Finally! Great info. Here is a bit more info for anyone interested: The head castings themselves are all the same from 9/2002 through 4/2007 for all JDM EJ205 and EJ207s, regardless of WRX, STi, Spec C, according to Subaru parts catalog. Though people often refer to certain Spec C heads as "Big Port", the standard jdm EJ205 have the same ones as you suspected. The cam choices are equally unexciting. Starting in 6/2003 through 4/2007, all EJ207s got the same cams, regardless of what Impreza it went in. The first Spec C made from 6/2001 through 7/2003 did get its own cams up until 9/2002 when the standard STi received those as well. But, just as a comparison, here are part numbers for camshafts listed for the legendary Type RA-R vs just a "standard" jdm WRX STi: GDB RA-R IN-L :13037AA610 IN-R: 13031AA610 EX-L: 13052AA482 EX-R: 13034AA482 Every standard JDM STi Impreza(EJ207) starting in 6/1/2003: IN-L :13037AA610 IN-R: 13031AA610 EX-L: 13052AA482 EX-R: 13034AA482 Exactly the same. Also, JDM EJ205 and EJ207 head castings, the so-called "Big Port" heads, Both the intake(from 2/2004) and exhaust( from 9/2002) valves between the JDM ej205 and JDM ej207 were the same. In the US, those valves came in virtually everything that had a tubocharged 2.5 engine. Nothing special. Valve springs were EJ207 specific however. EX valve: 13202AA411 IN valve: 13201AA371 Regardless of how much we love Subaru's special models and put them way up on a pedestal, Subaru is such a small company, the facts are that using super expensive parts(such as heads) for very limited runs of models was just not practical for Subaru. Another example is this: In the US, we have the STi S209. It would not be too far out of the norm that based on the fact that it has an upgraded turbocharger, upgraded intake system, and upgraded fuel system, all in an effort to make 341hp, that the cams would be different than the standard USDM STi. They are not. They are the same cams used in every USDM STi since 2010. Subaru is a master at don't fix what isn't broken. It works from a financial as well as a reliability standpoint. Instead, for the special models, they have always focused on smaller items that refine each model to the next level like bracing, suspension components, braking, etc. as well as shedding weight. The typical japanese way of tuning, and the origins of the OEM+ culture. While there are definitely some parts that were specially made and could only be gotten by contacting STi directly in Japan for certain special models, the engines were quite common between most of the GDB cars, Over the years, the internet loved to dramatize many parts as being "Spec C ONLY" parts, when in reality the actual beauty of the "Spec C" is the entire package and how well it transitioned from the showroom to motorsports, whether it was rally, gymkhana, or circuit racing. Great video.
We also subscribed to your channel! Love the info, especially the one with the spec c part no one one knows about, we have had many GC8’s and when we got a RA with that piece that didn’t have AC we geeked out about it lol.
@@OkiSubies Haha! Thanks so much. That was just something I did/do just for fun. My youngest son asks from time to time if any of my videos' views made it out of single digits yet! LOL! If someone else finds any of it interesting, then it was worth it. I've watched your channel for a while and really enjoy the information. You have a very unique dynamic in that you are American(?) but live and work on Subarus in Japan. I really enjoy that perspective. Always looking forward to more of your videos!
Big ports are primarily on the jdm heads as eu and au have small ports. I can confirm the v7 avcs 205 and 207 use the same head casting; however, the 207 has different lift and duration as well as 0.5mm larger valves.
Great videos always good to learn more about the platform. A video on what gc8 sti heads can flow hp wise before needing to look at porting with stock cams would be good to know
That is a good idea! So many people over here that want to push more power are changing to the 02-07 platform so it might be a little challenging gathering the info but we will definitely do that!
You know it's super easy to measure port volume. There are plenty of shops that can measure port flow. You don't have to speculate on this stuff it can actually be proven.
Ive currently got a ej20x in my subie in the future i want to go either new 207 ra shortblock with some used 207 heads, a full used 207 long block or an ez30r turbo, my power goal would be between 400 and 500 whp while keeping as much response as possible, what would be my best compremise between budget and realizability/longevity? Also would be looking at using a twinscroll g30-660 turbo unless you have any better suggestions Love your informative content keep it up!
I have a V4 STI EJ20K. The LH head has suffered (educated guess) a burnt exhaust valve due to zero compression on Cylinder #2. Should I rebuild the EJ20K head, or get a JDM EJ205 and use those heads? Ive been told the EJ20K head is the 2nd best flowing heads other than a v7/v8 EJ207 heads. However, im wondering if the AVCS with a EJ205 would be better than the EJ20K heads.
Well the amount of work that it would take to get the ej205 in the car would be a lot more than just swapping the head and you would still have to get it built for it to outperform your EJ20k heads. If you had a standalone Ecu it could be worth it But I would probably lean towards building the ej20k heads with something like a version 10 short block.
@@NATEDIZZLES813 yeah I would be willing to bet the jdm engine would be better flowing. I am looking at an ej20x/y right now and the ports are even bigger than the v7-v9 heads. They look just like the jdm GRB ej207 heads
