Lets see if I can get this rolling again...
Crucial to the piston/rings is the cylinder bore itself.
There are 2 cylinder bore treatments which are by far the most popular choices for motorsport applications.
1. Nickasil is a Mahle trademark although there are many other providers of chemically similar electroplating services, can be layered on very thick (for electroplate) in a relatively short time with good conformity. Particularly good when the material being plated has low impurities, cast iron generally does not plate well but steel and alloys do. Hardness values mean diamond honing stones are required to produce a cross hatch pattern.
2. Sume-Bore is a Sulzer-Metco product (other good providers are available) and uses a rotating head to spray plasma at extremely high velocity into the bore substrate material. Can cover almost anything, hardness values below Nickasil (?).
There are 3 primary block types within motorsport.
1. Parent metal bores, where the material used in the casting of the block is suitable to be used as the cylinder bore running surface, mainly cast iron, as found in cars since the beginning of time and still surprisingly widely used, particularly because it requires no specialist bore work to be ready to use, the ability to have cast iron bores honed into a cross hatch pattern for oil retention is widespread and cost effective. This group also includes newer technologies such as the Alusil type by Kolbenschmidt where an aluminium block consists of about 30% silicon purely to improve the wear properties of the bore, specailist iron based piston coatings are required in Alusil bores as the characterstics of piston and bore material are close enough to induce seizure.
You will notice that this effectively reverses the role of piston and bore material, the iron now being on the piston and indeed Alusil blocks do not use a crosshatch pattern for oil retention, a chemical etch is performed on the bores to remove aluminium deposits and expose silicon particles.
Typically used in Porsche engines since the 944 up to currently used in 997, not including GT3 engine, a similar technology also used in latest Toyota 190hp 1.8 VVT engines.
Parent bores allow thin gaps between cylinders giving light compact engine blocks but are subject to several compromises, heat dissipation becomes difficult between bores and the material choices cause problems, iron blocks are heavy, Alusil blocks can be brittle and require thickening in many areas to avoid breakages and this can add quite a bit of weight. Both Iron and alusil have realtivly short service life when subjected to prolonged high revs/load.
2. Linered blocks - Non structural (dry liner). A thin layer of material which has superior wear properties to the material of the block is inserted or applied to the bore to improve performance/duration of lubrication properties, this can include the coatings listed above, among others or a thin steel, alloy or even iron liner (possibly with a coating of its own applied) inserted into an over-bored block. This is most commonly found on production based engines which have been modified for Motorsport. Alloy Audi V8's can be found with thin alloy liners coated with Nickasil, Iron Cosworth YB straight 4's may use Nickasil coated steel liners, BMW V8's may have Nickasil coating directly on the bore material.
If a coated metal liner is used, expansion characteristics must be taken into account i.e. no alloy liners in an iron block, in order to be a good fit in a cold block they may over expand and crease at running temperatures. Electroplating or spray coatings generally keep excellent conformity across the temperature range.
Using a thin metal liner is a good way to re-use blocks which have been re-bored/re-honed too many times due to wear, it also allows replacement of individual cylinders if damage occurs in just one or two. Essentially used to extend the life of rare, or valuable engine blocks, or where the parent metal is unsuitable for the desired coating, or the structure of the block means a thicker liner would damage the structural integrity.
Plating directly onto the block (essentially a thin liner) is excellent for weight/size saving and a popular choice amongst the 'money no option' teams with a ready supply of good quality blocks but often requires specialist tooling or long set-up times and can be expensive. Also usually can only take 1 or two re-hones before having to be chemically stripped using aggressive acids which can damage the block if not carefully executed. Bore coatings are generally less conductive of heat than iron, and even alloy's which means they cannot be made excessively thick or they may cause overheating issues. Conformity drops off at excessive thickness too.
Generally known as dry linering because non of the liner comes into direct contact with coolant solution.
3. Linered blocks - Structural. Thick steel liners can beef up an inherently weak alloy block, if the area around the main caps is chunky enough the liners can seat at the bottom of the block and transfer torque from the head bolts directly into this area whilst the diameter of the liner can resist the combustion forces with less deflection. Particularly useful on heavily turbo'd applications, where sleeving down and reducing cc's whilst using much higher boost may give more reliable power.
Nissan V6's take this well. Popular in drag racing where coolant chambers can also be filled to beef up block structure. In some cases the block may have individual cylinder towers (open deck) which can be completely machined away and replaced with a stand alone liner (wet liner).
I felt the need to inject some semi technical chat into the mechanical section of this site as I'm getting a little tired of politics and don;t know enough about aero, so discuss away, I have a little more to come on bore shape, hot honing and surface finishes but this has taken me far too long and I've got stuff to do!!!
FYI, although I
can't say what the F1 teams are currently using I
can say that you would be quite surprised (unless you already know!, which I doubt
) the variety of ways in which this is approached, considering the engines rules are so tight and the accuracy of simulation is relatively high it's amazing that there is still more than one way to skin a cat, even in F1.
(edited for readability!)
I can't go into it any further though as we are getting to the point where most firms would see this as specific enough to be hard won proprietary information. What a cop out eh? 
