Ok im saving

 

I think the choice comes down to the intended use of the car. Do you need to run over 450bhp? how and what do you want to use the car for? Every day use, occasional tack day, competing etc. it's pounds to return of power the cost between forging a 2.5 as stated under 3k or a fully built ej22 with the correct head work is in my book (after a few quotes here) its night and day and unless you have money to burn or never get it back then unless competing all you're left with is forum and pub talk. In a similar boat mate, heart would love a ej22 but head and wallet says stick with the 2.5.

 

I will never track or do stuff like that, I'm a traveling kinda guy, but just want that rocket from the lights feeling I get now but more so.

BUT on a standard work run, not effect the fuel consumption from what I have now. If I boot if diff matter and acceptable. Where's the cutoff point for that scenario, soon as you update injectors or larger the turbo does it start dropping..

I'm sure the cosworth had a better fuel return that the new sti, only slight but better anyone know why? And that was 400

 

Simple forged build, decat pipe will see 370-380 bhp and over 400lb of torque. For a rough estimate 3500 quid. Run it get bored then bolt on the turbo and injectors (ish) a map tweak and 450bhp+ and I would imagine same if not more of torque, happy days done i two stages so not a huge layout in one hit

Obviously it's not just as simple as that but you get the idea, would imagine the clutch would need doing on the second stage so may as well do the flywheel at the same time, if not do it when the block is out as I'm sure a majority of place would pop an uprated one back in instead of the standard one for no charge.

If your not tracking it the I would assume most would say there's no need for baffled sumps and oils coolers although a nice idea for safety I would imagine it's over kill for your intended use.

Soo many options, so many routes to take I would suggest think long and hard, speak to a few tuners and work out who you feel comfortable with and then seek their opinions. Think again then decide on with option, setup and budget best suits your needs but the 2.5 is a lovely engine for everyday road use as the low down grunt just makes everything so lazy.

 

Sweepstake anyone?

 

Two very well respected engine builders with differing opinions on what is best. Think that's allowed. Most on here would be more than happy to trust there pride and joy with either IMO.

Pity Subaru didn't have there input with the 2.5 engine. Might have prevented this very long thread.

 

I dare say you're right!
We had the opportunity a number of years ago to investigate the issues with the Hatch set up. It became obvious to me that there were several departments within Subaru that weren't actually talking to each other, at least not to the extent of listening.
Keeping it simple, the engine department wanted a particular piston, bearing in mind the brief they'd set themselves. Those responsible for mapping had their brief. The two are mutually exclusive. If they'd used a forged piston, the particular qualities they sought might not be met. If the mapping people hadn't run such an aggressive profile, the emission figures wouldn't have made the grade. It's ok for us to fit forged pistons and map it how we like. I bet some in the design dept. over there had sleepless nights.
Basically, there's nothing wrong with it, it just needs fixing, that's all.

Removing 5 thou from the bore will NOT create a problem that wasn't already there. Strewth mate, I could take that much off it with my c**k...

 

98mm wide c**k ?? wow, the ladies would be pleased ... or worried ;o

 

I'd come to the same conclusion about the map they use. What you say about the pistons would seem spot on because most people are going to use the cars as daily drivers not occasional track days!

Taking a slightly different direction for a moment, I reckon that this is the reason the STi is being pulled from this market as they don't believe that they can offer a reliable engine that meets all the emissions criteria. It would appear that they pushed the 2.5 too hard just to keep the emissions terrible in the first place! Maybe this rumoured 1.6 STi in 2014 may change my thinking if it has low emissions but I suspect it won't.

I suspect the 2.5 Imprezas will become very rare cars in the years to come if expensive forged internals and remapping is the only way to prevent an inevitable engine failure.

I did wonder a few months ago looking at some of the tumbling emissions, improving MPGs and increasing performances whether the aggressive maps used by other manufacturers will see a big increase in spectacular engine failures as there must be some very lean running engines hammering up and down our roads...

 

interesting school of thought, off the topic of the hatches i know but, i work for ford and 'we' make a 1 litre ecoboost engine as available in the new focus' etc. having driven it, i was surprised at the performance. its a 1 litre turbo but it drives like a 1.6 and revs amazingly. i was very impressed that a little 1 litre could do that in a car of that size. will be interesting to see how long a small engine being worked hard lasts.

 

I would say it's on topic to be honest, what we believe to be the problem on the 2.5s could quite easily be a problem elsewhere (or not due to specific aspects of design) and therefore be entirely relevant to the causes of our engine failures. Apologies if people think this is too much a digression.

The ecoboost seems to be a masterpiece but I guess even with incredibly strong head gaskets the engine would be prone to the same issues as our 2.5s if it regularly runs very lean to keep up with the competition. Maybe smaller pistons and displacement would minimise vibration and it isn't prone to failure? I'm not an engine builder maybe someone else knows a lot more than the keen but probably misguided layman's thoughts that I have?

I was more thinking about some of the performance engines such as my mate's Audi. It's a 1.8 turbo petrol but the emissions and power combined with fuel economy just seem too far fetched to me. At the other end of the scale, Porsche 911s have tumbling economy and emission figures also and I believe most of them run cast pistons too... and our 997.1 ran lean and had engine problems with ****ty emissions and fuel economy back in 2010!

 

It's true Porsche engines fail ( quite common )
& also a Boxer variant

 

thanks!
an ignorant question: whats an open and closed deck?

 

thanks Alan

 

Open



Semi-closed



Semi-closed and pegged/pinned




Closed




"Closed" deck insert by Alyn (Stockcar) at AS Performance

 

many thanks Don.

Is an open deck better, since it will, in theory cool better? Or is it intrinsically weaker due to less side wall support>?

 

Your second comment.

Without the extra support the central bore casting tends to move under higher power loading usually leading to Head Gasket failure amd more.

Big power - closed deck block is preferable or the pinned and insert route.

 

ok, makes sense.

if i buy a new 2.5 sti today...is it an open deck?

 

Semi closed. (EJ257)

 

thanks Alan.

 

Re head gaskets, we've never had head gaskets fail on any engine we've built.
The head gaskets themselves aren't the problem, unless it's the old 2 litre composite variety. We figure that the nice chaps on the production line just don't tighten up the bolts enough, as we see blow by, but not actual gasket failure.
Cosworth stopper gaskets and ARP studs are a complete solution.

 

Alan, how many 2.7 liter stroked motors do you build in a year?

 

None. I dare say we would if somebody asked! We spend most of our time building 2.1 and 2.35 strokers where we have acquired a certain confidence.
I did once speak to a very well known manufacturer and tuner about having closed deck 2.5 blocks custom made. The cost was an issue!

 

ah, ok, i see. if the current model is built with a semi-closed block, which models had the closed 2.5 as standard? or was the issue with this tuner to convert it to a closed from a semi-closed?

 

They never made a fully closed deck 2.5 block.
It's fair enough, the decision to tune the car is ours!

 

Changing the subject slightly, the South Africans like their fast cars, don't they? I recall the Ford Capris and Sierras, available only in SA with V8's..

 

haha....ye..we also had the only Alfa GTV 3litre models in the eighties and BMW only produced the 333i and 325is E30 model here. The 745 from the early 80s had the M1's engine. The rest of the world had a turbo 3.3 litre.
Such a pity about the low octane fuel available here lately. ...

 

I seem to recall an SA Sierra V8 at about the time of the UK XR4x4, before the Sierra Cosworths. Australian V8 I think.

Don't recall a similar Capri.

 

The Capri V8 was the Piranha, in South Africa.

 

I can imagine that handles.....er....interestingly