Hiya y'all. I am beginning to wonder if I am just really thick or something.

I keep reading references to The Terms "closed deck" and "open deck" in relation to our Scooby engines. Yesterday I did a thorough search on the net and found some really interesting information on this subject, but I still cant get it into my brain what the fundamental difference is between the designs.

I have a 1995 2.0 ltr (EJ20BG5) Legacy N/A.

It seems that if you want to greatly increase horsepower by modifying things, you really need to have "closed deck" to cope with the extra power.(as well as a pile of other mechanical changes).

If anyone can explain these two terms to me, in simple english, I would be really grateful.

I get the feeling that it has do do with cylinder sleeves or something, but really dont understand the basic differences.

With an open deck engine design, removing the cylinder head will allow you to look down into the coolant jacket all around the cylinder wall. closed deck engines are like a solid flat piece at the head gasket surface with some relatively small holes that match up with holes in the cylinder head for coolant flow. since the top of the cylinder walls are completely connected to each other and to the side walls of the engine casting, they are more rigid and more able to withstand the side to side forces generated by the moving parts.

Here is a picture of a closed deck short block courtesy of Crawford Performance:

 

 

Here is a picture of a semi-closed deck short block also courtesy of Crawford Performance:

 

Here is a picture of an open deck block courtesy of Cobb Tuning:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Hopefully, the copyright gods will forgive me for this post!!

Nice pictures Chip. I learned something new that I was not aware of. Thanks.

Thanks guys !! That is now very clear. All I need to know now is what type I have in my Legacy. I dont think I will be going down the hot rodding mod route with it though. Maybe just look for a B4 RSK or something similar. Gotta keep up with my son in his 2.2 V-Tec Honda Prelude somehow. ? LOL???

Cougar wrote:

Nice pictures Chip. I learned something new that I was not aware of. Thanks.

Same here. Thanks.

P.S. The open/closed deck engine isnt really an issue unless you are talking turbo.