Vilhuer

I have had with Goetze products.

Tonight I measured 8 piston ring sets on almost perfect bore tolerance group 1 S4 engine. Block is definitelly healthy and bore diameter is ok. All 16 compression rings have 0.05-0.25mm over factory upper limit end gap straight out of box. Spec calls for 0.20-0.40mm. At least oil rings are within spec but most are far from lower end of it. Spec calls for 0.40-0.90mm and most of them are 0.60-0.65mm.

What the hell is wrong with Goetze? Why can't they make longer rings? This is 3rd set of 8 which all have shared this same problem. Doesn't matter if rings are for GTS or S4/GT/951 or to which block they are tried. All have had too wide gap or are at least at upper end of range. I just know this latest build will leak past pistons like public sewer if I use these compression rings.

Has anyone installed these lately? Have I won in lottery three times in a row or is this more generic problem? I don't want to keep on buying more and more sets if they all are same kind of crap. Sending current sets back to seller isn't much of a option. Can't even remember from where and when I got them as packages have been on the shelve for a while. Has anyone tried 100.50mm 1st oversize rings on std size pistons and bore? Maybe thats only way to get correct end gap. Probably stupid idea which would cause other problems? Or should I just slap current $#!? in and heads on top to test leakdown numbers and hope for the best?

Lizard928

Seeing as how I have a set of S4 and 951 rings this does not sound good.
I think I need to check mine quick

Shark_Week

my set was similar. although my top rings were .22 - .25 and the second rings averaged .38 to .43 end gaps. my oil ring gaps were all middle of the road. figured i wasn't going to get any better and didn't want to waste any more money on another set. a grand spent on one set of rings was enough

dcrasta

Have you tried assembling them with the proper offset (gaps) and doing a leakdown? Sucks but at least you were Pro enough to check the gap!

Have a drink on me matey!

Vilhuer

Based on previous similar experience with GTS rings they will leak badly. Might still install them and heads over the weekend just to see what happens in leakdown test.

BC

The gaps where biggish but I used them for the boosted motor. Hopefully it will work out.

WallyP

Sounds as if it might be good to buy 1st oversize and fit gap to cylinder.

BC

Although mine were not THAT large. I think it was around .30 if I recall. I should write this stuff down.

entropy_engineering

I prefer to hand file fit the rings in the motors I build anyway. Why not go ahead and just order one size bigger and file to correct gap?

blown 87

Mine were almost tight, go figure.

Vilhuer

1st oversize is for 100.50mm when this is 100.00mm. Will they work, for sure? If yes then thats easy solution. If not, I'll have yet another useless set and more $$$$ spend. Is 100.50mm even available anymore at any cost from Porsche or Goetze?

Lindsey racing seems to have special set available for 951. Maybe thats best option? Yet another $500 spend once again due to Goetze. And this was supposed to be temporary engine only until I can get dry steel liner 5.7L GTS crank setup together. Problem with Lindsey is that I haven't got any response from them ever I think to any questions about their products. Have tried few times over the years.

entropy_engineering

Yes grinding the rings will absolutely work. If you like I can post how I grind mine. It's a time consuming job, but obviously worth doing correct.

I've spoken with the owner of Lindsey Racing a few times now on the phone. He's a very straight forward person I've enjoyed dealing with. It might be worth giving him a call. If you get aftermarket rings they have to be very hard (gas nitrided if I remember correctly). Plain steel and I think plasma rings won't hold up.

Temporary motor? You may want to talk with him about aftermarket pistons as well. He has several sets he's used from Wiseco and now Wonser that have held up on turbo 951 motors for lots of miles and dyno pulls with no problems. They had Swain Tech. pc-9 coating on the skirts.

ptuomov

I am sure that you already know this, but: If you're building an S4 that is temporary for you but one that you'd like to last long in some other car, I think Roger has those 951 rings for sale that fit the S4 piston. I think those rings work well in the S4. Perhaps you've already bought some 951 rings and found those short as well?

In addition, Jim Morton has some configuration with one gapless ring that can be run in the S4 engine and provide a better oil control than the stock or stock style rings. You might want to pm him, in case interested in a more exotic solution.

Vilhuer

Alusil prep is so expensive and difficult to get right in here that I have given up on it some time ago already. Next new pistons will be "normal" set for dry liners. We have few Wössner sets on order through Chris White for other engines locally but I don't want to use Alusil in any other than this temporary engine. Seems even that is stupid choice.

Pistons are S3 modified to work with 968 intake valves. CR will be 10.6:1. Ring are 951 sets. These are not first such 951 rings we have seen this exact same issue. Friends low CR for Rotrex SC setup GT engine was build with them and had exact same issue, just not as exstensive as this time. We have began to thing this is on purpose. Maybe they are done so large that they don't need to be adjusted at all. Problem is that if they aim at larger end of factory spec they seem to shoot wide most of the time.