 3.0 mm pack?

I may be daring on one build and conservative on the other, still weighing alternatives

Thanks!

This may help to compare, .03937in = 1mm

[My427stang]

This may help to compare, .03937in = 1mm

I know how thick 1 mm is

My point is, in at least one brand, in a 2.0mm ring pack, each rail is .017, in the same brand 3.0 mm ring pack, each oil rail is also .017

So, the difference is the expander which takes up the space.

However, many people love the 3.0 but are afraid of the 2.0 pack, in fact I haven't heard any downsides of the 3.0 mm pack. Trying to figure out why that is, when it really sounds more like the 2.0 would work just as well if tension was the same, and in fact a 3.0 mm pack could even be worse for oil control depending on the spreader.

I likely deduced my own answer, but hopefully this week I can talk to a ring company to see if there really is any reason a 2.0 mm oil ring pack would be worse

I have used that Mahle 428 piston set before with the 10 , 1.0 , 2.0mm ring set and didn't have any issues. I'm 90% sure the radial dimension on the oil rails was a little smaller than the typical 3mm version. We shipped job almost a year ago.

Thanks, Barry Rabotnik reports the same with the Mahle 1.0/2.0 combo. Good to hear.

I don't really need anything fancy on either of these, but it's intriguing just the same. The question will ultimately come down to: Is there any significant gain (or downside) of a 1.0/2.0 ring pack versus a 1.5/3.0 mm if the oil ring package is similar tension?

[BLstangin]

We run them in some dirt track stuff work really good, zero oil consumption issues in 35 nights, run it 8 nights between oil changes with no lose of oil. But on a refresh at 18 nights it started to use oil pretty bad, found the owner had got the air filter on wrong and stucked some dirt in, that was the end of the rings, they really didn't like the dirt intrusion, and neither did the cylinders, but that's operator error nothing to do with the rings.

[jed]

As the rings get thinner, the old fumble fingers have to get more dexterous as well. I know guys who've been assembling engines for forty years who have had problems getting them together. It takes a precision ring compressor and the tops of the cylinders can't have much chamfer, or the thin rings can easily snag.

What suggestions do those of you who assemble the 1.0 mm rings regularly have for us who don't?

The top and second ring are not hard to install with the a ring expanding tool.
However the 3 piece, 2mm, oil ring are tricky. The expander is not the problem but the thin rails require
Very care full assembly.
To install the piston ring assembly you have to have a fixed bore compressor or an adjustable compressor nothing else will
work. Slide the piston and ring assembly in to the the compressor until the oil ring is almost to the bottom of the compressor.
Tighten the clamp tight then back off 1/8 turn. Just enough to enable you to slide the piston out.
It also helps to have the cylinder verticle then square the piston in the compressor by tapping around the cercumference of the piston then keeping the Compressor flat on the deck with a forceful tap/blow
On the piston top drive the piston into the cylinder.
John

[engineguyBill]

So, from what I have dug out of this and some research is that the compression rings are thinner (obviously), but the oil rings aren't much different, only the expander.

So, the question I am trying to still pick away at, is: Is the drag reductions with a 2.0 mm ring set because those rings typically come with a low tension expander? or is it just because of the reduction of thickness and tension of the smaller compression rings?

I will call around to the ring manufacturers, but I can't wrap my head around why a 2.0 set oil ring would have less drag than a 3.0 set. I certainly understand that any oil ring could have an expander with lower tension, but what does the total stack dimension have to do with both oil control and friction if each use a oil ring at .017 inches? And why could a 2.0 mm oil ring stack live with less tension if the rails are the same thickness?

A 2.0mm oil ring assembly does not necessarily have less tension that a 3.0mm oil ring assembly. The oil ring can be designed with whatever tension is desired. I have seen 3/16" oil ring assembly with less tension than 3.0mm oil ring or 2.0mm oil ring - it is all in the design of the expander and the rails used to make up the oil ring assembly.

[MadBill]

Assuming similar design and identical tension, what's the benefit of a 2 vs. 3 mm ring; just another 40 thous of real estate?

[swampbuggy]

A longer con-rod Bill, LOL.....Mark H. Oh crap maybe i should not have said that LOL.

[Momus]

Assuming similar design and identical tension, what's the benefit of a 2 vs. 3 mm ring; just another 40 thous of real estate?

Real estate but also a lower inertia, lighter assembly. 1.00 is a thick heavy 1st or 2nd ring in contemporary engines. I believe NASCAR has gone down to .7 - 028" and perhaps thinner. Air cooled small bore bikes I play with are using a single .8 compression ring that I reckon seals better than 1.0 and 1.2.

[BILL-C]

We have used .0274, .0274, 2mm ring sets many times on vintage road race engines ( some of them vintage cup cars) with excellent results. Yes, they are dry sump, but they have piston guided rods and also have piston oilers thay spray more oil on cyl walls and piston undersides than would normally be there with a wet sump street engine. Napier second rings have very good oil control. I have a couple of my workers stay busy doing warrantee engine work for the many local new car dealers and get to see all of the newest tricks from the oem's. Most new cars have been using very thin rings for many years, with 1.0 and 1.2 compression rings and 2.0- 2.8mm oil rings being the norm.

[swampbuggy]

Thanks Bill-C for that post, i have been thinking a lot about the ring package that is gonna go into my current S.B.C. build. In your last sentence where you mentioned O.E.M.'s employing THIN ring packs and most of those engines are wet sump set ups. This makes me even more comfortable going with .9 .9 2mm ring package along with a 6-stage dry sump , 4 to pan, 1 to lifter valley, and one pressure section, hoping for 20 on vacuum ?? Mark H.

[engineguyBill]

There is really not much performance advantage to be realized with very thin compression rings (1.0mm and less). The ring tensions are set by the radial thickness of these rings, not necessarily the axial width. The thin rings (compression rings and oil assemblies) will allow for less room taken up by the ring package, which will allow for smaller piston height (less piston weight) and/or longer rods.

[LSP]

with a forceful tap/blow On the piston top drive the piston into the cylinder.
John

I'd not recommend anyone do that, if you need a forceful tap or blow to get rings this small in, there's a problem that needs to be corrected.

I've always been able to get these and the smaller .023" rings to go in smoothly with my thumbs, and sometimes a slight rolling motion.

[BILL-C]

1.0,1.0,2.0mm rings should be pushed through a tapered ring compressor with your fingers. No hammering required. Those little suckers are fragile!

[rickseeman]

If you watch the youtube videos of engine assembly at Ferrari, Porsche, Mercedes, Bugatti and BMW the little girl pushes the pistons in with her thumbs. Is that telling you anything? I don't know if there is a single OEM that uses the giant rings of the past. The only people that use them that I know of are American rebuilders that wonder if 1.0/1.0/2.0 will work.

[engineguyBill]

Major engine rebuilders/remanufacturers in the USA, replace the rings with the same configuration of rings that were used in the engine when manufactured by the OEM's. in other words 5/32", 5/32", 3/16" ring package is built with that same ring width.