As stated in an earlier post i am looking a building a 2.5 or 2.0 engine looking for 450/450 power wise am siding with the 2.5 to be honest at the moment. Below is the spec i want to build the engine to

2.5 semi-closed deck block with a new nitrated crank, ACL race bearings, forged rods (manley), forged pistons (i have a set of used but perfect CP pistons here any others recommended though), 14mm headstud conversion, cometic head gaskets (not to sure on size yet suggestions welcome), 12mm uprated oil pump, with a set of STI 3/4 heads bolted to it (most likely ported/polished)

Any other things i need to do to get a good quality reliable engine??? may of missed a few things lol

Also wouldn't mind if it was a bit quieter than normal forged engines anyway of doing this i know mahle do a new piston that has very little rattle apparently

 

Mine is similar: Standard 2.5 litre STi crank. Manley rods and pistons, ACL Race bearings.

it has the uprated oil pump, but uses standard headbolts, so limiting the boost to 1.5 bar, and uses a Cometic head gasket.

But it's just standard UK V4 heads, with a larger turbo, larger 740cc injectors, tubular headers and matched up-pipe, and FMIC, and produces around the 400 bhp/400ft lbs mark and is MENTAL! In the DRY in 4th, it will spin all 4 wheels!

However, DO budget for a 6-speed box or similar if you haven't already. That sort of torque will strip 2nd and 4th straight out

 

have a 6 speed sorted lol,, what turbo are you running pal

 

Mines similar, but with Williams Rods, Weisco Pistons and the main difference being v8 AVCS heads. Running with Syvecs and about to have a 6 speed fitted!

 

If your car spins all four wheels in the dry at 400bhp, can I suggest you get your chassis sorted out then.

 

LOL thats what i thought, all 4 wheels? come on. Im running 470/500 tourqes in a classic and get reasonable grip in 2nd.

Clarky

 

Scot ring mark at laterall he will sort you out,

Clarky.

 

K1 rods & Cosworth hi compression pistons in mine,only a slight rattle when cold

 

12mm oil pump not required for that engine\head confirguration...10mm with the modified relief valve will be fine. Catch can is a must to sort the breathers out too

 

Forget the 14mm stud conversion, its pure overkill for 450bhp. Stick with the Cosworth 11mm head studs they'll be plenty good enough and will save you th £300 machining costs.

Cosworth headgaskets are a must far better than the cometic ones especially for the 2.5 due to the stopper layer.

Forget the 12mm oil pump and just go with a modified 10mm one. The 12mm believe it or not could be detrimental to a non AVCS engine.

Pistons, Cosworth or Wiseco due to them having offset pins this will quite them down. The Mahle ones are ok as you can run a smaller clearance on them.

If you're going to do track work then budget for an oil cooler as the 2.5's do run hotter.

Finally if you think you'll ever go for more than 450 then I'd strongly suggest getting the block pinned as I have with mine. It's coped with 600bhp and 585ft/lbs and on recent inspection the bores are still in very good nick.

Here's a picture of my pinned block


Hope that helps

Daz

 

should have added catch can with return to sump and an oil cooler but Daz has beten me to that

 

Can you explain the pinned block, Daz?

 

The dowels support the bores, so really a compromise between cdb and odb...you can see the where the dowels are placed between the bores and water jacket...don't think I missed anything did I Daz?

 

I'm running the Grimmspeed AOS on the crank and head breathers - about to put a catch can in to intercept the Crank to PCV line to cover all bases.

Think I'm also going to be fitting an oil cooler before the Brands track day!

 

Yup, Blocks that are unpinned are known to split where the recess for the case bolts are. The pins stop the bores from flexing and thus splitting down this recess. It's very effective.

 

May have a closed deck 2.5 block for sale, it has been converted for 14mm studs, can be supplied with 101mm wiseco pistons and also has been converted to have 6 locating dowels for the heads to improve head gasket sealing.

 

You not throwing the towel in are you Banny?

 

Defo not trails would miss it too much, this is from an old build that I was keeping as a spare

 

Glad to hear it...read your thread on 22b this morning hence the comment

 

101mm pistons? That leaves the liners pretty thin! Not sure that i'd risk that even with the pins.

 

Its a linered block Daz

 

ahh, that's a whole new ball game mate

 

Got Pat on the case, going to nip down to see him on saturday and hoping for good news but Im too addicted to the hassle to give it up

 

know the feeling

 

Watch for liner dropage in that case lol

 

Ran 620bhp for 6k miles before car was taken off the road and stripped to make way for another project

 

6k is nothing imo!

I noticed at bthe weekend that Tracktive have a scrapped linered block (don't know who did the liner's) from a customer, as one of the liners split most of the way down and the top hat had gone on the other liner (all in one block half). I didn't look a pretty sight and is far from uncommon on these linered blocks. That too was running circa 600bhp.

I'm not aware of any method being truly reliable (block integrity) at this sort of power level, when we are referring to a 2.5. I would need to know that a solution would take 550+ of hard abuse for 20-30,000 miles without crapping itself (block wise) before I would be convinced.... and on more than the odd engine.

My old OE block did (and still counting) over 16k miles without any integrity issues at over 500bhp, used hard, but I wouldn't suggest that is the way to go either.

 

I'll happily demonstrate when mine's back together

My failure was top end related due to an engineering **** up lol.

The company concerned have held their hands up and have paid for the parts for the rebuild. It'll be up and running again soon and shall be doing many a quarter mile and track day.

 

Daz,
Wasn't referring to your recent "issues" but I suspect you understand where I am coming from, with regards to methods proving themselves. I think we need to see a few more.

 

Totally agree Shaun. I didnt think you were refering to me. Whilst linering would be the best solution if it was a certainty that the liners wouldnt drop I honestly think pinning is the best option for a SC EJ257 Block.

When mine's back together it going to get pushed beyond the 600bhp it was at before.