After deciding i would go for the 2.5 conversion, i've been gathering the parts over the last couple of months, i was wondering if anyone could let me know what else i should be looking at replacing.

It's true what everyone said, the costs do seem to increase continuously and theres always something else that is needed.

Time wise as well, its taken longer than hoped, money being the limiting factor. However after a ride in a 2.5 conversion, this is very much what i want to go for so any more help would be appreciated.

The car is a 94 wrx sti v1
Current items sat in the dining room are,

2.5 short motor
Andy F TD05/06 Turbo
Hybrid FMIC (on its way) and catch tank
HKS Mushroom induction kit
Blitz Nur spec r exhaust
HKS downpipe
Denso 550 injectors
knock link and lambda link
oil and water temp guage
oil pressure guage
boost guage

Looking to get EJ25 heads converted to turbo spec and the cams reprofiled to wild road spec. Also looking at CP pistons and pauter rods.

The clutch will be replaced with an organic one at time of fitting the engine as will an uprated fuel pump.

Any ideas, suggestions, problems or comments anyone can see with this, please say now, before i go ahead with it.

I'm not very mechanically minded, only know what i've read on here so any hel would be appreciated.

Cheers Craig

 

Forgot to say, it will hopefully be mapped by andy F with the apexi fc and i'm also on the lookout for headers, just not sure which ones to go for.

Cheers Craig

 

i am thinking of a similar project soon so good luck mate.
what you doing about gearbox? weak point i have been told.


cheers david

 

fit a six speed

 

Think I might have to go with the six speed, surely it just won't last otherwise. £2200 is quite cost, but suppose if the whole things got to be done properly.

 

Craig

If you are looking for around 400 bhp then I wouldn't worry about wild cams or fancy heads, your WRX Sti heads will do the job just fine. Also, the CP pistons and rods are a bit overkill at this stage too.
I'd make the 6 speed box your next priority then get it up and running A genuine 400 bhp on a 2.5 has loads of torque and very little lag, it makes for an exceptionally quick car

Andy

 

Ditto what Andy has said.

 

Been told the early wrx heads would need changing because of being hydraulic lifter heads and having the wrong combustion shape.

 

Craig, if the motors got to be built up from bits (which it has) and you can afford to do the pistons,rods & cams now, it saves the expense & hassle of removing the engine later when your 400 bhp target suddenly moves (it will ). Save yourself money and do it all now if you can afford to. Gearbox can be added later alot easier than pistons,rods & cams can, then you can turn up the boost, when your gearbox is fitted

As for heads, I bought additional ones so I could sell my original engine in one piece and thats a good chunk of money back against all of the bits you have bought for the 2.5

Conrad

 

Doesn't the engine have to be removed to fit the gearbox anyway? Like i said, i'm not the one with all the knowledge so just want any ideas really. Cheers all.

 

No engine can stay in place.

 

I would not do the pistons, rods, cams on an EJ257, as the headgaskets will pop pretty much before anything else becomes a problem I reckon. Limit it to 400/400 and it should be fun and hold together, as well as being relatively cheap. It is very easy to introduce other problems by introducing unnecessary "upgrades". IMHO there is simply no need to go faster on a road car, it becomes too much for the rest of the car and is frankly silly, and you are well into diminishing returns country if you try.

 

Cheers John, what about the heads though, will i have to change these for newer version?

 

Wouldn't bother, just need the right headgasket thickness to get a sensible compression ratio, probably the thicker 1.6mm gaskets, R19KET posted the numbers in another of these 2.5 threads for phase I.

 

Early WRX heads have made over 400bhp on a 2.0, it will not be a problem on a 2.5.
What is the rpm red line on your Sti v1 engine ? If it's 7500 then you probably have a shimmed set up anyway, not hydraulic tappets.

If you are looking for much more than 430bhp on the EJ257 then in addition to the pistons, rods and cams that Conrad advises you will also need matching cam followers, shims, springs, caps, bigger turbo, bigger injectors, paddle clutch, head studs and finally a second car for when its off the road with blown head gaskets.......but hey don't let me stop you

Andy

 

is it not your ion tubo that keeps popping the gaskets plus wont you ad a little more boost to your car than what you would when you were mapping just a thought not criticism

 

Cheers everyone, not after the huge power figures everyones talking about, 400/400 would be more than enough. It needs to be reliable and hold together more than anything. Is there anyting missing that i should add to the list?
Cheers Craig

 

Andy, I am pretty sure all early wrxs were 7000, all those with the early type manifold were for sure.

The sti 2 still had hydraulic tappets but that redlines at 7500. Not sure about the sti 1.

on a more general note, I completely agree with andy and John on this. Having driven my car extensively at around that power out now, I simply don't believe a car as light as the impreza needs anymore than 400 of each. A genuine 400lbft is something very special. Also with targets at that level you can use a smaller turbo with incredible spool characteristics. For a lot less money overall you will end up with a much much faster car on the road.

Conrad has a point and you may start wanting more power, but you really would do well to listen to those who have done it and try to keep your power goals at a sensible level. Diminishing returns doesn't strongly emphasize just how much more it will cost you for ultimately a drop in drivability and performance.

If I could turn back time, it would definitely be a standard ej257 with standard heads and a well chosen turbo.

Think I would still run the pectel though

 

Steve, I've popped gaskets on the 20G and the iON, both when running higher octane and boost. 400/400 gives a 10-20% margin from the popping point as best as I could determine. Going faster than you ever need is nice (400/400), going stupidly fast and breaking things is not funny

 

Cheers Adam, still not totally convinced though, my WRX Ra (non Sti) was a version 1 with a 7500 rpm limit and had solid followers.

Andy

 

Lets clear one point up, its a NA EJ25 short motor that craig has not an EJ257 with the dodgy headgaskets problem. I would still recommend changing the pistons to ones designed for use in a turbo application and it would be even better with the original heads that have been reworked for turbo application. OEM cams (from EJ25) will need reprofiling if these heads are used or alternatively use your WRX heads as discussed by Andy.F

Conrad

 

Most common failure mode of the NA EJ25 engines wherever I asked? You guessed it...

All the EJ25s that were about that we were all trying to get cranks off to make stroker engines? Warranty claims for...

How many turbocharged EJ25s have run decent mileage at >400/400?

 

Sell the ej25 motor and buy the ej257, ej25 is a dead duck for 400lb unless you spend 2k plus on it.

The 257 also has the rather novel feature of being built by someone who knows what they are doing.

 

EJ25 ! oops ! In that case I would also advise pistons and rods.
I wouldn't be too quick to dismiss the cams though, NA cams are normally running more aggressive profiles than turbo engines.

Andy

 

Andy F, I think from the measurements I took on the cams they might be a little too wild for turbo spec.

John B, If there heads are turbo heads or the standard ones are modified to suit turbo application I cant see any problems.

And as for Hypoluxa's comments...

Crawford Performance in the USA would disagree with you and they have built far more EJ25's than than i suspect you have The weak link is the liners but thats no different on the EJ257 when pushing for big power. Keeping the boost at sensible levels and all will be well on standard liners. As for the EJ25 heads the ports on these are way better than standard turbo heads to start with.... but Craig has the option of either.

Conrad

 

How many EJ257's have the same problem????


Care to expand....


How many EJ257's have the same problem????

 

I think we might be talking at cross purposes a bit and actually agreeing... I thought the guy had an EJ257, so questioned whether it is wise to chase >400/400 no matter what the internals because of potential headgasket troubles on the semi-closed deck block and factory liners.

I can obviously see the point in upgrading the NA EJ25 internals to turbocharge. What I think is dubious is chasing over 400/400 on either the EJ25 or EJ257 when still on factory liners and open or semi-closed decks. The EJ25 is famous for losing headgaskets even at standard power, normally aspirated. The EJ257 is getting that way at raised power, at least with classic heads. I seriouly doubt the need to upgrade the pistons and rods in an EJ257 as I think the headgasket is the weak link having popped the headgaskets on 7 bores and cracked 1 piston - limited sample and all that of course, but others experience seems to back this up at least on Phase II heads. Better going for a linered or CDB instead?

 

Whoa, easy guys, now i'm really confused. Can someone please clarify what I should do? Conrad knows the short motor in question, but just need clarification on where to go from here.

 

wrx 7000
wrx ra 7500
ver 1 sti 7000
ver 2 sti 7500

Rob

 

Yes i think we are actually in agreement after all that.

Craig,

1. you will need to upgrade the pistons & rods in the EJ25 short motor.
2. You can either use the EJ25 heads with the short motor after converting them to turbo spec or alternatively use your WRX heads but take a close look at water ways between heads & short motor depending on which heads/headgasket gasket you go for.
3 Cams, you could use the EJ25 cams but they will be too wild IMHO or use your existing WRX cams. If going for 400/400 then I believe Andy and John think the standard items will do the job.