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Building the ultimate ea81 on a budget


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9 replies to this topic

#1 75subie

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Posted 12 November 2006 - 08:45 PM

need some suggestions. i`ve never actually "built" a motor, so i`m hoping to do this as a learning expierience for less than $5-600

i already have this ea81 with 88k on it out of an 88 hatch (i believe that would make it hydro lifters) anyway, i`d like to do something fun with this motor for my 85 brat. also hoping to get an msd ignition setup, decent exhaust, and a 5 sp d/r.

anyway, i've already decided to go with spfi off of a newer ea82 thanks to Generaldisorder's manual. but what else would you guys suggest?

are hydro or solid lifters better?
would spfi pistons up my compression? would it be worthwhile?
how about a better cam grind? if i sent mine to delta cams, what cam grind would be the way to go for this type of build?
should the valves or valve springs be upgraded?
are oil pumps with better displacement available?

what else would you guys suggest? this is on a budget, so i`m hoping minimal machining and porting is needed.

thanks
Jon

#2 4x4_Welder

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Posted 12 November 2006 - 09:00 PM

For mine, for better torque, I am going with a 250 grind from Delta. That, along with bearings, rings, gasket set, oil pump and water pump will run you about $450.
That's assuming the heads are ok, no need to have the block bored, just honed, new rings, new bearings, and put it back together. Also assuming you already have all the tools you need to do the job.
There really isn't much that can be done to upgrade these engines, not that they couldn't use it, but there really isn't much room for improvement with the existing parts. I'm sure if you could throw a set of dual port heads on, along with better head gaskets, but then there is the possibility of head bolt breakage or pulling out of the block.
There isn't a need to upgrade the oil pump, that puts out more than enough to lube the engine at any rpm. Just make sure the pickup is in good shape, and the tube isn't bent, dented, and doesn't have any holes in it.

#3 Hodaka Rider

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Posted 12 November 2006 - 10:12 PM

I would suggest that with the SPFI, better compression, and the proper cam grind, you should be able to come close to or hit the 100hp mark.

#4 jeffast

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Posted 12 November 2006 - 10:34 PM

I would suggest that with the SPFI, better compression, and the proper cam grind, you should be able to come close to or hit the 100hp mark.

the jdm dual carb ea81 engines put out 103 hp i would think with spfi you could see 110-115 easy maybe more with a little work

#5 75subie

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Posted 12 November 2006 - 10:36 PM

i`d like to get my hands on some dual carb heads. i hear they have bigger valves and intake holes.

#6 75subie

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Posted 12 November 2006 - 10:43 PM

do you guys think i`d be better off trying the spfi alone before spending too much money?


i`m thinking thats the way to go, and then after i`m done with welding lessons,go ahead and try an ej22 swap.

#7 kingbobdole

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Posted 12 November 2006 - 11:00 PM

the jdm dual carb ea81 engines put out 103 hp i would think with spfi you could see 110-115 easy maybe more with a little work

I think Jeff's crazy. 110 HP seems like quite the power out of an SPFI car. SPFI is like really, really fancy carburation. Changing the way you get fuel really doesn't up the HP, its just a more efficent way of throwing fuel through the motor. They start at 90 HP with the 9:1 compression. 20 HP gain seems out there especially with lower compression. All I'm saying is that 110-115 is not going to be "easy" on a SPFI EA81, its gonna take a bit of work to get there...

do you guys think i`d be better off trying the spfi alone before spending too much money?
i`m thinking thats the way to go, and then after i`m done with welding lessons,go ahead and try an ej22 swap.

Yes. The SPFI swap is awsome. MPG FTW!

#8 75subie

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Posted 12 November 2006 - 11:09 PM

with a cam grind, spfi, spfi pistons, hi flo exhaust, and msd, (plus accel plugs, ss coil, accel plug wires, good tune up) i think the 100-110hp mark would be in sight, but with just the spfi, it would probly be about 80hp.

plus i'd like to play the "let me see if i can get this thing to run" game with the spfi swap alone:-p

#9 daeron

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Posted 12 November 2006 - 11:16 PM

with a cam grind, spfi, spfi pistons, hi flo exhaust, and msd, (plus accel plugs, ss coil, accel plug wires, good tune up) i think the 100-110hp mark would be in sight, but with just the spfi, it would probly be about 80hp.

plus i'd like to play the "let me see if i can get this thing to run" game with the spfi swap alone:-p


Wise choice. If the brat already has a motor in it, and you are thinking of building a new one simply for the sake of learning and upgrading, then I would highly suggest you do the SPFI swap first, then build your motor on a stand in your garage. That way, you know the swap works 100% before you go after installing the new longblock.

This method also makes the engine rebuild an option that can be delayed or hastened upon at will, it turns one big bite into two smaller ones. a no-brainer, really.. something tells me that when it came time to do it, you PROBABLY wouldnt literally be working on both jobs at the same time... :rolleyes:

You could even (!) just build your motor, then build your ECU/FI steup, and test it on your new motor standalone before you install it into the vehicle.... :grin:

anyhow, good luck and have fun. You chose the right car to try with.

#10 GeneralDisorder

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Posted 13 November 2006 - 03:03 AM

Interestingly, my impressions of the SPFI EA81 was that it was on-par with a Weber swap. But can be cheaper if you source your parts right. I'm currently running a full SPFI EA82 in my Brat (EA81 is almost back together), and with the SPFI tuned up properly it's pretty damn fast. 90 HP is a bigger increase from 74 than I thought - especially in the Brat's light frame. 16 HP is not an insignificant amount I'll tell ya.

Driveability is VERY nice. It drives like a perfectly tuned Weber, but without the "little" cues that tell you it's a carb. The pedal isn't as "touchy". It's hard to explain, but it's like driving a newer car in a way.

The BIG difference (and the part that makes it not *just* fancy carburetion) is that the SPFI is capable of adjusting itself to the flow of the engine - open the exhaust for a little better flow and the ECU compensates with more fuel for more air. That's the purpose of the Mass Airflow Sensor - it detects the incoming air mass and adjusts fuel accordingly to acheive optimal mixture ratio for any given RPM. The engine is at it's core a big air pump - with the SPFI you don't have to worry about jetting a carb - that's the whole point. Rather than a fixed mixture system, the computer is there to calculate it based on sensor input.

Here's what I sugest.

1. Do the SPFI swap.

2. Convert to Mega-Squirt (I'll be working on a write up for that in the next 6 months or so when I get all my MS bits built)

3. Drop ANY engine you want in the car. I sugest the JDM EJ20 DOHC. They can be had for cheap, and are 150 HP stock to the EJ22's 135. They are cheap because it's "hard" to use them in the states because import engines don't come with wireing harnesses or ECU's..... but that's not a problem with MS - just upload new settings into your ECU, drop the engine in and go.

Once the vehicle is MS, it can handle ANYTHING you want. Want an EJ20G? No problem. Want to turbo an EJ22? MS has you covered up to 25 psi boost. Want a chev V6?..... endless possibilities and you will never again have to worry about wiring. Personally just being able to use cheap import engines like the EJ20 NA that we never got here in the states is enough of a benefit.

GD




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