5.3 piston ring gap
05-17-2020, 09:05 AM
#3
Generally on the top ring you want about .0045" of gap per 1" of bore for N/A; and open it up to around .0055" - .006" for boost. That works out to .018" or so N/A and .022 - .024" for boost. 2nd ring should have about 15% or so more than the top.
Never forget that there is no "one" "right" "absolute" "perfect" number; as in, the motor makes 100 less HP if you miss the "target" by .001" or something. Doesn't work that way. Rather, however much you use, you should always be aware of what happens when you use "too much" compared to "too little". Slightly too much - let's say instead of .018" you end up at .020" or some such - has almost no effect whatsoever, except for a very tiny increase in blowby. Too little however - by ANY amount - causes instant total catastrophic destruction and carnage, because the rings GROW when they get hot, and when the ends butt up, they seize to the bore. They may pop the ring lands off the pistons, they may wipe out the bores, they may break into little pieces, all sorts of things that AREN'T pretty. Boost makes this worse, because there's more heat; which is the reason for opening them up... just one of the MANY things that differentiate a motor BUILT FOR boost rather than just "throw a turbo on it". You either build it for boost, or build it for N/A; one or the other, not both. And of course, guess when this is going to happen: it will ALWAYS happen at max power, max RPMs, and especially if that's sustained for more than a couple of seconds.
ALWAYS err on the side of slightly too much rather than ANY too little.
Never forget that there is no "one" "right" "absolute" "perfect" number; as in, the motor makes 100 less HP if you miss the "target" by .001" or something. Doesn't work that way. Rather, however much you use, you should always be aware of what happens when you use "too much" compared to "too little". Slightly too much - let's say instead of .018" you end up at .020" or some such - has almost no effect whatsoever, except for a very tiny increase in blowby. Too little however - by ANY amount - causes instant total catastrophic destruction and carnage, because the rings GROW when they get hot, and when the ends butt up, they seize to the bore. They may pop the ring lands off the pistons, they may wipe out the bores, they may break into little pieces, all sorts of things that AREN'T pretty. Boost makes this worse, because there's more heat; which is the reason for opening them up... just one of the MANY things that differentiate a motor BUILT FOR boost rather than just "throw a turbo on it". You either build it for boost, or build it for N/A; one or the other, not both. And of course, guess when this is going to happen: it will ALWAYS happen at max power, max RPMs, and especially if that's sustained for more than a couple of seconds.
ALWAYS err on the side of slightly too much rather than ANY too little.
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swathdiver (05-17-2020)
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