Open vs. Semi-Open vs. Closed
Open Deck
USDM 2.0 WRX motor http://i5.photobucket.com/albums/y17.../engine012.jpg If you ask me, this was designed as an performance economy motor. Although it has a large water jacket to promote effecient cooling, but lacked strength around the cylinders. Semi-Closed USDM 2.5 STi motor http://i14.photobucket.com/albums/a3...emi-closed.jpg Stronger with great cooling and economical to produce. Fully Closed JDM Turbo Legacy EJ22 http://i5.photobucket.com/albums/y17...enginetest.jpg The strongest motor design, but also more expensive to produce. Also had cooling issues due to the small water jackets. The main thing I wanted was the visual of the motor design. I'll add more to this as I find more information. |
good stuff!
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open deck is not inherently weaker than semi-closed or closed - theres been a bunch of tests on RS25 to prove this (skully's EJ25D with stock STi internals putting down 600whp is proof enough haha)
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There are exceptions to the "rules". The open deck design might not be infact weak, but the semi and fully closed decks are mechanically stronger. It is doubtful that anyone pushing under 30psi will be able to oval or damage the cylinder walls unless something else fails.
Thomas (skully) was making over 400whp if I recall on an open deck EJ25D block. Mind you, he had a completely forged bottom end. |
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Yeah, and I think it was close to 30psi if I recall. Engine blow and wear due to abnormal combustion and bad maintenance. If the engine is running properly, even at 400whp....nothing should go wrong.
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Cool thread George, I always wondered about that. The STi is semi closed right? what about the WRX 2.5. Is that open like the 2.0 is?
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Wow I learned something! Thanks for sharing.
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But I've been lookin and can't find anything. |
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Yes it is. However we all know that most of all this power that these guys are putting down is do to the tuning factor of the vehicle. Anyone can make good power out of almost anything with good tuning. Notice he said he has AEM EM. Ive never messed with it, but people like using it and from what I hear its a awesome system for mangagement. Awesome pictures of the blocks. Everyone hears alot about Closed, Semi and Open blocks but dont really understand. Pictures speak a thousand words. The problem with our blocks isnt wether they are open,closed, or semi. The fact is, is that the oiling system isnt that great. At higher RPMs the oil gets pushed into the cylinder (bearing wise) in front of it starving the bearing of oil. There are a few things we can do to help this. We can have the crank cross drilled for better oil flow. We can also upgrade the oil pump. The Legacy JDM oil pump flows up to 20% more. Cosworth also makes an upgraded pump and so does JUN if you want to spend 900 bucks. Jodie |
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maybe but there are so many variations of the 2.5 :
N/A SOHC 2.5 L,I,RS N/A DOHC 2.5 RS F/I DOHC 2.5 WRX F/I DOHC 2.5 STi Im sure im missing some too. because with that kind of knowlage, you could end up picking a great block to build for alot less cash somewhere. |
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*edit* Just searched - EJ255 is semi-closed |
This is a fun thread. Troll should approve
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i've heard that crossdrilling has no definitely proveable benefits and thats its risky business messing with the oil system in the motor. of course others do think this is a solution. also, the discussion goes that you dont need to increase pressure, you need to increase volume of flow which the 2.2 pump doesnt do. in fact its just a normal pump with a shim in it and a lot of guys i've talked to dont feel like its necessarily beneficial. |
I will agree. Its very hard to say the cross drilling 100% works all the time no one really knows because there are so many different types of racing that people use our cars for. Drag racing, we are only looking at a few seconds of harsh use. But for those few seconds, the bearing are really taking a beating for the few people that running 30psi or more. Although its not very big out here yet, time attack people are having a hard time with our oiling systems. Im not sure why, I guess big power at super high RPMs for a longtime. Rally, Drivers really expect alot out of the cars. Everyone is really pushing the engines to the limit, people are really on the rev limiter or very high RPM again alot because of traction issues, of course. Road Racing, Lets look at the ICY team for a minute. When they were running the STis they didnt have alot of issues all season long and they where stock besides the suspensions. Good Tuning and Traction plays a huge part in why the cars stayed together. Even though they are running at high RPMs they shift before the limiter and such. The Torque curve is much like what you would see on a dyno. That is if they would stay in one gear. With Rally.. Your going from 0 RPM to 8500 back down and up with load on and off for a constant and very long time. So do I think that cross drilling works? To be honest I dont know. But as Troll says, oil volume is the only thing we can hope for on any of our blocks.
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^ well put
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