Closed Decks

[Hog]

Originally Posted by Billy Mild

The 944 series Porsche used an open deck design. The turbo did as well. At very high boost the cylinders move above and the head gasket loses its seal.

People started using drag racing cement and expoxy to stablize the cylinders at the base. Just enough to still allow water to flow. People have made huge power doing this old drag racing trick. 944/951/968 engines were all aluminum similar to the LT5 and is Alusil as the primary material for cylinders. Good thing the LT5 used Nikasil as it's stronger.

just a blurb I found.


"The Alusil aluminium alloy is commonly used to make linerless aluminium alloy engine blocks.Alusil, when etched, will expose a very hard silicon precipitate. The silicon surface is porous enough to hold oil, and is an excellent bearing surface. BMW switched from Nikasil-coated cylinder walls to Alusil in 1996 to eliminate the corrosion problems caused through the use of petrol/gasoline containing sulfur."

[Billy Mild]

Originally Posted by Hog

just a blurb I found.


"The Alusil aluminium alloy is commonly used to make linerless aluminium alloy engine blocks.Alusil, when etched, will expose a very hard silicon precipitate. The silicon surface is porous enough to hold oil, and is an excellent bearing surface. BMW switched from Nikasil-coated cylinder walls to Alusil in 1996 to eliminate the corrosion problems caused through the use of petrol/gasoline containing sulfur."

The one thing they forget to mention is that only a few machine shops in the USA can properly hone or bore a block.