Is R8 engine block cast iron?

[Glen]

Hi,
I was perusing the R8's specs on the AoA website and noticed that they list the R8 as having a cast iron engine block with aluminum heads. Is this correct? Seems odd that they build the entire chassis with aluminum and then use an iron block. Maybe it's a typo?

Thanks.

[randombloke]

http://www.audi.co.za/news/?articleID=924

The engine block is made from a high-strength aluminium alloy by low-pressure die-casting.

and from the spec/price brochure as per attached pic

[Glen]

That's what I thought, but the picture/specs I attached is straight from Audi USA's website.

[willyjp]

There's at least one other thing wrong with those specs you posted: the DOHCams are described as "belt driven," which is true of the original 4.2 v8, as used in the A8, A6, etc., but the RS4 and R8 have chain driven cams, which, btw, is a major improvement and maintainence saver (no cam belt replacement at 75k mi. or whatever). As with many alloy engine blocks, the R8 engine may have iron sleeves or liners for the cylinders...I'm not sure, just guessing.

[Glen]

Thanks. I guess even a major manufacturer like Audi can make mistakes on their website...obviously, someone wasn't awake when they published those specs.

[Dan1]

Even looking at pictures of the engine you can see it is aluminum.

And in the Audi book that was send to me, and I assume to all of you, (big Silver book with R8 embossed on it) it states it is an Aluminum Silicon Alloy block.
This tell us the piston bore is the block itself.
This is pretty common today, the Chevy Vega and Porsche 928 also used this early on.

No need for a cast iron sleeve which adds weight, reduces cooling and wears faster.

The weight of the engine is listed at 197 KG.

[willyjp]

It is pretty amazing that the Audi USA web site has the WRONG SPECS for the R8 engine, but I looked at it also, and they are indeed wrong!

I have a copy of the original Road & Track road test and tech analysis on the R8, and it says the R8 engine, which originally appeared in the B7-RS4 (and then was modified-dry sump, among other points) for the R8 has an all aluminum alloy engine. According the the R&T article, the R8 engine has an alloy block with Nikasil cylinder bores. "Nikasil" is a trademark owned my Mahle, the German engine component supplier that did pioneering work in alloy engines.

The name refers to a Silicon-Carbide compound imbedded in a Nickel plating that is electrolytically deposited on alloy surfaces to harden them. It or a generic version of it is widely used to harden cylinder bores in alloy engines.
"All the Japanese motorcycle engine builders" are said to use "Nikasil type" bore coatings.

It is described as a very hard surface, designed to mate with very hard chromium steel rings, and in the motorcycle engine lore about Nikasil, they all say that it requires a "hard running in," to properly bed the rings. The motorcylcle guys say if you don't vigorously "run in" your Nikasil bores, you will have perpetually high oil consumption!

Kind of fits with the R8 reports we hear of high initial oil consumption. I suspect that Audi likely drew on Mahle when it developed bore coating, rings and pistons for the R8 engine.

[Dan1]

"All the Japanese motorcycle engine builders" are said to use "Nikasil type" bore coatings.

It is described as a very hard surface, designed to mate with very hard chromium steel rings, and in the motorcycle engine lore about Nikasil, they all say that it requires a "hard running in," to properly bed the rings. The motorcylcle guys say if you don't vigorously "run in" your Nikasil bores, you will have perpetually high oil consumption!

.

I would love to know who these Motorcycle guys are, as I have been in the motorcycle industry for more than 30 years and that is NOT the case.

No motorcycle manufacture recommends breaking in any way other than the way Audi or any other car maker recommends, easy for the first 600 miles.

Nor does anyone in the motorcycle industry who is respected recommend breaking in using high loads at high RPM's.

Can you sometimes get away with a fast and hard break-in, sure, but it is due to the excellent tolerances, and quality of parts and design.

[willyjp]

Well, I am NOT a motorcycle expert, or even remotely familiar with them. In fact my actual hands on wrench experience is all with good 'ol US cast iron v8's. But I am familiar with stories about Nikasil bore coating, as I have heard plenty of horror stories about BMW and Jaguar premature engine failures from Nikasil bores degraded by hi sulfur fuel, etc., etc.. When this issue about the incorrect specs on the Audi web site came up, I went looking for the correct info and found out that the Audi alloy v8 uses Nikasil bores.

My initial reaction to that was rather negative because of the stories I've heard (above). So I did a little online research, and most of what I found out was about Japanese motorcycles. A typical quote would be

Nikasil is used in almost all racing dirt bike engines at this point (not used on trail bikes for the most part). It is extremely durable, and requires no significant break in. The single biggest advantage is its wear resistance, however if you do nick it (think piston explosion)you do have to send the cylinder in to be redone. The other big advantage is a thinner cylinder wall, promoting more even expansion, rounder bores, thereby improving sealing and wear.

I am not a motorcycle engine expert in your (or any) league. so I certainly wouldn't take issue with you or your experience. However, comments like that are all over the web and all you have to do is google "Nikasil" along with several choices of other terms to get a feel for it. Clearly it is much harder stuff. Everyone seems to agree that diamond honing is the only way to resurface it. And I think we can all agree that opinions about "running in" are all over the map and would rank right up there with other rich veins of folklore.

So don't misunderstand me. I certainly wasn't giving anybody advice about how to run in their motorcycle. Nor even their R8. Though I think you will have to agree that there have been a LOT of posts on this board, and other R8 forums, about very high initial oil consumption in R8's. And also a wide diversity of opinion about how to "run in" these cars, as well as whether factory advice was followed or not and how well it did, or didn't work. I can't help but wonder if some of this oil consumption stuff doesn't have to do with the particular combination of bore lining and rings chosen for the R8. Just idle speculation by an only partly informed amateur.

Fortunately, we have experts like you to enlighten us.

[Dan1]

I can't help but wonder if some of this oil consumption stuff doesn't have to do with the particular combination of bore lining and rings chosen for the R8.

As you already pointed out many Japanese motorcycles also use this same or similar combination.

It does not take an expert to point out that if that same combo was causing a problem you would see it there as well. It is not there.

As with cars there will always some problems, but it is certainly not even 1 % that have a problem.

What % of R8 are you thinking have a problem?

What % of these people have followed the R8 break in instrutions?