Whether an engine is responsive and high-revving depends very much on the inertia of reciprocating parts, i.e., crankshaft, pistons and connecting rods. While crankshaft material is still bounded to steel for reasons of sheer strength, pistons of high-performance engines are usually made of aluminium. The lighter the pistons, the higher the revs and power the engine can obtain.
Using alloy pistons is not very costly, what prevents most mass production all-alloy engines from using them is the friction generated between pistons and cylinder walls. Strangly the contact between two aluminium surfaces results in high friction - much higher than between cast-iron and aluminium. Therefore many engines with aluminium block have to employ cast iron pistons.
The most common solution is to insert a thin cast-iron liner to the cylinder, covering the cylinder wall and surrounding the aluminium piston. Of course, this lifts production cost a bit.
An alternative solution was introduced by Chevrolet Vega in the mid-70s. Its Cosworth-designed all-alloy engine employed iron-coated aluminium pistons, thus the block could be linerless. However, it's still more expensive than a cast-iron liner while not delivering as good performance as Nikasil treatment.
Instead of a cast iron liner, Nikasil treatment coats a layer of Nickel-silicon carbide to the inner surface of aluminium cylinders. Since the Nikasil layer generates even less friction than cast iron liner, revability and power are both enhanced. Moreover, it is only a few hundreds of a millimetre thick, therefore the spacing between adjacent bores can be reduced considerably, making the engine smaller and lighter.
Since the early 70s, Nikasil treatment has been one of the most favoured solutions used by high-performance cars. It also proved very popular in the high performance motorcycle world especially in two strokes. Less Friction also means less wear, Porsches Nikasiled cylinders are said to out last the car.
The last alternative is a fiber-reinforced metal (FRM) cylinder sleeve, which is used by the Honda NSX 3.2-litre. Its cost and power / space efficiency are both half way between cast-iron liner and Nikasil. A fiber-based material in the form of cylinder sleeve is first inserted into the die of the block. Melted liquid aluminium is poured into the die and integrates with the fiber sleeve. Then the cylinder wall is machined to the desire bore dimension, leaving only 0.5 mm thickness to the fiber sleeve which covers the cylinder wall. It generates lower friction than an iron liner, thus improves revs and power. Moreover, the fiber sleeve reinforces the block, allowing the distance between adjacent bores to be reduced yet maintain mechanical strength.