EJ SOHC Turbo Performance??

dodgybrumby · Post by **dodgybrumby** » Tue Feb 07, 2012 7:59 pm

Hello all,
I'm after any information you can give me for EJ18-22 SOHC Performance. I have had a google and cant really find much of what I'm after.

I'm wanting to change the EA81 out in the Brumby for something like a EJ20 SOHC and then eventually have it turbo charged. I'm not after a power house, but I don't see any reason why it couldn't be coaxed into making reasonable power (250-300hp). I'm wanting the car for street performance not off road, so no big lift kits or the like.

My main concern it to try and keep it as legal as possible, hence the SOHC. I've read that a EJ25 won't fit without chassis mods similar or worse than a DOHC engine, is this correct?

I'm thinking if I started with a WRX bottom end (or front cut, for stronger box ect) and retro fit the SOHC heads (i've read it's do able YES/NO), have them ported and manifold match ported & what not. Either that or start with a N/A engine and have it rebuilt with forgies ect. Would be run on a aftermarket ECU, so that would eliminate any tuning/interface problems associated with a factory ECU. Once the long motor is sorted, the actual turbo fitment ect shouldn't really cause much of a problem. Well not easy, but no worse than any other conversion.

I realise that it would be a fair amount of mucking around for what really is an inferior setup to the standard DOHC engines, but would rather leave the rails alone.....i must be getting old...... Is there a specific make/model of engine that has a 'better' set of heads suited to this application?

If you know of any SOHC build blogs or threads, pls put up the links.

Since brakes and suspension is fairly well covered on this forum and others, lets leave this purely for the engine side of things.

B00sting · Post by **B00sting** » Tue Feb 07, 2012 8:17 pm

Apparently the SOHC EJ25 will fit, but the DOHC EJ25 wont (without chassis rail mods).
Apparently the DOHC EJ25 'might' fit if your brumby is lifted, although i'm not sure if this is true, and if its true how much it would need to to be lifted.

In your case, I'd be also asking if chassis rail mods are needed to accommodate the turbo anyway? Possibly not, but worthwhile checking.

This rudimentary information is from searching on this forum, and I haven't being a member for that long either, though am planning an EJ 25 conversion with or without rail mods, it doesn't really bother me!

niterida · Post by **niterida** » Tue Feb 07, 2012 8:18 pm

If you are going to the trouble of an EJ conversion and you want it turbo charged then just use a WRX motor and be done with it. Turbocharging a SOHC motor will cost you more and leave you with an inferior engine. The hassle of slightly modifying the very front of the chassis rails (where it will have no detrimental affect) far outweighs the hassle of doing what you have suggested with the engine options.

And the resale will be far superior too....

Or do what I am doing and move the entire chassis rail outwards by 40mm and then bolt all the WRX bits straight in !!

YouTube · Post by **El_Freddo** » Tue Feb 07, 2012 9:18 pm

niterida wrote:If you are going to the trouble of an EJ conversion and you want it turbo charged then just use a WRX motor and be done with it. Turbocharging a SOHC motor will cost you more and leave you with an inferior engine. The hassle of slightly modifying the very front of the chassis rails (where it will have no detrimental affect) far outweighs the hassle of doing what you have suggested with the engine options.

^ That and you'll have to get it all engineered to make it street legal anyway - so the chassis rail mods should be covered in that engineering certification...

It's a tried and tested route to take with the WRX conversion in the brumby or MYs in general so it shouldn't be anything new to the engineering side of things.

But to answer your original question: It should be fine. The SOHC heads won't breathe as much but will still work adequately IMO. It will require more money as niterida has already said - probably about the same as engineering the chassis rails actually!

Oh, and you've got to modify the engine crossmember for the turbo up-pipe - this too would need to be engineered with everything else. So no matter which way you go about it, you're going to have to cut and shut something to get the turbo in there.

Cheers

Bennie

dodgybrumby · Post by **dodgybrumby** » Tue Feb 07, 2012 10:34 pm

niterida wrote:
move the entire chassis rail outwards by 40mm and then bolt all the WRX bits straight in !!

One simple statement, and many many hrs of work!! I have been following your progress closely, well done sir.

Thing is, every engineer i've spoken to is happy untill i start to mention that the rails need to be modified/shaped to clear the engine. As soon as i start to talk about doing that they just say "No you cant touch that, no matter how you do it". So i figured the SOHC would be a safer option.

Maybe i'm not speaking to the 'right' people.

niterida · Post by **niterida** » Tue Feb 07, 2012 11:07 pm

There are many many Brumby/MY cars engineered across Australia with this mod.

It is only at the very front of the chassis rail where it meets the radiator support panel where it needs to be modified so it is not really affecting anything structural.

I have seen one done where instead of notching the rails like most people do he simply reprofiled the rail - basically cut the corner of it off at angle (looking down from above). If you did it this way and didn't tell anyone they probably wouldn't even notice it had been done.

And as for my way of doing it - it may have taken me hours so far (132 to be precise but who's counting - oh wait I am - its all in an excel spreadsheet - including the total cost of $7349.15c

) but now that I know where and what to cut I reckon I could do it (the rail bit of it) in about 40hours or less !!

RSR 555 · Post by **RSR 555** » Wed Feb 08, 2012 5:19 am

SOHC EJ engines don't have the oil feed or return for the turbo.. this ofcourse can be done but just letting you know.

The EJ25 turbo or not turbo, will definately require engineering to pass licensing. I would make the small change to the rail and if it's done correctly and neatly, then I don't see any issues, as long as the strength and regidity is retained.

I have 2 EJ22 turbo SOHC engines that IMO are great low torque engines but if you're looking for performance then stick the the DOHC models.

B00sting · Post by **B00sting** » Wed Feb 08, 2012 4:57 pm

B00sting wrote: Apparently the DOHC EJ25 'might' fit if your brumby is lifted, although i'm not sure if this is true, and if its true how much it would need to to be lifted.

So does anyone know if this is true...?