Jump to content

Help identifying EJ25 Cams for a hybrid build


Recommended Posts

Hello,

I recently bought an ej205 long block from a '03 WRX as a spare which I plan to build for approx 450/500Whp for some fun on the track, time attack and similar. I know I'll need to either pin the block or do the closed deck conversion. Following a lot of threads and countless nights of reading on NASIOC I understand that EJ257 cams will fit the EJ205 heads, provided I close/weld the AVCS holes. I also plan on getting them nitridated in order to increase hardness/stiffness of the cams and valves.

I've been looking on eBay and I have found 2 RHS cams from a GDB/Hawkeye STI, and theres another chap selling 2 LHS cams from an STI EJ25 without knowing which model it is.

  1. As far as I understand, 06-07 STi cams are single AVCS and should all be hollow?
  2. Whereas later cams ('08 onwards) are dual AVCS and are not hollow?
  3. Is it safe to assume if it's hollow its a single AVCS and therefore an 06-07 STi cam?
  4. Can I tell the difference by the AVCS holes instead?

I want to stick with single AVCS since the gears should be the same with the non AVCS heads I'll be using?

I've tried looking for part numbers or other identification but Google isn't being helpful at all.

I would greatly appreciate any help with this, as it's doing my head in, and don't want to buy something on eBay that I'd have to resell.

 

Link to comment
Share on other sites


WHP is US figures and is somewhat , well very, over egged compared to ours. 450 horse power at the wheels would put the figure around 560bhp at the fly wheel over here, which isn't possible on the turbos they claim do the figures etc.

My advice, don't use nasioc for tuning info, they have a very strange way of doing things at times and massively over egg results.

 

So, that said,

what are your actual goals? a well setup 300bhp car will walk all over a 500bhp badly setup car and be alot more fun even with the lower power.

what Shell are you using do to it?

how extreme are you actualy going to go? full bare Shell with cage, or still in road trim?

What block are you going to use?  is it worth getting a closed deck block?

 

Road and race use are very very different animals, as well are multi lap race vs time attack.

 

Link to comment
Share on other sites

Hi Tidgy, 

Thanks for the advice. I'm generally sceptical about what's on nasioc, albeit I have seen some interesting posts.

Currently the car is lightly tuned:

  • full decat exhaust, up-pipe, downpipe, only the exhaust headers are stock
  • full suspension (tein) and whiteline ARB, etc...
  • TMIC HyperFlow, KN Air filter
  • VF34 with P20 housing and 1 bar actuator
  • pink injectors, TGV deletes, theral spacers, etc
  • Brembos front and rear

TDR in Warwick have tuned it to 340Hp/338Tq or 287Whp.

The turbo can do more, but the tuner thinks I'll brake the 5 speed if he does and the current motor is a bit old at 112K miles.

I am getting some blow-by, and have put a baffled oil catcher in place, but eventually the motor will go.

I'll use the same Shell (the 2004 Blobeye Wagon) since I already have it, and have gotten used to it, and because quite a lot of work has been done to it.

I understand it's not ideal, that it is a bit heavier than the sedan, but it will have to do.

For the moment I'll keep it road trim, have as much fun as I can over the Spring/Summer/Autumn, and then next winter I'll strip it for a roll cage, etc.

I've already got the 2nd block to use, an EJ205 which I'm thinking of pining (similar to close decking, but more ghetto and cheaper since they use alum rods to hold in place the deck of the cylinders). I'd like to go cheap as possible as it's my first time doing this, and I'll be doing most of the work myself. 

So I'm thinking of forging the internals: Manley 2.1 pistons, already have a EJ25 79mm stroke crank, and probably BC 625+ conrods, or something rated at around 700Hp.  I'd like to leave about 50-100Hp "breathing" space, so in reality 600Hp at the crank?

My current issue is that AFAIK the heads of EJ205 are ok, might do some light porting, since I don't want to do the AVCS conversion, but I could benefit from EJ257 cams since they are considerably more aggressive and open at the top? I'll keep the same valves, and change springs, retainers, maybe seats, and have them seated properly, etc.

Going for aftermarket cams is quite expensive, and the valves and stems appear ok, so I'm thinking that with some reconditioning and nitridating they could withstand 600Hp.

I plan to update to a 6 speed gearbox as the first step, then drop in the motor I'm talking about using the ported VF34, and then finally update the turbo, injectors, fuel rails, etc. This is a long term project and I'm not in a hurry to finish it, as the car is already fun to drive. It is currently my daily driver, but I don't commute much, and I'm already looking for an economic daily car, meaning this will soon be just for weekend fun.

Do you know if it is possible to identify EJ25 cam generations, simply by looking at their AVCS holes and whether they are hollow or not?

Many thanks!

Link to comment
Share on other sites

@Tidgy  NASIOC is full of swaps like that.

I've found Cosworth cams for 850 and Piper for 750, but I don't think I can justify such a cost ATM.

I think I'll lower my expectations, forge the internals, and maybe get stiffer valve springs and rebuild the heads after I get them ported. I think that anything below 500Whp is doable on a smaller budget, but moving over 500Whp/700Hp is becoming a lot more expensive, and right now I'd mostly like to enjoy the car in events. 

Any advice on valve springs?

People seem to prefer 70lb springs. I think the goal would be a Borg Warner EFR 8374, not sure of trim, but I'd like mid to high rpm curve.

Link to comment
Share on other sites

4 hours ago, Vortex said:

@Tidgy  NASIOC is full of swaps like that.

I've found Cosworth cams for 850 and Piper for 750, but I don't think I can justify such a cost ATM.

I think I'll lower my expectations, forge the internals, and maybe get stiffer valve springs and rebuild the heads after I get them ported. I think that anything below 500Whp is doable on a smaller budget, but moving over 500Whp/700Hp is becoming a lot more expensive, and right now I'd mostly like to enjoy the car in events. 

Any advice on valve springs?

People seem to prefer 70lb springs. I think the goal would be a Borg Warner EFR 8374, not sure of trim, but I'd likemid to high rpm curve.

 

 

no idea about valve springs im afraid, i know mine had supertech valve kit in it, but not sure on the specifics im afraid.

Link to comment
Share on other sites

I've decided to try Tomei springs for EJ20/EJ25 motors. They are rated at same dimensions, and are slightly stiffer in order to avoid high RPM vale float. I'll come back, posting pictures and videos of taking them apart, cleaning them and rebuilding them, mostly for my records but also in case it helps someone else. 

For the engine, I'll make a cast of the water jackets with wax, and then try to design in CAD the inserts, have them CNC and then get a nearby machinist to press them in. The block needs a few minor fixes (helicoil a water pump bolt hole, decking and skimming, boring, etc). I'll try to document that too. Not sure if I should start a new topic.

  • Like 1
Link to comment
Share on other sites

I haven't posted on here yet ,as I haven't worked or researched on a 2.5 ,  so can't help with tech comparability questions. 

Most cams do have number stamps to identify what their spec and fitment is afaik .  

I've been considering a 2.5 ltr build once my 2ltr needs replacing,  so definitely  feel free to start a project thread 😊.

I so I'm a bit patchy on my bug onwards spec . I think some bug /blob jdm sti's might have duel avcs and some do have "big port heads". 

If you've got access to cnc ?  a 14mm stud conversion might be worth doing too . I was just going to get Alyn at asperformance to cdb convert , bore ,hone, deck and 14mm stud convert a block for me .  

Think, Another thing that helps with "valve Jack up" is using the type of buckets with removable "shims" . Unsure if they do these for the phase 2 onward  heads though .

Might have some spec for the heads on a 2ltr ej207 (UK bug sti with single avcs cams )  , if it's any use ?

Best of luck with the build 👍

 

Link to comment
Share on other sites

@savage bulldogs Hi, yes the 14mm stud conversion is definitely on the todo list. AFAIK RCM do 14mm/12mm studs and 14mm/14mm studs. The prices for the head-studs are ridiculous, but RCM are the only ones that do this I think? (ARP used to but can't find anything anymore)

Another thing I'm considering is what they call a "fire"-ring or "O-ring" where the cylinder deck is machined with a small groove, in which a copper wire is placed. This according to the internet people, compresses against the gasket making a much better seal and avoiding leaks and gasket problems.

I've looked on eBay for months on EJ25 cams, and this is what I've gotten so far:

  • pre-2003 models have no AVCS (STi) and WRX didn't get it until much later (2008 I think?)
  • post-2003 have single AVCS which you just plug the holes, and use the non-AVCS cam gears
  • post-2008 have dual AVCS which is not easy to use with EJ205 heads, the cam gears are different

The reason I'm looking into single-AVCS STi cams is pricing: Tomei, Piper, Cosworth (and other cams) are all north of 700 quid, and I'm not looking for too aggressive cams, as I'd like the torque to be low-mid rather than mid-top. A common setup I've seen is with Tomei ponpon cams running 250 Intake, 256 Exhaust. In comparison, EJ25 cams **I think** are 256/256. I've also read a few horror stories of people running 270/270 cams which made the car undrivable, idle roughly and bog down at low rpm. Finally, I'm mechanically inclined and can't afford to spend 5K+ on an motor...

The problem with STi cams on eBay is that the markings I've seen don't show up on any Google search. Asking the eBay sellers is usually not helpful, most often they don't even know the year of the car they came from. Hollow STi cams seem to be from early single-AVCS EJ25 (2005-2007) which is what I'm after. Later AVCS are not hollow, and dual AVCS you can tell by the holes on both exhaust and intake cam. Most eBay sellers will sell them one-by-one, or two at a time, but I'd rather not risk it and would rather buy all 4 together.

I'm taking the heads apart once I've got the compression tool, and I'll be documenting it. I'm more inclined to make YouTube videos, but I need the pics and data in order to make sure I have a reference point for later on, as this will probably take months. I've been looking to find a company to nitridate the valves for extra hardness, so any recommendations or advise is welcome.

A.

 

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share






×
×
  • Create New...




Forums


News


Membership