Does anyone know what the function of the tail part of the piston itself, I mean the tail like parts opposite to the crown is, What happens if you cut them off?
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It's to keep the piston straight in the barrel. If you cut the bottom of the skirts off the piston wears faster (it will rock back and forth in the barrel more at the top and bottom of it's travel) and the ring seal won't last as long (creating more blowby). If you're fitting for stroker crank clearance, use a file or dremel tool and only remove enough to clear. Balance the pistons AFTER the motor's been mocked up. Turning the pistons into hockey pucks to clear a longer stroke crank is the WRONG WAY to make things fit.
Al as far as I know wieseco pistons dont have the skirt part at all. So wont they wear faster then?
Yes, they will, but at what rate is the question. Any motor built for longevity (that I know of) has piston skirts. And it will be more of a problem in a motor with a shorter rod ratio. Are you looking at using Wiseco's specifically for a motor?
Al is correct regarding piston skirt clearancing. You should only have to grind away a small notch from the skirt to get clearance, even with big 84 stroke, short 5.394 connecting rods, and "B" pistons.
I will not be using wieseco's, I intended to cut the skirts of mahle's indeed. Even if I did so how long would be the approximate life expectancy of the cylinders and pistons?
Not trying to be a smart-ass, but depending on how much of the skirt you cut off and the geometry of your engine, it could last from years to minutes.
Look at it this way; the skirts are on there to stabilize the action of the piston as it travels up and down the cylinder, but they also serve as a counterpoint to the action of the piston rod at both ends of it's travel as it momentarily tries to move the piston sideways (actually, in a rotational diagonal - the physics are interesting, too) as it changes direction. Notching the skirt just enough to clear the rod is fine as long as the rest of the skirt length (left and right of the notch) is intact to be that lever counterpoint. Take it away and the piston is allowed to cock itself when changing direction and can possibly severely scrape the cylinder walls with what's left of the skirts and the correspondingly opposite edge of the piston dome. Not good.
Thanx guys