How does single piston rings stand up

[popopboat]

*Not sure if im asking this in right category*

Anyway, was wondering how do single piston rings ( mainly think on husqvarnas) stand up?
Is there a difference in compressions? How much? Does is last longer than dual ones (if both threated well ofcourse).
And what are reasons for going with single piston ring? ..? Cost, friction?

 

[Steve]

Most cars only have one compression ring...

Less rings=less friction

I have not noticed one lasting longer than the other. Both rings will wear around the same. I have not put a single ring on a dual ring piston and then done any compression testing. Too much work!

Im a husqvarna guy if there is any merit in that. Long story short, run what you like and to hell with everyone else!

 

[Al Smith]

It depends on the application I suppose .On little "glow" engine they have no piston rings .On low speed high displacement engines like Caterpillar or John -Deere they might have 4 compression rings and two oil rings up to 5/16" thick .Large piston ,carries a lot of oil with it and last almost forever .
The trend these days on modern auto engines is thin rings but the tolerances and materials are much better controlled than previous designs plus the oil is much better .I grew up during the "good old days" which were anything but regarding old auto engines .On the other hand owning them you got real good at turning wrenches just keeping them running so from that aspect at least you learned something .

 

[huskyboy]

The 372xp is noticeably stronger with the one ring piston vs the two ring piston. Less friction and less weight. Two rings should last longer... in theory. Lol

 

[qurotro]

Well.. Lots of husky single rings saws earned their reputation though.. I just can't answer this.

 

[mdavlee]

The 372xp is noticeably stronger with the one ring piston vs the two ring piston. Less friction and less weight. Two rings should last longer... in theory. Lol

The fastest 372 true work saw I ever built had 2 rings[emoji2371]

 

[huskyboy]

The fastest 372 true work saw I ever built had 2 rings[emoji2371]

Just speaking from my experiences with one that I swapped recently, before and after the results were pretty noticeable.

 

[dmb2613]

I have an 024 with one ring and an 024 with 2 rings, dammed if I can tell any difference

 

[mdavlee]

Just speaking from my experiences with one that I swapped recently, before and after the results were pretty noticeable.

That was my experience except that one there. It made me think it might not be the piston.

 

[huskyboy]

That was my experience except that one there. It made me think it might not be the piston.

You swapped pistons and timed the cuts? There was a couple second difference in my testing and that was before the one ring piston even broke in.

 

[mdavlee]

You swapped pistons and timed the cuts? There was a couple second difference in my testing and that was before the one ring piston even broke in.

2 ring was a brand new p/c and single ring was broken in. And a I had a wiseco/dominant piston in one.

 

[Nutball]

Do you leave one of the ring slots empty or machine it out (popup) when converting to one ring? If leaving the gap, that could cause early flow velocity in the transfers before the transfers even open, giving the gasses a head start in moving since it would free port with the exhaust port.

 

[huskyboy]

Do you leave one of the ring slots empty or machine it out (popup) when converting to one ring? If leaving the gap, that could cause early flow velocity in the transfers before the transfers even open, giving the gasses a head start in moving since it would free port with the exhaust port.

The early 371/372 had a one ring oem piston. Later on they fitted a two ring oem piston. They can be interchanged and swapped with one another with no issues.

 

[qurotro]

The early 371/372 had a one ring oem piston. Later on they fitted a two ring oem piston. They can be interchanged and swapped with one another with no issues.

Hmm... Adding to this one is the piston ring thickness is different.

And one ring piston designs tend to use thicker ring too.