Open Deck, Closed Deck, Semi Closed Deck

[9krpm]

If OS can build an open deck engine that revs to 13k and makes over 1200hp without a problem then maybe there's something in that. maybe..

The high rev, 6 cylinders and high power application is probably why they chose the open deck.

Both opened and closed decks have their ad and disadvantages. Open deck has better head and the top part of cylinder cooling. Closed deck has better rigidity, allows O-ring for better chamber sealing at the expense of reduced cooling capability. My honda F20c engine has open deck stock and closed deck with Oring after rebuild. The chamber seal is amazing.

[FATGTS-R]

Mate has gone no expense spared on a holden/isuzu rodeo V6 which had a factory V6 open deck block. It was fine untill over 400rwkw where it started to make the headgaskets move around. The builder put it down to the open deck design saying the tops of the cylinders were possibly moving about with the power level.

They had a piece of ally machined up to slip into the open deck to close it up if that makes sense. It worked because power has now increased 30% and no headgasket dramas anymore.

[BezerkR32]

Referring to the block deck and the way the water jacket is formed around the cylinder, early engines have closed deck, just like RB engines, just water jacket drillings across the deck. Semi is similar to a SR20, where they have a large slot between cylinders. And then open deck is kind of like a sleeved block where the top of the block is open so you can see into the water jacket. closed is obviously stronger as there is a lot more material to strengthen block from twisting/ warping etc. does not have anything to do with cylinder heads or combustion chambers.

I have 2 questions and I will start a seperate thread for the other one which will probably get a one sided response... anyway.. for this topic..

Closed deck and so forth are frequently spoken about in Subawho circles in regards to the engine.

apparently the RS turbo Liberty's were the only ones with a closed deck and all the WRX ej20's after that have been semi closed deck.. and the NA ej engines are all open deck.

so that's all lovely, but what is it in reference to?

why is closed deck better?

is this "DECK" type something in all engines or just the boxer motors?

if in all engines, what are the RB range of engines?

cheers..