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Old 11-24-2011, 10:45 PM   #1 (permalink)
oil pan 4
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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.

1984 chevy suburban, custom made 6.5L diesel turbocharged with a Garrett T76 and Holset HE351VE, 22:1 compression 13psi of intercooled boost.
1989 firebird mostly stock. Aside from the 6-speed manual trans, corvette gen 5 front brakes, 1LE drive shaft, 4th Gen disc brake fbody rear end.
2011 leaf SL, white, portable 240v CHAdeMO, trailer hitch, new batt as of 2014.
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