Question on Ring Gap clearance

Hey team,

I've got an Alfa Romeo 147 with a 2.0 litre twinspark 16v engine, and have been rebuilding the engine to race in endurance events (up to 12 hours of track running per day) and am currently installing new piston rings.

I measured the old ring gaps and they were 0.6mm (+/- 0.01 or so) which got me reading into various options.

Using the chart on the HP ring gap page for a NA circuit car, the recommendation is 0.46 and 0.47 as a minimum. Should I be running ring gaps that much smaller than stock? (The TS is known for oil burning, could this be a contributor with loose ring gaps?)

Going further and continuing googling, comes up with multiple suggestions to increase the size due to the potential heat from endurance racing, and suggesting sizes such as 0.55 - 0.65.

Either way from all this, I'm getting a little confused. I may be reading into it too much, but it's also my first time filing and installing new rings. (The pistons are stock, and using cast rings)

The manual has the oil rings listed as 0.25 - 0.45mm being in spec, but does not list specs for the top and second rings of the 2.0 (it has the 1.6 which i've listed below)

If anyone could help steer me in the right direction, that would be most useful!

Cheers

Top ring

2nd Ring

Oil Ring

Stock 83mm bore

~0.6

~0.6

.25 - .45 is spec

HP Academy Circle Track

0.46

0.47

min 0.381

Wossner Racing NA

0.37

0.46

min 0.381

Wiseco Racing

0.46

0.44

min 0.381

CP-Carrillo

0.50

0.58

min 0.381

Google for endurance

0.55

0.65

0.4

alfa 1.6 ring gaps (82mm bore) from Manual

0.20 ~ 0.35

0.25 ~ 0.50

N/A

Alfa Forum suggestion

0.37

0.37

You should be fine, i've seen multiple test results of different ring gaps and there seems to be negligible difference until the 1.0-1.25mm range.

We'd all like to have them just short of butting up, but that doesn't seem to be critical - well, unless they DO butt up...

I didn't find anything about it, but this may have used lower tension oil control rings, which my hot have worked very well, leaving it to the second rings to do that and a bigger gap may help oil drain back. Oh, double check the 2nd ring isn't directinal, as some use a scraper design that HAS to be fitted the correct way up.

One thing I did find, if you weren't aware, is that the "Variator" that controls the camshaft timing, can be a problem with some models - so it might be wise to check and upgrade if required, especially considering the application.

Yeah I thought I might be reading into it too much, I'll just aim for the numbers that HP Academy suggest and go from there.

Yeah they also didn't have oil drain holes in the behind the scrapers, so I've drilled some in to hopefully help. Seems like the others that have done that, had a massive change.

Yep, our Variator is going alright, worst case can just unplug the 12v supply and leave it closed at an event for the expense of some mid range torque.

Thanks mate