Jump to content
Ultimate Subaru Message Board

EA81 Performance Mods--Best Bang for the Buck?

Recommended Posts

Originally posted by beauregaardhooligan

Dante, if you want torque, stay away from big pipe headers. You can put bigger tubes after the Y pipe, but keep it small off the heads.


Thanks beauregaardhooligan. I understand. If I have a header made it will be about the same size as stock back to the collector to preserve scavenging and low-end torque. One ea-81 builder I've been talking to said "Header primary length is critical to this engine, you need 1.625 od tubing (1.5 id) off the head 28" long into a collector". Others have used 1 7/8 ID and reported good results, but based on what I have read and heard here, in my ea-81 exhaust thread and elsewhere, i would not go larger than that.


I also got e-mailed and spoke with Joe Souza today. He gave me some interesting info. First, he said the runners on his Weber intake manifold are 25% larger (fatter ID) than stock and will enhance low-end torque. He also had lots of good things to say about the Japanese dual-carb head. He recommended getting that engine or at least the heads and cam if I was looking for the best bang for the buck. FWIW he said the dual carb heads are different from the US spec. ones and flow better then ported US spec. heads. He doesn't sell them, so I don't see why he would BS me about it...

Share this post

Link to post
Share on other sites

I have been reading this thread with interest, as I want a little more bang from my 88 d/r hatch. Sadly, I am not a gearhead at all.


What does it mean to recurve the distributor? I bookmarked the Philbin website for future reference, but what do I do...send them a disty and ask them to recurve it, maybe specifying what octane I want to run?


Someone else mentioned advancing the timing...is that the effect caused by the disty recurve, or is it something else entirely?


Yet another post mentioned installing EA71 pistons, which I guess would also involve a fairly major disassembly, and new gaskets throughout. Assuming I had that done, is the piston swapout all there is to it, or do you have to adjust anything else to capitalize on the newly increased compression?


So, currently I'm saving up for a Weber carb/K&N filter setup, an Accel Superstock 8140 coil, and Magnecore wires.


Tentatively, once I know more about these arcane concepts, it'll be a disty recurve and EA71 pistons. I'd like to know more about what those mods do, how, and why, before I go there.


Thanks so much for any clarification you can provide, and thanks especially to the nice fellow who told me that the guys at Ram Air deal with aviation mods...silly me!

Share this post

Link to post
Share on other sites

The disty revurve is done to change the characteristics of the engine - where do you want the torque? Basically you tell them if you want the HP in the low range, or the high range. The curve in the disty tells when the timing will advance - low RPM's or high RPM's.


EA71 pistons are ever so slightly different from EA81 pistons. They add more compression. Not a whole lot on their own, but they are part of a larger scheme of increasing the compression. The stock compression is 8.7:1. With the EA71 pistons, and decking the heads .020" and regrinding the cam to match, you can acheive about 9.5:1 compression. Add a weber and a better exhaust and your looking at around 125 HP or so. Much better than the stock 73 HP anyway....


I wouldn't worry about the magnecore wires - any good 8mm set should do just fine. You won't notice any difference on these engines, as the ign. system isn't that hot. If you went with a high voltage system - like MSD or something, that would be different....


Get a used Weber and rebuild it - the Kit is not worth the price they ask - believe me - the instructions you get are crappy, and well..... check out my website if you don't believe me. I scanned the instructions, and put them up on my site. And there's pictures of what comes with the kit. They don't even include the right air filter unless your running lifted. The adapter is about $30 - $40 online, and the filter is $9.99 from EMPI (VW performance manufacturer).



Share this post

Link to post
Share on other sites

The curve of the distributor does change the ignition timing while the motor is running, but you can also change the timing setting to run different octanes of gas.

The Accel coil will add some grunt, but you need to open the spark plug gap to take advantage of the hotter spark. I run .050.

A good set of stock wires will be fine. Subarus seem to prefer NGK plugs, I feel platinum and multi-gap plugs are a waste of money for a stock motor.

Share this post

Link to post
Share on other sites

i didnt see this mentioned. brat cams are supposed to be better low end torque, and i know my brat pulled a hlell of alot harder than my 2x hatch.


and on the exhaust thing. you can use an ea82 manifold, and they dont have the provisions for the air suction valves. and the header pipes go up further than the ea81s, so you would have to ditch the little spacers for the air suction valves.

then your ea81 engine compartment would be cleaner. ea82 is pleanty bigger, and the welds around the flanges arent so intrusive to flow.


and make sure you use an ea82 intake manifold, bigger runners(slightly)


and, the weber thing, i agree, dont buy the kit, unless you are lazy:D

i have had the tall air filter on both my ea81s and ea82s and the hood clears on both of them. it may touch, the hood, but it doesnt smash the filter.

Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now