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9 replies to this topic

#1 tdangelo

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Posted 19 March 2004 - 10:16 PM

I have a 1983 Subaru Wagon, in outstanding shape, that has the EA81 engine in it. I am interested in keeping it "stock in appearance" when you lift the hood. I have recently obtained an intake and carburetor from a 1987 Subaru EA82 which I understand is a large intake and carb setup. I am interested in knowing if anyone is running this combination on an EA81 and if so how much of and efficiency gain have you achieved? In addition I am going to change over to the FI heads for the EA81. The ultimate goal is to make this as efficient as possible useing "OEM stuff".

Thanks for the help.
yepabus

#2 GeneralDisorder

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Posted 19 March 2004 - 10:22 PM

You can run it, but I doubt you will have any serious effeciency gains - the low end torque will be a little better since the primary is bigger, but that's about it. You also have to modify the intake to fit - I'm not sure exactly where, but it will need some grinding I think. Others on this board who have done this will probably chime in.

As for FI heads for an EA81, the only FI EA81 was the turbo (it was MPFI), and this has injector bosses right on the heads. Not to mention they are increddibly rare. If you want better heads, then get some from a hydro lifter EA81 - they have bigger vlaves, and the engines are rated at about 7 more HP because of it. 85 and up EA81's are all hydro. 83 and 84 Automatics are too...

GD

#3 tdangelo

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Posted 19 March 2004 - 11:19 PM

I see that you have a Weber on yours. Is there a significant increase in efficiency with one of these? What does it do to your fuel economy, provided you keep your foot out of the secondaries?

#4 TheSubaruJunkie

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Posted 19 March 2004 - 11:26 PM

The Weber is the best mod you can do to a EA81... but it definatly wont appear to be stock.

The EA82 manifold will bolt to the EA81 with no modifications, but the thermostat is housed on the other side ont he EA82, so there are slight mods that have to be made when running the coolant hoses.

As far as power gains, i wouldnt expect to see any. And as far as going to MPFI, you'd need to find a computer to control the EA81 MPFI heads and injectors. Also you'd need the intake from the MPFI as well... all can be found from a EA81T, but they are rare. Also, the main problem with the EA81T is when they overheat, the heads crack... leaving the most important part useless.

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#5 GeneralDisorder

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Posted 19 March 2004 - 11:29 PM

Well - when the wagon was a 2WD, I got 32 MPG on a 600 mile trip doing about 80 most of the way. And I do use the seccondaries quite a bit. I would guess it could possibly do better if you kept your foot out of it. Now with the 28" mudders it gets about 17 MPG - but that's still better than a Hitachi gets with 28" tires, and the low end torque with the 32mm primary is awesome. There's no change in the high end from what I can see - I could do 110 with the Hitachi, and about the same with the Weber.

I have seen Hitachi's get upwards of 28 - 30 also, but never as good as my Weber got when it had small tires on it. The Weber's also run smoother, are easier to work on, and less complicated too... And they are even bigger than an EA82 Hitachi, which if memory serves is a 28/32. EA81 Hitachi's are 26/30

Oh - and I should mention that the SPFI system from an EA82 will bolt right onto an EA81. You need to wire up the computer, and change the disty drive gear on an EA82 disty for it all to work, but this would be a cool mod too....

GD

#6 the sucker king

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Posted 20 March 2004 - 02:09 AM

Originally posted by GeneralDisorder
I could do 110 with the Hitachi, and about the same with the Weber.


GD



realy? i would need such a long downhill i would be in HELL by the time i got to 110 mph in my ea81. you sure that aint kilometers? i honestly think i aproached 90 in my hatch. once.

#7 AKIRA

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Posted 20 March 2004 - 02:21 AM

my brat is pretty much stock and I can get it to do 85+ only after a fairly long straight stretch, and flooring it.

I think it's top speed is 90 at most.

#8 GeneralDisorder

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Posted 20 March 2004 - 03:12 AM

2WD 5 speed, EA81 with the feedback carb. All stock. I SWEAR I hit 110. Actually I think it was more like 112, but who's counting. I had to see my digi-dash go over 100. Now with the 28's of course I can't come even close to that, but I have seen my dash hit 80, which works out to a little over 95 MPH - and that's with 28" mudders!

I've had my Brat up to well over 95 (high as the guage reads) on the flat and level. It's got the standard hitachi, but a little more peppy hydro lifter EA81.

GD

#9 CIS Subaru

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Posted 20 March 2004 - 10:07 AM

I totally believe GD's 110mph claim.

My '84 DL 2wd 5spd Hardtop with the stock large valve 9.0:1 1600cc engine and stock feedback Hitachi will go 90mph with very little effort. I'm certain that it could break 100mph, but my speedo only goes to 85. On top of that, it gets 35mpg in normal driving!! On a long trip I once got 37mpg!!

The secret is the transmission.
The EA81 4spd 4wd has a 0.769 4th gear and 3.900 diff resulting it a total reduction of 2.999.
The EA71/EA81 2wd 5spd has a 0.725 5th gear and a 3.700 diff resulting in a total reduction of 2.683.

So in top gear at 4000rpm, the 4wd's wheels are spinning at 1333rpm while the 2wd's wheels are spinning at 1490rpm.
With 185/70/13 tires, that's about an 11mph difference at 4000rpm.

#10 GeneralDisorder

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Posted 20 March 2004 - 01:09 PM

Yeah - And I think about 4k is where she would top out - 4100 maybe. Hard to tell exactly with the digi-tach. I had not realized that the 2WD was a 3.7, but that does makes sense now that I think on it. Sucker really moves.

Thanks for the clarification on that CIS...

Also - the reason my wagon is still fast with the 28's is that I'm using an 82 4 speed D/R. It's got lower 3rd and 4th gears....

GD




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