Audi V10 damaged bore

[rayhall]

Hello,
I have had a Audi V10 with piston damage due to detonation. Ring lands broken and bore has marks. The marks are not deep and I have a new piston and rings. I want to fix the bore by honing ?. The bore is Aluminum and made with high silicone content.
How do I fix the bore ready for the new piston.
The engine is the 5L V10 from the bi-turbo RS6.
Thank you.
Ray.

[Ant180]

THE Ray Hall?
If so there’s only a couple of joints that I’ve heard of off hand in Aus, the etch after hone is critical as are piston and ring materials.
Please advise if you are the Aussie Ray Hall and if so I’ll chase up some contact details

[ptuomov]

A couple of questions, mostly to satisfy my curiosity:

Is the new piston original size or oversize?

Is the new piston otherwise identical to the existing pistons, including skirt coatings and rings?

Do you know what cylinder wall surface the engine runs? Alusil or Nikasil? Or has someone added aftermarket cast iron liners?

What does the factory service manual say about cylinder bore repair? Do they sell Alusil/Nikasil aluminum repair liners for a single cylinder?

[MotionMachine]

I mistakenly say nikasil instead of alusil about a minute in so ignore that. I've never done an Audi but I would imagine that it's the same alusil as BMW.

[ptuomov]

I mistakenly say nikasil instead of alusil about a minute in so ignore that. I've never done an Audi but I would imagine that it's the same alusil as BMW.

Volkswagen brands’ (Audi, porsche, lambo, etc.) engineers like to use Nikasil in their highest powered turbo engines. I wouldn’t be shocked if this engine also has Nikasil bores. In any case, the first thing to find out would be whether the bore is actually Nikasil Or Alusil.

[rayhall]

THE Ray Hall?
If so there’s only a couple of joints that I’ve heard of off hand in Aus, the etch after hone is critical as are piston and ring materials.
Please advise if you are the Aussie Ray Hall and if so I’ll chase up some contact details

Yes it is Ray Hall from Australia that sold Autronic ECU for many years

[rayhall]

A couple of questions, mostly to satisfy my curiosity:

Is the new piston original size or oversize?

Is the new piston otherwise identical to the existing pistons, including skirt coatings and rings?

Do you know what cylinder wall surface the engine runs? Alusil or Nikasil? Or has someone added aftermarket cast iron liners?

What does the factory service manual say about cylinder bore repair? Do they sell Alusil/Nikasil aluminum repair liners for a single cylinder?

Pistons are standard. The engine we bought new and came in a Audi box
All the pistons are the same I think the gudgon pins are offset on each bank.
From what I have read the bores are machined then etched to expose the silicon then honed
Manual I cannot read as it is in German
Ray.

[stealth]

If only light scratches...don’t butcher it...light hone and run it..

[ptuomov]

Pistons are standard. The engine we bought new and came in a Audi box
All the pistons are the same I think the gudgon pins are offset on each bank.
From what I have read the bores are machined then etched to expose the silicon then honed
Manual I cannot read as it is in German
Ray.

Sounds very similar to the Porsche 928/944 Alusil or later Porsche Lokasil cylinder.

The earlier-posted BMW video explains the honing and etching process.

One issue is that if the bore size is right now, honing and etching might make it too large. And some engines may require re-etching for new rings for the rings to seat, the new rings may require more silicon to be exposed for the right roughness level.

If you have the factory repair manual pages, shoot a photo and someone with enough German will translate.

[Ant180]

Ray,
My Honda guy tells me that Russell from Dominator Engines and Aaron Hambridge from APM both in Sydney can handle F20C S2000 bores, which I believe are Lokasil, the surface of which is similar to that V10 bore surface.
Afaik the specifics are provided by Sunnen, essentially diamond honing and then a silicone lapping step which selectively abrades the aluminium, leaving the silicone particles exposed.
If anything like those Honda bores, which use a fiber reinforced Lokasil cast in aluminium liner, the amount of honing that can be done is minimal, a couple of thou or so.

[rayhall]

I want to thank everyone for there help. I have decided to get full set of forged pistons made and fit iron sleeves to the bores. There is a company in Brisbane that has done this before and advised it was the best way so I will never have to worry about damaging the bores again. The problem I have is common on these engines when using the stock pistons, ring and aluminum bore, and pushing the power up. Stock was 580 HP and I am over 800HP at the wheels.
Ray.

[ptuomov]

I want to thank everyone for there help. I have decided to get full set of forged pistons made and fit iron sleeves to the bores. There is a company in Brisbane that has done this before and advised it was the best way so I will never have to worry about damaging the bores again. The problem I have is common on these engines when using the stock pistons, ring and aluminum bore, and pushing the power up. Stock was 580 HP and I am over 800HP at the wheels.Ray.

Alusil is great, retains oil well, and doesn't wear. That said, it seriously restricts the pistons that one can run. That's why many people install liners when they need non-stock pistons.

One more question: Is there a facility within shipping distance that can Nikasil plate the bores? Forged pistons run great on Nikasil.

[rayhall]

[

Alusil is great, retains oil well, and doesn't wear. That said, it seriously restricts the pistons that one can run. That's why many people install liners when they need non-stock pistons.

One more question: Is there a facility within shipping distance that can Nikasil plate the bores? Forged pistons run great on Nikasil.

The people making the forged pistons were not keen on making them for a aluminum bore. I think rings they can supply is also a problem.
The people that can do the bore honing are a distance away. That does not matter as I can ship the block to them. The company who can Niksil is further away, not that it matters.
Ray.

[gunt]

from limited knollage

is it not like the honda bores ,

i would say mahle will have something listed for them as they more than lightly even supply the oe

don't put liners in it , i think under ground are running 1200bhp and higher on std bores and the new gtr is holding 1800bhp on std bores and its v6

from mem pro line engines in the us do the building and machining for pro line .

the cost of liners and all would far exceed shipping and having it right , the cylinder seal if superior

[ptuomov]

from limited knollage is it not like the honda bores , i would say mahle will have something listed for them as they more than lightly even supply the oe. don't put liners in it , i think under ground are running 1200bhp and higher on std bores and the new gtr is holding 1800bhp on std bores and its v6.
from mem pro line engines in the us do the building and machining for pro line . the cost of liners and all would far exceed shipping and having it right , the cylinder seal if superior

I agree that Alusil is a great cylinder surface material, _IF_ you can find truly compatible pistons. Nikasil is arguably even better and all the normal forged aluminum pistons run on it well as long as you stay away from chromed oil rings. All in all, in my opinion, either option if correctly executed results in an engine that ends up being superior to cast iron liners installed in a high-silicon alumnimum block.

The practical problems is that it's very hard to get anyone to make truly Alusil compatible pistons and facilities that can Nikasil plate, bore, and hone a whole V-10 cylinder block (instead of just a loose individual cylinder barrel/liner) are few and far between.