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Is the 2.5 litre engine really that bad?


Benjijames28
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As you may have seen in my other threads, i am looking for my first Scooby.

Up to now, blobeye has been my choice. Mainly due to the older 2.0 engine having the better reputation for reliability.

 

What i want to know is if the 2.5 is really that bad and that much of a risk?

 

I can pick up a much lower mileage hawkeye for the same money as a good blob eye.

 

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yep if you can find a 05 its cheap insurance band,not many about though,from what i have seen most the problem was when they first bought sti suffered from ringland problems and wrx head gasket problems,if you do a lot of reading from usa and australia its mostly down to the new owners hammering them as soon as they got them,not looking after them right.their is plenty of info from tuners from their and their thoughts on it.i personally think if you got a hawk wrx with a good service history and been look after then if head gasket has not gone by now you probly going be ok with it,but not 100%,i have had 2 hatch wrx and first one headgasket gave up and it was standard but you could tell with how dirty engine was when i got it that it had not been look after and i sould have walk away from it and it was a lot cheaper then the rest,my hatch now 320bhp and no problem but was look after as it was a cumbria subaru club member car.but they are sport car and dont matter if its a 2.0l or a 2.5 if the head gasket is going to go then it will,you take a chance with it when you buy any car like this as you  have to think its most probly been hammered at some point in its life.

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The subaru specialist i use warned me the 2.5s are not as reliable as the 2 litres evan the newer warns,when i was looking for a subaru the amount of adverts for 2.5 cars that said new engine fitted or rebuilt headgasket recently done was incredible hardly ever saw one for the 2 litre,the new model impreza wrx which is out in 2018 is going back to 2 litres ?as Aucky said they are a performance car and how they have been serviced and looked after counts for reliability down the line😀

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if your after a hawk,dont no how much you want to spend but their is some nice one's out their something like this  http://www.ebay.co.uk/itm/2007-Subaru-Impreza-WRX-Roger-Clark-/262818532229?_trksid=p2141725.m3641.l6368  not sure if its right but I remember think it was a member on here that told me the hawk as the ej207 engine in and that suppose to be a good one,sure some one with more noledge with the engine type can tell you more about that.

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On 1/23/2017 at 0:38 PM, aucky said:

if your after a hawk,dont no how much you want to spend but their is some nice one's out their something like this  http://www.ebay.co.uk/itm/2007-Subaru-Impreza-WRX-Roger-Clark-/262818532229?_trksid=p2141725.m3641.l6368  not sure if its right but I remember think it was a member on here that told me the hawk as the ej207 engine in and that suppose to be a good one,sure some one with more noledge with the engine type can tell you more about that.

Hawks have 2.5...unless JDM? from what I'm aware?

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  • 2 weeks later...

Get a hawk, get the engine forged and you will have the better engine and it will be reliable, they really are a gamble otherwise, there is no hard and fast rule to why/when the 2.5 break, mine was bought already broken with a meticulous service history

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On 1/27/2017 at 3:56 PM, Seminole81 said:

Hawks have 2.5...unless JDM? from what I'm aware?

Yep, UK/euro hawks wrx and sti are 2.5.

 

the one linked will have had ringland failure, mentions overbore which will be because of liner damage when the ringland failed.

 

As said, 2.5 out the box is a big of a dog, can be nice and sweet all its ife or one day just jumps up and bites you. Headgaskets and ring lands are the biggest problems. That said built it right and its a cracking engine for road use.

 

Standard block will do 450bhp without loosing reliability, closed deck convert it and your up to a reliable 550bhp. but by the time you get that far your talking mega bucks to build and in supporting mods.

 

When the 2.0 wore out in my type R i;ve had a closed deck 2.5 put in it and boy does it go well :D

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7 hours ago, Tidgy said:

Standard block will do 450bhp without loosing reliability, closed deck convert it and your up to a reliable 550bhp. but by the time you get that far your talking mega bucks to build and in supporting mods.

 

When the 2.0 wore out in my type R i;ve had a closed deck 2.5 put in it and boy does it go well :D

Yep. How much £ you talking roughly to hit 550whp? I mean 450 you could technically do (unreliably obviously) on a stock engine with just a front mount and bigger turbo yeah?

Does anyone know what the standard STi hawk gearbox is able to hold (safely) without changing syncros etc.

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1 hour ago, Seminole81 said:

Yep. How much £ you talking roughly to hit 550whp? I mean 450 you could technically do (unreliably obviously) on a stock engine with just a front mount and bigger turbo yeah?

Does anyone know what the standard STi hawk gearbox is able to hold (safely) without changing syncros etc.

Bit of a novel upcoming response but hope the reason makes sense. Also bear in mind while so of this is fact, alot of the 'better' options are personal preference and there is no right or wrong answer.

 

whp is typicly US value and is major over eged.

Fly wheel BHP is the typical measure, at the road you loose roughly 23-25% (very rough figure, alot of things affect it condition of gearbox, oil thickness in the gearbox, any loses through the diffs etc etc)  so 550bhp at the wheels will be 700bhp at the fly based on a 25% as an easy figure.

What the stock engine will do is very dependant on where the starting point is. A jdm is 2.0 and has proper forged pistons so will prob do 450 with bolt on's. 6 speed box has the synchro weakness as you say, but typicly not an issue.

But there's also more to it than that. Car use has a big difference to how you would achieve it.

A race car will be belt and brace, possibly Linered closed decked etc etc masive list of supporting mods, coolers, etc etc mega overspeced and then run at lower power to try to retain reliability. Most top race cars, eg gobstopper, have a refresh after every event and can still fail. They typically run at high revs and high boost so generate alot of heat and wear quickly.

A road car is a very different kettle of fish. You need to look at matching gearing and engine. If they mismatch you could find the ratios mean the turbo can;t spool up before your changing gear (i had this issue on mine when i was running a 2,5 on short ratio 5 speed box, the torque the engine was producing meant the turbo couldn't keep up so the car pulled harder in 3rd and 4th than it did in second)

For a road car there is a phrase, 'there's no replacement for displacement'.

 

So to answer your question,

450bhp at the fly is a good figure for the road. A 2.5 is my personal preference (why i went that route), they produce considerably more torque than a 2.0 so have power lower down the revs. EG 2.5 400bhp/450fltb, 2.0 400bhp/350ftlb or a mix there of. I'm running 398bhp/465ftlb. Combined with the right ratios (im on a uk hawk DCCD box) they are fantasic on the road.

So let say you go for 450bhp on a 2,5. A reliable 450 which is the key to it

Your gonna be looking £4.5-5k for a built 2.5, forged piston, rods, head gaskets, acl race bearings, arp headstuds. (possible additional if heads need rebuilding).

Then you need to look at what else you need to get there, it will only perform as well as the weakest part,

Option to closed deck the block £500

turbo £2k

Front mount £2k

Injectors £400

Fuel pump £200

Inlet pipe £250

Decat £600

syvecs (ECU struggles to cope at this level) and other options are available, but IMO not as good, £2500 inc installation and mapping

Clutch £1000

fuel pressure reg £250

3 port boost solenoide £100

4bar map sensor £200

 £13,000

 

then add in all sort of ancillarys that are advisable to do, oil and filter, water pump, oil pump, cambelt and tensioners etc etc

and your prob up to £14k give or take. works out alot of money when you look at whats involved.

Pick up your chin now lol

 

Can you get there cheaper? yes you can, will it last as long and be as reliable? 9 times out of 10 nope.

 

 

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Makes sense. I had about £5-6k roughly in my head spent to rebuild engine and upgrade turbo and a front mount, that's with no labour though as I'd do it myself (aside from machine work etc.) Figured it'd be able to hit 450ish easily and reliable. Didn't think about ECU though. I've got a few bits and bobs, like the APEXI AVCR and a Sard FPR already. Probably would pick up things like the decat off forums etc. as I wouldn't be bothered about those being new. All future plans mind. Happy enough running stock for time being. Was hoping to spend about £10k and get a full respray done as well (including engine bay while it was out).

My God you sound like a Yank with that "no replacement for displacement" statement! Haha! Of course there is...massive turbos and power to weight ratio goes a long way! Never forget my mate who had a hawk STi with a FP Green on it (supporting mods, front mount and that's about it really) Stateside that raced a hillbilly with a V8 Camero. V8 boy thought it was the best thing ever because he had a K&N filter and straight pipes (obviously this adds like 100hp to his LS1 engine which is the best engine ever). Put $500 on the race because there was no way a little 4 banger could keep up with a V8, needless to say, the Subaru walked all over him and the V8 kid couldn't believe it. Asked my mate what his car was running on and he just said "hopes and dreams and tears of people like you" hahaha

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1 hour ago, Seminole81 said:

Makes sense. I had about £5-6k roughly in my head spent to rebuild engine and upgrade turbo and a front mount, that's with no labour though as I'd do it myself (aside from machine work etc.) Figured it'd be able to hit 450ish easily and reliable. Didn't think about ECU though. I've got a few bits and bobs, like the APEXI AVCR and a Sard FPR already. Probably would pick up things like the decat off forums etc. as I wouldn't be bothered about those being new. All future plans mind. Happy enough running stock for time being. Was hoping to spend about £10k and get a full respray done as well (including engine bay while it was out).

My God you sound like a Yank with that "no replacement for displacement" statement! Haha! Of course there is...massive turbos and power to weight ratio goes a long way! Never forget my mate who had a hawk STi with a FP Green on it (supporting mods, front mount and that's about it really) Stateside that raced a hillbilly with a V8 Camero. V8 boy thought it was the best thing ever because he had a K&N filter and straight pipes (obviously this adds like 100hp to his LS1 engine which is the best engine ever). Put $500 on the race because there was no way a little 4 banger could keep up with a V8, needless to say, the Subaru walked all over him and the V8 kid couldn't believe it. Asked my mate what his car was running on and he just said "hopes and dreams and tears of people like you" hahaha

haha, you can get a 2.7 kit as well :D

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