Piston rings

[MarkGolf 0]

Hi..

 

I'm picking up a bottom end (2.9 VR6) which has covered 93k..

For piece of mind, I'd like to fit new piston rings and big end bearings...

Well, I've been told I can't find OEM VW piston rings as they wont wear in correctly due to the bored being a bit worn after doing 93k? If this is true, what can i do....

 

I've not got a huge budget, so whats the best route to take with getting this bottom end to a trust worthy reliable level...

 

Thanks

 

(I dont want to buy new pistons, crank regrind, reprofiling e.t.c e.t.c as it al costs tooo much for a student!

 

Mark

[vondribbley 0]

I am not an expert but...

 

I have just fitted new OEM piston rings into my 150,000 mile VR. As far as bore wear is concerned the main problem seems to be oval wear in 1 and 6 as opposed to the bores getting bigger all round. To measure this you need to follow the guidlines in the Bentley manual. Ir there is no ovality then I would say that you should be fine fitting OEM piston rings.

 

You need to bear in mind that they cost approx £70.00 per set (i.e. 3 for each cylinder) from VW.

 

HTH

 

Rob (thankfully no ovality in 1 or 6)

[MarkGolf 0]

Um, stil hope for a 93k one then!

 

I saw on a site, £80 for piston rings.. I presumed that was for all of them! Not just 3!!

 

This is where I wish I went for a valver! lol

[Scruffythefirst 0]

If you fit new piston rings then make sure you have to bores honed first. If you take the pistons out, take the rings off the pistons and measure the gaps in their bore and they are within tolerance, you can put them back in. Its not ideal, but it's ok to do. If the bore wear isn't excessive the best option in the long run would be to have the cylinders re-bored a tiny ammount so they are still within spec of your existing pistons and fit new rings. That should then last you another 100,000 miles +.

[Rpmayne 0]

If you do want to do the piston rings, I have enough for 5 of the 6 for sale. You'd just need to get one more set. They're original VW, can't remember how much they cost me now, £180 for the set sounds familiar but will check. I was just going to re-ring mine but had ovalisation so went the rebore / oversized pistons route. 16vg60 did the bottom end rebuild and one of the new oversized piston rings was damaged in transit, so rather than wait around for a replacement we used one of the VW ones.

[yellowslc 0]

Ouch.. 81mm rings sets are ~125USD over here.. I wonder what the 82's run.

 

Prior to taking the block apart, I would use an internal micrometer/bore gauge to measure the bore. Once to take the pistons out, it is unlikely you will ever get it to seal like it does now. I also suggest that you hone the block prior to installing new rings. The crosshatch left by a hone is a must.

 

R

[yellowslc 0]

I've made a few calls trying to find the OEM abv/82mm piston ring sets.. no luck as of yet.. I can get JE forged pistons cheap though ;)

[MarkGolf 0]

lol

Your bad for the bank account!!

lol

 

How much out of interest?

What sorta gains will they give, im begining to think 'F it' and go mad..

[dazzyvr6 0]

http://www.eiptuning.com/eip/vw6cylinderpistons.html

[Rpmayne 0]

Stealth sell the Mahle (original make and quality) pistons and rings set, I bought a set of oversized 82.5 pistons for about £600.00.

[MarkGolf 0]

Bloody hell!!

Thats only £445 for a set of pistons from EIP!..

I take it they dont include piston rings, so thats a bit more on top ?

[MarkGolf 0]

Scrub that...

I've just seen you get a piston ring set..

 

Im gonna put the VR conversion on hold for a bit, so I can get the pennies together to get the 3.0 ltr pistons and get my mate to bore the block for me...

 

The pistons are 83mm, what would I get the block bored to? 83, 83.1??

[Kevin Bacon 5]

83mm pistons are for 83mm bores. i.e. bore the cylinders to 83mm and the pistons will have been designed to fit that size after expansion.

[Rpmayne 0]

I think the difference between the piston and the bores is 0.125mm. The originalpistons which came out were stamped as 81.985mm, and the bore (unworn part) was 82.00mm. Think you've got to be abit careful how big you go with the rebore, any more than 83.00mm and problems like ovalisation can occur more easily. Speaking to Stealth they didn't think the extra 0.1cc (83.00mm) capacity would make alot of odds, plus thats the final rebore size so next time its new block time. Hopefully that will be along time away though, theres alot of info about this on the Vortex forum somewhere.

[MarkGolf 0]

Hopefully my man doing the rebore will know, but he says to me to try my best to get the most accurate figures..

 

The pistons are 83mm according to the site, but that could be refering to the bore size..

I'll have a caht with the EIP tuning guys or whoever I buy from when I order the pistons, I guess they'll know!

 

Thanks

[dazzyvr6 0]

Hopefully my man doing the rebore will know, but he says to me to try my best to get the most accurate figures..

 

The pistons are 83mm according to the site, but that could be refering to the bore size..

I'll have a caht with the EIP tuning guys or whoever I buy from when I order the pistons, I guess they'll know!

 

Thanks

 

 

let us know how you get on with eip as im looking at going the same route as you :)

[MarkGolf 0]

Mate!

Its YOUR fault!

If you never showed me that the pistons were that cheap, I wouldn't be doing it!! lol

 

Thanks ;)

Wont be ordering till mid sept though, when the old student loan comes!

[Rpmayne 0]

The pistons will probably be 82.985.

 

Pistons that cheap.. Wait until you start redoing everything else though to keep up, all the bearings, gaskets, oil pump, head work, chains/tensioners. Afterall, if you're doing the pistons you may aswell do everything else plus some...

 

I seriously regret not working the figures out better before I started. Look at how much you can get a re-manufactured VR for, then work out the hassle you'll avoid if you pay someone to do it on an agreed price. Then look at your parts list. Even sourcing the right bits is a laugh.

 

With the money plus mistakes I made, I could have had a reconditioned 2.9L with a turbo now. :shock: Live and learn.

[MarkGolf 0]

So you've got alot of experience, you'll be the one to come to ;)

Not all bad!

 

So im more than likely going to have to get the bores done to an exact 83mm...

 

Im doing ALL gaskets, even T/B, chains and guides are mint already luckily, oil pump im going to change and thats all for now.. Getting flywheel done, decat and full system, then keep money for petrol and myself through winter... Hopefully be a nice runner fingers crossed!

[yellowslc 0]

FYI.. JE stocks the 82.0 and 83.0mm pistons in both 9:1 and 10:1 compression. A set of 6 with wristpins, locks and piston rings are $800 (i'm on dialup at the moment so.. http://www.xe.com for the conversion to lbs). I am setup with NASA's thermal barrier coater here in texas so for another $250 you can get the tops gold coated and the skirts dry film lubricant coated. All other bores/compression ratios are custom order. Turn-around being 2-4 weeks at a cost of $950/set once again with pins/locks/rings. For bores larger than 84.0mm clearancing of the block is required (main journals will interfere with piston skirts). I would not suggest using FI on bores larger than 83.5mm.. period.. The torque gains is where the difference is when increasing the bore size. Honestly, I would only suggest pistons if you have high mileage/reduced compression or if planning on serious levels of boost. Remember, the weakest link in the vr is the connecting rod bolts. Spend the money and upgrade to arp hardware throughout. I have built 5 83mm bottom ends for friends and over 20 ported/polished cyl heads some larger valves.. some with extensive porting. I am currently building two engines for my corrado.. the first being a balanced/blueprinted 81.0 mm using oem pistons, arp hardware, etc. to use as my mock up/initial stand alone tuning lump. The second is the race engine. 83.5mm JE lightweight coated pistons, manely 4340 coated rods, lightened/cryo treated/coated crankshaft etc etc.

 

My goal isnt to sell you guys parts.. moreso to help you to not be misled and broke. any questions.. parts inquiries.. send them via PM as it's easier to keep up with them.

 

R

[Kevin Bacon 5]

Good to have you onboard yellowslc, that is some superb information there 8)

[yellowslc 0]

Thanks, I've been doing this for 12 years and have learned from my own failures. Why not help others? I am planning a holiday to the UK and Ireland for next may.. trying to drag phat along with me as well.