I’ve been thinking about these two engines for some time now. I’ve heard many great things about the EJ207 and how Fuji Heavy should’ve given us the EJ207 instead of the EJ257. Personally, I think this is mostly JDM envy and I will admit I had a little bit it myself. 🙂 Having owned both of these engines I thought I would give a comparison of both for those thinking about either of these engines.
I should point out that I have had two EJ25s (EJ255/EJ257) and one EJ20 and all of them had 4-2-1 style equal length headers on them at one point or another and all had single AVCS. I’ve actually never driven a Subaru without AVCS. All have been tuned by the same tuner as well, sans when I bought them.
Let’s start with the EJ207.
EJ207 Version 8
Bore x Stroke: 92mm x 75mm
Compression: 8.0:1
Turbo: VF37 (Twin-Scroll)
I think the main draw to the EJ207 are the forged pistons in the Version 7 engine. It makes for a cheaper alternative to building a new shortblock. However the Version 8 comes with hypereutectic pistons which is what I have. I don’t plan on running a ton of horsepower so I’m not worried about not having forged pistons.
The EJ207 is a very smooth engine, or at least compared to the EJ257. It revs almost effortlessly to 8,000 RPMs. It sounds about the same as my equal length EJ25s so it took some getting used to revving it past 7k. My natural instinct was to shift around 6800 RPM. However it was clear that it has some more power up top.
With the twin-scroll setup I am hitting peak boost around 3,800 RPM. It isn’t anything to write home about. And I’m still on stock downpipe (albeit with gutted cat) so I’m sure I can get that down a couple hunndos with a larger downpipe.
Even with the stock downpipe this engine is putting out some decent power. I suspect it is in the 280 HP range. My injectors are pretty maxed out already (+95% IDC) so I will probably need to upgrade with an intake and a 3-inch exhaust.
The main downside to this engine is the lack of low-end torque. It has zero. Basically from idle to 3500 RPM are just placeholders of my rotating assembly. However once the boost hits it hit HARD! And from a roll the boost response is immediate. It astounds me every time it happens. What this engine lacks in low end, it makes up in the mid-range to the top.
Now I suspect most of low-end woes can be attributed to the exhaust setup. When I put ELs on my EJ257, I lost most if not all of my off boost low end torque. Accelerating from a stop on a incline with the a/c on, was very challenging. However, lightweight wheels, carbon fiber driveshaft, and 2-piece rotors help out in this area. One day I will put out a review on those items.
If you want to learn more about exhaust design here is a great video by /drive.
EJ257 (2005 STi)
Bore x Stroke: 99.5mm x 79mm
Compression: 8.2:1
Turbo: VF39
The EJ257 is essentially a bored & stroked EJ20 engine. The torque band almost reminds me of driving a 5.0 Mustang back in the day. You get 300 ft-lbs almost as soon as you wanted it but then the power dies off up top. At least in stock form.
With equal length headers it shares the wealth a bit and broadens the powerband outward by sacrificing the low end torque, along with the Subie rumble. It isn’t nearly as smooth as the EJ207, but with the right mods I suspect it will rev just as willingly to an 8,000 RPM redline.
Peak boost hits right around 3,000 RPM, if I remember correctly, and it falls off shortly after that. While the EJ257 seemed more powerful, or more torquey, the EJ207 powered Bugeye seems faster. Could be the 200-pound weight difference or it could be all in my head. The close ratios can sometimes make a car feel slower.
With the equal length headers, lightweight crank/flywheel, Grimmspeed TMIC and a few other mods (typical stage 2 pieces) the EJ257 rev’d to the 7,000 RPM redline fairly quick. So much so that I began thinking about what it would take to bump the redline up a few hundred RPMs. Which led down the rabbit-hole of destroking for more revs and eventually led me to contemplating the EJ207’s natural 8,000 RPM redline.
Just for kicks, here a video of a destroked 2.34L pull to 9,000 RPM!
Now that I have driven both, I’d probably go with the EJ257 if I had to do it all over again. I would just build it to rev to 8K on a twin-scroll setup. And if I pop a ringland on the EJ207, I would try to go with a 2.5L closed deck short block from IAG, with the +2mm rods to slow those pistons down a little bit so they will survive up top. I’m addicted to the 8K redline and I don’t see myself giving it up anytime soon. 🙂
Overall I wouldn’t say either engine is better. As with most things this comes down to personal preference. The EJ207 is a blast when driven hard, but can be a chore in DD situations. The EJ257 can leave you wanting more when driven hard, but is much easier to tool around town in. So obviously we need to get these two engines together to make a EJ baby. 🙂
Cheers!
Notes:
SF Sprite Credits: O Illusionista
B.黒曜石 