what kind of pistons would I have?

[bevans6]

I have a 1980 8V-71.  the manual discusses two kinds of pistons, trunk type iron one piece pistons, and cross head (presuming iron but it doesn't say) two piece pistons.  What kind would my year of engine likely have?

Thanks,  Brian

[luvrbus]

Best way to tell is remove one air box cover the 1 piece will be a alloy and the cross head will be iron on the top and aluminum on the bottom also there is a small gap on the cross head below the top 2 nd ring.
A 81 model I would put my money on cross heads

good luck

[bobofthenorth]

So for the unwashed among us, what are the tradeoffs, advantages, disadvantages of each type?  I'm assuming I have the crosshead type because I watched Oscar putting them together like some gigantic mecano set held together by glorified o-rings.

[luvrbus]

Bob,on the cross head being a 2 piece construction the piston skirt is free from the vertical and thermal distortion caused by the gases that push down on the crown so the piston pin takes the load where on a 1 piece the skirt and crown takes all the load.
clear huh now you know what the o ring is for.  


good luck and we are having some nice weather here now not even running the AC

[TomC]

If your engine has been overhauled in the past 10 years, you most likely have cross head pistons, or 2 piece pistons.  It maybe either the non turbo compression ratio of 18.7 to 1 or the turbo charged compression ratio of 17 to 1.  I turbo'd my engine with the 18.7 to 1 pistons, with 9G75 injectors and using a 12.7 liter Series 60 turbocharger with waste gate to keep the boost down to about 15psi.  So far no problems.  Once the engine and exhaust are warmed up, no smoke on a long hill pull-no matter what the altitude.  Get a bit of smoke on start up, but quickly disappears once the turbo kicks in. Good Luck, TomC