hey guys

I have a very limited amount of knowledge on the whole engine building subject. I have a 2002 WRX with the stock 2.0L block and I have bought a used EJ257 shortblock to replace mine with. I am running a FPgreen and cannot take the lag any longer.

I have searched around a bit and found many different views about what and how to approach a 2.0 to 2.5 block swap.

I have the following already:

2.5 Sti 2004 shortblock (all stock internals) around 15k on the motor
ARP head studs
Sti head gasket kit
installation date (last week of April)
tuning and dyno session date ( 2nd week in May -Topspeed)

What else could I benefit from to yield a complicated free install and safe install?

Are my 2.0 heads gonna do well with this block? I have seen different opinions on this subject.

Upgraded timing belt?
How about upgraded cams? need'em?
Looking to make solid power, but nothing nuts. ~375 ish

Thanks for any constructive input

the pistons in the STi block arent gonna work w/ your heads. i believe the dish in the 2.0 head is large. your compression ratio wont be squat. check out www.crawfordperformance.com for pictures on STi pistons then STi pistons using wrx head. Basically, what im saying is your gonna have to get new pistons from the manufacturer of your choice, to raise the compresssion ratio.

the pistons in the STi block arent gonna work w/ your heads. i believe the dish in the 2.0 head is large. your compression ratio wont be squat. check out www.crawfordperformance.com for pictures on STi pistons then STi pistons using wrx head. Basically, what im saying is your gonna have to get new pistons from the manufacturer of your choice, to raise the compresssion ratio.


Thats not true at all, your compression ratio will be around 8.7:1 ish I believe. The stock Sti block with stock internals will swap over fine. You can however opt for lower compression pistons, which you could benefit from if you plan on running a lot of boost. 25+psi.. You just will need a tune that accompanies the higher compression ratio.

You can get cams such as crower, dpr, or helix, I would personally go with helix just because the value, they come with upgraded valvetrain also for just under $1000.

There are lots of threads about 2.0 heads with 2.5 block and compression ratio, you should take the time to read them and decide what you feel would be best for you.

sealant
torque wrench
motor stand
I think the arp stud nuts are 1/2 inch 12 point(you'll need that socket).
Set of 21-30 mm deepwell sockets(oil filter stem).
set of allen head sockets(up to 10mm)
couple cans of brake clean
towels
torque specs and pattern for the head bolts and cam cap bolts.
clutch alignment tool
large c-clamp for the belt tensioner
parmanent marker to label the buckets before they fall out
gasket scraper or razor blades are always nice

That's all I can think of right now.

Thats not true at all, your compression ratio will be around 8.7:1 ish I believe. The stock Sti block with stock internals will swap over fine. You can however opt for lower compression pistons, which you could benefit from if you plan on running a lot of boost. 25+psi.. You just will need a tune that accompanies the higher compression ratio.

You can get cams such as crower, dpr, or helix, I would personally go with helix just because the value, they come with upgraded valvetrain also for just under $1000.

There are lots of threads about 2.0 heads with 2.5 block and compression ratio, you should take the time to read them and decide what you feel would be best for you.
i guess i was backwards....itll raise your compression ratio. i guess its not that much. .5 point or so. Either way...your running an FP green, you'll break the stock STi piston ringlands sooner or later. if it was me, get a new set of forged pistons. if you dont and break a ringland later, youll pay more then and essentially do the job twice. i guess it depends on how much money you have in your budget. Sorry to mislead you initially.

i guess i was backwards....itll raise your compression ratio. i guess its not that much. .5 point or so. Either way...your running an FP green, you'll break the stock STi piston ringlands sooner or later. if it was me, get a new set of forged pistons. if you dont and break a ringland later, youll pay more then and essentially do the job twice. i guess it depends on how much money you have in your budget. Sorry to mislead you initially.

I agree while you have the block out you might as well do it right the first time. Get forged pistons and not have to worry about those ringlands breaking, and if you feel like you need to get pistons that will match up with the 2.0 heads. I should post a picture of the piston that came out of my block almost all the way around it took a big chunk off. Maybe once I start my build ill get some pictures up here.

how long does it take for ringlands to break? Buddy of mine with a big 35R puts out 448whp on stock motor, has 39k on the motor and ran an 11.6 @ 121 at the drag strip.

how long does it take for ringlands to break? Buddy of mine with a big 35R puts out 448whp on stock motor, has 39k on the motor and ran an 11.6 @ 121 at the drag strip.

I think the general census on ringlands is that it is the weakest part of the "stock" motor. Having said that, I have seen many people making big power numbers with stock pistons. I think its just a matter of whether your tune is spot on or not.

I will throw my two cents in....


I am running a 2.5L block, WRX heads - ported, helix 264 cams. weisco piston and STi head gaskets with a VF22 and front mount.

the heads cc'd in around 51, so we figured a CR of about 9.1:1 ish with the STi gaskets. I wanted to use cometics, but they didn't get here in time.

I have about a thousand miles on the motor, at 320 hp, 340 ft/lbs.

IMHO, spend the money while the engine is out on the things farthest from a wrench. like the crank, rods, bearings, pistons.

i would also reccomend getting the kevlar reinforced STi timing belt. if you're goign to run cams, and there is no reason not to, protect your investment with a good timing belt.

no sense in putting a stock replacement timing belt on a motor you just spent an untold amount of money on.

like i said, spend the money on the farthest thigns from a wrench.

some of the locals here laugh at my VF22 and they are running greens or bigger on a stock bottom end. who's going to have the last laught after 20K miles of running the hell out of thier car? me or them?

spend the money in teh block. you will be glad you did later. I'd rather get laughed at for a VF22 now, and be saving up for a bigger turbo later on, than get a big turbo now and be fast for a few months then grenade my stock short block. you dig me?

i'm rambling, time for bed. hope that helped. feel free to IM/PM me if you'd like to get some pointers, tips and tricks.

Thanks for all the great responses guys.

I think what I would like to for now is keep the block stock due to the cost. I realize forged pistons and upgraded ringlands would be better.

I guess what I really need to know is - Can I swap a 2.5 in for my 2.0 and not do anything to the heads, and drive away? Will I be dissapointed coming from my 2.0 "power"?


If it helps I have:

FPgreen
TXS FMIC
PE800 inj
Cobb AP - Protuned by Doug @ Topspeed (325whp, 293tq -93oct)
Perrin Bigmaf
Perrin 3" inlet
TXS DTEC boost controller
APS down, up, TBE
Turbonetics EXt WG 40mm
Exedy hyper clutch
ACT lightweight flywheel
Vishnu lightened pulley

Thanks

Here's something taken from a recent thread that might help you. The entire thread can be viewed here:
http://forums.nasioc.com/forums/showthread.php?t=958323&highlight=helix+cams

Copy that. I put in a stage #2 - 2.5 with stock heads. I've spent way more money trying to figure out why it wont mak whp at $250 per hour of dyno time. The solution after 1,200$ is the wrx heads don't work with a 2.5 sb. Wish I would have done the heads while I had the engine out, to begin with.
wrx heads are bad ju ju for the 2.5 anyway. Do it right now and save a lot of money.

We're of the same opinion; running the stock WRX heads with the 2.5L SB doesn't yield a whole lot more power but it does yield a much fatter midrange torque band. We've installed and tuned the Helix 264s w/ valve train in the WRX heads on a 2.5L SB more than a couple times now and have been very impressed with the results. I wouldn't say that these cams make the WRX heads equivalent to the STi heads (since the AVCS makes a lot of midrange power and torque) but from our results, it appears that these cams make the WRX heads capable of having higher peak airflow. For the price, they're an excellent option that lets you use your WRX heads and still optimize the 2.5L block. As for gasket thickness, we use the .051 for this hybrid.

Thanks,

Geoff

A few other comments. I'm fairly certain your ringlands will actually be fine running a Green on a stock 2.5L block. While we consider the ring lands and the bearings to be the weakest points of the USDM STi block, we still rate it as being able to handle 465 CHP consistantly. I don't think you'll be able to get more than 420 CHP out of a green on 91 octane (even with the STi AVCS heads) but I don't know what type of octane you'll be running and how often.

how long does it take for ringlands to break? Buddy of mine with a big 35R puts out 448whp on stock motor, has 39k on the motor and ran an 11.6 @ 121 at the drag strip.

You can't really put a time period on it because it depends on your tune, how hard you drive your car and what octane fuel you use. We just tuned a stock block STi with our GT30R kit the other day and it made 404 WHP (low reading Mustang 4WD dyno) on 98 octane. That's about 485+ dynojet WHP and the motor is still OK but we don't expect it to last long.

So in short, I think you'll be fine with your stock block but I would recommend doing the cams. As someone also suggested, you might also want to do a PE or Greddy timing belt since those are about the same price as stock but are much better.

Thanks,

Geoff

Awesome Geoff , thanks! i am now looking into a reasonable priced upgraded cams.

Don't mention it. I'd have to plug the Helix cams there. I won't post a price here but they're the most affordable complete cam / valvetrain solution we've come across that produces excellent results. They include cams, ti retainers, springs, and spring seat locators. Some other popular choices are Crower, Kelford, and Cosworth.

Thanks,

Geoff

I will put in a plug for the helix cams too....

on a 2.5L, with WRX heads, they do make great mid range TQ.....

i was very pleasantly suprised with how much mid range my motor had. PM me for dyno graph.

Thank you - after much researching and a fair quote on the Helix cams, I believe I will be pursuing those. Thanks again guys and I will repost after the swap has started.

sorry to highjack your thread but i also will be doing a 2.5 block/2.0 heads swap shortly. which timing belt is needed? wrx or sti? and are new head studs neccessary?

sorry to highjack your thread but i also will be doing a 2.5 block/2.0 heads swap shortly. which timing belt is needed? wrx or sti? and are new head studs neccessary?
The belts are the same.

Guys please do some searching. I did my entire 2.5L swap without posting a single question. Everything and THEN SOME is in these forums.

Correct, Heads studs and timing belt are the same.

-Geoff

Stock head studs will work just fine from what I understand as long as you aren't boosting 25+ psi and then again some are still holding.

Little update here:

knee deep into the swap - everything is going pretty well, we decided to do the tumbler deletes in the process.

Stripped a cam bolt and damaged the pulley trying to get it out. New one is ordered and will be arriving tomorrow. :rolleyes:

EJ25 block has most all sensors back on and heads to go on soon.

Painted my intake manifold crinkle red, of course.

One question: What do/will I do with the extra crankcase vent on the new block?

Oh, and now that we have taken everything apart and have seen into the belly of other "mechanics" work with my previous bolt-ons - I can say - I will never again let someone else do my performance mods.

My up-pipe/ext.wg setup was only finger tight at the header!!
2 out of 4 PE800 injectors were not seated(one was totally crooked) - I have pictures to prove it and a messy gas/yuck mix all around them. :mad:

But all in all, I am pleased and I am learning and thats what i enjoy the most.

One question: What do/will I do with the extra crankcase vent on the new block?
Like many JDM swaps, the driver-side port can either be capped-off or T'd to the valvecover vents. I tapped mine off and only recently hooked it up.

Okay - I will just t it in. Thanks.

Wed. update

Heads back in and torqued to spec (tricky)

Deleted tumbler valves back on and ready

Oil pan and stuff back on.

Now on to the easier stuff!!!

Should be on the road Friday. Oh and I ordered the Cobb street-tuner upgrade. Tired of driving 6 hours one way.

And I ordered a Tial WG today to replace an old turbonetics racegate wg. Its amazing how much you "extra" you decide to purchase once the car is ripped apart... :rolleyes:

I will post some pics of the project soon and some dyno numbers too.

Drove the car today for the first time and MAN, the new torque is crazy. I did not get into boost at first and it felt very strong.

I got into boost a little bit (8psi) and it definitely needs a new tune. Car was very hesitant when i reached that point, kinda jerky. Tune or vacuum leak?

Thanks

Nice! I would say that it's probably the tune. You should post some pics when you get a chance.

Pics coming in the next couple days. Just got back from driving again (2.5L is addicting) and the car is very smooth. I'm surprised it runs as good as it does with all that stuff done to it. I also backed my boost down to 7psi.

I got into boost a little bit (8psi) and it definitely needs a new tune. Car was very hesitant when i reached that point, kinda jerky. Tune or vacuum leak?

Thanks
I'd be careful. Mine would knock in those low load areas do to way too much timing when on stock ECU. I'd make sure you dial your tune in well.

I'd be careful. Mine would knock in those low load areas do to way too much timing when on stock ECU. I'd make sure you dial your tune in well.


Thanks TypeC - I'm sure with the new compression ratio and bigger displacement - a tune is badly needed. I have turned my DTEC boost controller to 6psi, just for caution, and I have an appointment for a protune with Jorge (riftsWRX) May 3rd. I'm gonna wait on the street-tuner kit, plus with the hybrid setup, I don't want to experiment, I just want it done right!

Thanks