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Old 19 Jul 2009, 09:41 PM   #1 (permalink)
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Flat Four

Can anyone with knowledge of the flat four describe what the difference is between closed deck block and open deck block???
And how can you tell the difference without taking the engine apart?

Or am i just talking complete and utter bull s***


I heard that the RA engines are in a completely different league in regards
to strength etc and the better block to go for if you wanted to build a engine

Any advise would be greatly received
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Old 19 Jul 2009, 10:50 PM   #2 (permalink)
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It has to do with the deck surface. This is where your cylinder heads mate up to your block.

An open deck block will have more area around the cylinder where the coolant flows (watter jacket). A closed deck block will have less area around the cylinder for the coolant to flow.

The advantages of a closed deck is that the cylinders will be stiffer, therefore more able to withstand higher cylinder pressures.
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Old 20 Jul 2009, 12:37 AM   #3 (permalink)
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Re: Flat Four

Legacy Central - Open vs Closed deck As Pete said and heres pics
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Old 20 Jul 2009, 01:36 AM   #4 (permalink)
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Re: Flat Four

Core blimey you two are legends in your own right
Thanking you
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Old 20 Jul 2009, 01:46 AM   #5 (permalink)
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Re: Flat Four

Is there anyway to tell from the o/s of the block which one you have?
i.e my 93 WRX?

I posted a while back bout transplanting a 2.5 engine, but upon speaking to a few tuners they reckon the 2.5 lump isn't all that and better of sourcing a RA block/closed deck block? was it just the RA that had this type of block? or other models and if so what years of production?
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Old 20 Jul 2009, 02:03 AM   #6 (permalink)
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Re: Flat Four

JDM Subaru Impreza WRX STi


1993 Subaru Impreza WRX WRX description


Subaru Impreza WRX STI - Wikipedia, the free encyclopedia Might tell you more
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Old 20 Jul 2009, 02:23 AM   #7 (permalink)
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Re: Flat Four

Cheers Darren,
you guys are a wealth of knowledge.........
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Old 20 Jul 2009, 12:02 PM   #8 (permalink)
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Re: Flat Four

closed deck blocks normaly have cross hatching on the external casing, but like all things scoob, not always the case
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Old 20 Jul 2009, 08:12 PM   #9 (permalink)
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Re: Flat Four

Tidgy thanks for the advise will have a look on mine
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