Update on project Chicago, Alpina B7 (Patreon)

Unfortunately, Alpina is dead, again! 

In short, the engine suffered catastrophic damage due to the block not being sleeved properly. 

After the test drive, I found metal shavings in the oil filter housing so I thought it spun a bearing. Before pulling the engine out, I decided to do a visual inspection of the cylinders and if everything looks good, do a compression test. 

As you can see from the pictures, it didn't look good. Cylinders 4 & 8 are utterly destroyed so the engine needed to come out. Took me 5 hours to remove it (getting good at this).

Today I stripped the engine to a bare block, trying to understand what the hell happened and what caused the carnage. Since I didn't find a smoking gun, I took the block to a nearby machine shop and we measured all cylinder bores.

Conclusion: The engine failed cause there was not enough clearance between the pistons and the cylinder wall.
Our new cast iron sleeves are not cylindrical, but sorta conical, wider at the top, narrow towards the bottom. This is actually not that uncommon cause of the honing process.

However, piston-to-wall clearances are wrong and all over the place. We measured 0.04 mm on the top and then 0.02 mm towards the bottom of the cylinder.
Some show 0.04-05 mm and then you measure 90 degrees in the opposite direction and get 0.01 mm so they are also egg-shaped. Only cylinders 1 and 5 showed 0.02 mm all around.
Cylinder 4 that failed, shows 0.06-07 mm where the scratches are and 0.01 mm of clearance where there are no scoring marks which is far too little clearance. 

So how did it fail? Well, pistons are made from aluminum and aluminum expands with heat, cast iron sleeves; not as much. Cylinders 4 & 8 that failed are at the back of the engine and they see the most heat as they get the least amount of cooling.
As I was driving, pistons expanded, cast iron sleeves didn't, then the pistons didn't have enough clearance so they made some by beating and scraping the crap out of cylinder walls.

Result: the block and 2 pistons are officially dead. Conrods are okay, bearings didn't spin but have some light marks from shavings circulating in the engine, crank is okay but has one or two smaller scratches.

Now, I knew about dissimilar metals and thermal expansion even before I sent the block for sleeving and of course the guy who sleeved the block knows about it as well. I even specifically discussed with Nenad on this topic when we talked and he told me not to worry, that he will leave enough clearance as he has experience with this. 

I called Nenad today and told him what happened and what we found. He was pretty shocked, bummed out and taking responsibility for it. He told me that he would never let the block leave his shop which such measurements all over the place and that he spent extra time with my block cause he knew it'll be used in the video, so he measured everything million times and left clearances 0.025-0.030 mm on all cylinders. Clearly, that's not what we found and it's evident that the engine failed due to not enough piston-to-wall clearance. The local machinist told me that for cast iron sleeves in Alu block, the clearance should be a minimum of 0.05 mm.

You all know the lengths I went to find someone to do this job, Nenad came highly recommend, he's been sleeving Alusil blocks for 10 years, S62 E39 M5 engine that he's done for my friend is still going strong after 50k km, he's done so many engines Porsche, BMW, Audi, drift competition engines... and none failed. I just can't explain what happened here cause he is not an amateur. He told me he's been sleeving them with 0.025-0.030 mm clearance always without any failures and that he doesn't go more than that cause the engine can have high oil consumption. The clearance topic needs to be further discussed. 

So what next? As I mentioned, Nenad without any hesitation or argument said he will make this right, to send him back the block and that he will try to source 2 pistons to replace the destroyed ones (no idea where he'll find pistons that only Alpina engine uses).
This is fair, but I just wasted a huge amount of time on this project, spent a ton of money on parts and now I need to buy one-time-use parts all over again: head gaskets, head bolts, rod bolts, rod bearings, all gaskets, disassemble and clean the heads...

And here's the thing, we all know how long it's going to take to get the block back. It'll be months of waiting, parts scattered everywhere and a dead unfinished car sitting in my lap. I have so many other projects that I want to get to, but can't because of this. I'm so preoccupied I don't even have time to do a simple oil change on E46.

Therefore, I want to get Alpina back on the road differently. I found a used Alpina H1 engine for sale in Poland, the price is 5k shipped to my door. It was Imported from Japan, supposedly only 80k km (50k miles). No proof though, as with all used engines. Japanese cars typically do come with low mileage and great maintenance so it's not impossible and from the outside, it looks clean, a lot cleaner than what I removed from project Chicago.

But anyway, mileage on a used engine is not relevant, the condition is. The guy told me they checked the compression and it was 12 bars across all 8 cylinders. They offer 2 week warranty on the engine.
I explained that, upon receiving the engine, I would do a visual inspection of the cylinders, compression test and leak down test. If something is not good, it's going back and he agreed. 

If the engine is good, then the plan is to use that block. Leave the pistons and cylinders alone, replace the rod bearings, use my refurbished heads and bolt all new parts that I bought to it (chains & guides, water pump, injectors, etc...). This way, I can have the Alpina back on the road within a week or two. 

In the meantime, I will send my current block back to Nenad and let him do his thing, sort it out and have that block as a backup for whenever the other engine inevitably blows up.  

I gotta say, I couldn't sleep these past few days thinking I messed up something during the engine assembly, going over everything in my mind. Even though the whole situation sucks, knowing I didn't make a mistake when it putting it back together does make it easier. 

That's the update for now. I'll start editing the next episode tomorrow and keep you posted on how it turns out with the used engine.

Thank you again for your patience and support!