90-92 Brumby EA81 Mods

[Hamish71]

I have spent the weekend surfing this forum, and there is lots of advice out there relevant to my queries. However, I will specifically ask my question, as well as seek general advice.

I wish to buy a 90-92 Brumby as a daily driver to work, carry the dogs, and the ktm. This will make my wife happy, as the dogs wont be in the back of the XT Forester, and I wont get her car "dirty" towing the trailer.

Firstly, I have queried expected price etc elsewhere.

Secondly, I cant leave good enough alone. The XT runs a xede ecu, full ss exhaust, and hammers. The MX5 is a n/a high compression, race ported screamer, 120rwkw.

The Brumby...well, I will try and leave it alone, but know I wont be able to. I can say this, I dont want to turbo charge it...nor drop in an EFI engine. I have been through the engineering process in Victoria once, and I dont want to do it again. My preference would be to stay with the EA81, rebuild it with higher compression, and a weber and do bolt ons. I will do most of the assembly.
Specific queries resulting form what I know so far:

Cylinder Heads: It appears the EA82 head is a better unit. Is it a bolt
on to the EA81? Does it respond well to a valve job, polish and port?

Intake manifold: What can be done to improve the intake?

Gearbox: I would prefer the 5 speed. My understanding is that the EA82 five speed is a bolt on assuming you use the EA82 clutch and flywheel. Is that correct?

EJ20/EJ22: Is it posible to run either of these engines using a weber, and thus not needing to run efi, or touch the dash? If so, how effective is that?

[dfoyl]

EA81 - to increase the compression you can source either EA71 pistons, I think EA82 Turbo (or MPFI ?) pistons also improve compression but not as much as EA71 units. Weber some people get value out of WRT improved performance but rougher idle issues. EA82 is OHC so it's not bolt-on BUT I do know of a USMB member who was playing with modified EA82 heads on a EA81 block. He was using this as the basis for mild porting and showed unremarkable results.

Intake - as stock, not much! Your options are EA82 intake (very slightly better flow than EA81 and is a bolt-on), or rare dual-port EA81 intake.

Gearbox - correct, you also need to source a longer tailshaft or use the L-series 2-piece unit with appropriate support in the middle. The 5 speed is a much better box in every respect than the EA81 4 speed.

EJ20 - I know of a handful of EJ16 and EF18 engines found in NZ without FI as delivered ex-factory, again a few members on USMB have hacked EJ's to run without FI...

[Hamish71]

What did the dual port intake come standard on?

[Suby Roo]

What did the dual port intake come standard on?

Im assuming on the turbo ea81's. They were on the ea82 turbo motors.

[El_Freddo]

Im assuming on the turbo ea81's. They were on the ea82 turbo motors.

Not entirely true. The twin port EA81 heads are very different to the EA82 heads and used twin carbies (or was it quad? can't remember).

The EA81 twin port heads will need a different camshaft to run them. The intake and outlet ports are opposite to the bog standard EA81 single port setup - Inlet ports on the outter edges of the cylinder bank, exhaust port in the middle (head valve order will look like: intake, outlet/outlet, intake).

These parts are very hard to find. But with these and the right build you can have a revs-its-tits-off literally bomb proof engine... I've heard good for 10,000 rpm...

Or (and i know this is an EFI setup but check all options anyway) you can fit the single port fuel injection system as it was sold in the states. Nb: will need to import these parts. Also check out ultra light engine build up sites - there are some interesting things going on here - re-designed heads for a straight torque curve, efi systems etc etc.

Ask Brumberty about carbie feeding an EJ, he's doing this to one in his jet boat project. If you're going to shove and EJ22 in there apparently you need to cut the chassis rails to fit the cam covers in (i've also heard of someone "massaging" these rails with a pipe to create the cavity needed).

There's always a turbo application to add too - check this out - from post #106 onwards

Last option is to just rebuild what you've got and be done with it...

As for the gearbox the L series 5 speed will fit with some crossmember mods. Make sure you get a carbie engine gearbox - this way your drive shafts will not need any modding (the MPFI gearbox axil stubs have 25 splines as opposed to the carbie ones with 23 splines). You'll also need to space the starter motor out with some washers so it clears the flywheel. You use the flywheel/clutch assembly from the L series (will be a direct bolt on).

Cheers

Bennie

[Suby Wan Kenobi]

Going the EFI route isnt a bad choice as you do get some benefits over Carb. If you use an EJ18 your capacity has not changed but you gain an extra 20KW or there abouts and it will run smooth and economical compared to a hotted up Carb motor. Adaptors are available to adapt the EJ engine to EA gearbox.

The L 5 speed bolts on the back of your EA engine should you go down the Carb EA hot up but you will have to change the clutch plate as well, you will also need the longer L tailshaft as well.

[daza]

Intake manifold: What can be done to improve the intake?

Don't just think outside it, throw the box away.
Go to your exhaust guy with a 40DCOE webber and tell him to make some nice long runners to mount it up above the trans with the filters where the spare was!!!

EJ20/EJ22: Is it posible to run either of these engines using a weber, and thus not needing to run efi, or touch the dash? If so, how effective is that?

I used to think the Ea81 was a good little motor, till i went Ej.
I'd have an Ej16 over an Ea81 now, because of the EFI.
And there's no need to touch the dash.

Daza.
the ex Brumby driver...