Piston rings m62 b46 4.6

[Wingphil]

Hi all
I am rebuilding my 4.6, as part of the rebuild I would like to change the piston rings but am having problems finding a set.
Does anyone know of a supplier who can get them, apart from bmw of course who want a fortune.....
Thanks.
Redoing question as realised I should have put the pisto ring in title!

[J.Belknap]

The rings (and pistons) are made by Mahle for BMW specific to this bore and cylinder wall coating. I would be surprised if you could find a non-oem part.

copy and paste edit:

1) After reboring and honing to size the critical thing in bore preparation is the correct polishing operation with Sunnen felt pads and AN-30 silicon paste to expose hard silicon crystals above the aluminium base. This process closely duplicates the aluminium etching process originally used at the factory to remove aluminium from between the silicon crystals to leave them standing proud.

2) Pistons must be tin or ferro coated to prevent aluminium/aluminium contact which is not a good wear interface in this application. The piston skirts will be a golden or dark colour rather than the normal silver aluminium colour if this has been done.

3) Piston rings must be barrel shaped on the outer faces to prevent sharp upper or lower edges from ripping the exposed silicon crystals out of the aluminium matrix. Most ferrous ring materials will be suitable including chrome plated as long as the barrel shaped outer faces are present.

Conventional rings for iron bores are usually taper faced or parallel faced to assist in oil scraping and compression sealing. These shapes will not work with Alusil.

You want to be absolutely sure the rings are compatible, build the engine the right way with oem parts.

[Ricky Bobby]

^^^

[StephenVA]

+2

[Wingphil]

Mahle do not list them unfortunately or I would buy direct.
The issue of manufacturer is an interesting one, Oem is not always better.
A car manufacturer making a large number of cars will save money where he can. A pound here and there makes a big difference over a few hundred thousand cars.
Bmw are no different to anyone else in this, look at the timing chain as a perfect example, redesigned to be cheaper. Does not work as well but cheaper.
if I can get Mahler aftermarket, or similar quality rings I would have no problem rebuilding with them, and expecting them to last as long as Oem would.

[Ricky Bobby]

^If we were talking about a M54, maybe I'd agree.

Not on a very limited production engine like the 4.6

[electricalserv x5]

BMW all the way, I have pictures of my 4.6is rebuild, how where the heads looking?clean ............I wish I could post them for You, I have to reduce the size and it .

[Wingphil]

Unfortunately once an engine is slated for production the accountants get involved, and they cut corners.
Only vehicles in the hand build areas seem to avoid this problem.

I have built a large number of engines, for the road where usually I have used Oem if reasonably priced, and full race engines rarely using Oem stuff. None have failed due to component failure.

I do agree using Oem is less risk, and by choice I would follow that route. But although I can get Oem 4.4 rings at about 150gbp for a set, the 4.6 seem to be several times that.
This one is my car so cost becomes more important, well as long as they don't break!

[J.Belknap]

Good luck with your engine.

[Wingphil]

Yeah
Found a ring supplier, I think, who is reasonable for Oem rings.
Now I have to go through the parts book and find all the part numbers for the bearings, main and big end, gaskets and oil seals.
If anyone who has built one wants to help out with a list of part numbers......
Thanks