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Posted by Chriscase [76.212.164.124] on Thursday, January 07, 2010 at 10:06:49 :
In Reply to: Food for thought posted by hemimech [71.10.56.36] on Wednesday, January 06, 2010 at 23:35:41 :
'91 Mopar 318 taper .010, out-of-round, .005
Some of the four bangers are less than .001, some are .005 and .003
I don't understand the ten times magnitude of difference. Can't be smog laws, same laws apply to the different models. Any change in rings/mettallurgy is un-obvious.
My guess is it's the piston design. Some 4-bangers have no piston skirt. Oddest thing I saw about my Bro's minivan engine. No skirt to keep the piston straight, just enough piston to hold rings and rod. My guess is that no skirt means less friction, better mileage. But it threw a leg out of bed before there was any knocking.
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