joe joe88

iTrader: (2)

I have finaly stripped down the front end of my 1998 classic and have dominated a store room at work to use as a workshop, for breaking down and re-building the engine with forged internals.

http://i557.photobucket.com/albums/s...8/DSC03086.jpg
http://i557.photobucket.com/albums/s...8/DSC03088.jpg
http://i557.photobucket.com/albums/s...8/DSC03090.jpg
http://i557.photobucket.com/albums/s...8/DSC03091.jpg

First things first i need to get the engine out, so if anyones got any tips or guides, they would be appreciated very much. I have re-built engines before, just not japanese.

joz8968

iTrader: (13)

The following makes for a great read, and should be exactly what you're looking for :-

https://www.scoobynet.com/projects-4...e-rebuild.html

joe joe88

iTrader: (2)

Nice one mate thanks alot.

Anyone else??

How much should i be looking to spend on uprated internals?? I dont want to go too mad but the engine has 86,000 miles on the clock and i want to run it over 350BHP (with supporting mods/turbo, injectors etc) , so obviously the re-build is a must!!!

joz8968

iTrader: (13)

Coincidentally, I'm currently getting my engine rebuilt by Zen - see here for spec:-

https://www.scoobynet.com/general-te...ke-easily.html

Paul, the boss, says this will EASILY handle 350bhp, but he said that he wouldn't like to run much more than that on it. So you'll need much stronger internals than STi 3/4 forged pistons and STi 9 rods.

I think Carillo H-section rods are extremely strong and possibly Mahle pistons? - I'm no expert, ask around. A MLS head gasket set is a must and so are ACL 'Heavy Duty' or, even better, 'Race Series' big-end and main bearings. it also helps if the block is a fully closed deck block (CDB), but even a open deck block (ODB) is apparently good for 400-450bhp (maybe more?).

I'd also chuck on a new water pump and Zero Sports 71deg stat (opens 7deg earlier than the OEM one). Also, an uprated oil pump (RCM, API or Zen do them), where the relief valve has been modified, would make absolute sense. An unmodified valve can stick - not good...

joe joe88

iTrader: (2)

cool, that sounds reasonable. How much are closed beck blocks and what are there advantages??

joz8968

iTrader: (13)

ODB (open deck block)
Block has metal die-cast 'out' i.e. free air space around all the cylinders' height

CDB (closed deck block)
This metal is present all the way up to the cyl head face, from the bottom to top i.e. no air space around cylinders' height

SCDB (semi-closed deck block)
Cross between the two - metal die-cast 'out' halfway down the cylinders' height


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


Find out if your car is fitted with a CDB first! (it'll have the ODB, at the very least).

If it is an ODB but you want to upgrade to the stronger CDB, then ask around the specialists first - you never know what they've got lying around their workshops! Try Zen first, then API. RCM will be far too costly, I reckon.

joe joe88

iTrader: (2)

Thanks that link you send was great as i now understand and got to visually see the differences.

I'll try and get one of those peoples attention on here to see if they can give me advice on what block to use and how much i should expect to pay.

rossibeater

there's one on ebay at the moment
Subaru Impreza STi Closed Deck Block 1994 on eBay, also, Subaru, Car Parts, Cars, Parts Vehicles (end time 01-Mar-09 11:38:51 GMT)

joe joe88

iTrader: (2)

although i appreciate that link, since im doing a re-build isnt it just better and safer to buy new blocks as long as i can afford them??

joz8968

iTrader: (13)

A new CDB won't be cheap. I have no idea what they cost new - but I bet it's north of a £grand!

I'd ask around the specialists to see if they have some spare, but perfectly good, 2nd hand ones. All it'll need is a good hone (if that's acceptable practice on these blocks?).

joe joe88

iTrader: (2)

what does that mean ('to hone a cylinder')????

joz8968

iTrader: (13)

It's a straight-forward machining process that uses an eccentric, mild 'cutting' tool that goes up and down in the cylinder bore to remove the tiniest layer of metal. It leaves a diamond effect 'pattern' inside the cylinder walls. I think the idea is to totally true-up the cylinders i.e. to make good perfectly circular bores. It also creates a nice keyed surface for the piston rings to properly bed in against, for the optimum gas-tight seal. This prevents combustion gas 'blow-by', and allows maximum compresiion ratio for optimum performace...

STI_Baly

iTrader: (23)

POssibly try Lateral or Roger Clarke Motorsport. Closed deck blocks are no longer manufactured AFAIK but these guys have either had them re-manufactured or used old decent blocks which have been extensively cleaned and checked for spec.

scoobjam74

iTrader: (11)

the honing prosess puts minute scratches on the surface of the cylinder walls so then the oil fills them up so when running the rings and piston are running on the oil not the metal as if they where running in mirror finished bores the rings would be scraping the oil off as they moved hope this helps

joz8968

iTrader: (13)

Thanks for the science scoobjam - makes sense and is interesting to boot.

joe joe88

iTrader: (2)

yeah nice one mate thanks. i suppose this results in less friction/wear on the piston rings and cylinder bore??