I don't know a lot about WRXs and was hoping some of you guys could answer some of my questions. I want to get a WRX and need to learn some things about them. How much power can a stock EJ20 motor handle? If you do aftermarket rods and pistons, do the stock sleeves still limit the power greatly? Can the stock EJ25 blocks handle a lot more power? Do people ever have problems with the different cranks for the EJ motors? Why does it seem like you can't rev these motors very high? Is it a valvetrain problem or short block problem? Even with Cobb Tuning's built motors, they only recommend an 8000RPM revlimiter. Honda and Mitsubishi 4 cylinders can do that on stock parts. How much power can the WRX tranny hold? Is the STi tranny a lot stronger? Are their any reasonable aftermarket options? What do you guys prefer for tuning systems? Ecutek, UTEC, Cobb Tuner, Autronic, others?
welcome to the boards! I don't have a WRX(MY00 2.5RS =D) but there are alot of them here. From what i've heard and seen, the ej20 stock motor can handle 350hp or so. we have a few guys here running aorund with stage 3 and 4 WRX with that much power. Depending on which ej25 you are talking about, the power they hold varies from 250-500whp and there are no known problems with the cranks or what so ever. the EJ series motors don't need to rev high for power. They make alot more power in the mid range/high range and if you have good tunning/porting.valvetrain, they will make VERY GOOD high end. Honda's and Mitsu may be able to rev high, but they dont have low end for crap. They need to rev high to make power while subarus make it all over the power band. the wrx trannies are some of the most broken trannies, the gearings on them are too tall so they eventually break down on your between hard shifts, if you don't beat on it every day, it should be able to hold 300+ hp easily. then again, im just speaking from what i've seen so correct me if im wrong. also, as of right now, people seem to favor the access port over the utec. both are great. but for me im aiming for the powerfect power.
As stated above, the EJ series engine makes torque so it doesn't need to rev to 9000 to make power. There are STis on stock block and internals making 500whp at under 7000 rpms. WRX gearset....it isn't how tall they are, its just that they are crappy gears. Never meant to be shock loaded much or handle alot of power output. STi gears have been holding 600+whp without any real problems that I have heard of. Safe to say, they are much stronger. The EJ20 and 25 motors are limited in that they are a semi-closed deck. The sleeves aren't pressed into a solid block but rather into a space that has supporting edges. There are a couple of solid closed decks in the Subaru world, but they are becoming scarce. You could always purchase a custom built race-block, but why bother? Are you really aiming for more than 500-550 whp? Obviously not if you are looking at a WRX as an option. I would figure out what goals you have in mind for your car. What do you want it to do for you in the long run? The AccessPort is a pretty nice solution for most people. You can start out with their staged "canned" maps, but as your mod list grows and you go beyond the staged setups, you can get custom tunes or take a crack at tuning it yourself. Best part is it utilizes your stock ECU. There are some limitations, but I wouldn't worry about those at this point as an AccessPort really doesn't depreciate in value.
Small turbo Mitsus and Hondas can have low end power. Look at a stock turbo older DSM or an EVO, they have decent power bands. A 2.5l STi will obviously have an advantage or a 2.0l 4G63 or 1.8l because of displacement. The Honda and Mitsu guys can easily rev high, so they tend to throw very large turbos on them that kill the low end power, but give very high top end power. A 20G seems to be a big turbo in the WRX world, while it is considered a somewhat small turbo nowdays in the Mitsu and Honda worlds. Is there a problem with the valvetrains on the WRXs? Why not have an even longer powerband and rev it higher. The EJ motors don't seem to have very long strokes, so I assume it isn't a pistons speed or rod ratio problem. When you say the EJ20 can handle around 350HP, do you mean at the wheels or at the motor? Which Subaru motors have a solid closed deck block? It sounds like I need to look more towards an STi. The EJ20 and it's tranny sound quite weak.
You can alter the valve train if you wish, but it really isn't a weakness if you consider how much power is being made at 6800 rpms. If high revving is what you want, then you might want to look at headwork. The crankshaft is also a problem. THey can be spun out to 8500-9000 but above that you might want to think about having your crank balanced. A nice set of titanium springs and retainers along with some stronger valves will help. Cams would probably be a plus too. If you are planning on making a fully built motor, then get an RS. Why bother paying all that money for a motor you don't plan on using. And you still didn't really answer the most important question: What are your goals for the car? Drag racing, Auto-x, etc... I really don't think the WRX or the STi were built for drag racing, but they can hold their own I suppose. But making 10 second subarus is an expensive hobby. There was a JDM 2.0L that was closed deck I believe, and there is also the EJ22t from the 1991-94 Legacy turbo. Those are the only closeddeck blocks that you will find available. Someone will of course come in here and say, "Don't forget the 22B, LOL" but you wont find those, and if you do, you wont like the price tag much. Especially considering you can do the same thing with the EJ22t block. If big ass power is the goal, I recommend finding a chassis....probably a 97-01 2.5RS coupe. Then, source a motor, closed deck preferably. Get your heads worked over, get some forged internals and have your crank balanced. Then run a GT35R or a 40R. THat will get you to your 500+ whp goals. Also, you will want some kind of hardened gearset. Either an STi 6speed or a PPG straightcut gearset. Look to spend around 10-14,000 on motor and tranny and assorted turbo parts for this project. Then add the price of a chassis in decent condition.
big bore and a small stroke = a low redline small bore and small stroke = a higher redline It has to do with motor design
Sort of. Your top redline is mostly dependant upon the length of the stroke (and your valvetrain). A longer stroke will net you more torque, but it will also increase piston speed -- thus limiting your redline. High-revving engines are all usually "oversquare," ie, their bore is larger than their stroke.
STi's are very very trickey to make a lot of power. it seems like making power under 400 whp is really easy and anything more seems like it takes a ton of work
Thanks for the info guys. I would be building it for a fast street/drag strip car with some limited road race use. Definately not for small autox courses where you need instant spool.
The EJ20G is also closed deck, but some are, some aren't. Just because it says ej20G on it deosn't mean its neccesarily closed deck. They were found on ver 1-3 WRX and STi, and the Liberty RS turbo. Doing a swap from a EJ20G can be anoying though, sine cmost left are in liberty turbos of VIN's that aren't closed deck. making it have no real advantages ovar an ej207 swap except that its cheaper, and has crappier flowing heads, and will probably come with a useless automatic tranny attatched to it. I'd also recommend starting from an L or LX than starting from an RS for a swap build, as they're the same chassis, and at 150+ WHP it's going to need new brakes and a new suspension anyways. And the 22B is not based on the EJ22t, its a bored EJ20g.
i might be alittle late to chime in but i will none the less. there are ej series motors out there that have been prepped to redline at 10k, however it is very expensive to get or make one of these. the closed deck subaru motors (that i know of) are the ej22t which is found in teh turbo legacys, the ej20g which is found in ver.1 - ver.3 STis, and the ej22g found solely in the 22b (the ej22g was made from an ej20g). hope this helps.
Wow, Dynapar, that might be the first time I have ever seen someone manage to squeeze a post in between someone else's double post.
Seems to me that there is kind of a boy-racer fascination with spinning a motor to 9000+ RPM. As readymix is saying, Subaru motors tend to produce this handy thing called "torque"...if you don't need to wind it out to 8 or 9 thousand RPM to make power, why on earth would you want to? You'll spend thousands of dollars just to be able to say that you can rev to 9000? :?:
...and what Honda or Mitsubishi 4cyl produces torque equivalent to a WRX (excluding the EVO, I will compare that to the STI)?
An STi should have no problem making more torque than a DSM/EVO or Honda. You are talking about a 2.5l vs 1.6l-2.0l cars. Displacement makes torque. Stock turboed DSMs usually make more torque than HP with a couple mods. A stock 95-99 Mitsu Eclipse with intake, exhaust, boost controller, stock turbo will make around 225HP and 255ft-lbs torque. I have a friend with an older 90-94 Eclipse that made 296HP and 330 ft-lbs of torque with the stock turbo on that car. When you goto something the size of a 16G, then the HP and torque numbers are usually about even. If you goto a big turbo then the HP numbers are usually higher, due to it taking longer to spool the turbo. Quick spooling turbo = high peak torque number.
its not the torque peak that we're talking about, some subarus may make lower torque than another car but it uses it more efficiently. we're talking powerband wise. Subarus will peak their torque early in the powerband and carry that torque over the RPMS to help the car accelerate alot faster than most cars with the same amount of HP/torque.
