OK, I am trying to get a grasp on the concept of closed and open deck engines, there is a little bit of info that I have found so far. But what I don't understand is, how does the coolant work on a closed deck engine, and is the STI engine what some call "semi-closed" I just need some enlightenment Pics from another thread, I'm guessing open and semi-closed: http://www.wrxatlanta.com/forums/showthread.php?t=11733&page=2 Pics from a sandcar build site, open and closed deck: http://www.cgperformance.com/subaru_block.htm Sorry I can't post the pics directly, they aren't mine! I'm not the best with searching, but I wouldn't mind some help, either! -Matt
Closed deck: Most of the open spaces between the upper cylinder wall and the inner structure of the outside of the block is closed off, creating a very strong bracing effect for the upper combustion chamber. The only openings are for the coolant passages into the head, and the usual oil return and feed galleys. Open deck: Almost all of the area previously mentioned it open. However, in a SUBARU engine (EJ and EG...EZ is similar) there still exists two major bracings...the two cylinders connect to each other, and there is another spot where each cylinder connects to the outer block as well, this is on the 'horizontal plane' when looking directly at the block from the 'top' of the bores. Semi-Closed: Same as open deck....BUT with the addition of two bracings on the vertical planes when looking at the bores from the top. See the difference now? The closed deck engines were a medium cast pressure aluminium....it did not dissapate heat easily, thats why the semi closed engine came along. Basically the same strength, but more reliable.
Thanks Will! That's what I thought, but wasn't sure. So, to further my enlightenment, which subaru models use the semi-closed deck? AFAIK the STi has semi-closed,right? Also, if you remember my 2.5i mod thread, you mention the wrx snorkus mod. You wouldn't happen to know what parts I need for that and where I could get them? Thanks again! -Matt