Identifying closed deck blocks
 

Question , Is there way of identifying a closed deck block from open deck block.
Thanks
Guy

The CDBs have a checked pattern on them, search, there's been photos posted on here in the past.

Mo beat me to it, there is a checked pattern beside #2 and #3 piston on the block.

Russell

matches up to the checking on the heads doesnt it?

Cheers for the help guys

Whats the difference between open and closed deck blocks?

Yeah whats the differance?

Obvious will the heads off!
The closed block has cast aluminium around the head gasket face with 'small' holes cast to allow the water passages to the heads.
The open block had almost the entire top od the block where the gaskets go open to water passage, hence the two phrases.

The CDB is the strongest due to the extra rigidity but only for high output engines.
My Sti v3 is open deck block and can run 407 bhp @ 1.41 bar.(all day long)
Graham.

Is there an easy way to identify the type i have?

I followed the hatching marks method above before API removed the heads to do the gaskets and i thought I had a CDB, but it is an open deck.
My car is an Sti v3 facelift.
Graham

a cdb has oil squirters in the bottom of the liner these are the best blocks for strengthopen deck blocks are fine to as harvey did over 500 bhp no problem on hissti6 wagon i would go for a semi closed deck of a new age car for all round sterngth, cooling reliability

The ONLY certain way to tell is to take a head off, but we have always found that the cross hatching/chequer finish on the hub above the modine / oil filter is the only sure way to tell from the outside.

We do see an awful lot of blocks here certainly over 1000 in 6 years oiur data is hard earned.

David APi Engines / APi Impreza
www.apiengines.com

There is a problem with the semi-closed deck if it is used as an O/E short engine, in that the bore clearance is very tight so a piston can be easily nipped. Not an issue if the semi closed deck block is rebored for after market forged pistons however.

From what I initially posted. Looking at a copy of an SAE document below,
it seems to say closed deck block were cast using a medium pressure diecast with sand core, rather than High pressure diecast they used for open deck. Someone on another forum was saying the sand cast process had a duller finish. Though how you would tell that now on a 10 year old block I'm not sure
http://surrealmirage.com/subaru/files/SAE_boxer.pdf

High pressure die casting produces a high integrety casting, thinner wall sections can be designed and a general lack of porosity.

For 'normal' engine mods I think the open block is every bit as good as the CDB, but over 400/450 maybe the CDB wins?
This is for classic engines.
Is the 2006 Impreza block semi CDB like the 2.5 is?

Graham.

I would guess so G, hasnt the sti block been semi since V.7?

Must admit I don't know, but seeing that Roger Clarke can wind 600+ bhp and torque from the modern 2 liter something must be good!
Graham.

The 2 litre RCMS engine in Halldor's car is substantially different from the factory engine. Over 700 bhp from memory.
I ran the previous engine, open deck, to between 535 and 585 bhp, subject to fuel. The current engine is a 2.2 litre closed deck block sleeved down to 2 litres and we expect to take it over 600 bhp. No NOS etc.

I think this is a silly question...
How easy are (knackered or otherwise) 2.2 Legacy engines/blocks to come by?
From what i gather, there are no new ones left (word from the USA engine site, name escapes me now), but are there many in UK now?
How expensive are cylinder sleeves etc?

Back to the turkey (not my Impreza!)

Graham.

What block is the V7 sti >> (I have one for sale )

Alan,
I was sure the v.7 was semi closed, could be very wrong mind and the only way to see for sure is to lift the heads

Andy

Hello

So anyone can tell me wich Subarus had definatly Closed deck blocks?
Subaru Spare part Number?
There must be new closed deck blocks availible because a USA Tuner uses this Blocks for his motors!

cheers

Markus

So this would be a closed deck block then :)

http://homepage.ntlworld.com/mantasp...ip/pistons.jpg

As a additional question is anybody after a closed deck block and how much is one worth?

Yes i have one spare in the garage that i will sell :thumb:

Picking up on what Graham said, out of sheer curiosity I took an open deck and closed deck block into work a few years ago for a look see in one of our Microfocus X-ray machines (225kV, 225W, 5um focal spot) I found that the grain structure in the CDB was very open compared to the open deck, the structure of which was clearly better. However the CDB compensated by being thicker walled.

Hello

@tim this should not be a Problem because i will use sleeves and these are strong enough. Just need the closed deck block so the sleeves dont move.

anyone a CDB in the Garage for sale?

cheers

Markus

Markus, don't get me wrong, I'd use a closed deck block in a flash for a higher power build for exactly the reasons you are. Much as I feel the production quality of the open deck block is higher, it's still an open deck which is a pain if you want to reliably run at high boost pressures (ie greater than 1.5 bar) IMHO

I'd be curious to see what can be done with a semi closed deck block, but know that the EJ257 block isn't up to the job in it's standard form (the liners are far too thin)

Hello

A friend of me have build the same 2,5l block like me and used 1,75bar of boost on that and the OE liner breaks!
i now try to build a block with a closed deck block and darton sleeves that can handle a "little" bit more than 2 bar of boost ;-))


markus

APi has a supply of perfect used CDB in 2.0 form if it;s any help to anyone.

David APi Engines / APi impreza
www.apiengines.com

david,

can you bore and sleeve them to 2.2? , rough price?

or maybe even reliner them to 2.5? I have a CDB block now sitting in the garage waiting for the next phase of the project ;)

I have been wondering for a while if it would be possibel to reliner a CDB to EJ257 bore to make a closed 2.5L.

David, any input?

Dan.