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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)
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
Location: @Junc 12, M40 Warwicksh; 01926 614522 CV33 9PL -Use 9GX for Satnav. South Mids Alcatek ECu dealer
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.
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
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?
High pressure die casting produces a high integrety casting, thinner wall sections can be designed and a general lack of porosity.
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.
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)
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 ;-))