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Old 06-14-2005, 12:57 PM   #1
CitySubie
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Default Close deck? Why?

Our NA 2.5 liter engines are opened deck from what I have learned here.
The WRX's 2.0 is closed deck and the STI is a semi-closed deck (or semi-opened, 1/2 full vs. 1/2 empty)
Being closed-deck help with the "bullet proof" reputation, correct?

What's with the open deck? I can't think of one reason other than less material being used for our cars to be open-deck.

Someone please enlighten me.
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Old 06-14-2005, 01:08 PM   #2
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the WRX is open deck! and the reason why subaru make open deck instead of fully closed ones is the $$$. Making a fully closed deck one cost a lot more $ than casting an open deck block ! And before breaking the 300 hp line, open deck block do the job !
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Old 06-14-2005, 01:12 PM   #3
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Closed deck are also not as efficient in cooling as semi-closed deck.
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Old 06-14-2005, 01:31 PM   #4
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Quote:
Originally Posted by map
the WRX is open deck! and the reason why subaru make open deck instead of fully closed ones is the $$$. Making a fully closed deck one cost a lot more $ than casting an open deck block ! And before breaking the 300 hp line, open deck block do the job !
I think you're wrong
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Old 06-14-2005, 01:44 PM   #5
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us market ej20's are open deck. I've seen it first hand. older jdm motors were closed deck. map is correct. you may think otherwise, but i've been in that motor.
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Old 06-14-2005, 02:05 PM   #6
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V3 and 4 were closed deck and the old 2.2 Legacy Turbo was closed deck. Everything else is open or semi, I have seen ALL these motors opened up. MAP was correct in his statement.
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Old 06-14-2005, 02:13 PM   #7
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Quote:
Originally Posted by Boost-Free Subee
us market ej20's are open deck. I've seen it first hand. older jdm motors were closed deck. map is correct. you may think otherwise, but i've been in that motor.
Then I appologize
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Old 06-14-2005, 02:43 PM   #8
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ver 1-2.. maybe 3... 4 is open.
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Old 06-14-2005, 04:35 PM   #9
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Quote:
Originally Posted by RC0310
Closed deck are also not as efficient in cooling as semi-closed deck.
And because of this, the open deck block with the larger water jacket area heats the coolant up quicker meaning in the winter time, you get heat sooner.
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Old 06-14-2005, 06:02 PM   #10
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Something that has not been said....it's in regards to the material of the block. I know the ej22t block is made of a denser aluminum then the ej22 open deck blocks. While stronger, it doesn't transfer heat as quickly as the less dense allow of the open deck designs.

I'm tearing down an ej22t for my motor swap. You can see the cooling passageways in some of these pics.
http://www.main.experiencetherave.co...mages/ej22t/2/
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Old 06-14-2005, 06:32 PM   #11
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So which would be more efficient for a turbocharged car: open, semi-closed, or closed? What about a N/A car: open, semi-closed, closed?
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Old 06-14-2005, 06:43 PM   #12
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efficient?

i don't know what you mean. open is more efficient, but less strong. closed means the crankcase(shortblock) and it's associated coolant lines are completely closed off from the heads... that makes the block stronger but it doesn't really make it any more efficient...
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Old 06-14-2005, 06:48 PM   #13
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Legacy 777:

what are the two little venty-looking things on the underside of the EJ22T in the teardown pictures? are they oil passageways?
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Old 06-14-2005, 07:09 PM   #14
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Jesus Josh. And I thought I was a shutterbug in my garage.

Anyways, I don't buy that there is a huge heat transfer efficiency difference in open vs. closed deck. Most people don't realize that it is just the deck that is closed. The block is not solid all the way down to the crank girdle. It is wide open in there. And where the gasket surface mates to the heads is still the only place for coolant to flow between the block and heads on either design. I think it is an old wives tale.

Subaru stopped doing the closed deck motors because of changes in WRC rally rules. The use of restrictors on the turbos in the mid-90's significantly dropped the power levels of the cars. As such, there just wasn't any point in making them closed deck anymore. Especially since the closed deck engines, as has been mentioned, were a medium pressure sand cast block that was very expensive to manufacture. So, if racing rules don't warrant doing these things in the production classes, then why produce them in either the race cars or the street cars? Open deck Subaru engines easily support 400chp.

But this is only on the Ej20 and Ej22's. The Ej25 wasn't designed (until the creation of the Ej257 a few years ago) with high horsepower in mind. It's crank girdle isn't as beefy, and the larger bore make the pistons more suseptible to ovaling and walking.

For a high powered NA build, I think an open deck EJ25 is fine. There is a limit there, and I figure it to be around 250hp. And other parts of the equation effectively limit you from going much beyond that anyways without real big money and no streetability. Some of the tuners disagree with me, but I have seen enough closed deck NA tuner blocks fail to doubt that the closing of the deck is what will make an Ej25 bulletproof...
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Old 06-14-2005, 07:56 PM   #15
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i find myself pursuaded by matt's arguments here.

the open deck is not the weakness of the block, it's the application for which it was designed.

but dude, it's "its crank girdle" not it's.
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Old 06-14-2005, 08:35 PM   #16
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Quote:
Originally Posted by Handsdown
Legacy 777:

what are the two little venty-looking things on the underside of the EJ22T in the teardown pictures? are they oil passageways?
By "venty" do you mean that tube traversing the bottom of the crank case with a checked-looking casting? That, I would guess, is a coolant passage. Just going by the plugs on either end.
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Old 06-14-2005, 08:35 PM   #17
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Quote:
Originally Posted by Handsdown
Legacy 777:

what are the two little venty-looking things on the underside of the EJ22T in the teardown pictures? are they oil passageways?
Not exactly sure which thingy you're talking about, so I labeled a few things
http://www.main.experiencetherave.co..._internals.jpg

1. Crank case vent hole leading up to the oil separator, and then to the port on the top of the block that goes to the PCV valve
2. Block's internal bracing
3. Coolant passage from one side of the block to the other
4. Dummy hole
5. Hole where the oil intake tube & screen goes into. That hole goes to the front of the engine on the suction side of the oil pump.
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Old 06-14-2005, 08:37 PM   #18
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Quote:
Originally Posted by Handsdown
i find myself pursuaded by matt's arguments here.

the open deck is not the weakness of the block, it's the application for which it was designed.

but dude, it's "its crank girdle" not it's.
I got a look at a Mopar NASCAR engine that one of the instructors at my school got a hold of, and guess what...it was fully open on the deck surface. The main caps, however, were six bolt, where it really matters.
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Old 06-14-2005, 08:40 PM   #19
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Quote:
Originally Posted by Legacy777
Not exactly sure which thingy you're talking about, so I labeled a few things
http://www.main.experiencetherave.co..._internals.jpg

1. Crank case vent hole leading up to the oil separator, and then to the port on the top of the block that goes to the PCV valve
2. Block's internal bracing
3. Coolant passage from one side of the block to the other
4. Dummy hole
5. Hole where the oil intake tube & screen goes into. That hole goes to the front of the engine on the suction side of the oil pump.

You know, the boxer configuration looks to me to be hugely superior to an inline or even V in terms of how you mount the crank shaft. Would you agree?
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Old 06-14-2005, 08:51 PM   #20
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Quote:
Originally Posted by Matt Monson
Jesus Josh. And I thought I was a shutterbug in my garage.
Oh I'm a picture whore....you have seen pictures from my swap haven't you?
http://www.surrealmirage.com/subaru/swap/pictures.html

Here's a few more
http://www.main.experiencetherave.co...images/accomp/
http://www.main.experiencetherave.co...es/b4calipers/
http://www.main.experiencetherave.co.../brakebooster/
http://www.main.experiencetherave.co...brakebooster2/
http://www.main.experiencetherave.co...es/edmproject/
http://www.main.experiencetherave.co.../images/ej22t/
http://www.main.experiencetherave.co...ges/injectors/
http://www.main.experiencetherave.co...s/jointcustom/
http://www.main.experiencetherave.co...rtboybushings/
http://www.main.experiencetherave.co...ages/reardiff/
http://www.main.experiencetherave.co.../stereorewire/
http://www.main.experiencetherave.co...es/timingbelt/

you get the idea....


Quote:
Anyways, I don't buy that there is a huge heat transfer efficiency difference in open vs. closed deck. Most people don't realize that it is just the deck that is closed. The block is not solid all the way down to the crank girdle. It is wide open in there. And where the gasket surface mates to the heads is still the only place for coolant to flow between the block and heads on either design. I think it is an old wives tale.
I wouldn't say there is a huge difference in heat transfer efficiency between the different deck designs either. But looking solely at the material alloy aspect, the denser alloy "retains" heat better due to the molecular spacing when compared to the less dense alloy.
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Old 06-14-2005, 08:54 PM   #21
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Quote:
Originally Posted by ringe
You know, the boxer configuration looks to me to be hugely superior to an inline or even V in terms of how you mount the crank shaft. Would you agree?
Yeah I'd agree. It's an inherently balanced engine due to opposing forces on the pistons. Plus it's more compact. There's quite a few benefits IMO.
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Old 06-14-2005, 09:29 PM   #22
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Quote:
Originally Posted by Legacy777
Yeah I'd agree. It's an inherently balanced engine due to opposing forces on the pistons. Plus it's more compact. There's quite a few benefits IMO.
Well, I was thinking more along the lines of the strength inherent in that bottom end. Of course, a flat engine doesn't have a "bottom end" in the sense that most V or inline motors would have.
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Old 06-14-2005, 09:31 PM   #23
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BTW, how was that manual tranny swap? Seems like it would just be tedious work, tearing out the interior to get at what you need to on the bulkhead. did you need different wiring harnesses or a different ECU?
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Old 06-14-2005, 09:33 PM   #24
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Ah, nvm, dumb questions, lol. I see from your pics that you did.
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Old 06-14-2005, 10:12 PM   #25
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Quote:
Originally Posted by Legacy777
Not exactly sure which thingy you're talking about, so I labeled a few things
http://www.main.experiencetherave.co..._internals.jpg

1. Crank case vent hole leading up to the oil separator, and then to the port on the top of the block that goes to the PCV valve
2. Block's internal bracing
3. Coolant passage from one side of the block to the other
4. Dummy hole
5. Hole where the oil intake tube & screen goes into. That hole goes to the front of the engine on the suction side of the oil pump.
thanks, that's helpful, but i actually meant the two ones on the underside of the block in this picture:
http://www.main.experiencetherave.co...2/DCP_4309.JPG
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