Just trying to back up what I once over heard.

Apparently with the 14mm conversion due to lack of material around the holes once drilled it can cause the head to deform when tightened appropriately?

I've searched and searched but never found the actually yes or no to the facts.

I've seen some big power ones actually go back to d25 heads due to high flow capacity but struggling for info on w25 heads

Thanks in advance

 

My closed deck 2.5 with duel Avcs and 14mm head studs seems fine @ 500+bhp

I wouldn't build another engine without using 14-14 head studs

 

Domino46 who built your engine please?

What I heard was it deforms slightly the cam journal (between cap and head).
It's been in my mind for a while obviously the 2.5 needs building to be "reliable with power"

I'm chasing similar 500 but if it's 550 then brilliant but don't wish to be capped. I've looked at risk 14/12 kit but no reviews really and cosworth/arp 625's 11mm but again limited info.

 

The W25 heads are a problem with distortion when using 14mm studs, if you pull them down to the specified torque/stretch of the stud manufacturer in most cases the cams will not turn in the casings, you will have to back off the torque on the stud.


They are also very restrictive on the exhaust ports for big power, with the added bonus of very thin port walls so porting is very hit & miss, & the l/h head casting does suffer from cracking into the water jacket under the valve spring seat.

 

So it's very true coming from yourself.

Re the water jacket is that in standard form or once modified? Is there anyway around it? What do you recommend to achieve power goal? I think the closed deck is a cert then the liners are as safe as can be.

 

The water jacket has been on 11mm heads, seen 4 that's cracked in that area, only l/h head, & you will not find the crack on pressure test unless the head is pulled down onto a block & tested.
Closed deck insert won't stop split liners, as they stay the same thickness whatever you fit.
I don't recommend anything on 2.5's to hit & miss.

 

Andy kindon built my 2.5 and has been running fine for the last few years was 400 for a couple of years and is now 531 to be exact but is rated to around 600 from what Andy has said but I'm happy with the power where it is ,, mine is very reliable as iv driven it all over the country and it has been used as my daily at one point and has even done a hill climb or two lol , heads are still standard with no porting or anything

 

There is a company over in the states (IAG) they have had some amazing results with cdb the plate inserted is different thicknesses. I know the liner dimensions doesn't change but isn't it about the support and load spreading that helps keep in tact? Do you only suggest 2.35 then, you have some very good results with 2.5 so am surprised I read throw bob Rawls build and that gave a lot of inspiration for 2.5.

Is it worth welding effect are to try and support or a case of build run and if it craps itself bin and replace?

That's a good result on std heads. Does your car use much oil or water at all? I suppose std casts are all hit and miss good and bad that maybe the why I've heard some horror stories some amazing results

 

Bob,s build was one of 3 for Litchfields, they were brand new blocks, all were cdb, 14mm converted, sent for cryo freezing stress relieving, with the blocks being fully torqued up, with main bearings fitted, 2 off the blocks required line honing afterwards as the main bearing tunnel went out of square, this process is not always done by others, as they use used blocks, but I recommend the cryo process, the blocks were final honed to pistons after the treatment, in all a costly exercise.


As for liner thickness this often hit & miss as the machining when manufactured is not always central in the liner due to casting core shift & alignment of the casting in initial machining, so you end up with a few blocks with offset liner thickness, which when already thin, is compounded even more, these blocks will & do fail easily, there is enough evidence of this over the years.

 

What sort of cost is cyro freezing?
There are a few ej22t's popping up again if cost of cyro exceeds then obviously 22 maybe the route.
Re rods and Pistons they would be replaced either way and slight extra cost of 22 matching which out weighs the other is key I suppose

Regarding Heads Paul anything can be done or is it a see what happens if it fails replace? Would updated springs hinder the failure? (More load on the seat??

 

Doesn't use any oil or water , also mapped by Bob

 

Cryo freezing a single block I don't know, when I have stuff done its in bulk, inc pistons,rods, & cranks.


For a road based unit the 2.5 is very good deliverer of torque & effortless performance, its as a serious competition unit it fails on, especially on the racetrack where its pounded round lap after lap.


EJ22 blocks are getting harder to source, especially ones that are any good & not full of porosity.


The w25 heads crack from the central gallery plug, to under the spring platform above cylinder 4, springs have no bearing on the failure, its a very thin casting full of avc's oil drillings.

 

not just in the states @Jampot

https://www.facebook.com/ASPerformanceUK/photos/?tab=album&album_id=940150562663346
we have undertaken hundreds of CDB conversions on 2.5's (and continue to do so) as well as various other Subaru blocks and myriad other manufacturers.......

Paul (@MOTOR S GT) has some valid points but the insert does definately assist in maintaining the liners integrity although ultimately there are specific block casting issues.......

 

Hi Alyn I sent a few emails re headers up pipe and coating them but you never come back to me.

What is the thickness of your inserts with cdb conversion?

 

sorry no idea who you may be but in general we dont ignore mails or correspondence so either its simply been missed or we haven't received your enquiry for some reason
we deal with hundreds of enquiries by phone & email daily and once its passed over its easy to miss............just to add there is no luxury of any "admin" and the mails simply get answered in between whatever woarkload is required that day

we dont at this point offer any form of coating service for headers / up-pipes but your welcome to purchase and arrange yourself

the CDB insert is slightly thicker than the OE Subaru block at approx 12mm