# VR6 12V piston ring end gap help



## GinsterMan98 (May 19, 2008)

Since it will be turbo I figured I would ask in here. I want to know how you guys adjust the rings? Do you use a file in a vice or is there a better tool for increasing the gap? I did this on a Honda motor, but my freind had a fancy grinder of sorts for this purpose, he lives in NM so I don't have acess to it. Since we are also on the subject of rings, do you guys use the vw piston install tool or do you use your fingers? I know alot of guys who stick with stock bores and pistons just wing it, but I only want to do it once.:thumbup: TIA, Dan


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## KubotaPowered (Jan 27, 2005)

I use the VW piston compressor to drive the pistons in. As for ring fitting, I usually just use a fine file and make sure there are no burrs left over from the filing.


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## GinsterMan98 (May 19, 2008)

About how wide? how did you remove the burr's? Thanks for the reply btw.


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## KubotaPowered (Jan 27, 2005)

GinsterMan98 said:


> About how wide? how did you remove the burr's? Thanks for the reply btw.


I don't mess with the width of the rings, they are set from the manufacturer for their piston specs. I usually put a slight bevel on the ring ends where I opened up the gap to take any burrs off.


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## GinsterMan98 (May 19, 2008)

Oh, I ment how wide of a file,lol. So your saying you taper the inner part of the ring opening?


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## KubotaPowered (Jan 27, 2005)

GinsterMan98 said:


> Oh, I ment how wide of a file,lol. So your saying you taper the inner part of the ring opening?


The width of the file depends on what size you feel comfortable working with as long as it doesn't have an aggressive cut to it. Taper the inner part very slightly, you don't want it looking like a knife edge.


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## GinsterMan98 (May 19, 2008)

Thanks for the help on that one. :beer::beer: for you
Oh and since we are on the subject, why does the bentley tell you to check the end gap with the ring at the bottom of the bore? Seems odd as the rings never go down that far.


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## KubotaPowered (Jan 27, 2005)

I never check them down there. I always put the ring in the cylinder its going into and then take the corresponding piston, turned upside down and push the ring down far enough to where it will sit at the proper angle.


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## GinsterMan98 (May 19, 2008)

Just far enough or more like 1/4 of the way in.


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## KubotaPowered (Jan 27, 2005)

You got it!


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## GinsterMan98 (May 19, 2008)

Sorry for the million and one questions, just want to get it right. Thanks a bunch man, you always help me out.


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## schimt (Jan 15, 2007)

are you cutting the block? or just honing and new rings? the reason the bentley advises you to check ring gaps at the bottom of the bore is that the top of the cylinder wears faster then the bottom due to higher pressure on the rings at the top of the compression and combustion stroke. So if you gap the rings at the top, they will be a different gap at the bottom (closer) and if the gap is too close at the bottom of the bore, when the rings are hot and the gap is smaller they can touch and you can imagine what that is going to lead to.


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## KubotaPowered (Jan 27, 2005)

That is correct to an extent, the cylinders will become bottle shaped over time. However, if there is no cylinder wall gouging and the walls are in otherwise good condition, you will be fine. Plus re-ringing a block that has cylinders that are not true is like putting a bandaid on a bullet hole.


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## GinsterMan98 (May 19, 2008)

I can assure you both that the block and pistons I have are in very good shape. They came out of an auto jetta with 108k on the clock. I know I would be fine just slapping that block in, but I want to do this for the simple fact of doing it I guess. 
On to the new point that was brought up. If the bottom of the bore doesn't wear than setting your rings to that bore diameter would just mean that the rings will only expand as they ride up in the cylinder. Wouldn't this lead to blowby or oil burning? So you would want to go with the law of averages here, measure at the middle and shoot for the medium of the max gap? My next question was were do you want to be gap wise on a FI motor, do you guys run OEM spec or more loose due to increased heat?


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## KubotaPowered (Jan 27, 2005)

Depending on boost and power levels, you want to open up the gap. .018in is factory spec I believe for both compression rings, I doubled that, and I have seen other run .050-.060in. Go to an engine shop with your block and have them measure the cylinders top, middle and bottom, chances are they will do it for free, after that its simple math and computing an average for your gap. Like I said though, unless you have severe wear and/or th factory crosshatching is not visable, you will be fine.


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## GinsterMan98 (May 19, 2008)

Thanks again, I will have them check it while its there.


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## schimt (Jan 15, 2007)

you should also talk to the ring manufacturer, depending on the material that the ring is made of it may expand more or less. Also in a forced induction setup you are most likely expect higher temperatures so usually dont want to use OEM specs. Because lets face it, the only reason we have any ring gap is to account for thermal expansion, if we didnt have this issue we would shoot for .0001 gap


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## GinsterMan98 (May 19, 2008)

True, I am not in the U.S right now so I can't get ahold of them until early next month. They are OEM rings though, so I was just looking to run what others have done on stock bore/ stock piston setup shooting for around 400hp. Thanks for the info BTW guys, I know there is no clear way to do this, but people run oem bottom ends to 400 no problem, so wouldn't I be ok running the medium of the oem gap for both compression rings and the oil scraper ring? I was thinking .30 for the cr rings and .37 for the oil scrapper ring as long as the bores measure in tollerance. I think they will as the bores all have very visable crosshatch and the piston skirts only have slight wear with the machining marks still being visable under the wear marks. Very suprised by the condition myself for the milage.


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## need_a_VR6 (May 19, 1999)

Check the gap at top/mid/bottom of the bore and compare, on a used motor you might be surprised.


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## GinsterMan98 (May 19, 2008)

Ok, I might be having a dumb spell. I understand taking the average of the three measurements, but how do you translate that into your ring gap? You have to excuse my lack of knowledge on this as I have only helped with this. I also understand what your saying need_a_VR6, you don't want to just wing it without knowing the bores shape. Man, this seems so simple but complex at the same time.


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## GinsterMan98 (May 19, 2008)

Wait, correct me if I am worng but I think I got it. Take the average of the bore and just correspond that to the ring gap? I mean you have min and max of the ring gap and you also will have the min and max of the bore, so if the ring gaps are for a new 81mm bore than all you would have to do is add the diffrence to the ring gaps?


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## schimt (Jan 15, 2007)

just the min dude, there shouldnt be that much of a variation, but again the issue it the gap closing up and touching hot, so you are only worried about the miniumum gap, which should be at the bottom of the stroke.


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## GinsterMan98 (May 19, 2008)

Ok then, that does make sense then. So when an engine gets worn out what is really happening, is it the ring wearing down and the end gap getting to large causing blowby? Or is it just the bore surface getting to many imperfections causing the loss of seal? I know it may be a nOOb question, but I think it will help me understand better. It does make sense why the bentley says to check it at the bottom based on what has been said. I guess on a fresh bore and hone it wouldn't really matter where you checked it, correct?


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## VR SEX (Apr 2, 2002)

When I file rings, I usually file from one side only using the opposite side as the reference side, it helps keep the side your filing straight as you check and recheck inside the bore. That way you can keep and eye as to whether or not your favoring the front or back edge and angling the gap
/l 
\l
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## need_a_VR6 (May 19, 1999)

For a forced induction motor set the gap on the tightest part of the bore, and at the top end of the spec. Put the ring in, and measure the gap at top middle and bore bottom, compare. You can even go as far as spinning the ring to see if it changes (it can on a ovaled bore).


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## GinsterMan98 (May 19, 2008)

Thanks, I think thats what I was looking for. Thanks to all of you for helping me with this.
I also bought a ring grinder as its only 30ish dollars and that way I won't have to worry about keeping it square while it's cut. Then I will deburr as KubotaPowered said to. Thanks again everyone.:thumbup:


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## viw28 (Oct 8, 2008)

Hey guys, turning up an old thread here but thought it better rather than starting a new one... about to fit my new Wossner pistons to my 24v block and was wondering what to end gap the rings to? Plan to run 25psi after it's run in and once I have a short runner. 

Have done a bit of Googling and it seems I should be gaping them anywhere from 0.018" to 0.030+"??

Engine has had a full rebuild, all new bearings etc plus a good bore hone. 

Pistons are 81mm, 8.5:1 

Looked at this thread - http://forums.vwvortex.com/showthre...s-Wossners-Wall-clearance-ring-gap&p=67794015

I read this document - http://ftp.tm-developments.com/Piston_Install.pdf

Thanks in advance!


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