ALi-B

iTrader: (1)

Alternator is fine...it was the voltage regulator that was fried...made in "Great" Britain as well...figures

£22 for an OEM replacement - can't moan too much really

THOMO

THATS WHY THERES NOT AN ISSUE ON EVOS BLOWING UP OR
NEEDING KNOCK LINKS.
JEEZ HOW MANY THREADS OF MY ENGINES BLOWN DO WE NEED .WAKE UP MAN.

john banks

I fitted my Knocklink to the Evo and it isn't coming off. I was hoping to take it off, but IMHO it is needed based on what I observe on a modified car running an already mapped ECU (on rollers) or the stock ECU at higher boost. All can be fine on the rollers or in a lower gear, but if you for example played with a high gear a lot on a warm day you might have trouble.

ReggieMY99

With all respect i think theres a hell lot more imprezas driving around in the world then there are evo's

im currently driving a MY99, ive had 3 imprezas and 2 subaru leones since 1995, 1,6 boxer 1.8 and 2.0 with and without turbo charger

the one i have now has 155 000 miles to it, never had any problems with it, lightly modded with full decat uprated fuel pump manual boost controller

goes like stink, i drive a 100 miles to and from work every day and have in the last 2 years and oil changed every 9300 miles

now tell me that subarus boxer engines are weak, i had a MY98 couple of years ago chipped and modded to 280 bhp, when i picked it up some ******** had been given a test drive in it the day before and had kindly put 92 octane fuel in it, no knocklink installed, needless to say i burned a hole in piston 3 after some spirited highway driving lol

but that has nothing to do with a weak engine has it ?

cheers

Bob Rawle

85% of the 2.5's I have been involved with were rebuilt as uprated after being installed and mapped (not by me) as std EJ257's then damaged, so I would say there was a huge misunderstanding out there, personally I treat even uprated 2.5's with great deferance, there are those that would say otherwise BUT a well built 2 litre will outlast (and in many cases perform) a 2.5 almost any day. I've only been really impressed with three 2.5's and those were all either built or supported by RCM. (actually Simon Bollens was an exception, that is a quick one)

Don't want to start any arguements here.

Sure there are some good engines around but the run of the mill stuff appears to be at variance

bob

bob

THOMO

HAVE A CHAT WITH DAVE AT API HE IS NOT VERY BUSY IS HE .TRY READING
A FEW THREADS.I LOVE SCOOBS BUT BUT IF YOUR TELLING ME THERE BULLET
PROOF COMPARED TO EVOS YOUVE BEEN BRAIN WASHED.
http://bbs.scoobynet.co.uk/showthread.php?t=520180

YOU WONT SEE A ABOVE THREAD REAGARDING EVOS PAL.

Bubba po

Take your caps lock off Thomo, for the love of pie.

john banks

Interesting stuff Bob, quite horrifying statistics as well for someone tuning their stock EJ257s and fits well with my record on the EJ257, I'm glad I didn't get an STI now. No disagreement with your thoughts on the strength of the 2.0, but the trouble is with a lot of newer Subarus having well over 1400 kg to lug about, can the 2.0 really cut it in terms of usable power band? Whilst a good 2.0 can go well, they are a bit dead in the area where most of us like them to be responsive, surely you can see what I mean in terms of torque compared to the GT2 for example? The 4G63 running 1.9 bar at 3500 RPM feels a bit flat to be honest in comparision to an EJ257 running just 1.6 bar at similar RPM (albeit on rotated GT30R-12), gave a real kick whilst it lasted. Would be nice to have an inexpensive setup like that that held together, but it really means an engine build on either Subaru or Evo doesn't it?

I love the package and overall handling of the Subaru and Evo, but I want Supra style torque hit everywhere...

THOMO

your not a pie eater are you bubba ? who eat all the pies who eat all the pies

you

Bubba po

I eat pies but I'm from Yorkshire, not Wigan.

ALi-B

iTrader: (1)

Time for somebody to start playing with H6's with Supercharges/turbos

More pistons....spread the load

scoobysmiff

iTrader: (2)

I've been told (by a well known and respected personality off SN) that the new age 2.5 is more fragile because of it's tollerances, Subaru have coated the pistons with something called Eutectic (i think thats the stuff) which is supposed to give a superior thermal heat barrier, well it does, at std Hp anyway, once you build up the boost and HP it gets hotter then it becomes unstable and dosen't offer the protection that it should and because of the tight tollerances it causes issues, piston nip in the bores for a start.

ricardo

Hypereutectic.

http://en.wikipedia.org/wiki/Hypereutectic_pistons

tharoka

Thanks for your participation.

The main point of the original topic was to determine if the Euro MY06 has any know specific problems or new parts wich become it weaker than previous USDM 2.5 units.

If my (Euro MY06 STi) engine is as strong as the MY04 USDM 2.5 unit I would be a totally happy, since I have experienced from first hand an imported car from the US with standar internals wich suported 550 hp (with an APS DR65) without any problems, until it was totaled. Also in the US there are a lot of hi hp engines on standar internals keeping fine.

As for my I checked the subaru piston references in a dealer for the Euro MY06 WRX and STi and they were different. But now someone told my that this is not an evidence of they are different. Can this be true? Has this happened before (ie, same part, different references)?

I also have seen an Australian oficial subaru document wich states that the MY05 and MY06 uses an IHI RHF55 turbo and I thought that the USDM used untill now a VF-39, so this may prove that not all the 2.5 are identical?

So finally, is the MY06 the same unit in Europe and US?

Has the USDM unit sufered any changes for the 06 year?

Whould not like to bother you with this question, but then, where in the hp range are located this limits, are you refering to those 340/340? would be those aplicable for any market 2.5 STi engine?

And may I ask what are your thoughts about the comparison from standar 2.0 Euro STi vs Standar Euro 2.5 engine reagrding their limits?

scoobysmiff may you be refering to this?, pasted from the previouly mentioned australian data sheet: 'Pistons
The piston head and ring grooves are coated with Alumite and the piston skirt has a molybdenum coating to reduce frictional resistance with
the cylinder bore. The piston pin offset has been reduced to accommodate tighter piston to bore clearances and therefore eliminating unburnt
gas build-up between cylinder wall and piston head. This aids fuel consumption and reduces combustion gas contamination.
The compression ratio on the non-turbo engine is 10: 1 for greater thermal efficiency, on the turbo engine the compression ratio remains at 9.0: 1.
The high static compression ratio on the non turbo is possible due to the ‘Tumble Swirl’ action that provides better atomisation and mixing of
the fuel with the air and hence is less susceptible to detonation or pinging.'

The original document can be found here: http://subaru.com.au/downloads/6DB71...09F1192CDD.pdf

RB5_245

Dunno if thin walled liners are the main culprit here. USDM 2.5's seem to be running huge WHP stock engines, though I don't read nasoc to find out how long they last. Crawford with their rep as it stands are pushing 2.65's in road tume and 2.8's in the race spec Are they just using longer stroke?

I think a major factor in inducing det is mixmatched bores and heads. How many times have you heard of STI heads being stuck straight on? which s pretty much removing squish area entirely? Of the machined heads, how many have gone to be re-hardened afterwards? Not many I think, and at this level of relatively low peak pressures with studded heads and top knotch head gaskets what other reasons is there for major failure (if the us 2.5s are standing up to it)

ALi-B

iTrader: (1)

I wonder what compression ratios the US tuners run when getting these massive WHP. If they drop it as low as 7:1 or 7.5:1 then it could cope much better with boost, but that would involve different pistons, of course

Would be a pig off-boost though.

scoobysmiff

iTrader: (2)

scoobysmiff may you be refering to this?, pasted from the previouly mentioned australian data sheet: 'Pistons
The piston head and ring grooves are coated with Alumite and the piston skirt has a molybdenum coating to reduce frictional resistance with
the cylinder bore. The piston pin offset has been reduced to accommodate tighter piston to bore clearances and therefore eliminating unburnt
gas build-up between cylinder wall and piston head. This aids fuel consumption and reduces combustion gas contamination.
The compression ratio on the non-turbo engine is 10: 1 for greater thermal efficiency, on the turbo engine the compression ratio remains at 9.0: 1.
The high static compression ratio on the non turbo is possible due to the ‘Tumble Swirl’ action that provides better atomisation and mixing of
the fuel with the air and hence is less susceptible to detonation or pinging.'



No mate, i dont think i was refering to this process as this, i believe, is how they manufacture the Sti pistons, as they are coated are they not

If you look at the Hypereutectic sticky above you will see and understand the process and why they do it, if this is how Subaru have made the new age pistons then it will be a problem if you want to build even just a big'ish (for this day and age, circa 350+) power engine.

I'm almost certain that you will need new forged pistons and a rebore to the correct tollerance as a minimum if you want to go to something substantial, which to me is a bit of an own goal by Subaru considering the aftermarket industry which exists around their cars, or maybe they just don't want us playing with them anymore

Tim W

iTrader: (1)

The Euro MY06 Sti short engine is the same as the USDM Sti, and the MY06 Euro and USDM 2.5 WRX. The heads of the two Sti's are the same, the WRX's are different to the Sti, but again are the same as each other.

The problems with most of the EJ257 conversions we have been seeing can mostly be put down (IMHO) to using 2 litre heads and a completely stock bottom end. The combustion chambers of the 2 litre heads are much smaller in diameter than the bore of the 2.5 and with hard edges involved in the combustion area there are all sorts of interesting flame front effects to consider, as well as strange squish effects creating hot spots, which I feel contribute to the accelerated head gaskets problems. Quite appart from the thin liners and support walls that like to flex in high boost/rev combos

Then we have the pistons...a hypereutectic (high silicon content) cast alloy design, intended to have the light weight and strength characteristics of a forging with the low cost and expansion properties of cast. Basically they've been made for cost reasons...great. These pistons really don't like high loads, they're not very forgiving when it comes to det, and with the design of the piston and ridiculously tight factory tollerances (my engine had a maximum of 0.2 thou clearance before I had the bores honed to give 1 thou) which Subaru decided to use, probably to prevent piston slap. Anyway the clearances, design and material choice mean that under high load the ringlands fail very easily, if you haven't already lost the head gasket...

My theory to maintain the life of EJ257 engines is to avoid high loads, ie, keep the boost down below 1.4 bar and don't get carried away with trying to get the ultimate power out of them. Concentrate on making them breath, and be happy with 400 of each (stock components) 450 to 500 of each when properly built with forged components and decent heads.