EJ20 SOHC build (bore & stroke to 2.35L)

[dfoyl]

I am thinking about a short block-up rebuild of a EJ20 SOHC for my Brumby (BRAT). The reason for using a EJ20 block is simple - it is within the 10% requirements that avoid an engineering certificate locally (Vic, AUS). So please, no responses of  "Go EJ22"... Also, DOHC is out for the same reason (requires cutting the rails, which is an engineering certificate). And ditto turbo.

 

I am currently running a (phase 1) EJ20J (ex-1998 Forester, early year) in my Brumby, and have read the best (in terms of factory performance) SOHC option is the BL-BP Liberty/Legacy from 2003+, which has a revised intake and heads for better flow. I have been able to obtain a suitable intake and heads for the grand sum of $50, and will have the heads hardness tested and then machined flat (with some mild porting if worthwhile).

 

I have also obtained a complete long engine (phase 2) EJ202, which will be the basis of my build ($10 due to spun big end bearing). And I have a line on a complete EJ25 (phase 2) with (surprise!) a blown HG.

 

I have been quoted "around" $600 to machine out the existing EJ20 liners and replace with EJ22 liners. An EJ25 crank will drop straight in (as long as it's the same phase 2 model), and I believe using the stock EJ25 rods will also work - which means only custom pistons (and I would need new pistons for the EJ22 bore anyway).

 

Externally everything will be EJ20, and as I am using all phase 2 EJ20 block and heads and intake it will all go together (although there is no reason that I know of why I couldn't use the EJ20J block with the EJ202 heads and intake - the only reason I am using the EJ202 block is it minimises downtime and I can then sell the EJ20J as a complete running engine).

 

The questions I have are,

 

1. Any obvious issues with the above proposal.

2. Can I use my existing cut-down EJ20J wiring, and adapt it to the EJ202 intake ?

3. As I am using EJ20 SOHC cams, which are not exactly common in the US, would Delta be able to grind them (I am thinking the "1000" grind, which is street version no CELs) ?

4. Will the EJ20 intake be sufficient in terms of flow to support a 2.35L (I know plenty of US guys have fitted EJ20 heads to EJ25's because of the EJ25's HG reputation, but I don't know if they have used a matching intake or have used an EJ22 or kept their original EJ25 intake ?

5. Will the factory ECU handle this, or do I need to go aftermarket (and if so, which brand would be suggested).

 

 

 

[idosubaru]

You're fine on the ECU, it'll handle that flow no problem.  EJ25's plug and play just fine into EJ18 equipped vehicles, my EJ25 equipped legacy ran an EJ18 just fine with great gas mileage so it adjusted fine, people install forced induction with a few PSI on stock controllers. 

 

I'd be surprised if Delta couldn't do something. 

 

in the US Phase I stuff is such that you have to swap the intake manifold to bolt EJ22 heads to an EJ25 - they are very different heads with different bolt patters for the intake manifold. so Phase I swaps like that are running the EJ22 stuff.

 

i wouldn't worry about intake flow at all personally, other than generally speaking, but specific to this swap it's going to be negliigible. 

[86BRATMAN]

The largest glaring issue that I can see is putting ej22 liners in an ej20 case. It's going to leave you with a cylinder wall that is approximately 5mm thick including the new liner (I have no idea how thick those actually are so you may have no aluminum casting left to support the liner).

[dfoyl]

Thanks for the feedback gents. I thought the ECU might be able to handle it, but good to get some feedback. On the phase 1 and phase 2, as long as I keep the heads to suit the intake (or vice-versa) it should all be lego (I am told there is a unique EJ25 phase 2 that ISN'T interchangeable with anything else in the mid -00's era but I don't have the details...once I was told it didn't apply to EJ20 I didn't really worry )

 

On the liners - I'm pretty confident there will be enough material. The engine builder/machinist believed it would all be fine but I do have to take the block down before he will know for sure. I am trying to avoid Darton wet sleeves due to higher cost (both in the sleeves themselves, plus the machining cost basically doubles).

[LPGsuperchargedBrumby]

I know of one person here that made a mold of the EJ20 'label' casting and cast a new one(out of what i have no idea)..... he then ground off the EJ25 'label' and glued the new EJ20 casting on and used RTV silicone to fill and smooth off any trace of the join line......he then painted the whole block with aluminum silver spray paint.

 

While you have things apart to play mix an match......EJ20 heads on a EJ25 block get you a high compression ratio.......

Edited January 14, 2017 by LPGsuperchargedBrumby

[dfoyl]

I like the EJ20 label idea  I have a damaged EJ20 block I could cut the label off...

 

I took the EJ202 block down to the machine shop today, they said there isn't enough material for EJ22 sleeves and their recommendation is Darton sleeves which "only" go to 96mm (instead of 96.9). So with the EJ25 crank I should get 2.28L which isn't quite what I was aiming for but isn't a bad step up. Waiting on prices ATM.

 

Have also sent a message out to Darton to ask if they support using EJ22 sleeves in an EJ20 block (they go from 97 up to 100mm)...

Edited January 16, 2017 by dfoyl

[87subbomber]

why not by an ej25 shortblock and use ej202 heads and use a thick headgasket to bring compression down? it will me gobbs of torque and still have decent milage to cruise on. building a hybrid stroker is not an easy task. it looks like you are doing it backwards. start with a 2.5 block, use an ej22 crank and custom rods and pistons will get you about 2.35 liters if i recall. that is if you want to spend that much money and shift your whole powerband higher in the rpm range. i plan on running a carbed ej25 in my 87 GL this summer, and looked into the 2.35 setup but it wont make the torque of a 2.5 and lots of money on custom parts (rods and pistons). since this will be my wheeler, im going simple and a 2.5 will be put on place

[dfoyl]

If I use an EJ25 (or 22) shortblock it needs engineering certification for all mods - potentially several thousand dollars. if I went that path I'd go a DOHC EJ25T or get an EJ206 from a B4 and go TT.

 

I have now sourced an EJ204 block, have spoken to Darton on the EJ20/22 97-100mm sleeves (they don't recommend the 97-100mm sleeves in the EJ20 as the block needs a slight trim but allow it is done a fair bit with no reported issues), sourced a phase 2 EJ25 crank & rods (I might end up using the EJ204 WRX rods, not sure which is better at this stage), and am pulling down the heads for the cams to be reground by Delta. Probably looking at a final CR of 11:1, and around 2.38L depending on suitable pistons.

[dfoyl]

As an update on this, I have found a local shop that does the EJ22 sleeves in the EJ20 blocks quite regularly (they claim to be Subaru Australia's Melbourne engine rebuilder, and do about 1 Subaru engine a day (they showed me several blocks, including an EJ25 with Darton sleeves, plus had a couple of WRX's up on lifts). The latest suggestion was to use the longest OEM rods possible, with shorter pistons, which led me to the possibility of offset grinding a phase 2 EJ25 crank to 83mm and then using the phase 1 EJ25 rods. This would give me a 2.50L EJ20 with a 98mm bore. Would need to look into clearancing issues but otherwise sounds promising.

[dfoyl]

Some pictures for anyone interested in the differences in blocks :

 

From left to right, EJ205, EJ202 and EJ252.

 

The EJ202 shows it is weaker here :

 

The EJ205 shares the thicker sidewall support with the EJ252 :

 

Edited February 12, 2017 by dfoyl

[dfoyl]

The thicker walls of the EJ252 make removing the case bolts difficult. The factory has machined a very light clearance in the cylinder :

 

 

[dfoyl]

Even the gudgeon (wrist) pins change :

 

 

From left to right, EJ205, EJ202 and EJ252. The EJ202 gets shorter pins, while the EJ205 has a sunken centre which reduces weight. They all share a common OD.

 

And finally rods. I didn't bother with the EJ202, but here's the EJ205 (left) and EJ252 (right). The only obvious difference is the flat end at the bottom for the EJ252, and a very slight increase in length at the top :