Definitive EJ255/EJ257 Tuning Thread (Reducing odds of popping std pistons)
22 July 2013, 06:39 PM
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Definitive EJ255/EJ257 Tuning Thread (Reducing odds of popping std pistons)
right, id like to sort the facts from the wives tales with just what can be done safely on these engines before the need to go forged and hopefully if this thread goes well and turns into a nice little fountain of knowledge we might even get it stickied to help future members.
i am hearing loads of people saying that you need to go forged before anything else which is a good safety net but for folks looking to gain some HP without breaking the bank its not such great news.
it seems many on here firmly believe you need to go forged first and foremost but according to an article i read as well as a few posts found here and there via google 300bhp (actually 300whp in the article) is supposed to be do-able on standard internals. now this is coning from 3 decent names in tthe industry across the water so there has to be some truth to it as all 3 places say more or less the same thing for a target of 300whp so to me that would make me thing tuning for 300bhp would be safe as houses.
heres the article:
http://www.importtuner.com/tech/impp...h/viewall.html
and incase the article should disappear in future here are snippets of the relevant info given by the 3 shops.
further to the above and regarding damaged pistons, ringland failure and related fun stuff.. reading the Crawford Performance HP/mods snippet in particular mentioning the use of an AOS (air oil seperator) and the subsequent things that can happen without it.. im wondering how many of the people that have popped a piston or ringland at or below 300bhp have had an AOS fitted (assuming the mapping was of a suitable quality and not by a cowboy tuner).
my humble opinion (or rather theory at this early a stage of scooby ownership) is that rather than the issue being an increase in HP up to roughly 300bhp (or 300whp in the case of the article which would be nearer 400bhp) causing pistons or ringlands to go boom it may simply just be a combination of a bad or mediocre tune and/or the lack of an AOS or lack of cleaning out the intercooler and intake plumbing prior to or after fitting an AOS as it would seem.
i would like to hear from knowledgeable people in the EJ tuning/mapping circles or long time EJ owners who have had heir fair share of turbo EJ's. if its not first hand experience or is something your mate heard from his mate, etc then please do not comment. im looking to single out the contributing factors to piston/ringland failure at HP levels that should, in theory, be completely safe.
now lets let the **** hit the fan and see if this thread flops or not lol
i am hearing loads of people saying that you need to go forged before anything else which is a good safety net but for folks looking to gain some HP without breaking the bank its not such great news.
it seems many on here firmly believe you need to go forged first and foremost but according to an article i read as well as a few posts found here and there via google 300bhp (actually 300whp in the article) is supposed to be do-able on standard internals. now this is coning from 3 decent names in tthe industry across the water so there has to be some truth to it as all 3 places say more or less the same thing for a target of 300whp so to me that would make me thing tuning for 300bhp would be safe as houses.
heres the article:
http://www.importtuner.com/tech/impp...h/viewall.html
and incase the article should disappear in future here are snippets of the relevant info given by the 3 shops.
Quirt Crawford Of Crawford Performance
300 whp: To obtain this horsepower level, the EJ motor only requires an upgraded intercooler, larger sized fuel injectors, and a retune of the ECU-no internal engine modifications are required. We highly recommend the use of an air/oil separator (AOS) on any turbocharged EJ motor to eliminate oil from coating both the intake tract and the inside of the intercooler, which causes a reduction in cooling efficiency that can cause detonation.
400 whp: There are no internal engine modifications needed at this power level. The car would need a larger turbo, intercooler, fuel injectors, fuel pump, AOS, and retune of the ECU.
500 whp: At his point, we suggest replacing the OE rods with a set of stronger, aftermarket forged rods, along with forged pistons, head studs, and the external components listed under 400 whp.
500+ whp: The same engine components are needed in the 500-whp package but you will probably need a larger turbo, and of course, proper tuning.
300 whp: To obtain this horsepower level, the EJ motor only requires an upgraded intercooler, larger sized fuel injectors, and a retune of the ECU-no internal engine modifications are required. We highly recommend the use of an air/oil separator (AOS) on any turbocharged EJ motor to eliminate oil from coating both the intake tract and the inside of the intercooler, which causes a reduction in cooling efficiency that can cause detonation.
400 whp: There are no internal engine modifications needed at this power level. The car would need a larger turbo, intercooler, fuel injectors, fuel pump, AOS, and retune of the ECU.
500 whp: At his point, we suggest replacing the OE rods with a set of stronger, aftermarket forged rods, along with forged pistons, head studs, and the external components listed under 400 whp.
500+ whp: The same engine components are needed in the 500-whp package but you will probably need a larger turbo, and of course, proper tuning.
Albert And Robert Bonamici Of Auto Master AMR
300 whp: The EJ20/EJ25 engines can handle 300 whp maximum with stock internals with no further modifications other than a proper fuel management tune.
400 whp: We suggest a set of forged AMR pistons and billet rods to safely boost up the engine.
500 whp: The same components previously mentioned in the 400-whp package but also include our AMR 9/16-inch "Big Boy" head studs, AMR plate hone, and O-ring the block to increase sealing of the heads to the cylinder block.
500+ whp: Previously mentioned items with the addition of a line-hone to ensure proper bearing clearances, AMR billet crankshaft, and ductile iron sleeves for additional cylinder strength.
300 whp: The EJ20/EJ25 engines can handle 300 whp maximum with stock internals with no further modifications other than a proper fuel management tune.
400 whp: We suggest a set of forged AMR pistons and billet rods to safely boost up the engine.
500 whp: The same components previously mentioned in the 400-whp package but also include our AMR 9/16-inch "Big Boy" head studs, AMR plate hone, and O-ring the block to increase sealing of the heads to the cylinder block.
500+ whp: Previously mentioned items with the addition of a line-hone to ensure proper bearing clearances, AMR billet crankshaft, and ductile iron sleeves for additional cylinder strength.
Paul Yim And Paul Leung Of Yimi Sport
300 whp: No modifications are required to the stock block, assuming all the bolt-on parts and ECU tuning are working in harmony.
400 whp: For an EJ205, you should be doing a basic build on the block that would include forged pistons, rods, good bearings, and head studs. Obviously, quality machine work and tight tolerances/quality control are crucial. For an EJ255 and EJ257, all the block needs is a set of forged pistons. 400 whp (particularly on 91 octane pump gas) is when cylinder pressures are high enough that a random knock event can take out the stock pistons. The rest of the internals are more than up to the task.
500 whp: We suggest adding forged rods, aftermarket rod and main bearings, and ARP head studs to the EJ25 along with making sure that the oiling system and cooling system are in 100 percent operating order.
500+ whp: For over 550 whp, we recommend sleeving the block, as the stock sleeves can become a failure point. For really high-horsepower applications, pinning the mains and oversized head studs and/or an O-ringed cylinder head may become necessary.
300 whp: No modifications are required to the stock block, assuming all the bolt-on parts and ECU tuning are working in harmony.
400 whp: For an EJ205, you should be doing a basic build on the block that would include forged pistons, rods, good bearings, and head studs. Obviously, quality machine work and tight tolerances/quality control are crucial. For an EJ255 and EJ257, all the block needs is a set of forged pistons. 400 whp (particularly on 91 octane pump gas) is when cylinder pressures are high enough that a random knock event can take out the stock pistons. The rest of the internals are more than up to the task.
500 whp: We suggest adding forged rods, aftermarket rod and main bearings, and ARP head studs to the EJ25 along with making sure that the oiling system and cooling system are in 100 percent operating order.
500+ whp: For over 550 whp, we recommend sleeving the block, as the stock sleeves can become a failure point. For really high-horsepower applications, pinning the mains and oversized head studs and/or an O-ringed cylinder head may become necessary.
my humble opinion (or rather theory at this early a stage of scooby ownership) is that rather than the issue being an increase in HP up to roughly 300bhp (or 300whp in the case of the article which would be nearer 400bhp) causing pistons or ringlands to go boom it may simply just be a combination of a bad or mediocre tune and/or the lack of an AOS or lack of cleaning out the intercooler and intake plumbing prior to or after fitting an AOS as it would seem.
i would like to hear from knowledgeable people in the EJ tuning/mapping circles or long time EJ owners who have had heir fair share of turbo EJ's. if its not first hand experience or is something your mate heard from his mate, etc then please do not comment. im looking to single out the contributing factors to piston/ringland failure at HP levels that should, in theory, be completely safe.
now lets let the **** hit the fan and see if this thread flops or not lol
Last edited by DmcL; 24 July 2013 at 08:25 PM.
22 July 2013, 08:20 PM
#2
well I am a d.i.y'er but have had 10 Subaru's over approx. the last ten years and every one I have tuned to a degree, and have never split any of my cars blocks to replace pistons/rods and the like and have never really had any failures or massive problems, my current blob sti is awaiting a new map from Andy F and am hoping for a shade over 400 at the fly
22 July 2013, 08:25 PM
#3
doubt you will get a definative answer
i have a hawk 2.5 and have decided to prempt any problems and am getting williams motorsport to do me a
2.5cdb
forged internals
14mm arp studs
acl bearings
cosworth gaskets
rcm tgv deletes
rcm air pump deletes
rcm parallel fuel rail/rcm pump/rcm 1000cc injectors
rcm tubular headers
md321t turbo
hybrid fmic
he estimates its good for 600bhp but mine will be pegged at 450bhp approx
i have a hawk 2.5 and have decided to prempt any problems and am getting williams motorsport to do me a
2.5cdb
forged internals
14mm arp studs
acl bearings
cosworth gaskets
rcm tgv deletes
rcm air pump deletes
rcm parallel fuel rail/rcm pump/rcm 1000cc injectors
rcm tubular headers
md321t turbo
hybrid fmic
he estimates its good for 600bhp but mine will be pegged at 450bhp approx
22 July 2013, 08:35 PM
#4
Firstly I don't believe anyone has said you can't do 300 bhp on standard internals...you can but due to the bad design of the 2.5 engine it's an inherent problem even on stock OEM maps that they dont like headgaskets and piston ringlands...check out the 2.5 hatch thread, I don't own a 2.5 never had and never will if I'm honest....Unless its got a closed deck insert and 14mm head studs....2.0JDM all the way for me 
22 July 2013, 09:02 PM
#5
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400WHP with no internal modifications on a 2.5!?
Now I don't normally say things as direct as this against a tuner that has the reputation of Crawford - but that is utter bollocks! I should I say it's utter bollocks if you want anything remotely reliable.
Surely that statement from Crawford has been taken out of context..... surely.
Now I don't normally say things as direct as this against a tuner that has the reputation of Crawford - but that is utter bollocks! I should I say it's utter bollocks if you want anything remotely reliable.
Surely that statement from Crawford has been taken out of context..... surely.
22 July 2013, 11:15 PM
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well I am a d.i.y'er but have had 10 Subaru's over approx. the last ten years and every one I have tuned to a degree, and have never split any of my cars blocks to replace pistons/rods and the like and have never really had any failures or massive problems, my current blob sti is awaiting a new map from Andy F and am hoping for a shade over 400 at the fly
were any/all cars equipped with an AOS and mapped by a good tuner (not necessarily a popular one as popular doesnt automatically equal good). also how many of these cars were 2.5's as thats mainly what im interested in as we all know the 2.0 is a bit more sturdy or so everyone says.
400WHP with no internal modifications on a 2.5!?
Now I don't normally say things as direct as this against a tuner that has the reputation of Crawford - but that is utter bollocks! I should I say it's utter bollocks if you want anything remotely reliable.
Surely that statement from Crawford has been taken out of context..... surely.
Now I don't normally say things as direct as this against a tuner that has the reputation of Crawford - but that is utter bollocks! I should I say it's utter bollocks if you want anything remotely reliable.
Surely that statement from Crawford has been taken out of context..... surely.
i know its comparing apples and oranges here but from territory im more familiar with the mid 80's BMW M20B25 (6 cyl 2.5) can handle mucho boost with standard internals even being an originally n/a engine. on those the main failure points with boost are headgaskets so the popular fix (and what ill be doing to my turbo 325i in progress) is to weld the water jackets in the head as they can flex due to their design and subsequently allow the gasket to push out in that area. secondly they all like to O ring the head (easier than doing the block as head is aluminium). with water jackets welded, head O ringed and ARP headstuds the bottom end is good for over 500whp, some have even ventured over 600whp. and that is with the standard CR of 8.8:1. anyway getting somewhat back on topic.. the main killer of the weakpoint on these (headgasket in this case) is bad tuning. when the tune is good the gasket holds, within reason anyway.
this is what im trying to sus out about the EJ255/257, pistins/ringlands may be a weak point but im betting the failures have a cause and arent just random.
from what i read its a slightly different kettle of fish for the hatchback and newer EJ255/257, possibly a change in production methods for parts or something? maybe someone can elaborate on why more of the 2008ish onwards 2.5's seem to fail than the older 2.5's like in the hawk.
wanting to dispel fact from fiction on these engines so people will know what they should safely be able to make without major risk of the engine grenading itself. also because i have a 2.5 hawk and im itching to start playing with it but its my DD while the 325i is being built up so i dont want it to go pop without another car as a backup lol
Last edited by DmcL; 22 July 2013 at 11:18 PM.
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22 July 2013, 11:25 PM
#8
Im on a scdb 2.5 440/440, but thats with forged pistons on the standard rods, block, crank.
Got a few years under its belt and the short engine side of things has been great.
Way I see it is, starting with a standard 257-
-first weak link is the chocolate pistons, and shouldnt really be trusted on a hot day with anything other than a bob on map at anything above 340ish.
-next weak link is the liners, which if never pushed boost wise or ever ventured into det when mapping are good for 460/440 If youve got the studs to hold the Hg's and liners in place.
So above that your looking at closed deck inserts.
Would be interesting to find out what the next weak link is, but I dont know anyone personally whos gone losed deck insert, let alone anyone who has and stuck standard rods and crank back in.
Just my 2p, i could be wrong.
Got a few years under its belt and the short engine side of things has been great.
Way I see it is, starting with a standard 257-
-first weak link is the chocolate pistons, and shouldnt really be trusted on a hot day with anything other than a bob on map at anything above 340ish.
-next weak link is the liners, which if never pushed boost wise or ever ventured into det when mapping are good for 460/440 If youve got the studs to hold the Hg's and liners in place.
So above that your looking at closed deck inserts.
Would be interesting to find out what the next weak link is, but I dont know anyone personally whos gone losed deck insert, let alone anyone who has and stuck standard rods and crank back in.
Just my 2p, i could be wrong.
Last edited by legacy_gtb; 22 July 2013 at 11:27 PM.
23 July 2013, 06:48 AM
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the crawford statement wont apply over here as USDM have been using 2.5 engines for years before us and they were built in america when we were still getting the 2.0, add that to the fact they will use different internals then i think it could be possible to have 300whp from a USDM, but in uk due to the poor design this causes issues, thats my thoughts take it as you wish
23 July 2013, 06:51 AM
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Im on a scdb 2.5 440/440, but thats with forged pistons on the standard rods, block, crank.
Got a few years under its belt and the short engine side of things has been great.
Way I see it is, starting with a standard 257-
-first weak link is the chocolate pistons, and shouldnt really be trusted on a hot day with anything other than a bob on map at anything above 340ish.
-next weak link is the liners, which if never pushed boost wise or ever ventured into det when mapping are good for 460/440 If youve got the studs to hold the Hg's and liners in place.
So above that your looking at closed deck inserts.
Would be interesting to find out what the next weak link is, but I dont know anyone personally whos gone losed deck insert, let alone anyone who has and stuck standard rods and crank back in.
Just my 2p, i could be wrong.
Got a few years under its belt and the short engine side of things has been great.
Way I see it is, starting with a standard 257-
-first weak link is the chocolate pistons, and shouldnt really be trusted on a hot day with anything other than a bob on map at anything above 340ish.
-next weak link is the liners, which if never pushed boost wise or ever ventured into det when mapping are good for 460/440 If youve got the studs to hold the Hg's and liners in place.
So above that your looking at closed deck inserts.
Would be interesting to find out what the next weak link is, but I dont know anyone personally whos gone losed deck insert, let alone anyone who has and stuck standard rods and crank back in.
Just my 2p, i could be wrong.
23 July 2013, 10:15 AM
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I believe the op got his statement from this ?
www.importtuner.com › Tech
I know guys in the states who have done almost magical things to the EJ257
But you have to be serious here your putting mega £ notes in
For a killa build .
450 / 480 makes for a great road car & most wouldn't want or need more .
A decent job & dedication to ones car will see most reach this figure if passionate
Back to standard oem
It's impossible to be acurate
Don't sustain high speed
Give it as much help to keep cool as poss
Don't high / or over rev
Cap at 1.3 bar
& U have done pretty much your end in the driving seat , only for you to go out 1 morning to succumb to failure
If you want more power strip the engine & rebuild it
Or buy a car that already has your suggested figure .
Regards
www.importtuner.com › Tech
I know guys in the states who have done almost magical things to the EJ257
But you have to be serious here your putting mega £ notes in
For a killa build .
450 / 480 makes for a great road car & most wouldn't want or need more .
A decent job & dedication to ones car will see most reach this figure if passionate
Back to standard oem
It's impossible to be acurate
Don't sustain high speed
Give it as much help to keep cool as poss
Don't high / or over rev
Cap at 1.3 bar
& U have done pretty much your end in the driving seat , only for you to go out 1 morning to succumb to failure
If you want more power strip the engine & rebuild it
Or buy a car that already has your suggested figure .
Regards
23 July 2013, 01:02 PM
#12
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Dmcl,
First mistake is to compare a BMW engine with a 2.5 Impreza engine!
The problem with the 2.5 is not only the OEM rods and pistons (although I believe the rods take more than the pistons will cope with), but it's the design of the 2.5 block - it's inherently weak for higher power applications.
There are enough of us here who have been there and done it, found the issues and looked at rectifying the shortfalls. I've been one of the few (that survived to tell the tale lol) who pushed the OEM scdb case to over 600/600, using the car for competition abuse - flex in the cylinders was evident upon strip down (amongst other imperfections of the design and build-up process by Cosworth).
The general rule of thumb is don't go beyond a Stage 1 type modification (exhaust, induction and remap) with an OEM Impreza 2.5 engine.
I've said this before (like a stuck record lol): I wouldn't touch the current 2.5 platform again, but that's my personal opinion (for a number of issues/reasons). I basically don't trust it.
Steve's STI,
Who told you that the US 2.5 engine spec is different to the EU 2.5?
The biggest difference appears to be that their WHP figures relate to our flywheel figures.
First mistake is to compare a BMW engine with a 2.5 Impreza engine!
The problem with the 2.5 is not only the OEM rods and pistons (although I believe the rods take more than the pistons will cope with), but it's the design of the 2.5 block - it's inherently weak for higher power applications.
There are enough of us here who have been there and done it, found the issues and looked at rectifying the shortfalls. I've been one of the few (that survived to tell the tale lol) who pushed the OEM scdb case to over 600/600, using the car for competition abuse - flex in the cylinders was evident upon strip down (amongst other imperfections of the design and build-up process by Cosworth).
The general rule of thumb is don't go beyond a Stage 1 type modification (exhaust, induction and remap) with an OEM Impreza 2.5 engine.
I've said this before (like a stuck record lol): I wouldn't touch the current 2.5 platform again, but that's my personal opinion (for a number of issues/reasons). I basically don't trust it.
Steve's STI,
Who told you that the US 2.5 engine spec is different to the EU 2.5?
The biggest difference appears to be that their WHP figures relate to our flywheel figures.
23 July 2013, 04:35 PM
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yip i know they go by whp but reading through their forums it appears the earlier 2.5l engine can handle more the the newer 06 onwards, is it possible the internals were changed to cut costs? im sure anything is possible lol
23 July 2013, 08:42 PM
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this is what im wondering.. there seems far more reported failures of 2.5's in the generations after the hawkeye (i f***in hope so since i have a hawk lol).
yea i know comparing any two engines are like apples and oranges but you would think there is atleast some scope for increased power from the standard engine without risking grenading the engine.
for the purpose of this thread im not looking to see how high you can go on standard internals but rather how high you can safely go so right out of the box that pretty much rules out anything over about 350bhp from what im hearing on here. the interviewed shops in that article all mention 300whp but no talk of how safe that is and id imagine 300whp would need to be something in the region of 375-400bhp or so which again going on whats been said here is well into no mans land.
so the general summary im getting here is:
so in a nutshell the way im reading this is dont drive like a complete bellend and bounce off the limiter like all the cool kids do, make sure your engine stays cool as there can be knock on effects otherwise and dont drive at sustained high speeds where the TMIC scoop becomes ineffective (also cooling related).
seems to me the majority of problems are either caused by retarded owners/drivers (Bee*R limiter?
) or the engine getting hot while being driven hard. the latter makes me wonder if subaru may not be adding a sufficient amount of fuel and/or pulling a sufficient amount of ignition timing as and when the engine heats up beyond the usual sorts of engine temps experienced driving normally or briefly getting on the skinny pedal.
so to answer my own personal question regarding just what i can safely(ish) get out of my hawkeye 06 WRX.. i should be ok aiming for say 300-325bhp assuming engine has no hidden underlying issues, its mapped well (id probably retain the standard rev limit) and measures are taken to ensure engine remains as cool as possible. does this sound accurate to you guys with experience on the 2.5's? im not looking uber fast just enough to walk a standard STI lol
i will be looking to drop in forged pistons at some stage. i was hoping i could avoid it but for safety/reliability and most importantly peace of minds sake i should stick a set in at some point but for the time being i should be safe to throw an intake/exhaust on the car, maybe some cooling mods, and a conservative map by a good tuner.
my last question.. am i safe enough to chuck in an exhaust/intake and maybe a manual boost controller and up the boost a few psi on the standard ECU/maps or will the ECU not compensate the fuel mixture and risk grenading the engine? if this is a grey area knowledge wise i could stick my wideband on the car and closely monitor AFR while incrementing boost higher ever so slightly..
EDIT: one more thought here, if the 2.5 WRX is slightly higher CR than the 2.5 STI then in theory the WRX pistons should be marginally more robust as theres more material on the top of the piston no?
yea i know comparing any two engines are like apples and oranges but you would think there is atleast some scope for increased power from the standard engine without risking grenading the engine.
for the purpose of this thread im not looking to see how high you can go on standard internals but rather how high you can safely go so right out of the box that pretty much rules out anything over about 350bhp from what im hearing on here. the interviewed shops in that article all mention 300whp but no talk of how safe that is and id imagine 300whp would need to be something in the region of 375-400bhp or so which again going on whats been said here is well into no mans land.
so the general summary im getting here is:
- dont bounce off the rev limiter like a tard (common sense id think?)
- dont let the engine run hot, ideally take measures to make sure it runs cool? (lower temp T stat, intake drawing cool air, exhaust wrap and/or heatshielding)
- sustained high speed may pose an issue with cooling as bonnet scoop becomes ineffective at higher speeds leading to increases in engine temp?
- dont exceed 1.3 bar or ???? (what happens beyong 1.3 bar? head/gasket or pistons?)
- ringland failure seems to be caused mainly by the engine getting too hot (and/or detonation or due to detonation as a result of higher temps id think) and can also go unnoticed at lower HP levels
so in a nutshell the way im reading this is dont drive like a complete bellend and bounce off the limiter like all the cool kids do, make sure your engine stays cool as there can be knock on effects otherwise and dont drive at sustained high speeds where the TMIC scoop becomes ineffective (also cooling related).
seems to me the majority of problems are either caused by retarded owners/drivers (Bee*R limiter?
) or the engine getting hot while being driven hard. the latter makes me wonder if subaru may not be adding a sufficient amount of fuel and/or pulling a sufficient amount of ignition timing as and when the engine heats up beyond the usual sorts of engine temps experienced driving normally or briefly getting on the skinny pedal. so to answer my own personal question regarding just what i can safely(ish) get out of my hawkeye 06 WRX.. i should be ok aiming for say 300-325bhp assuming engine has no hidden underlying issues, its mapped well (id probably retain the standard rev limit) and measures are taken to ensure engine remains as cool as possible. does this sound accurate to you guys with experience on the 2.5's? im not looking uber fast just enough to walk a standard STI lol
i will be looking to drop in forged pistons at some stage. i was hoping i could avoid it but for safety/reliability and most importantly peace of minds sake i should stick a set in at some point but for the time being i should be safe to throw an intake/exhaust on the car, maybe some cooling mods, and a conservative map by a good tuner.
my last question.. am i safe enough to chuck in an exhaust/intake and maybe a manual boost controller and up the boost a few psi on the standard ECU/maps or will the ECU not compensate the fuel mixture and risk grenading the engine? if this is a grey area knowledge wise i could stick my wideband on the car and closely monitor AFR while incrementing boost higher ever so slightly..
EDIT: one more thought here, if the 2.5 WRX is slightly higher CR than the 2.5 STI then in theory the WRX pistons should be marginally more robust as theres more material on the top of the piston no?
Last edited by DmcL; 23 July 2013 at 08:48 PM.
23 July 2013, 08:54 PM
#15
I dont see why everyone is so scared of this engine, If it is set up correctly, treated correctly and ran correctly there should be no issues.
detonation is the cause of ring land failure etc, so you need to be looking into the cause of the detonation to understand why they fail.
I also dont see why people give advice about forging it before tuning it.
Tune it, if done properly it should last, then save up for forging if required in the future. Why fix something if it isnt broke and like many engines last for a long period to come?
detonation is the cause of ring land failure etc, so you need to be looking into the cause of the detonation to understand why they fail.
I also dont see why people give advice about forging it before tuning it.
Tune it, if done properly it should last, then save up for forging if required in the future. Why fix something if it isnt broke and like many engines last for a long period to come?
23 July 2013, 09:20 PM
#16
this is what im wondering.. there seems far more reported failures of 2.5's in the generations after the hawkeye (i f***in hope so since i have a hawk lol).
yea i know comparing any two engines are like apples and oranges but you would think there is atleast some scope for increased power from the standard engine without risking grenading the engine.
for the purpose of this thread im not looking to see how high you can go on standard internals but rather how high you can safely go so right out of the box that pretty much rules out anything over about 350bhp from what im hearing on here. the interviewed shops in that article all mention 300whp but no talk of how safe that is and id imagine 300whp would need to be something in the region of 375-400bhp or so which again going on whats been said here is well into no mans land.
so the general summary im getting here is:
so in a nutshell the way im reading this is dont drive like a complete bellend and bounce off the limiter like all the cool kids do, make sure your engine stays cool as there can be knock on effects otherwise and dont drive at sustained high speeds where the TMIC scoop becomes ineffective (also cooling related).
seems to me the majority of problems are either caused by retarded owners/drivers (Bee*R limiter?) or the engine getting hot while being driven hard. the latter makes me wonder if subaru may not be adding a sufficient amount of fuel and/or pulling a sufficient amount of ignition timing as and when the engine heats up beyond the usual sorts of engine temps experienced driving normally or briefly getting on the skinny pedal.
so to answer my own personal question regarding just what i can safely(ish) get out of my hawkeye 06 WRX.. i should be ok aiming for say 300-325bhp assuming engine has no hidden underlying issues, its mapped well (id probably retain the standard rev limit) and measures are taken to ensure engine remains as cool as possible. does this sound accurate to you guys with experience on the 2.5's? im not looking uber fast just enough to walk a standard STI lol
i will be looking to drop in forged pistons at some stage. i was hoping i could avoid it but for safety/reliability and most importantly peace of minds sake i should stick a set in at some point but for the time being i should be safe to throw an intake/exhaust on the car, maybe some cooling mods, and a conservative map by a good tuner.
my last question.. am i safe enough to chuck in an exhaust/intake and maybe a manual boost controller and up the boost a few psi on the standard ECU/maps or will the ECU not compensate the fuel mixture and risk grenading the engine? if this is a grey area knowledge wise i could stick my wideband on the car and closely monitor AFR while incrementing boost higher ever so slightly..
EDIT: one more thought here, if the 2.5 WRX is slightly higher CR than the 2.5 STI then in theory the WRX pistons should be marginally more robust as theres more material on the top of the piston no?
yea i know comparing any two engines are like apples and oranges but you would think there is atleast some scope for increased power from the standard engine without risking grenading the engine.
for the purpose of this thread im not looking to see how high you can go on standard internals but rather how high you can safely go so right out of the box that pretty much rules out anything over about 350bhp from what im hearing on here. the interviewed shops in that article all mention 300whp but no talk of how safe that is and id imagine 300whp would need to be something in the region of 375-400bhp or so which again going on whats been said here is well into no mans land.
so the general summary im getting here is:
- dont bounce off the rev limiter like a tard (common sense id think?)
- dont let the engine run hot, ideally take measures to make sure it runs cool? (lower temp T stat, intake drawing cool air, exhaust wrap and/or heatshielding)
- sustained high speed may pose an issue with cooling as bonnet scoop becomes ineffective at higher speeds leading to increases in engine temp?
- dont exceed 1.3 bar or ???? (what happens beyong 1.3 bar? head/gasket or pistons?)
- ringland failure seems to be caused mainly by the engine getting too hot (and/or detonation or due to detonation as a result of higher temps id think) and can also go unnoticed at lower HP levels
so in a nutshell the way im reading this is dont drive like a complete bellend and bounce off the limiter like all the cool kids do, make sure your engine stays cool as there can be knock on effects otherwise and dont drive at sustained high speeds where the TMIC scoop becomes ineffective (also cooling related).
seems to me the majority of problems are either caused by retarded owners/drivers (Bee*R limiter?
) or the engine getting hot while being driven hard. the latter makes me wonder if subaru may not be adding a sufficient amount of fuel and/or pulling a sufficient amount of ignition timing as and when the engine heats up beyond the usual sorts of engine temps experienced driving normally or briefly getting on the skinny pedal. so to answer my own personal question regarding just what i can safely(ish) get out of my hawkeye 06 WRX.. i should be ok aiming for say 300-325bhp assuming engine has no hidden underlying issues, its mapped well (id probably retain the standard rev limit) and measures are taken to ensure engine remains as cool as possible. does this sound accurate to you guys with experience on the 2.5's? im not looking uber fast just enough to walk a standard STI lol
i will be looking to drop in forged pistons at some stage. i was hoping i could avoid it but for safety/reliability and most importantly peace of minds sake i should stick a set in at some point but for the time being i should be safe to throw an intake/exhaust on the car, maybe some cooling mods, and a conservative map by a good tuner.
my last question.. am i safe enough to chuck in an exhaust/intake and maybe a manual boost controller and up the boost a few psi on the standard ECU/maps or will the ECU not compensate the fuel mixture and risk grenading the engine? if this is a grey area knowledge wise i could stick my wideband on the car and closely monitor AFR while incrementing boost higher ever so slightly..
EDIT: one more thought here, if the 2.5 WRX is slightly higher CR than the 2.5 STI then in theory the WRX pistons should be marginally more robust as theres more material on the top of the piston no?
Mick
23 July 2013, 09:57 PM
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ok so pistons are essentially the same then. any info on the difference between WRX and STi in those respects?
shouldnt be any major difference in attainable HP from either from a tuning point of view if going for a mild 300bhp setup? one should be just as safe (or unsafe) as the other?
shouldnt be any major difference in attainable HP from either from a tuning point of view if going for a mild 300bhp setup? one should be just as safe (or unsafe) as the other?
Last edited by DmcL; 23 July 2013 at 10:00 PM.
23 July 2013, 11:07 PM
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Sorry the link won't paste / copy from my iPhone
Basically showing differance from pistons
Stick to the fundamental's
The reasons why they fail
What can be done
Any re occurring issues
Tell tail sighns / prompts
Solution
Yes , it's a big can of worms
Basically showing differance from pistons
Stick to the fundamental's
The reasons why they fail
What can be done
Any re occurring issues
Tell tail sighns / prompts
Solution
Yes , it's a big can of worms
23 July 2013, 11:28 PM
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differences aside either variant of the engine should handle similar power with similar mods/tuning/uprating?
what im wanting is reliability as close to standard as possible but also bump up HP to as near to 300bhp as possible given the goal of a reliable DD without forging. basically looking to make the most potent setup possible without risking piston/ringland damage so some choice cooling mods may be in order.
to help quash any temp related issues i can wrap the downpipe (guessing headers would need to be off to be wrapped), fit a lower temp thermostat, ensure any intake i build/fit is drawing cool air (always do this anyway) and avoid sustained high speeds. additionally i may fit a larger scoop and/or larger TMIC and maybe one or two other little tweaks, perhaps shim the bonnet and/or rim out a section of bonnet seal at the back for added ventilation. done this on a few cars and always works nicely.
also has anyone tried using electric fans on the IC to help pull the air in? perhaps at speeds where the scoop would otherwise be ineffective or even get them set to kick in when the radiator fan/s kick in? would take some digging to find a couple suitable size/power 12v fans though id imagine.
what im wanting is reliability as close to standard as possible but also bump up HP to as near to 300bhp as possible given the goal of a reliable DD without forging. basically looking to make the most potent setup possible without risking piston/ringland damage so some choice cooling mods may be in order.
to help quash any temp related issues i can wrap the downpipe (guessing headers would need to be off to be wrapped), fit a lower temp thermostat, ensure any intake i build/fit is drawing cool air (always do this anyway) and avoid sustained high speeds. additionally i may fit a larger scoop and/or larger TMIC and maybe one or two other little tweaks, perhaps shim the bonnet and/or rim out a section of bonnet seal at the back for added ventilation. done this on a few cars and always works nicely.
also has anyone tried using electric fans on the IC to help pull the air in? perhaps at speeds where the scoop would otherwise be ineffective or even get them set to kick in when the radiator fan/s kick in? would take some digging to find a couple suitable size/power 12v fans though id imagine.
Last edited by DmcL; 23 July 2013 at 11:29 PM.
23 July 2013, 11:53 PM
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Motorbike fans work a treat , ideally located on bulkhead , above turbo etc etc
But you are missing the point m8
We all want lower temps in the engine bay
But ringland fracture is ultimately caused by the internal engines blueprint
The way it is able to deal with expansion / contraction of its operating components . What tolerances it has , & what it can deal with . . There are many factors to throw in .
Putting a large scoop on & fitting a rad cool panel will do **** all to change that .
That's my 2p worth
But you are missing the point m8
We all want lower temps in the engine bay
But ringland fracture is ultimately caused by the internal engines blueprint
The way it is able to deal with expansion / contraction of its operating components . What tolerances it has , & what it can deal with . . There are many factors to throw in .
Putting a large scoop on & fitting a rad cool panel will do **** all to change that .
That's my 2p worth
24 July 2013, 12:30 AM
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so ringlands can simply let go if combustion temps rise above a certain level which is loosely dictated by bhp/tuning or operating temps? doesnt seem like its got nearly as much of a safety margin before potential failure as it should? if thats the case then thats **** poor engineering.
also lower bay temps = lower engine temps to an extent so allthough they wont have an effect on instant heat such as combustion events they would help to reduce overall operating temps which would have a very minimal affect on combustion temps as would a cool/cold air intake and improved IC cooling. cooling tweaks would be more of a "prevent engine from running hot" sort of thing, not an effort to reduce combustion temps as boost is increased, etc, etc as theres not much you could do there unless looking into water/meth injection or something along those lines.
regarding the small fans, i mean mounting them directly onto the IC to force airflow wen stopped and potentially also when at speeds high enough to make the scoop become ineffective on its own.
just thinking up possible solutions to known issues and whatever turns out to be good or seems worthwhile bang for buck wise i will most likely do.
also lower bay temps = lower engine temps to an extent so allthough they wont have an effect on instant heat such as combustion events they would help to reduce overall operating temps which would have a very minimal affect on combustion temps as would a cool/cold air intake and improved IC cooling. cooling tweaks would be more of a "prevent engine from running hot" sort of thing, not an effort to reduce combustion temps as boost is increased, etc, etc as theres not much you could do there unless looking into water/meth injection or something along those lines.
regarding the small fans, i mean mounting them directly onto the IC to force airflow wen stopped and potentially also when at speeds high enough to make the scoop become ineffective on its own.
just thinking up possible solutions to known issues and whatever turns out to be good or seems worthwhile bang for buck wise i will most likely do.
Last edited by DmcL; 24 July 2013 at 12:34 AM.
25 July 2013, 12:10 AM
#24
this is the sort of story im hoping to hear.. setups running for some length of time on standard internals with no issue.
were any/all cars equipped with an AOS and mapped by a good tuner (not necessarily a popular one as popular doesnt automatically equal good). also how many of these cars were 2.5's as thats mainly what im interested in as we all know the 2.0 is a bit more sturdy or so everyone says.
even being a newbie to scoobs having heard the good old chocolate pistons jokes before i got my WRX and from reading what little i have so far since getting mine on friday past id have to be inclined to agree there. though from my tuning background (old BMW's not subaru's) and seeing in general just how many of the average joes get one pulled over their eyes by cowboy tuners it makes me wonder just how many cases of 2.5's failing when modded are actually down to the engine itself and not the tune or even the owner not looking after it properly or what have you.
i know its comparing apples and oranges here but from territory im more familiar with the mid 80's BMW M20B25 (6 cyl 2.5) can handle mucho boost with standard internals even being an originally n/a engine. on those the main failure points with boost are headgaskets so the popular fix (and what ill be doing to my turbo 325i in progress) is to weld the water jackets in the head as they can flex due to their design and subsequently allow the gasket to push out in that area. secondly they all like to O ring the head (easier than doing the block as head is aluminium). with water jackets welded, head O ringed and ARP headstuds the bottom end is good for over 500whp, some have even ventured over 600whp. and that is with the standard CR of 8.8:1. anyway getting somewhat back on topic.. the main killer of the weakpoint on these (headgasket in this case) is bad tuning. when the tune is good the gasket holds, within reason anyway.
this is what im trying to sus out about the EJ255/257, pistins/ringlands may be a weak point but im betting the failures have a cause and arent just random.
from what i read its a slightly different kettle of fish for the hatchback and newer EJ255/257, possibly a change in production methods for parts or something? maybe someone can elaborate on why more of the 2008ish onwards 2.5's seem to fail than the older 2.5's like in the hawk.
wanting to dispel fact from fiction on these engines so people will know what they should safely be able to make without major risk of the engine grenading itself. also because i have a 2.5 hawk and im itching to start playing with it but its my DD while the 325i is being built up so i dont want it to go pop without another car as a backup lol
were any/all cars equipped with an AOS and mapped by a good tuner (not necessarily a popular one as popular doesnt automatically equal good). also how many of these cars were 2.5's as thats mainly what im interested in as we all know the 2.0 is a bit more sturdy or so everyone says.
even being a newbie to scoobs having heard the good old chocolate pistons jokes before i got my WRX and from reading what little i have so far since getting mine on friday past id have to be inclined to agree there. though from my tuning background (old BMW's not subaru's) and seeing in general just how many of the average joes get one pulled over their eyes by cowboy tuners it makes me wonder just how many cases of 2.5's failing when modded are actually down to the engine itself and not the tune or even the owner not looking after it properly or what have you.
i know its comparing apples and oranges here but from territory im more familiar with the mid 80's BMW M20B25 (6 cyl 2.5) can handle mucho boost with standard internals even being an originally n/a engine. on those the main failure points with boost are headgaskets so the popular fix (and what ill be doing to my turbo 325i in progress) is to weld the water jackets in the head as they can flex due to their design and subsequently allow the gasket to push out in that area. secondly they all like to O ring the head (easier than doing the block as head is aluminium). with water jackets welded, head O ringed and ARP headstuds the bottom end is good for over 500whp, some have even ventured over 600whp. and that is with the standard CR of 8.8:1. anyway getting somewhat back on topic.. the main killer of the weakpoint on these (headgasket in this case) is bad tuning. when the tune is good the gasket holds, within reason anyway.
this is what im trying to sus out about the EJ255/257, pistins/ringlands may be a weak point but im betting the failures have a cause and arent just random.
from what i read its a slightly different kettle of fish for the hatchback and newer EJ255/257, possibly a change in production methods for parts or something? maybe someone can elaborate on why more of the 2008ish onwards 2.5's seem to fail than the older 2.5's like in the hawk.
wanting to dispel fact from fiction on these engines so people will know what they should safely be able to make without major risk of the engine grenading itself. also because i have a 2.5 hawk and im itching to start playing with it but its my DD while the 325i is being built up so i dont want it to go pop without another car as a backup lol
24 October 2017, 04:13 PM
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400WHP with no internal modifications on a 2.5!?
Now I don't normally say things as direct as this against a tuner that has the reputation of Crawford - but that is utter bollocks! I should I say it's utter bollocks if you want anything remotely reliable.
Surely that statement from Crawford has been taken out of context..... surely.
Now I don't normally say things as direct as this against a tuner that has the reputation of Crawford - but that is utter bollocks! I should I say it's utter bollocks if you want anything remotely reliable.
Surely that statement from Crawford has been taken out of context..... surely.
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