pistons and cylinders

[norustscott]

OK...It is decision time...I am completing a top-end rebuild on a low milage 73 2.0l. The heads have been rebuilt..guides valves...springs. Now it is time to replace the P&Cs. Stock 94mm...Originally the engine had the US dished pistons...I am contemplating going with flat top Euros. Are there any problems with these...Are they Mahle only or are others availible? German vs. Brazil?

I am concerned with the quality of the sets. I tore down a 76 2.0 with flat tops and was amazed by the amount of Blow by ! Black on the piston around the wrist pin sides down to the bottom edge of the skirt.

Also, how do they differ with ring size? Wrist pin offset? Deck Height (other than the fact that they are flat)

I understand the increase in CR. 8.?to 1 is reasonable on 89-91 octane.

What do you guy's have to share? Your experience would be appreciated...

Thanks, Scott

restored 62 sunroof bug
90 WBE carat Vanagon
73 914 2.0

[Bleyseng]

How many miles are on this engine? Putting rebuilt heads and new P&C's on a high milage engine is not the best plan. Have you checked the rods for wear?
How about the end play? Does the flywheel need to be resurfaced?

Going with the Euro pistons is a great idea! They add a little power and work fine with todays gas.

If you are going this far, spending some good money, look at rebuilding the bottom end too. It's not that hard and then you can balance the whole rotating mass too!
Geoff

[norustscott]

I hear you...however,

74K documented miles...since new. Car was driven 15K over the last 15years

(new seals.front/rear...oil cooler...Flywheel resurfaced /new disc.
.005 end play)

Bottom end should be good for 200K. Other than possible cam and lifter wear it could go longer.

Valve Guides where worn. Replaced along with new exhaust valves for insurance..haha

I have heard of horror stories of bad pistons. Poor quality control. I guess German made Mahle 94mm Eros are the "Standard"

lsg.

[Bleyseng]

That doesn't sound too bad.... For pistons why not try to get your good 94 barrels bored out to 96mm. Then get some J&E 96mm pistons for them to get a 2056cc motor. Jake Raby is doing this to a get good quality 96mm set up.
Geoff
(I am running a 2056cc set up)

[Ron Meier]

It is my understand that "boring" existing cylinders may not be cost effective, as they need to be "jigged" in order to get them all correct (straight holes).

Secondly the cost of the boring and new pistons may exceed the cost of a new 96mm piston and cylinder set.

It is probably best just to purchase a new set.

Brazilian (and others) parts were known (at one time) for poor quality castings (quality control) and poor metalurgy (cheaper material=cheaper cost).

Just my thoughts.

[SteveStromberg]

Rimco charges $15 per cylinder to bore to your pistons. Steve

[MASSIVE TYPE IV]

The bored 96s are the best way to go for longevity. The quality of the new cylinders is getting worse, not better. I have had sets with .007 run out in the very recent past!

The most cost effective way is not the best in 99% of the situations.

The JE pistns only have the 22mm wrist pins, mostly for stroker applications, with T I rods or chevy. They won't wor with a 24 pinned rod without having the rod re bushed....

[SteveStromberg]

Rimco will rebush the rods to 22mm for $15 a rod. Steve

[Pritchard]

How much do the J&E 96 mm pistons cost?

Pritchard

[yoh!!!]

I had to make a similar decission a couple of weeks ago.
I ended up using Kolbenschmidt P/C kit which establishes the same compression ratio than a Mahle Euro spec. kit. A lot of knowledgeable people here on the list stated that the Kolbenschmidt kit is at least Mahle quality and the weight differences between the individual pistons would be smaller...
...in case this sounds interesting, check the old postings. I think it was titled Kolbenschmidt vs. Mahle.

Patrick Koch

[norustscott]

Hello to all,

Thought I would share my recent P and C adventure. P's & C's came yesterday...Brand new Kolbenschmidt 94mm from der fatherland...Well, I began to check them out and quickly discovered that the wrist pin keeper groove was too narrow to take the snap ring. In fact, only the ends would seat in the groove. This could be simply that the snap rings sent with the P&C kit were too wide..? However, every other snap ring in the shop was also too wide...even the very used ones! Moral of the story...check everything. Leave nothing to chance.

Another interesting thing...the wrist pin fit very snug...like they are supposed to. Even cleaned and lubed the fit was snug requiring a light tap to insert. So, I used a heat gun to "warm" the piston to check fit. It is amazing how much the piston will expand when heated. With the piston warm to the touch, the wrist pin glided into place. The expansion was also evident when the warm piston was trial fit in the cylinder. Without rings the piston fit perfectly. Keeping in mind the cylinder was room temp. As the piston cooled to room temp it became "sloppy" in the cylinder.

Impressive, Pistons and Cylinders are taken for granted..There is actually a lot going on for them to operate properly. They can also tell you a lot during a tear down,

Have you every had to beat the wrist pin out of the piston and rod...know why? The crank shaft is more than likely the culprit. Either the crank has flexed during operation( High RPM) or the rod journal(s) is not parallel with the crank main bearing surface ( from the last grind and polish job). The offset from either will force the rod to bind on the wrist pin and pound the wrist pin against the keeper causing a burr on the piston to form.

Well, Just more to keep in mind. Don't over look the Piston and Cylinder details.

BTW...I will be using a the Total Seal, second compression ring...I have had very good results with them on several Type 1 engines.

Finally, I add for more discussion..Which Oil ring design is better? The old style 2 piece ring ...the main ring with the spring inside. Or the three piece consisting of two thing rings, upper and lower sandwiching a " digital wave" shaped center ring? I have both and have zero data on either...confused:

Cheers,




:

[MASSIVE TYPE IV]

It would amaze you if you knew where those pistons were actually made...it was not Germany, and has not been for 3 years.

Watch those total seal rings in a TIV engine. We have had no luck with them, as a second ring, or entire set. They seem to evacuate too much of the oil film from the cylinder, something that a T IV engine already has a problem with and needs mods to overcome.

I have taen some of my test engines apart at 10,000 miles to notice that the rings never seated completely with the total seals. We use standard rings with no issues.

[yoh!!!]

Checked the clips of my new Kolbenschmidt P/C kit last night...
... The clips included in my kit fit in the grooves. Yah!!!
My kit came OF COURSE from PELICAN PARTS. ;-)

[Otto]

Mahle forever only!!!!!!!!!!! Deves rings forever only!!!!!!!! OTTO

[Laura-Hergesheimer MotorS]

OTTO's on board? If this is the infamous John, you have to value his opinion !!

Hergie

[JP Noonan]

It is not often I burn bridges, but....

I may trust Otto's opinion, I will not however ever try to buy parts from them again. Non-existent customer response, out of date NEW catalog, and down right rude in my opinion.


I have heard they are capable mechanics, and been in 914's for 20 something years. Considering that I live 3000 miles away that doesn't help me much. I expected much more.


(from previous post)
BTW tried Otto's twice. Both times I had to call them (weeks later) to find out my parts were, the first time, NLA. and the second time they said the price had gone from $210 to $370 ("plus I have to ad $40 to that to cover my cost. But then you should have known that they cost more.") excuuuuuuse me. I'm suposed to know the their 6 month old catalog is out of date??? Oh, I'm sure they still list 1.7L BB kits for $165 NLA and 2.0L MPS for $220, but YOU should know that they cost $410...

[Otto]

I am not a computer guy, just a Porsche guy. The web site is 6 years old and has not been updated. I kind of got disillusioned with the whole computer thing from a past bad experience four years ago. Only now I have come back to the real Porsche philes to help them with their adventure in the Porsche world. I am in the process of re-making the 96mm p/c kits that NPR did many years back. I have someone helping me with updating everything now. Sorry to all who think I have done wrong. TTOD OTTO

[norustscott]

Soooo......how about that weather we are having????

[JP Noonan]

Originally posted by norustscott
Soooo......how about that weather we are having????

Fair enough....

OTTO: Apology/explanation excepted, wish it came earlier, but I do appreciate it.

I tend to forget some of us are still better mechanics than computer geeks.

[Patrick]

I am in the process of re-making the 96mm p/c kits that NPR did many years back.

Why? European Motorworks already did with Keith Black pistons. You can also get the J&E's.