I don't see much benefit to sleeving a block that doesn't have bore-wall-thickness problems.Need4Spd said:My thoughts, too. The etched bore design I think is superior in most respects. Only hot rodders who like to bore out their own blocks dislike this because they can't.
Plated? What's plated?Lscman said:wet sleeves (Cadillac etc) and definitely below one-piece plated designs used by BMW and Porsche.
Sorry for the poor "descriptor". Many are familiar with the sorted history of the Vega cylinders & the spinoff 928 motor (lol). Maybe the uprated 140 HP 4 valve DOHC Cosworth version got them excited! I was comparing sleeved vs non-sleeved engines in general. There there are many methods used to improve non-sleeve cylinder wear resistance. Performance motorcycles and cars have been utilizing cylinder coatings, heat preps, platings & chemical treatments of various kinds.JEM said:Plated? What's plated?
Lscman and I do not always see eye to eye on matters technical, but he has the physics correct here. I might have put the likelihood of a bad result at 95% instead of the 100% implied in the post.Lscman said:Of course it can be done, but what is the result?
Since these dry sleeves are super thin & less than 1.5mm thick between cylinders, it will be interesting to hear any feedback about it's in-service performance parameters. These sleeves will not transmit combustion heat to the surrounding metal anything like the plated one piece OEM cylinders. Dry sleeves change shape when subjected to elevated power & temps. As such, ring seal (blowby) & head gasket seal is invariably compromised. It's been my experience that dry sleeves are at the bottom of the pecking order, below wet sleeves (Cadillac etc) and definitely below one-piece plated designs used by BMW and Porsche. Hot rodders & mfrs abandoned this technology for performance motorcycles and cars 30 yrs ago. Maybe some new process has been developed to improve heat transfer such as injecting Pentium 4 heat sink compound during the sleeve-pressing process (lol).
This recipe has been tried thousands of times & results are consistently poor.
My initial assessment is it looks like a good way to "save" a damaged block (otherwise worth $10K) for reuse in a car going to auction or a used car lot.
If my opinion off base, I'd like to hear why.
Here is a explanation of the Alusil (late BMW) vs Nikasil (early BMW) bore finish in these websites.Need4Spd said:My thoughts, too. The etched bore design I think is superior in most respects. Only hot rodders who like to bore out their own blocks dislike this because they can't. :M5launch:
So many comments, I always enjoy the feed back from others.JEM said:I don't see much benefit to sleeving a block that doesn't have bore-wall-thickness problems.
At the same time, there's really nothing wrong with it so long as the sleeve can be properly retained in the block and that block expansion/contraction does not result in the sleeve 'pulling away' from the head - usually a rib or step at the top of the sleeve and a counterbore in the block. IIRC Darton did these sleeves, and I'd have no trouble trusting their stuff.
It is possible to resurface an Alusil bore, though I think few shops are set up to do it, and in the S62's case there isn't room to bore it anyway.
It might be a matter of piston sourcing and piston/wall compatibility.
Sleeves are at least replaceable if something does go wrong...
You are right about the bore spacing and the unusual shape of the sleeves. Look at the old post below (#117) and you will see the issues of sleeving the block.RRoberts said:Lscman and I do not always see eye to eye on matters technical, but he has the physics correct here. I might have put the likelihood of a bad result at 95% instead of the 100% implied in the post.
Heat rejection is a big issue on modern high-output engines, and it becomes bigger still as power level is increased without compensating changes to the water and oil systems. Reduce compression ratio for supercharging and proportionately more of the fuel energy goes into the cooling system. A pressed-in steel dry liner in place of a monolithic high-conductivity aluminum cylinder wall will make the issue worse. It might be ok on a stock engine in a temperate climate but maybe not. Here we are talking about doubling the power and thus the amount of heat that must be transferred to the water jacket.
The added fact that the liner is thinner than typically used, made necessary by the tight bore spacing of the S62 block, is also moving in the wrong direction. A thin liner will more likely distort under load; heat transfer to the jacket water will be further compromised if clearance develops under load between the liner and the underlying aluminum structure. This will cause local overheating of the liner, which will be self-aggravating.
Sad to say, but the S62 block design is pretty close to the limit as it comes from BMW. And without doubt, the hot rodders among us would rather be playing around with cast iron bore surfaces than the rather delicate and not real forgiving Alusil. A case can be made for a custom block, aluminum billet with wet liners or maybe even an iron casting, if the ultimate S62 were the plan. But then a Chevy would cost so much less and would probably fit.
Regards, Dick Roberts