l28 ring gap for turbo motor

twoforty

twoforty

Well-Known Forum User
Can anyone tell me what an exceptable piston ring gap would be for an l28 when using a turbo>? I guess it's the same as a 280ZXT right?
 
I will consult my bible tomorrow, .025thou is in my mind but that may be for something else.

You know turbo rings are different than n/a ones, they have more meat in them as they say.

Ever thought of 'endless' or 'gapless' rings, very big in the states, apparently a bit of a B-hatch to fit though.

Night

Nigel
 
Thanks. Yep I know the turbo rings are meant to be different, slightly thinner on the top ring and also I thought they would have a slightly larger gap to allow for the faster heating but the 280 ZXT says its smaller.
0.19mm-0.33mm top ring 0.15-0.3mm second ring
My new rings have pretty much no gap so I was wondering if I need to file to fit.
 
Sorry for the delay in getting back to you, but I've had one of those 'end of weeks':rolleyes: .

My tech data manual lists:

Ring in piston groove clearance (compression rings only)
(1) 0.043 - 0.073mm
(2) 0.030 - 0.063mm

Ring gap in bore
(1) 0.25 - 0.4mm
(2) 0.15 - 0.3mm
(3) 0.3 - 0.9mm

So yes a bit of filing is required.

In general it can be said that a 'new' or 'overbore' set of rings will always come basically without a gap, this allowed the builders to do a 'quick' fix with the hone gear and replace original pistons, the only real reason to need an oversize was severe bore damage that the hone couldn't clean up.

Be very careful and use a fine flat needle file with the ring well supported, they are fragile, little at a time, no rushing.

Enjoy

Nigel
 
Thanks Nigel, The machine shop said the bore were no good and would nned to be bored. I ended up buying some 86.5mm piston set off DJ.
I will make a note of the rings specs you listed and compare.
Thanks again
 
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