Eric Posted February 17, 2006 Share Posted February 17, 2006 the fsm says a min of .025 on the top and .30 on the second ring. the rings i bought mic at .018. my engine builder thinks that that should be fine and that the books numbers seem a bit high. what do u sesoned builders think i should go for just a stock rebuild? Quote Link to comment Share on other sites More sharing options...
1 fast z Posted February 17, 2006 Share Posted February 17, 2006 PLEASE use units! And I belive you have some decimal error. I BELIVE your trying to say, that the FSM says .25mm and .3mm. Typical is 4-5 thousands of a inch per inch of bore. If this is a NA motor, run like .012" on the top, and .015 on the second. This is MINIMUM specs, I would recomend. Quote Link to comment Share on other sites More sharing options...
Eric Posted February 17, 2006 Author Share Posted February 17, 2006 If this is a NA motor, run like .012" on the top, and .015 on the second. This is MINIMUM specs, I would recomend.well, they both check out at .018" as pulled from the box. so should i just leave them as is? Quote Link to comment Share on other sites More sharing options...
dr_hunt Posted February 17, 2006 Share Posted February 17, 2006 Well, not enough info. .004" per inch of bore for NA, for turbo you'll need more than that or they'll butt and pull the top of the piston off. Quote Link to comment Share on other sites More sharing options...
Eric Posted February 17, 2006 Author Share Posted February 17, 2006 it's NA. everything is stock; bore, pistons, etc. the manual said top ring at .025" min, and second at .030" min. all of mine gap at .018". should i have them at the books specs, or is that too much. if it's too much, what should i have them at? Quote Link to comment Share on other sites More sharing options...
Guest norm[T12SDSUD] Posted February 19, 2006 Share Posted February 19, 2006 Hey Eric I am rebuilding my engine and my gap is also .018. My rings only have 15K on them and so I am reusing them since they are the $150 Nissan Rings. You should be just fine with that gap on an N/A. Later,Norm Quote Link to comment Share on other sites More sharing options...
dr_hunt Posted February 19, 2006 Share Posted February 19, 2006 Well, there is a reason they call for that gap. Heat causes the rings to gain length and thus close the gap at operating temperature. Too small of a gap and the rings butt ends causing severe drag that can ultimately pull the top of the piston off, and scuff the cylinder walls. The gap depends on the ring land position, turbo pistons usually have the ring package lower on the piston to eliminate heat buildup in the rings. That kind of a gap sounds funny for stock pistons, but the norm for hyper's. That being said, the performance gain from tight ring gaps is typically less than 2% on a fresh bore, so your not gaining anything really that you can feel, going with book specs gives a correct build that you won't have to redo cause it wasn't right the first time. I'd go with the book spec's myself, but it's your motor. Quote Link to comment Share on other sites More sharing options...
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