Trust me, that's twice what he wants to pay for one!

 

I know but it's on his doorstep and to see what you get it's a good option.

 

Just make sure that when you go to look at any car you give ALL four wheels a good kick that will show any weakness the car may have.

 

Don't talk complete rubbish! We all know you should never kick a tyre on a 2.5 impreza, the engine will blow up!

 

Yeh I am going to stick at looking at blobeye for now as I just cant afford to take a risk right now.
and yeh that penarth one is nice he always sells nice cars but too much for me .

 

That doesn't really answer my question are we talking like a bit of hessertation under boost?

 

Are you always this easy to break you said you want a hawk.Go to Google and put 2006 sti engine failures there's an USA site where they did a very big survey. It was well done and they had a very big response much bigger than any on here.They set out some ground rules and only wanted standard cars and mileage etc.Try find it your self and have a good read through it.Some people give misleading info but the guys on the site chase them up and get the truth if you stick with it.

P.S if you are that easy to break can I have your pin

 

as a fresh member to the scooby and hawk eye community coming from a BMW background with experience mapping (allbeit much older cars and a totally different system/manufacturer) i took all of the horror stories and wives tales with a pinch of salt after buying my hawk WRX.

i did some homework and majority of 2.5 failures that are not due to ringlands seem to nearly all be associated with a certain engine block casting which from what i can find was not in the hawk and only in the later generation 2.5.

regarding ringland failure (not just on the 2.5). the construction process of the pistons makes them a bit brittle for starters. also ringlands dont just fail for no reason whatsoever unless the piston is defective or previously damaged. from searching and asking folks that map these cars in the opensource community (all EJ engines, not just the 2.5 tuners) it appears that the cause of ringland failures can nearly always be traced back to something causing excessive heat in the combustion chamber. one guy went so far as analysing some failed 2.5 pistons.

as far as i can tell what seems to happen when the ringlands fail is that something causes excessive combustion chamber temps, then one of the piston rings (the iron one if memory serves) will expand and givent the tight tolerances/gaps then if temps get to a point then the ring will expand enough to contact itself where it splits. when this happens the ring has nowhere else to go but up/down so the ring puts pressure on the ringlands which then breaks the ringlands.

this seems further supported by many of the open source tuners having run some big numbers on standard pistons with no issues but the key point is their setup is always well tuned.

what i gather the main causes of ringland failure are (given it all seems to point to conbustion chamber temps) would be are sustained high speed driving at speeds high enough to cause the TMIC to be inneffective as air essentially jumps over the scoop. bad tuning or lack of tuning causing lean conditions which generate alot of heat or bad tuning which generated alot of heat. this also seems to tie in with some of the engine/ringland failure posts dotted around the net that i have glanced over. some failures may be on a car where the owner has added lots of mods and had no tuning, others where you get the impression the owner would be the sort to get a scooby and then drive with their foot welded to the floor for weeks including top speed attempts and then engine mysteriously goes bang, etc, etc. also one other not to forget is people running their turbo well above what it should be, ie- someone boosting the crap out of a td04 as running a turbo out of its efficiency zone/band or whatever you call it will heat the air charge more than a bigger turbo operating cooler at the same boost.

id be confident enough to build my 2.5 WRX up to 350bhp on standard internals if not a little more though from what i hear 350bhp is about it before running into potential 5 speed gearbox issues, thats something else i need to look into..

my planned setup will be based firmly around ensuring the engine does not get over hot so i will be doing things like installing phenolic inlet spacers/gaskets, ensuring intake air is as cool as possibly (airbox, shielded/boxed short ram or CAI with filter behind bumper), possibly upgrade to STi or aftermarket TMIC and ensure good seal between bonnet scoop and IC, a slightly lower temp t-stat or a higher flowing standard temp t-stat and so on. also i dont plan on extended high speed runs with a TMIC, if thats your bag then a FMIC may suit better.

thats my take on it anyway..

 

Hawk 5 speed box is stronger than previous 5 speeds so should exceed 350bhp with ease so I'm reliably informed! Some now say 450 capable. But it's torque that kills boxes not power and the 2.5 delivers very good torque.

 

So in other words you are saying all of us have been thrashing our motors continuously causing a great engine to fail or we have tuned incorrectly, I guess it's my fault my pistons shat themselves and not subaru in a standard car I've looked after from quite new. Hmm no ask any engine builder why the go, I'm guessing the diesels ej engines have same issue terrible drivers. Don't think it

 

yea heard its the torque that does it. interesting hearing the hawk 5 speed is meant to be stronger.. first time i have heard that. whos the reliable source? curious as ideally id like to see around 400bhp or so longer term. id love 500 or more but i think beyond 400 gets into no mans land regarding box and engine internals, particularly pistons.

if money wasnt an issue id have my 5 speed rebuild with PPG gears and forge the engine. ifthose two things were done then in theory the sky is the limit, or atleast until there were issues with the block, etc. but if i were to forge it id probably look at pinning it or something as no point opening up an engine twice.

regarding torque killing boxes.. i have been wondering about potentially limiting torque via tuning to allow more HP than folks would usually run on a standard 5 speed. like say trying to keep torque below X amount and tune the top end for HP instead of trying to optimise HP and TQ as much as possible like 99.9% of people do. would feel interesting having the engine pull progressively harder up to max HP rather than kitting a torque peak and then a flat-ish run out to peak HP.

 

where did i say every instance? there are far too many variables.. different manufacturing processes, different castings, revised parts/tunes, etc, etc so every model and every generation or even every part revision could potentially be a different story.

i think there are plenty of genuine failures but i also think there are far more where there is more to it than just "bad subaru engineering". also in the case of a tuner popping your engine.. would they all own up and say they pushed it too far or would they use the old get out of jail card and blame subaru engieering, etc.

im also in the process of potentially disproving the "need a tune for an intake" brigade. yes, ideally you should adjust your tune for almost every alteration to an engines setup from a mapping point of view but as for people saying your engine will spontaneoudly combust if you fit an intake and dont map for it then so far as my initial results id beg to differ as im seeing no deviation in AFR's worth mentioning nor am i hearing or feeling any adverse effects but thats a seperate issue/thread..

 

It would hold back on boost then out of the blue go back to full boost, I reckon the issue was too much oil passing damaged Ringland resulting in my wideband sensor pulling ignition due to erratic inputs from sensor

 

so your going to disprove every tuner in the subaru world that ringlands dont fail due to design or the cast their from and that the maf doesnt need rescaled with uprated intake.. were all obviously doing it all wrong

 

See this was a train of thought I'd had. If the key cause of ring land failure is heat build up in the cylinder/piston area, then surely modifying to keep the engine cooler would help minimise any risk.

 

i have never said anyone is doing anything wrong. i am simply stating my own observations. what you, or anyone else, does with tat is your decision. obviously if all or most subaru tuners reckon there is an issue with the pistons then there most likely is but you are aware that people also like to latch onto things and will likely just point a finger at a known issue when presented with a problem they dont know enough about.

i did not say my word is gospel and everyone else is wrong. i just said that i have found quite a few cases seem to trace back to excessive combustion chamber temps and that most folks tuning their own car seem to be able to run in or beyond the "no mans land" for piston failure and as of yet have not have their engine go pop and they all coincidentally do not do things or tune in such a way as to risk scenarios where excessive combustion chamber temps may be introduced.

this kind of reminds me of how people told me you cant do XYZ on a standard BMW ECU, which i then did. if something is repeated enough by people with a bit of knowledge that others will listen to then the average joe will take it as gospel when it may not always be the case.

 

It's alright boys, internets knows more than people who actualy work on things

 

Not to mentioned the number of standard 2.5 Hawkeyes that have gone pop.

 

oh because i dont work on things? and just regurgitate what others say online? LOL

dont get all butthurt just because someone introduces a new idea now boys. as said, my word is not to be taken as gospel, these are just observations.

pistons are a problem, but are they as big a problem as folks like to believe? i think not quite as much. id still forge any EJ nevermind a 2.5 for peace of mind though if building something with a fair bit of power so dont think im saying otherwise.

 

Look at this little nugget I found from Andy Forest Performance, and let's face it; they know a thing or two about engines.

On their 2006-2007 WRX Packages:

"On 06/07 WRX/STI 2.5 the pistons run very tight bore clearances. On Level 4 and above we recommend a forged piston upgrade. The forged piston upgrade is also recommended for level 3 if used for sustained high speeds or if used regularly on track."

A level 3 upgrade is anywhere from 360-390 bhp, enforcing the fact the feel they engine should easily be able to achieve 350 without too much stress on the engine.

I'm not that informed when it comes to engine stuff, so apologies if this is not relevant.

 

that is completely relevant actually.. it even mentions they run super tight bore clearances, which as i said previously, seems to be a contributing factor to ringland failure in many cases. he also mentions sustained high speeds, again i mentioned that earlier..

rather than sit here and go round in circles why dont some of the folks slating me ask andy why he mentions the tight bore clearance and sustained high speeds and ask him if he knows about an issue with one of the rings expanding enough to break the ringland. id hedge my bet that he will come back with what i have already said about the ring expanding and breaking the ringland.. and we all know what makes things expand, right? heat!

 

No one is gonna be expanding my ring.

Sorry thought I'd inject some humor into this thread

 

good shout

 

Well I'm gonna get my 06 WRX to 300 and drive it sensibly(ish). No track use, weekend warrior style and hopefully I shouldn't have a problem.

 

seems to be alot running similar figures with no major issues.. though with ringland failure its more of a surprise so..

personally on my 06 WRX i feel comfortable enough to chase 300-350bhp providing i address any little cooling improvements i think of (sluightly lower temp stat or tridon high flow stat, phenolic inlet spacers, possibly STi TMIC or similar, etc.) plus ensure the tune is conservative and knock maps are good. also id be fitting a relevant sized turbo that can run those sorts of figures without being pushed too hard so as to not introduce more heat than necessary.

 

Nowt wrong with the 2.5 hawkeye lump ! I run 495 bhp and had no issues as yet ! I reckon it's just hearsay !! :-)

 

As much as I would love to do all the work myself, I don't understand most of what DmcL just said. I think I am just going to get a package done on it from AFP or ScoobyWorld or something similar. Well definitely add the cosmetic bits myself though.

 

have heard of a few folks running similar numbers if not slightly more on standard slugs but personally id be crossing my fingers every time i gave it full throttle.. the suspense would kill me and id end up forging it just for peace of mind as there is no definitive yes or no associated with any HP levels above like 350 or so.

out of curiosity how long have you been running like that for and whats the spec of the engine, cooling mods if any, etc?

@dabiscuit, definately better to play it safe, regardless of knowledge. those running high-ish numbers on standard pistons do so at their own risk and what works for one may not necessarily work for another.

 

''sustained high speeds, again i mentioned that earlier.. ''

what sort of figures are we talking here?

 

there was a rough figure thrown around for when the bonnet scoop supposedly becomes less effective but i dont remember off hand. i think like 130 plus, maybe more? some folks reckon above a certain speed the scoop for the TMIC becomes ineffective eith the air basically jumping over it. seems quite possible but id want to test the theory out with some wool tufts or ribbons attached to the bonnet to actually see what the airflow over/into the scoop was doing before fully believing that as if the scoop wasnt catching air then why does the bonnet lift at higher speeds? mind i have only had my WRX up to about 140 but i could notice no differing movement of the bonnet, seemed to lift a little under 100 and remained until i slowed down again.

the main thing regarding sustained high speeds though would be long periods at full throttle where the engine is boosting full for a while so like top speed runs or similar. whether the bonnet scoop also factors in somewhere would need to be proven or atleast have some decent evidence suggesting it plays a part such as wool tuft/ribbon testing.