Evo 4g63 Ring end gaps issue

Hi fellas, having a lil issue with a Evo 4g63 build, around 450kw 30-35psi setup

currently using wiseco HD pistons and coming to do ring gaps the 2nd ring straight out the box is measuring at .22” .. it’s 85.5mm bore with 0.004” PTW, going by the spec sheet calculating bore size to application which is .0050 top .0055 bottom equals to about 18-19 “

anyone have issues with rings being bigger straight out the box? Thanx

Hi,

I've ran into this issue before. I ended up using an oversize ring set, and filed the rings down to my target spec. I actually posted a thread here, before doing so to ensure that this is an accepted practice: https://www.hpacademy.com/forum/general-engine-building-discussion/show/ring-end-gaps-6.

I've also worked with many Wiseco pistons/rings and indeed they do come with a very generous 2nd ring gap out of the box. In most cases it's only slightly over my target so depending on the application I leave it be.

I have used Manley, CP, Mahle pistons with rings and never seen ring gaps bigger than recommend straight out from the box..

Yeah I’m not comfortable using the 2nd ring being at .22” , gonna try get another set of file back rings that will give me the desired ring gap by filing hem down.

Is that " .22" " the actual number or a misprint? If the former I'd contact the supplier as, while rare, mis-packaged rings aren't impossible. If the latter and it's actually 0.022" I'd just fit and run them

Numerous studies have shown you need to get into the 40-50 thou' range before any detectable torque and leakage issues are measurable with the top ring gap and the second seems to be mostly acting as an oil scraper, anyway - but given a choice I'd also use the spec' gaps.

i have recently done some testing on ring gaps for 2nd rings and found that there was no difference to power or blowby at .005 extra on the 2nd ring of a 2jzvvti engine, so my thoughts would be to fit them unless you are looking for the last 1-2 hp out of it

Regards Ross