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pee vee
14-02-2006, 18:43 18
hi
just wondering what the basic make up of an imprezza engine is?

ie. pistons; are they forged/cast/squeezecast?
Rods, steel crank etc?

Also, are they Quad cam? as they have 2 heads.
or is it single OHC on each head?

thanks!
:confused: :biggrin: :biggrin:
Neil G
14-02-2006, 18:47 09
Quad cam mate with two heads lying flat (bitch to do spark pugs)!

Cast internals in std WRX hence boost limits when upgrading....IIRC STI has forged internals and closed deck block.....definately the one to go for.

Not the most bulletproof engines around....problems made worse with imports and low grade fuel etc.
pee vee
14-02-2006, 18:55 50
ah right!
yeah i have heard the problems with the lower grade fuel over
this country.
thanks!

Also, what are the power/boost limits of a standard (lower then STI) spec engine?)
Broxi
14-02-2006, 18:59 22
Neil how do you tell the difference between a WRX block & a Closed Deck Block?
Neil G
14-02-2006, 19:00 47
Big problem with Imprezas mate

I had a knock meter on my old WRX which did make me feel a little safer about the fuelling issues....I even ran it on SU 97 without any det issues.

IIRC the std boost pressure on the WRX import is around 0.9bar....I'm not sure what the exact limit you can take them to boost wise is but over this it has a pretty detrimental effect on the pistons!
Neil G
14-02-2006, 19:06 33
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.

Also..found on SN and of some use Derek

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.
pee vee
14-02-2006, 19:11 59
thanks neil

as a side have you ever seen what happens to pistons when
suffering det?
if its bad, piston rings can go in seconds,
and the rest of the piston can look like this!
http://www.hastingsmfg.com/Service%20Tips/images/p26.gif
Olly P
14-02-2006, 19:24 31
The Daddy has a better pic than that.
Olly P
14-02-2006, 19:28 47
Incidently, early cars with the TD05 ran about 0.7bar and the later TD04 models ran 0.9bar.
WRX's have been found with CDB and forged pistons, and sti's have been found with cast pistons and ODB's.
Apparently Subaru used whatever they had at the time.:eek:
Neil G
14-02-2006, 20:03 23
Cheers Olly....I thought the TD05 was 0.9 bar!

Phil...that's a good pic...really, really bad damage:eek:

What car did that come from?
bob
14-02-2006, 21:16 22
As olly say's strip any Scoob and find mishmash of parts....:hysterical: :hysterical: Eary STI's had close deck blocks. STI3 has closed deck but after that most were oped deck.

Open Deck:

http://www.bob.szhosting.net/images/open.jpg

Closed Deck:

http://www.bob.szhosting.net/images/closed.jpg


These are 2.5 engines but the same princible.

Lots of 2.5 engines coming from the good old USA has semi closed decks. So as not to restrict the waterways to much but still give strength..
pee vee
14-02-2006, 21:54 15
ah i see;
so the open decked engine is ALMOST a linerd type thing
(bit like renault 5 engines and pug mi16s)

very interesting, thanks bob!
The Daddy
14-02-2006, 22:18 06
look for the 7 in the engine number......this denotes closed deck apperntly...ie ej20/7
The Daddy
14-02-2006, 22:21 22
this is piston damage....

70shot of nos at 1.4 bar in 4th at just under 120mph.....

http://i12.photobucket.com/albums/a220/jools964/****ed3.jpg

http://i12.photobucket.com/albums/a220/jools964/****ed2.jpg

http://i12.photobucket.com/albums/a220/jools964/****ed.jpg

:giggle:
Neil G
15-02-2006, 09:52 44
Blimey...That is one f**ked piston Barry
Agent Smith
15-02-2006, 10:05 44
Is there a semi-closed deck aswell.
Neil G
15-02-2006, 13:57 46
Think there is mate

You can really see from Bobs pics why the closed deck is more rigid/stronger
Agent Smith
15-02-2006, 14:47 15
Thought so, as I was led to believe the newage STI's have the semi-closed deck blocks.
bob
15-02-2006, 18:51 34
Is there a semi-closed deck aswell.

See comments below my pic's....:wink:
Batfink
26-02-2006, 19:17 23
Interresting read
gavo
09-04-2006, 20:01 14
Well i have just stripped my 93 WRX and found it has got the metal cam pulley's and also it is has a closed deck block.Which by the way is the complete opposite of the WRX engine that i picked up yesterday ie: plastic cam pulleys and an open deck.
SWS Test Account
09-04-2006, 21:13 46
Exactly the same with mine mate took out my old one this weekend and it is a closed deck so gonna rebuild that one with some real tasty internals to replace the new one when it goes bang
gavo
09-04-2006, 21:25 54
yeah im rebuilding my closed deck now,they are stronger and take more boost lou.
pee vee
10-04-2006, 17:10 39
exactly that really.
if you look back at the pics of the open block
they cylinders are literally just that, cylinders with the water jacket
surrounding them..

where as the closed deck has its bores encased, so they are stronger.
and able to withstand more abuse/boost etc :)
Neil G
11-04-2006, 17:52 44
Yep..quite noticably stronger just from looking at the differences between the two.
Agent Smith
11-04-2006, 17:54 11
& semi-closed deck pics anyone?
bob
11-04-2006, 18:32 33
& semi-closed deck pics anyone?

No pic's of semi sorry...:redface: But most 2.5's now come with semi its just the faces have a few plates welded in. Gives a little extra strenght and does not interfear with the waterways helping with the cooling.
Agent Smith
11-04-2006, 18:37 49
so for most the best of both worlds.