I got offered a '84 EA81T Wagon. I dont have any desire to have, run, and maintain a EA81T, so i was thinking of maybe using it for a project. How difficult would it be to convert the EA81T into a stadnard MPFI EA81? I was thinking of pulling the pistons and replacing with 1600cc pistons. Also replace the cam, and possibly deck the heads. The engine would stay in the same body, and use the same ECU & fuel lines, just missing the turbo and forced induction stuff.

My target will be 10.5:1 CR, but 10:1 would be reasonable. This would be my off-road rig, so i would like more power in the low revs. Obviously i'll have it lifted 3" and have a 5spd D/R behind it.

 

-Brian

I would think that it would be best to use the MPFI components from an EA82T - using the injectors and manifold from the EA81T, and making sure the sensors were proper. From what I understand the ECU system on the EA81T is the same as the one in the early EA82T's..... did they have N/A MPFI's in 85 or 86? That would be the way to go if you could find one.

 

GD

i could have sworn i saw NA mpfi on an 84 sedan, digi dash and auto 4wd

I'd keep the EA81T a Turbo. Those motors are getting pretty damn rare and it seems like you could pretty easily swap someone who wanted a T for an NA version.

 

I do understand your hesitation in maintaining the EA81T. It just seems like you're talking about a pretty involved rebuild/swap and in the end we'll have one less EA81T on the road

Brian,

 

One of the Mechanics at the Subie Shop I worked at did that conversion on an EA81T for someone wanting to use if in his kit aircraft. For the Engine Management he used the EA81T ECU, wiring harness, fuel injectors and all but on sensor. The one sensor he didn't use was the boost sensor; he replaced it with the vacuum sensor from an 85/86 non-turbo MPFI. Remember EA81T and the 85/86 EA82 MPFI / EA82T use almost identical Bosch fuel injection systems.

 

For the short block he just replaced the turbo pistons with N/A pistons.

Put an EA82 MPFI in there. find an XT non turbo. More common than turbo XTs around here.

Craig, thats exactly what I wanted to hear.

 

Garner... i dont want carburation, timing belts, or the hassle of swapping fuel lines, ecu, etc. I know how rare EA81T's are, do you know how long ive been looking for one to do this project with. The only real work that'll need to be done is replace the piston's. Everything else is just removal of un-needed equipment.

 

Miles, there are only 3 types of EA81's. 1bbl, 2bbl and MPFI Turbo.

 

-Brian

Perhaps, MPFI turbo w/ EA71 pistons and cut heads. Use an SAFC to get the mixture refined. On 93 Octane you should be able to reach 120~130Hp easily.

i woul;d think a NA mpfi from an 85-86 would be a good choice, you can adapt it to work with the ea81t's ecu, and therefore spare a complete ea81 motor for trade value

I WANT TO USE THE EA81!! I preffer the OHV over OHC. And since this is going to be an off-road rig, i dont want turbo whatsoever.

 

If i remove the boost with the turbo, will the EA81T ECU start to freak out? or will the added compression with the 1600cc pistons ballance things out?

 

-Brian

my ecu didnt freak when i had the turbo removed for a day from my GL-10...

if you take out the boost sensor and find a way to complete the circuit. (I think thats how it work the boost sensor tells the comp to give the engine more fuel so if you complete the circuit it should run just fine, right? or do you even have too complete the the circuit?)

should not even have to mod any electronics. Just take the turbo off, and fit a y-pipe, and use nonturbo intake peices...bam, its done....unless you replace the pistons and cam....then youd have to take the engine apart ofcourse!

 

I seriously dont think any more mods other than those would be nessisary to make it N/A....pistons, cam, intake and exhuast to accomodate the absence of the turbo. Oh, and block off the turbo coolant and oil lines. Easy peasy.

Why cant i just use the MPFI intake? Also, arent the EA81T pistons dished? I'd want N/A pistons to make up the CR. Also, im dreaming of putting an aftermarket cam to help bring the power into the lower revs. But thats not a neccessity.

 

-Brian

Maybe i didn't explain it well enough. With the Bosch EFI systems, with the vain style MAF there is a sensor that measures manifold pressure. There is two versions of this sensor one for Turbo engines the other is for non-turbo engines. You should be able to replace the one that measures boost in your EA81T with one that measure vacuum from a non-turbo 85/86 MPFI. Your best chance to find one would be from a 85/86 non-turbo XT.

oh FYI EA81 and EA81T use the same cam same goes for EA82 Carb and EA82T

Awesome Craig! thats something i'll need to remember.

 

-Brian

i think that he just means fooling with the air filter pod and hoses.

NOT all EA81's use the same cam. the hydro lifter engines are different as they have different valves - thus an 83 or 84 non-hydro engine will have a different cam than an 83 / 84 turbo. On top of that, the Brat has yet another cam..... there's actually a BUNCH of cams for the EA81's - depending on year, hydro lifters, and turbo. Even the performance cams from Delta are different if you intend to put them in a hydro or a non-hydro... you have to tell them which you want.

 

GD

Brian, I know how much you want to use the EA81T. But remember, the injectors are in the heads. If you use another intake system, you will have to plug the bosses.

I would suggest using a EA81 NA block and put the early EA82 MPFI intake on. The ECU will be able to handle it. I think it would be a much more reliable off road rig. And theres always someone looking

for a good EA81T.

Just my .02

Just use a carbed EA81 block, and an EA82 SPFI intake, wirign, and computer. Would be easier than doing all that work to the EA81T

I know the MPFI and Turbo EA82's use the SAME air flow meters for 85-86, and the same MAF for 87+ The thing that measures the manifold pressure is a sensor. The thing that measure HOW MUCH AIR is flowing into the engine is the air flow meter. There are no differences between these items on MPFI and turbo. The MPFI is turbo ready.

Brian, I wasn't very clear, sorry. I meant to say that you could use the EA81T as a NA setup. Using EA71 pistons and decking the head a bit shooting for about 11:1~11.5:1. Run a weber IDF 44 carb (or dual IDF40s) and get your cam cut for a longer duration with a bit more overlap.

 

130Hp easy, no reason not to hit 150 leaning toward a bit higher CR and cleaning up the ports.

Brian,

I agree with whoever it was that said you'd be okay by just eliminating the turbo and swapping in the NA pistons. The boost/vacuum sensor swap also sounds reasonable, except that I don't remember any sort of pressure sensor on my '85 MPFI car.

 

You'll probably need to make a custom intake duct to go from the MAF to the throttle body, but that's no big deal. I have an MPFI non-turbo "elbow" from an '85 that fits to the throttle body if you need it. It'd be a shame to cut the turbo one.

 

The way I look at this is: a turbo car does not always have boost, and most turbo cars will still run (poorly) with a seized turbo, SO I see no reason for this car to have any problems running with no turbo and 10:1 compression AND I fully support your decision to try this.

 

I don't know if you've thought of this, but you'll have a knock sensing ignition too! (unless the disty curve doesn't work out and you have to swap in a NA disty.)

SubaruBrat: I want the MPFI, im sick of Carb's... reason behind this entire idea is to keep the EA81 and its OHV, but dump the Hitachi and carb idea all together.

 

CIS: Thanks for the support, i wont be needing any parts... i should be able to get everything from here. I was thinking the same, my roomates EA82T had a leaking exhaust that didnt provide 100% pressure to the turbo. It ran like crap, but still ran... so im thinking the EA81T with N/A pistons should work out just fine.

 

And also... why is everyone suggesting to use EA82 parts? Is it needed? Why cant I just use the same MPFI Intake and parts from the EA81 (minus the plentum). If EA81T and EA82T injectors are identical, than this should be easier than i assumed.

 

-Brian