john banks

What about starting with an STi 7 semi-closed deck block to start with? Roger Clark quoted me about £1000 IIRC.

Is it fair to say that piston and rod failures are most common? (maybe because of det, what is more likely to fail just because of torque?) Not many cranks or head gaskets fail?

What are the real priority hotspots to sort out aside from the pistons and rods?

Is Harvey's block still open deck?

What about wire ringing the block as well as or instead of closing the deck? Am I right in saying that wire ringing mainly assists head gasket integrity?

Is the issue with an open deck block actually making holes in the bores ? Or do they "wiggle"?

What about just changing the pistons to reduce conrod load and keep the rev limit sensible or even reduce it on STi engines?

Lots of questions, lots of opinions I am sure. Keep it rolling, reading with interest.

[Edited by john banks - 1/1/2003 9:03:17 PM]

Pavlo

I already have one pukka closed deck block thanks.

The aim of the exercise is really aimed at, erm *cough* larger blocks...

Closed deck EJ22 block is more like £700 depending on which way you achieve it.

Closed deck EJ25 block is even more, and not something that can be made from a relinered EJ20 closed deck block.

Paul

R19KET

John,

The semi closed STi7 block is supposed to be very strong, it's just much more expensive than the earlier CDB, and not so easy to get hold of.

Mark.

Gez

I thought EJ25 CDB blocks didnt exist???

Gez

Pavlo

It doesn't Gez, that's why they are so expensive. Because to get one, an open deck block has to be welded, and because of the scarcity of people doing it, they are very expensive.

Paul

Andy.F

A guy in the states just sticks a sleeve in the 2.5, brings it down to 2.4 but adds enough strength to the bore to run 35psi boost plus a 200 shot of N2O .....nice

Gez

Sorry to vere off the subject but when an engine rebuild is undrtaken and a block has to be re-linered what does it mean and is it always necessary when re building??? Sorry if i sound daft but im new in the game and trying to do as much research on the subject as possible.

Gez

Pavlo

not daft at all Gez.

The (relatively soft) piston has to run on a hard surface within the cylinder. Tradtionally this has been cast iron, obvious when you think about cast iron blocks that have been used for donkeys years.

With the advent of alumnium blocks, there still needs to be hard surface. There are a number of ways of doing this, including liners made from ductile iron, or cetain steel alloys, held in place either by interferance fit, held in by the head, or have the block cast around them. You can also directly treat the surface of the aluminium (so no liner) either by plating or deposition.

The subaru liners are in place when the block is cast, this ensures very good thermal join, and means a very thin wall liner can be used. To reliner the block you either heat the block and it might drop out (for inteferance fit iners that is) or just bore straight through it. Once done, you then fit a new liner, which will be an inteferance fit, put the block in the oven, the liner in the freezer, and drop/press in place.

In the case of relinering an EJ20 to a 2.2 block (92 to 97mm), it's done because you would otherwise be left with about a 1.5mm wall thickness on the liner, which would distort and not be able to keep itself in place.

For a normal rebuild, you can just bore and hone, up to the top limit of the block, which is +0.5mm (also +0.2mm available giving you to goes).

Paul

Fuzz

To recap then

For the power hungry amongst us,
<joke>
what you need is a 2.5 phase 1 CDB which doesn't exist
</Joke>

Edit to insert : "legacys only", I take it, after a quick scan of API engines web site ????

Ok so the closed deck side of things is what's missing I know.
So where does one source a 2.5 lump, how much of the parts around that 2.5 lump is interchangable with say the 2.0l variant ?
I'm not talking ready closed deck of course (that's something for me to look into, as I'm in the right trade, got the lathe side of things but not an oven )

Andy


[Edited by Fuzz - 1/1/2003 11:05:50 PM]

Trout...

Andy,

if I was building an engine it wouldn't be for Well Lane - want to make sure everything is right

Pavlo,

comment about which engines are CDB was in answer to earlier post and not intended to suggest that all Phase Is were CDBs, more that other way rounds - all CDBs are Phase I But thank you for pointing it out. BTW - I have just remembered - someone posted a pic of a semi-closing done in the UK - he got a welding company to build up the joins - it might give you some guidance. From memory it was early in 2002.

Good luck with your welding - for £250 plus donor block - I would still go with the real thing - but that is my personal view

Fuzz,

You can order a 2.5l semi-closed deck block from Cobb - £1,000 to £1,500 IIRC. You can also get them from Oz, but like all these things they are expensive. The additional bits are probably quite expensive as not much is shared with the 2l.

Of course you could get a 2.5l, run it with 2.0l crank and get a very oversquare high-revving screamer. You would still need rods and pistons - and I suspect the latter are not off the shelf items. But I am sure someone can sort you out

Trout

[Edited by Trout - 1/1/2003 11:17:19 PM]

Pavlo

Mine too really, depending on what you're doing, like I say, an EJ25 block is what i would like to be able to do.

Paul

David_Wallis

anybody got the photos of one being closed?

I believe the one I saw was done welding rods in..

David

Tim W

iTrader: (1)

That looks a tad too closed IMHO I think there need to be some coolant pathways where the two bores meet in the middle...there certainly are on the Cobb EJ25 blocks:



You'll notice that there are only a few small areas of bracing on this block when compared with the stock block:

Fuzz

Tim, Harburing,

Excellent photo's, looks easy


Trout,
Good luck with your welding - for £250 plus donor block - I would still go with the real thing

Not sure what your quoting me there ?? the oven de-stress costs?? machining costs??
How much is a open deck 2.5...from a legacy?? going to set me back (average) ?

Cheers
Andy

P20SPD

iTrader: (1)

Thats the welding costs i think.

Tim W

iTrader: (1)

Cribbed straight from Cobb's website, just to give you an idea

>>>>

http://cobbtuning.com/impreza/engineblock3.html

For high-output Turbocharged or Supercharged use, we offer our Stage 3 Short Block. Extensively tested and proven through many forms of competition, our Stage 3 Turbo Short Block represents the leading edge in high output Subaru engines. With the race winning history of our engines in a wide variety of motorsports, you can be assured that our short block is the result of experience and testing – not fantasy and unproven ideas.

Our Stage 3 Short Blocks utilizes specifically engineered and tested components that have proven themselves under the most stressful of environments. While some steps we take may seem overkill, we do all that we’ve found necessary to ensure our short blocks are the last of your concerns in your quest for ultimate power.

Successfully tested to withstand over 600HP and 2 bar (~30psi) of boost pressure.

Our Stage 3 Short Block features:

EJ25 Phase II Short Block (2.5L Displacement)
Strong Billet 4340 Steel Connecting Rods
Custom 100mm Turbo Forged Aluminum Pistons (8.5:1 CR)
Heavy-Duty Chromoly Piston Pins
Anti-Friction Piston Skirt Coating
Ceramic Piston Crown Coating
Turbo Specific Piston Rings
Modified Crankshaft (79mm Stroke)
Fully-Closed Deck modification
Wire-Ringed Cylinder Deck
Computerized Balance of rotating assembly
Specially Machined Block w/ improved oil and water passages

All Short Blocks are sold with a $1000 Refundable core charge. You have 30 days from the date of purchase to return your original short block to our factory. All short blocks must be in rebuildable condition to receive full refund of core charge.

The term Short Block refers to the cylinder block itself, without cylinder heads, water or oil pumps, or any accessories located outside of the cylinder block.

Price: $4950 + $1000 Core Charge


So now you know how much the short block costs, just add Heads, ancileries and building costs...oh and shipping

ChristianR

iTrader: (1)

Open Deck


Closed Deck

Trout...

Fuzz,

I was quoting Pavlo's welding costs


Tim,

that sounds like an absolute bargain....however I don't think that Cobb are keen on export...still £4,000 for a short engine of that quality is a bargain

Trout

Fuzz

welding costs !!

what welding costs

Andy

Tim W

iTrader: (1)

David, they'll export...but you've still got to pay shipping, block surcharge, tax and VAT...worked it out and it came to nearer 6.5k GBP landed in the UK with all the work still to do But you already knew that

Pavlo

I was hoping £250 would cover the following

Initial block preperation (if used)
Weld area prep (cut back 0.25-0.5mm)
Weld
Stress relieve
Skim decks

So add to that the cost of a new/used block, and the price of a rebore.

The welding costs are quite a small chunk really.

Paul

harbering1

the welding was 100 euro.

Pavlo

Having checked out the properties of the casting alloys suitable for such a block, it's interesting to see that the T5 heat treatment offers 67% of the strength available from full T6 heat treatment, and some that's nearer 90%

What this means, is that the quenching is probably not necessary, which is good, as when held at 520ish degrees for 18 hours, then plunged into water at 30 degrees, distortion can be a problem.

Interestingly, if a fusion weldling process with blocks was used, there wouldn't be a such a change in grain structure, and a precipitation heat treatment should restore most of the original strength.

It's all just hoopla until I've got a few done though.

Paul

hypoluxa

Harbering, I would suggest re-machining your block to replicate the deck of a genuine CDB. They seem to have blocked off 6 of the 14 water ways on yours.?

Regarding 'monster builds' IMHO I wouldn't use your existing short block/crank as a base for an engine build. For the sake of circa £800 you would be throwing away a perfectly good set of pistons/ rods/ gaskets/ seals/ bearings etc. Your car wouldn't need to be off the road for anywhere near as long and you would have a spare 'running' short engine to fall back on just incase the all new improved one goes pearshaped... forgive the pun

Trout...

Mark is correct - the biggest problem with joins is peel stress. A join can be very strong - but if there is a slight flaw in the edge finish will break away easily.

Think of a a piece of paper - with a perfect edge it is quite strong - but put the slightest flaw in the edge and it will tear quite easily. This is the big problem they have when assembling aeroplanes.

Also - the joins should be rounded out - again stronger then having corners - for the same reason.

Trout

harbering1

Mark i dont want to use this short block.
I want a 2.2 or a good good build 2.0 (build by a pro).

the short block is for sale
If you have some 550 cc phase 1 injectors i want to trade
with oem pistons rods and new bearings

Pavlo

550 injectors for phase 1 rails available in a few weeks BTW

Also, adapters to put phase 2 subaru injectors in phase 1 rails

I was thinking about this last night, and think that if full heat treatment is the way to go, that joining the block halfs for the process may well minimise distortion.

So the process would roughly be:

Prep
Weld
Solution heat treat (heat soak and quench)
Cryo stress releive (won't undo initial heat treatment)
Precipitation heat treat (hold at 155'C for 4 hours)
Machine

One thing I would say. that the corners on the welded block above could be dressed to radius them, and this should help.

Paul

Trout...

Paul,

isn't the block heated for the welding to reduce local stress and distortion during the welding process? In your approach it would imply the block is welded ambient and then heat treated.

Trout

Pavlo

Trout,

I was being brief. Yes you would pre-heat the block for welding, but as part of the welding operation as a whole. This is quite normal.

If you solution heat treat after welding, then you will inherently stress releive the part, as it involves heating to over 500'c for an extended period of time. The stress releif after the solution heat treatment is to get rid of the stresses put into the block during the quench operation (but these should be low anyway). Cryo stress releif is best if it works with this alloy (will find out soon) as it doesn't rob any of the properties from the solution treatment.

It's best to wait till after the full heat treatment before machining, as the precipitation treatment will harden the material, and make it much better for machining generally.

I am still not sure of how the cast in liners will affect the (solution stage of) heat treatment of the block, but I should have some answers next week. If it's not possibly, then at least it means the strength will not be down over std.

paul

Trout...

Paul,

since you are reboring anyway - why not remove the liners for the treatments and reinsert afterwards - especially if you are going for one of the specials which you can see on my website

Don't know how to link the pic to here tho'

Trout