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Piston ring help

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So i bought a set of arias pistons 84MM for my sleeved b20b. The first time the piston rings had too big of a gap, we are talking 0.050 or so. Arias being very orofesional and always good customer support he told me to break the rings and he’ll send some new ones with a 0.010 gap. Issue now is that i got the rings and i put them in my engine to check the gap to so i can file em. But when i check the gap it was 0.020. The issue is also not my feeler gauge cause i bought a new set and remeasured them. My goal is mid 700whp, and if i remember correctly Arias says on the brochure that for a turbocharged app it should be 0.018 the top ring. So am I in the clear? What should I do? Can I get away with these piston rings?

The specified ring gaps are the minimum recommended for the application - I have seen reports where larger ring gaps were tested and, IIRC, there was negligible loss of power/torque until they were increased to over 50 thou'(1.25mm).

That minimum is important, though, because it has to account for the ring expansion as they are heated in use and if they run out of clearance that means the only way they can expand is radially - they will get bigger in diameter - this instantly increases the force applied to the cylinder walls, potentially causing severe scuffing and, as the increased friction drastically increases the temperature of the rings, it becomes a run-away affect that usually results in either broken ring lands (if you're lucky) or, as is not uncommon, broken pistons, connecting rods, engine blocks, crankshafts and other nasties.

What I do have some confusion about is the representative telling you to "break in the rings", as i would have expected that to have compromised the bore surface for the replacement rings. There are some ring designs that can be used on a 'run in' bore, but not sure about your circumstances.

Hey Gord,

Did you read the part of "break the rings" as break the rings in? I personally read this the same, i think he means dispose of the rings?

Newbie23 at a goal of 700whp i think you should be aiming to make your rings looser than the minimum gap. if you look at webinar 125 and 149, that might give you some more insight on what your ring gaps should be.

just as a side note for every .oo1 extra bore wear or machined your ring gap will be also increasing by about .005 there is a formula but no need to go into that,

.020 will be perfect for your build with that hp goal

regards Ross

0.00314 ;-)

Terry, that puzzled me too, darned if I can see why one would want to 'break in', the engine and immediately replace the rings, as they'd be the primary part being 'broken in'.

I might be missing something, though - wouldn't be the first time :-)

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