[SfValley335i]

Here is some info I came across, just makes you wonder what the N54 can take...

Originally Posted by spda-online.ca

Closed Deck vs Semi Closed Deck vs Open Deck Blocks





The deck is the surface where the head is bolted too.

The open deck design is for ease of manufacturing and not good for high cylinder pressures. This cylinder wall design is supported in 2 places. Many people will say that these engines cannot be turboed effectively but that is not the case. There are a couple here in the club that have run low to medium boost without issue. The problem is where the top of the cylinder where it meets the head will distort from high cylinder pressure and damage the head gaskets ability to seal in the combustion gases.

A semi closed deck design is a little harder to manufacture, but supports the cylinder at the top, bottom and sides. (four places). This is stronger then the open deck design and therefore can take higher cylinder pressures.

The fully closed deck design uses a different casting process that takes longer to manufacture and weighs more. These blocks have the most support to the cylinders, which will enable you to run the highest cylinder pressure of the available choices.

Subaru introduced the closed deck block for homologation reasons to be able to run it in their rally cars. This engine was made famous when a very similar version to it was installed in the limited edition 22B. With the casting methods and alloys available at the time Subaru chose this route to ensure a strong motor. With todays “modern” casting methods and alloys even the semi closed deck designed motors are very strong.


As a guide I would say the following;

Open deck blocks will work for all NA or low to medium boost applications.

Semi closed deck blocks are better suited for boost applications that are not extremely high or prolonged.

Closed deck block are best suited for applications where there will be very high boost for extended periods of time.

WRX motor at 22PSI

- Block is Semi Open deck





N54 motor

- True Open deck block

[JB335]

Thanks for the info man. I was curious in the last thread when this was being discussed.

[nyc335i]

]Just a thought...are you sure that's an N54?

It says 06/2004 on the picture. I'm assuming that is the date? I never heard of the N54 in '04. I might be wrong though...just a thought.

As a matter of fact: I found your image on the net. It is the N52 not the N54.

Here is the N54:

[Asclepius]

Hmmm, interesting info. I wonder how much more HP we can really cram into our motors without causing harm. Im guess not much more than the best current tune. I guess through trial n effort someone on this forum will give us the answer!

[JB335]

Originally Posted by nyc335i

]Just a thought...are you sure that's an N54?

It says 06/2004 on the picture. I'm assuming that is the date? I never heard of the N54 in '04. I might be wrong though...just a thought.

As a matter of fact: I found your image on the net. It is the N52 not the N54.

Here is the N54:

Nice catch, though its still the same style deck.

[Boost Gomez]

That's actually some very interesting information. Thank you.

[Black Chili]

In fairness to the WRX, forged steel rods and piston pins can do a HUGE amount of damage when they let loose, like punching fist-sized holes through the side of an iron or aluminum engine.

I don't think it says anything either way- the engine runs as an assembled unit not a bare block. I'm guessing BMW knows how the block stresses are and accommodates them well; it's not new territory for any engine manufacture. Typically you'd be replacing everything else inside the block before micro fractures, stress cracks, the cylinders going out-of-round under load, cracked mains, blown head gaskets, ect..). Unless it's a heat issue…

[Ninji]

What a crock of shit. That "information" is a bunch of nonsense and there is no way to relate block design to how much boost pressure an engine can handle.

Detonation is what cracks sleeve, esp. lean detonation which smashes the thrust surface of the pistons into the cylinder sidewalls. As long as you aren't detonating, you can run 40+psi of boost on an open deck motor with thick enough sleeves.

And if you have a problem with cylinder walk blowing head gaskets, the standard fix is to upgrade the head bolts to high strength aftermarkets (e.g. ARP studs) to increase the clamping force between the head and the sleeves.

[JoeyFiasco]

does this (open, closed, semi) affect engine cooling at all? if it did, it would help decrease knock by helping keep temps under control no?

[Dr_Dirt]

So this supra block is obviously a closed type...

so is this Mitsubushi 3000GT VR4 motor but these still needed race gas to go over 16psi

[bdkevoIX]

I didn't know the n54 was an open deck. good info.

I always thought although possible, it wasn't 'safe' to shove 50+ lbs of boost into an open deck motor?

All the ones i've seen with 50+ lbs of boost were AMS evo, ETS evo, handful of supras and skyline gtr?

[Mike@N54Tuning.com]

Thanks for that. Some cool info.

Mike

[Turkishexpress]

I thought the n54 was a semi open deck like the subies... hmmm... We got iron sleeves though

[veightkiller]

Nice find, i thought only subaru has close and open deck.

[SfValley335i]

Originally Posted by Turkishexpress

I thought the n54 was a semi open deck like the subies... hmmm... We got iron sleeves though

Iron sleeves






Crap

[scollins]

Well, we don't really know under what conditions these blocks have failed. But since the N54 block is open, I'm guessing it will never get to the same power levels that the Supra blocks were capable off, even with upgraded internals. Not that I ever thought of going there anyway......

[jpsimon]

Looking at this one open block out of context doesn't really tell us anything

Originally Posted by Ninji

What a crock of shit. That "information" is a bunch of nonsense and there is no way to relate block design to how much boost pressure an engine can handle.

Detonation is what cracks sleeve, esp. lean detonation which smashes the thrust surface of the pistons into the cylinder sidewalls. As long as you aren't detonating, you can run 40+psi of boost on an open deck motor with thick enough sleeves.

And if you have a problem with cylinder walk blowing head gaskets, the standard fix is to upgrade the head bolts to high strength aftermarkets (e.g. ARP studs) to increase the clamping force between the head and the sleeves.

Originally Posted by scollins

Well, we don't really know under what conditions these blocks have failed. But since the N54 block is open, I'm guessing it will never get to the same power levels that the Supra blocks were capable off, even with upgraded internals. Not that I ever thought of going there anyway......

[BavarianBullet]

Originally Posted by SfValley335i

Iron sleeves



Crap

Thanks for starting this as a dedicated thread as it's certainly good to get it out in the open and get people talking about it.

My point in the original thread was that when some feisty individuals do eventually want to surpass "the magic number" (where parts will start to break or need upgrading en masse) of say, 500WHP, they're going to probably need to rebuild/change so many other parts of the engine that it won't be that out of the question to sleeve the block properly to handle serious HP.

I had hoped someone familiar with open-deck blocks (from subie world, etc) might comment on their or others experiences with blown parts and what was/is done to avoid issues caused by an open deck block. Here is an example of what I was looking for: http://forums.nasioc.com/forums/show....php?t=1630198

There are some interesting links from the above URL. One is to a company that literally takes used open-deck subie blocks and, with some fancy machining and custom sleeves, puts in new iron sleeves with material at the top that is pressed in so as to make the block a (semi)closed deck design.

IOW, it won't be cheap to get 600HP out of an N54 and the block will be just one more challenge- one that can be overcome IMO.

BB

[scheherazade]

Originally Posted by Ninji

Detonation is what cracks sleeve, esp. lean detonation which smashes the thrust surface of the pistons into the cylinder sidewalls. As long as you aren't detonating, you can run 40+psi of boost on an open deck motor with thick enough sleeves.

Closed vs semi vs open can be the difference between making 1200whp or 600 whp or 400 whp.
Regardless, it's usually not an issue until you're way up there.
(the numbers are not scientific, just examples of whp's I've seen on some cars with each deck type.)

Originally Posted by BavarianBullet

I had hoped someone familiar with open-deck blocks (from subie world, etc) might comment on their or others experiences with blown parts and what was/is done to avoid issues caused by an open deck block. Here is an example of what I was looking for: http://forums.nasioc.com/forums/show....php?t=1630198
BB

Quotes from another forum (http://forums.dcawd.com) :

"
That really shouldn't be a concern. The EJ205 (the engine in the USDM 02-05 WRX) was an open deck design and there are many, many people who get very good power out of them (300+ whp) and they continue to run for hundreds of thousands of miles. Unless your thinking 400+whp the open deck, closed deck argument just doesn't matter that much.
"

"
Take a look around NASIOC in the 2.0 turbo charged section and you will find all sorts of deep forums of folks who have gone very far with the open deck engine. And when a failure does occur, it is almost always ringlands, not a cylinder wall failure. That said, the current line of WRX/LGT/STI all run semi closed decks, and they have been proven to be very stout even at 450+ whp.
"

"
Of note, the only closed deck that Subaru has ever made was the 22t, aka, the JDM Legacy 2.2L turbo motor.
"

-scheherazade

[scheherazade]

Originally Posted by SfValley335i

Iron sleeves






Crap

SfValley335i << Do you have the story/circumstance behind this pictured failure?

-scheherazade

[SfValley335i]

Originally Posted by scheherazade

SfValley335i << Do you have the story/circumstance behind this pictured failure?

-scheherazade

Negative

[ar design]

*sigh*.

LOL