Hey chaps

Used the search but didnt manage to find much.

I am looking at planning future power mods for my 01 JDM STI, and it has finally come to the time of getting some knowledge.

so can someone please explain what the following means to me:

Short Block

Long Block

Closed Deck

Open Deck

And what the advantages or disadvantages are, what type is needed if going for big power, etc etc.

Or link me to where i can find the info.

Many thanks to those who reply.

Oh, and once i know what the score is, i will start another thread asking about capacities!

 

A short engine generally consists of an assembled crank, rods, pistons and block halves ready to take all the ancillaries such as oil pump, sump, valve timing gear, cylinder heads and other ancillaries.
A long engine would have cylinder heads on it but you would need to clarify just what else was on it.
A closed deck block was the construction method in some of the early Subarus. It is called a closed deck block because the liners have far more support than with an open deck block for instance and these blocks are favoured by some tuners for big power builds however there are many 500 plus bhp 2 litre Subarus running open deck blocks.
Open deck blocks were the most common block form in Classic Subarus. The cylinder liner has less support than that of the closed deck block.
There is also the semi open deck block and these became available with the New Age cars and have some more cylinder/liner support than the open deck block but not nearly as much as the closed deck.

The theory is that the liners can "walk" in an open deck construction at high power/pressure loading/revs. Chances are you don't need a closed deck block unless you are planning to spend many thousands of pounds to achieve spectacular power outputs.

 

And to illustrate harvey's explaination:-

Google Image Result for http://legacycentral.org/images/members/justin/open_deck.jpg

 

Good replies, been wanting to ask that question for a while now.

 

And for the record, a SCDB (semi-CDB) has the top half of that cavity empty i.e. there's metal present halfway up it. So strength-wise, it's midway between the difference between the ODB and CDB.

 

many thanks for the replies!

So what would the engine in my 2001 Bugeye STI JDM be?

And would it be worth using this, or searching for a rare closed deck block?

I am aiming for 450-500bhp, but super reliable for track day use.

 

From what I've learnt on here, the 'weakest' ODB is still good for upto a reliable 500bhp or so!... Maybe more?

 

A MY01 bug sti will have a semi closed deck block

Banny

 

You don't need anything other than the block you already have to build 500 plus bhp. This business about needing a CDB is very much overplayed.