Nicosil chipping on rare set of 92mm 2.8 Mahle barrels.

FransE36 · 07-24-2009, 02:40 PM

After throwing a rod bearing in my 2.8L I noticed that the Nicosil is chipping a little on one of the barrels. The chipping is on the case side of the barrel and is minimal, but these barrels were part of an old Mahle set that is not really obtainable anymore. (for under $6k)

Can I still run these barrels with the small chips?
Can I have the barrel "re-nicosil-ized"?
I also need to know where a good place in Los Angeles to get my crank machined.

Any help would be greatly appreciated, as I have an expensive hobby and NO money to move forward at this point.

Steve@Rennsport · 07-24-2009, 03:11 PM

Quote:

Originally Posted by FransE36

After throwing a rod bearing in my 2.8L I noticed that the Nicosil is chipping a little on one of the barrels. The chipping is on the case side of the barrel and is minimal, but these barrels were part of an old Mahle set that is not really obtainable anymore. (for under $6k)

Can I still run these barrels with the small chips?
Can I have the barrel "re-nicosil-ized"?
I also need to know where a good place in Los Angeles to get my crank machined.

Any help would be greatly appreciated, as I have an expensive hobby and NO money to move forward at this point.

Hi,

The chipping you see is due to detonation and this was not uncommon with the 2.8's when insufficient octane was used with the high compression ratios.

Mahle changed the design a few years ago by eliminating the CE ring groove which stiffened the tops of the cylinders which allowed them to resist the effects of detonation (much less vibration).

I'm sorry to say that they become "decorations" as the chipping does continue in use. Further, if the rings pass over the chipped areas, you lose ring seal and thats a serious problem. Its possible to have the Nikasil removed and replated but you may have some issues with ring sealing.

I would send them to US Chrome to see if they can repair and replate them to the original size. With new factory rings, you have a fighting chance,...

FWIW, I do have a brand new set of Mahle 92mm RSR P/C's (new style) if you need them and they are well under $6K.

Flieger · Flieger's Garage

How do detonation and the head gasket affect the bottom of the cylinder?

It sounds like he has some chips around the base of the cylinder where it meets the case spigot.

Steve@Rennsport · 05:58 PM

Quote:

Originally Posted by Flieger

How do detonation and the head gasket affect the bottom of the cylinder?

It sounds like he has some chips around the base of the cylinder where it meets the case spigot.

OOps,........My error,.....I misread where the the damage is,..........

Chips and fractures are very common at the tops of these older 92mm cylinders.

Without seeing it for myself, I wouldn't care to speculate about how the bottoms became damaged. Its possible that the cylinders were loose for some time but I'd really need to see them for myself. I would suggest posting some sharp close-up pictures, if you can.

longhornchris04 · longhornchris04's Garage

In addition to US Chrome, there's LN Engineering. Charles Navarro (the owner I believe, if not, he's one of their top guys) posts in the Tech forum regularly.

They offer cylinder reconditioning in addition to manufacturing their own cylinders for 356,911, etc, so he may be able to help.

FransE36 · 03:17 PM

W

W you guys. Thanks so much. I will recheck the cylinders as I was VERY upset when I noticed the chipping. The car did ping a little, so I may have mistaken the top for the bottom. I will take some snaps tomorrow and post them up. I am interested in finding another set of 92's or maybe even going to a 3.0. Coming from Type 1 VWs there is a whole lot of sticker shock when I see the prices of 2.7 high performance parts. I could get a few bugs for the price of porsche nuts and bolts.
::Exaggeration::

-I really appreciate all of your experience, and help as I usually find out the hard way-

EDIT: The chipping is at the head side of the barrel...

Steve@Rennsport · 07-27-2009, 04:32 PM

Quote:

Originally Posted by FransE36

EDIT: The chipping is at the head side of the barrel...

Thats what I see most and what I was referring to in my original response.

2.8 litre engines run VERY well but do have have high compression ratios when used with 2.4 or 2.7 heads and this requires twin-ignition and race gas in the majority of cases. I would need a LOT more detailed information about your engine to offer further assistance. You need to do whatever it takes to prevent any detonation as the consequences are very expensive.

As you've noticed, there is a quantum difference between Porsche parts and VW parts, especially race components which are made in very small quantities.

andrew15 · 07-29-2009, 08:14 AM

I may have a few spare / used 92mm cylinders w/ the ce ring groove on top. Let me know the size and height you need if interested.
Regards,
Andrew M

Mark Henry · 07-29-2009, 08:20 AM

Quote:

Originally Posted by longhornchris04

In addition to US Chrome, there's LN Engineering. Charles Navarro (the owner I believe, if not, he's one of their top guys) posts in the Tech forum regularly.

They offer cylinder reconditioning in addition to manufacturing their own cylinders for 356,911, etc, so he may be able to help.

Yes Charles is the owner. If he can't fix it he'll make you a new set. None of this is cheap though...but you knew that.

FransE36 · 07-30-2009, 03:59 PM

Quote:

Originally Posted by andrew15

I may have a few spare / used 92mm cylinders w/ the ce ring groove on top. Let me know the size and height you need if interested.
Regards,
Andrew M

I am going to the shop this weekend to snap shots of the cylinder that is chipping, and measure the barrel, so is there anything specific that I would need to measure other than length, and Inside diameter? I am interested in replacing the one chipping barrel, so I want to provide sufficient measurments. Thanks, Pete.

FransE36 · 08-12-2009, 03:05 PM

I got the pictures of the barrel and the chippping.
I was told by one person (no validity that I know of) that they were easily fixable and for cheap, but I have yet to find out how/where. Seems like I am going to be selling one of my other cars to fund the rebuild of the ol' 2.8.
Anyone have any suggestions as to what route I should go? I have been considering going 3.0, but I really like the 2.8. ::torn noob::

john walker's workshop · 08-12-2009, 03:14 PM

that's more than the nikasil chipping unfortunately. the whole inner lip is gone. wall art now.

FransE36 · 08-12-2009, 03:24 PM

I want my mommy......

Thanks,
I kind of figured, but was not sure as I am new at this.
The search begins for a new (set?) barrel (singular?)
The type 1 streetable sleeper bug is going on craigslist right now...

I'd rather have the 914/6 back than the little bug that could anyday, but it will be missed.

Steve@Rennsport · 08-12-2009, 04:14 PM

Thats the typical damage I've seen for the past 25 years with those things and its all detonation-related. Its not repairable.

Thankfully, the modern versions don't do that since Mahle eliminated the CE ring groove,....

haasad · haasad's Garage

I have a set of 90mm cylinders I was about to get bored and replated at 92 mm here in GB for my 2.8 BUT posibly now I think I need a set without the CE groove so better buy new , How does the head seal without the ring fitted or is it "face to face" .

Am I worrying needlessly

john walker's workshop · 08-13-2009, 04:31 AM

the CE seal is for fluid seepage. it's not really a head gasket in the normal sense.

FransE36 · 08-13-2009, 11:04 AM

Anyone have any cost efficient (yeah right) suggestions for a new set of pistons and barrels that will produce similar performance results without the nicosil? I am open to any suggestions/options that may help. I really liked the slipper skirt 2.8 Mahle piston/barrels for nostalgia, but would be open to any piston barrel manufacturer. JE makes pistons, but no barrels, but the barrels are what I really need as I still have the 92MM "s" pistons in great shape. Who makes modern/stronger barrels.

911 tweaks · 08-13-2009, 12:02 PM

nickies... aka LN Engineering... great guy and product and he frequents this site often...
Good Luck!
Bob

FransE36 · 08-20-2009, 01:43 PM

Getting a 91mm Barrel from User Tom, and having EBS bore and re-coat it, so hopefully this will work.
I can not afford a whole new set.
I am, however, going to be running race gas ALL THE TIME from now on.
I will put up some pictures of the barrel as I get it from Tom, and then I will post pix of the AFTER once I get it bored from 91mm to 92mm, and re-coated.

Thanks everyone for all the help and support.

cnavarro · 08-20-2009, 03:09 PM

It is possible to resurrect one of those damaged cylinders with the CE groove - it involves stripping the cylinder, then turning the CE groove into a ledge, and making a copper sealing ring to sit in there. I've done it, but adds a few hundred dollars to the re-plating cost, plus the sealing rings (varies because market price for annealed copper).

That said, it's worth checking with a rockwell tester was the cylinders measure before going through all the trouble, because they are useless if they've been heat cycled to many times and have gotten soft. I forget which shop told me this was the process they used to determine if a cylinder should be retired...