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Best build?

25K views 21 replies 9 participants last post by  ericwudi0830 
#1 ·
Ok so I have a 04 wrx. It has a stock ej205 in it. I'm looking into building a motor to put into my wrx. I'm looking for something peppy. High revs and something with heavy acceleration. It will be my daily driver so I want something reasonably reliable. I take my car to the track either. What's my best option if money wasn't an issue. Build the ej205. Build an ej207 or ej257. Or some sort of hybrid motor. maybe ej257 with ej205 heads? I don't need a ridicoulsly high horsepower car but something that's pretty fast and picks up fairly good. What's your guys opinions and what's my options. I'm not to fimiliar with this kinda stuff so any knowledge you have would be helpful.
 
#2 ·
This is an incredibly "open to interpretation" question. Everyone will give you a different response but it really all depends on what mods you plan on putting on your car and what power figures you're looking to achieve.

You're talking about a strong motor that has a hard pull and good reliability, but it's not at all the motor itself that governs those things in our cars. Sure a 2.5 liter block will produce slightly more power than a 2.0 liter block... but it's your turbo and supporting mods that will define how much power your block has, when the turbo kicks in, and how reliable it is... those things depend on supporting mods... and MOST importantly a quality tune.

Also, when you say "building a motor" are you talking about building internals, or assembling a long block?

To have a high revving block you will not only need a built short block but also head work done to support the higher revs. Some blocks/heads rev higher from the factory, I believe it's certain JDM ones but I do not know those details.


As far as BEST, "if money is not a limit" hypothetical situation... you asked for it, here it is:
IAG / Willall Stage X Billet Aluminum EJ25 Subaru Short Block

https://www.iagperformance.com/IAG-Willall-Stage-X-EJ25-Subaru-Billet-Short-Block-p/iag-eng-1610.htm

Billet means that the block itself is not cast, but is machined from billet aluminum. It's capable of holding over 1000hp.

If money isn't an option, that's the "best".... for $15k without accessories. Please note, you will still need built heads, a turbo that's big enough so it makes sense with that kind of motor... completely different fuel system and just about everything else on the car including built transmission to hold the power without exploding and a clutch that can transfer that power... and once again... just about everything else.

-----------------------More reasonable approach
Pick your maximum reasonable desired horsepower (in HP, not WHP) for this particular car's FUTURE plans... add 20-30% to that figure for headroom in reliability (I just made that number up)... and buy an IAG built short block to reflect that figure. Find built heads or quality cams/springs which will allow you to Rev higher.
 
#3 ·
get a twin scroll version 8 or version 9 EJ207. dont split the case or you will release the unicorn magic. can easily reach 425/425 safely on Ethanol with a bigger turbo & injectors. sell the JDM turbo for mad $$ because its JDM gold and replace it with a TwinScroll Dominator 1.5XTR. 100% by far the best bang for your buck.

in a 2800lbs car with 425whp (roughly 500bhp) that will put you faster than a 2011 Ferarri 5.8L V8 Spyder or a 2015 Lamborghini Huracan 610-4 Spyder

you can easily get down to 2800lbs in a 2004 sedan and still have a full interior.
you would roughly be 400bhp per UK ton

ferarri is roughly 393bhp per UK ton
lambo is roughly 390bhp per UK ton

http://www.autosnout.com/Cars-Bhp-Per-Ton-List.php
 
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#6 ·
Don't go billet, many people get into the hype of "it holds stupid power" and yes it CAN but not for a reliable build. Aluminum doesn't like heating up and cooling off (especially in cold weather) and will warp over time causing all that money you just dropped on the block to go bye bye.

If you find yourself in city driving more than highway driving and you're looking for a meaty powerband then build a 08+ EJ257 and have it balanced for 8000RPMs. The balancing is what gives you the speed that those 6speed ratios lack in lower gears compared to 6500RPMs stock and the EJ207 (8k factory). Reasoning behind a EJ257 build is you'll find yourself wanting more low end grunt out of boost which the 205 lacks sometimes (the 207 is twinscroll and boost helps this issue a bit). Also the 08+ EJ257 is Dual AVCS which helps spool the turbo faster than Single AVCS and allows you to not only move your powerband but increase the overall powerband, and don't forget the AVLS in upper RPMs.

For a stock high revving engine go EJ207 v8/9 as titter mentioned. They're great for what they are and if you want better city MPGs (out of boost) this is the way to go. If you find yourself driving in the upper RPMs anyways (which is where the powerband is regardless) then you won't really care about the .5liter you're missing down low. If you really find yourself wanting 2.5L spool but don't want to go 2.5L, swap the EJ257 crank for the extra stroke and you'll spool faster, this does require block machining.

I personally have an EJ205 build, it's bored +1mm and stroked using a 2.5L STi crank with forged stroker pistons and even on a basemap (and 360cc injectors) I pulled on a stage 1 2.0L wrx. I planned on balancing to 8500RPMs with custom 254 cams to aid in midrange-topend power as the stroker I find is plenty for city driving atm, but I also have Tomei UEL headers/UP, 3" catless TBE, EBCS, ver.6 STi 5MT, and other goodies. Life got in the way so the build is on hold, and I've been thinking about building a 08+ EJ257 as mentioned above (D-AVCS, maybe custom 262 cams, full exhaust, EWG, intake, TMIC, and a custom Garrett turbo) for a mad street machine capable of DDing reliably yet able to eat Muscle/Euro/Exotics in my area. The 2.5L is very capable as is the 2.0L but the extra flow will help my turbo I'm building (think GTX35 power with GT28 spool or better).

Reliability is not just about how you drive it, I don't care who you talk to. From an engineering standpoint when you increase cylinder pressures (psi or CFM) you add stress, that's why you can blow an engine with a huge turbo at low boost over time just as you could with high boost on a smaller turbo. Efficiency just changes with CFM and PSI.

Recap:

DD street monster - built 257
Highway monster/MPG - built 207
 
#7 · (Edited)
a full DAVCS 257 in a GD chassis is a wiring nightmare and will cost you more than the build unless you can wire & pin your own ecu/harness. this is the reason ppl do hybrid motors, completely different ecu. one is 16bit one is 32bit. you will require the a standalone ecu (or oem ecu) and have to re-wire 70% of the car and then merge the remaining harness with the new one.

there is reason you dont see full 257's in a GD. i mean they exist... but they are RARE.
 
#9 ·
a full DAVCS 257 in a GD chassis is a wiring nightmare and will cost you more than the build unless you can wire & pin your own ecu/harness. this is the reason ppl do hybrid motors, completely different ecu. one is 16bit one is 32bit. you will require a standalone ecu and have to re-wire 70% of the car and then merge the remaining harness with the new one.

there is reason you dont see full 257's in a GD. i mean they exist... but they are RARE.
DAVCS in a GD...Bah not as bad as one might think. Get yourself one of them there wrecked JDM cars with a EJ20X/Y(04-05 Legacy GT) and the ECU out of it and then find the wiring diagram and it should work itself out pretty easy. May have to add a few wires here and there, but nothing to serious. It's also a twin scroll set up, but sadly only comes with a VF38/48 which are smaller than the VF36/37, although if you want reliability, go buy a 257 and go with simple bolt-ons and a good tune and leave it at that.

Then again what do I know.:|
 
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#8 ·
A pain to do, maybe if you have little patience. Wrecked cars have their perks ;) And making a harness isn't even hard, the only connectors you need are the ones for ECUs and other modules. If we're doing things the right way then ya gotta do what you gotta do!

Also anyone who tells you a hybrid build is reliable is probably drunk lol. Can they make good power for less than other builds, yes definitely but they also can't run any timing, require a low C/R (compression ratio), and you can't run high boost either as the CC (combustion chamber) is so compact that you need to be careful of detonation. Can one last 50-60k? Maybe if you're nice to it, but who builds an engine and doesn't have fun with it?

I plan of getting at least 60k out of my stroker if not closer to 100k. How you ask? Using good fuel, correct oil weight, LETTING IT WARM UP (this is the one of the biggest cause of early EJ deaths over time), having an amazing ECU mapping (the other biggest cause of EJ deaths), and having A/F, oil pressure gauges to watch for issues while driving (just in case).

Allowing your car to reach operating temps before you touch that throttle (even putting around) can take off between 5k-30k miles on a forged build. Different metals take more time to expand than others causing excessive wear and blowby, and in cooler temps the oil doesn't flow so well. A great investment to aid the oil flowing at startup is an engine block heater (which I still need to get).
 
#13 · (Edited)
I just sold my blue '04 WRX, and used it like you want to. It's a great car - especially with an EJ207.

The 2.0L turbos have an oiling weakness and the 2.5L turbos have fragile pistons, but both can be reliable if you respect and address those.

I lost both EJ205 engines at the track, in the exact same spot. They were Stage 2 COBB tunes with 285 Hp/285 TQ on a 93 octane tune, but both spun big-end rod bearings - oiling issues.

The built motor was $6,500 CAD and 2 months with the car out of service, and the EJ207 after it was $6,500 CAD and 1 month out of service. All costs included in those totals.

Both the EJ205 and EJ207 have 'square' WRX pans, which aren't as good as the 'triangle' STi pan.

If you want them reliable I recommend this:

1. Protune - prevent detonation,
2. AOS - keep oil vapour out of the intake and prevent detonation,
3. STi pan kit - more oil around the pickup, and
4. Racing baffle - keep oil in the pan (last picture below).

The EJ207 is arguably the better deal because it had 318 Hp with the same turbo-back exhaust and a protune - it's a more potent package with the turbo and high flow cyl. heads. However, it requires a bulkhead wiring harness to run the cams and a periodic ECU swap for testing emissions.
 

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#14 ·
Btw when you do an STi oil pan swap, you need to swap the dipstick/tube for that year pan if you want your reading to be accurate. I went with an 05 STi pan/killerB pickup and baffle but kept the 02 wrx dipstick/tube and I had to mark a new spot for the "full" level. It make me hesitate during checks to keep an accurate reading sometimes lol
 
#18 ·
I didn't know about this until after I had my stroker built unfortunately, so I just notched a new FULL mark on my dipstick lol. I would recommend getting the KillerB pickup over OEM, I personally have one so I can corner like a mofo, along with their windage tray, but that link doesn't include the dipstick tube...and keep in mind there are a couple STi oil pan revisions, so make sure you get the dipstick/tube that match the year STi oil pan you're getting or it will read incorrectly.

BTW STi pans should allow for EL headers, not that many of us would want to destroy that sexy rumbumbumbumbumle XD
 
#21 ·
Look into the JDM EJ205 w/ AVCS... 250bhp, and can hold power better than your USDM EJ205. Has hyper-cast pistons, better head casting, more aggressive cam profiles, and of course AVCS.. That's if you want to remain fairly inexpensive..

If spending a grand more isn't a problem, then get a V7 EJ207.. V8 will be cheaper, but it's the V7 that is more sought after.

Just hit up Wali Tanaka with JDM Racing Motors. I got my swap from him.

I personally have a MY01 2.5rs w/ JDM EJ205 w/ AVCS.. Completely catless, Perrin short ram, and blue injectors. I'm on a base map right now, doing some logging.. But when I get my protune next week, my tuner believes I can reach around 270-290awhp. We will see!
 
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