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-   -   Low tension oil rings (

oil pan 4 11-24-2011 10:45 PM

Low tension oil rings
This was for a diesel build, forget about using them in a gasser.

There were doubts even by me.
It turns out you dont need "standard tension" oil rings in a diesel (I consider them standard friction oil rings now). Its mainly to keep the the oil out of the combustion chamber in engines that draw a lot of vacuum like the gassers, this was the only reason I found for really needing to have them. I never could find a good reason why they were needed in a no vacuum N/A or turbo diesel.

I had my doubts when the brand new engine consumed a little over a quart of oil with in the first 500 miles of highway driving.
Then the next 1,700 miles it didn't consume any oil as far as I could tell.
I am sure the valve seals I installed helped too.

The standard tension oil rings pack 20 to 25 pounds of spring force when installed. Since I dont have the fancy oil ring spring tension gauge I reduced the spring length until the tension felt as if it was reduced to between 1/4 to 1/3 what it started out as. I was going for about 7 pounds and no less than 5 pounds of spring. Then after I got the first oil ring the way I wanted it, from there on it was only a matter of cutting the other oil ring springs down to the same length. (I took about 3/8'' off them)

Why reduce oil ring tension?
Less friction, more power to the wheels, easier to crank the engine over when cold and better fuel economy.
A side by side comparason with low tension oil rings Vs. standard showed the low tension oil ringed piston was much easier to push and pull up and down the cylinder bore by hand.

Frank Lee 11-24-2011 11:26 PM

Funny you just posted that, as I'd been thinking about 2-ring packs, extra-skinny rings, and low tension ring packs lately. I've been meaning to research the Metro XFi 2-ring system to see if I could incorporate that theory into some of my gassers.

oil pan 4 11-25-2011 04:38 PM

The problem with running low tension (about 5 to 10 pounds) or very low tension (3 to 5 pounds) with an engine that draws a strong vacuum is the possibility of increased oil consumption.
Gassers that do run low or very low tension usually run vacuum pumps (maintain no more than 8 to 10 inches of Hg).
There is a new dodge that runs low tension rings but the block has been engineered to maintain bore roundness through heating cycles and many thousands of miles of driving.

The only way we can get close to that engeering is to have your block machined while torqued with a deck plate, mains torqued and block heated to near operating temperature.

jakobnev 12-02-2011 07:23 AM

Maybe moving the restriction on PCV could increase the vacuum in the block on a gasser, and make it more suitable for lower tension oil rings.

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