open and closed deck engines

[uno turbo]

hi folks, whilst looking up info on rebuilding my friends engine, he came across the terms open and closed deck engines. its a term neither of us has heard of, and i was wondering if anybody could help with an explanation... cheers... rich...

[sti pretender]

You get 3 types of block, open which has open water channels round the cylinders, semi-closed which has more more webs and closed which as very little space round the cylinders. Closed deck is a stronger engine when going for more power.

Picture of open & closed.

[BalliSTIc]

Howdy mate

This one gets asked a lot. (FYI there is a search engine on the forums that may be useful in future )

Basically it relates to how well the engine cylinders are supported. Scooby engines are best thought of as hollow, with 2 banks of horizontally opposed cynlinders (hence "boxer" engine... punching towards each other).

If you think of the cylinder end-on (ie a circle or clock-face):

Open deck block cylinders have support at 3 o'clock and 9 o'clock

Semi-closed deck block cylinders have support at 3,6,9 & 12 o'clock

Closed deck block cylinders have support all the way round.

This effectively makes closed deck blocks (or CDB's) the strongest. Theoretically they run a slightly higher risk of overheating (more metal support = less room for coolant), but that's very rare in practice... never seen it.

Hope this helps.

[uno turbo]

cheers for the help chaps, more than answers the question. and in plain english too, so i could understand it... will let my mate know. this will help him decide which way to go...

[R4CS]

Sorry for bringing up a dead topic but how do you find out which type my engine is? Is it between a certain year? It's a 1996 WRX STI.