Allowed piston ring gap?

[Thuppu]

Mahle original pistons one have a 0.03mm ring gap size. 2nd step oversize are 81.48 and bores need to be 81.51

You didn't put them in with that ring gap?

[A80Avant]

i may be wrong with that the ring gap and cylinder clearance is!

i was talking about bore to piston clearance not ring gap! sorry

pistons came with the rings, so we didnt care about the ring gaps.

[Thuppu]

You really need to check the gap between the ring ends:

too tight= wrecked engine......!!!!!

[A80Avant]

has been checked actually by the machine shop and its ok.

[Thuppu]

Ok, great.

[caterpillar]

if you have the engine to high output: more than 6-700hp; the advice you need some more clarence in the ring gap, than the mashinshop tells you (and mahle)... to tight= wrecked engine/ sylinder/piston

[A80Avant]

I don't really understand your writing there mate. Engine is not 600.

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[caterpillar]

if the engine run att high rpm and high HP the ringgap have to be some bigger than the advice from piston maker....if not the pistonrings will go together under the heat( they goes to be longer, and the end will meet) then they dont have any place to go, and then you have no engine...you need a bicycle..

[A80Avant]

thanks for the advice.
my engine is mortal stage, so no high rpm, no high power, so ill follow the advice of the makers. Good to know though. ill go and look for a bicycle just in case

[rst]

if the engine run att high rpm and high HP the ringgap have to be some bigger than the advice from piston maker....if not the pistonrings will go together under the heat( they goes to be longer, and the end will meet) then they dont have any place to go, and then you have no engine...you need a bicycle..

Can you please tell us whats the minimum ring cap in your opinion? For example 6-700hp engine that goes up to 7500rpm.
I left the top ring gap 0.45mm and second 0.4mm. I hope i wasnt to conservative.
Otherwise i have to breakin the new engine TOO long.

[Thuppu]

thanks for the advice.
my engine is mortal stage, so no high rpm, no high power, so ill follow the advice of the makers. Good to know though. ill go and look for a bicycle just in case

Your engine has about the double hp more of a stock one? You must use it hard sometimes? UrSboy told: "Gap New = 0.15 to 0.35 mm" with stock pistons. I wouldn't put 0,15mm on a upprated engine, more like 0,3-0,4mm. I rather put little to much gap than too little. If I was you I would be really interested of how much ring gap the machine shop left...

[A80Avant]

No it hasnt double. Since the rs2 has 315hp, double means 630. Mine shouldnt have more than 470-490 with the most positive dyno equipement out there. Yes i did use it hard, but now ill be much more conservative.

I have stopped being paranoid about a few things and leave people who know what they are doing to just do their job. The mechanics i chose are not hobbists, and know what they are doing, so i trust their judgement. As a paying customer, if there is a failure, ill demand a refund and rebuild. I will leave the perfectionism to those who get their hands dirty a lot more than i do, as i have no time for that anymore. I know it may sound naive, but believe me i cannot go mental everytime a little detail pops up in the forum and everyone posts as if we are building race engines or 600hp drag cars!

I took off my super HX40 long ago! Didnt like it!

[Thuppu]

Ok, it's fully understandable. I did mean a stock S2 230hp. Hope you also have get over the paranoia of changing the sparks plugs at every oilchange?

[A80Avant]

yup, over that already. i wasnt changing them over EVERY oil change, more like every second change, but now will be keeping them quite a bit.

im telling you! we have got to get over the fact that there are 4-5 people in every forum doing really highly uprated engines,the rest we would have been fine with a simple remap! haha

[Billman]

Ok, it's fully understandable. I did mean a stock S2 230hp. Hope you also have get over the paranoia of changing the sparks plugs at every oilchange?