Best spec to bulid a 2.5 engine to
14 March 2011, 06:32 PM
#1
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Best spec to bulid a 2.5 engine to
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 
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 lolAlso 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
Last edited by Scott@ScoobySpares; 14 March 2011 at 06:51 PM.
14 March 2011, 06:40 PM
#2
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
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
14 March 2011, 06:48 PM
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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
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
14 March 2011, 06:54 PM
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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!
14 March 2011, 06:59 PM
#5
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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
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
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14 March 2011, 07:38 PM
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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 
14 March 2011, 07:41 PM
#10
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
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 lolAlso 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 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
Last edited by dazdavies; 14 March 2011 at 07:43 PM.
14 March 2011, 08:30 PM
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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?
14 March 2011, 08:31 PM
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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!
Think I'm also going to be fitting an oil cooler before the Brands track day!
15 March 2011, 12:30 AM
#27
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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 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.
15 March 2011, 12:44 AM
#28
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.
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.
15 March 2011, 08:49 AM
#29
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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.
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.
15 March 2011, 11:15 AM
#30
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.
When mine's back together it going to get pushed beyond the 600bhp it was at before.