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Hot-Rodding a Brat in two stages - Suggestions?


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Here's what I'm talking about....

 

CAVEAT; I do not care about "street legal" restrictions or laws whatsoever!


I want to first improvise to squeeze more power out of my old 1983 EA81 Brat just to take a mountain grade I have to drive without getting bogged down to 40mph in third gear until I can figure out an afford to replace the engine with something with significantly more horsepower.

 

I need whatever help, suggestions, ideas, sources (for S. Calif area),etc.

 

Stage #1:
(A) Start looking for a 5 speed tranny

(B) Improvise horsepower by possibly linking both barrels of my standard carb together, saw something about this here somewhere, need to know exactly how to do that; maybe use better grade of gas, and/or add improvised octane booster like paint thinner or lacquer thinner or something; I do plan on replacing exhaust with something completely different using 2 inch exhaust pipe, which for a Subaru is like headers (Yes, I know about the back-pressure issue, already factored into design.

Question: I have a tiny parts store air cleaner on it, only maybe 5 inches across, will bigger air cleaner/filter make a REAL difference? Also thinking about improvising some kind of ram scoop to crudely force a little more air into the carb; Maybe get webber carb unless that would be replaced or eliminated by whatever the next engine is. Imprvisations/suggestions?

 

Stage # 2:

New/used engine:

Preference #1: EA81 dual carb engine if I can find one, install webbers, super-charger(s) - why?
(A) I prefer super charging over turbo

(B) I prefer not having a timing chain or electronic ignition - I just do.

© (Forgot, lol)

Preference #2: EJ2200 or similar as per people's suggestions, whatever has the maximum possible horsepower within affordable limits and will bolt into my Brat, - hopefully.

 

I don't want to go broke going too extreme, would prefer the simplest, most affordable way to seriously boost horsepower and speed up a mountain grade regularly.

 

Thank you in advance for all suggestions/ideas...

 

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From all the various threads I've read on here, the easiest, lowest cost, reliable, significant hp upgrade is to ej 22 it.

 

None of the options are easy. I doubt turbo or supercharger would be cheap. Both increase stress on the stock lower bits of the engine, which are solid, but that is why they are reliable. There are a few things that can be done that are either expensive or time consuming to get small increases. Side note, these engines make power at higher rpms, so downshifting is preferable to lugging.

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From all the various threads I've read on here, the easiest, lowest cost, reliable, significant hp upgrade is to ej 22 it.

 

None of the options are easy. I doubt turbo or supercharger would be cheap. Both increase stress on the stock lower bits of the engine, which are solid, but that is why they are reliable. There are a few things that can be done that are either expensive or time consuming to get small increases. Side note, these engines make power at higher rpms, so downshifting is preferable to lugging.

 

You are absoluytely right about the downshifting and RPM, etc.

However...

(A) I do not like pushing the RPMs on an engine already in less than perfect age/condition

(B) I like the lower RPMs, and my exhaust is in just bad enough condition that is actually sounds like a cross between a Harley and some hotrod, lol...

But yes, You do make a valid point.

 

However, what I saw on linking the barrels together seems like a very real and inexpensive way to get noticeably more power.

Its a must as far as I'm concerned.

I can't sem to find that again, apologies, but the search function on this site sucks, lol...

 

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I have a moderate amount of experience looking at engines. Low rpm high tourque ones have noticeably wider connecting rod and crank bearings than high rpm low torque engines. If I remember correctly, EA81 lower end is very similar to ea82. Ea82s start making power around 3500 rpm. And perfectly happy spinning 4000 on the highway.

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I have noticed a small power improvement with a K&N air filter... Weber or SPFI conversion will add more power from what I have heard. I think I remember reading somewhere that using 8mm plug wires instead of 7mm (or was it 6mm??) will also give you a boost. RAM Performance sells EA81s that push out something like 160HP (again, not sure about that number, might be 130HP) however at two grand they are not cheap. 

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I have a moderate amount of experience looking at engines. Low rpm high tourque ones have noticeably wider connecting rod and crank bearings than high rpm low torque engines. If I remember correctly, EA81 lower end is very similar to ea82. Ea82s start making power around 3500 rpm. And perfectly happy spinning 4000 on the highway.

 

Ah, so there are engines that are better hill climbers, mine is more the higher RPM.

It is one of the paradoxes of Subaru (Brat) Freakdom, in my case.

I have owned more than one, pushed them Way, WAY past their limits, beat the living snot out of them offroading, etc. etc. and like few people know what these Subarus can do and can take, and they are wondrous in design and constitution,

but, without explanation or excuse, I do fear the higher RPMs because I have been in a vehicle that threw a rod or something and went to pieces inside, and it is one of the most horrific feelings to occur, especially to a Subaru (Brat) freak.

And, I shamelessly admit, when my Brat sounds so cool, especially at certain RPMs, I lust for it and love the lower RPMs.

My rule is that I try not to go above 3500, but maybe that is good anyway as that is where your power band starts, so the logical compromise would be near but not over 4000 RPM maybe. I will try pushing the RPMs a but more and see how it works out.

 

 

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I have noticed a small power improvement with a K&N air filter... Weber or SPFI conversion will add more power from what I have heard. I think I remember reading somewhere that using 8mm plug wires instead of 7mm (or was it 6mm??) will also give you a boost. RAM Performance sells EA81s that push out something like 160HP (again, not sure about that number, might be 130HP) however at two grand they are not cheap. 

 

Didn't get exactly what you meant by RAM performance...

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I don't really do offroading. But my ea82 powered 4wd 3 speed automatic wagons see 5000 to 5500 rpm getting going in 2nd onto the highway. Keep the

cooling system good, use good oil.

 

Just replaced radiator with new. My gauge redlines at 4000 I think.

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I really want to find that discussion about wiring or linking the barrels of the carb together, I am sure that will make a difference in itself, combined with a little this and that, I'm confident I can be satisfied with the power/speed until I can get a better set-up.

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Just replaced radiator with new. My gauge redlines at 4000 I think.

My 84 ea81 redlines at 5500rpm on flat ground i get 75mph at 3200rpm with a webber, but hills are definitely a killer for the 4spd the 5spd will be a big improvement because of better gearing, so if you want to keep the ea81 get a webber do a 5spd swap or get an ej22 and ej25 put the 2.2 heads on the 2.5 and swap a 5spd and you'll have much more power on your hands.

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msd ignition boxes work wounders under 3000 rpms by far the best bang for your buck just adding more fuel wont help if the engine cant burn it also fuel injection will increese your drive ability by adding the right amount of fuel when you need it good for maybe 5hp there isent a easy/cheap way to get power out of that motor you could boar it stroke it and shave it then do a port and polish job a big fat carb and custom intake and a free flowing exaust but that takes alot of time and or money and it still wont give you as much power as a ej swap but thats not always the best option ether

Edited by ferp420
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My 84 ea81 redlines at 5500rpm on flat ground i get 75mph at 3200rpm with a webber, but hills are definitely a killer for the 4spd the 5spd will be a big improvement because of better gearing, so if you want to keep the ea81 get a webber do a 5spd swap or get an ej22 and ej25 put the 2.2 heads on the 2.5 and swap a 5spd and you'll have much more power on your hands.

 

I was not aware of the EJ25 engine. Why put 2.2 heads on a 2.5 engine? You really got me there, lol...

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Got a lead on a wrecked '97 Legacy wagon with a good engine for next to nothing. Owner does not know what kind\size engine, might be able to use the engine? I can get the vehicle for less than the core charge on a motor, but nowhere to keep it right now, lol

What do these things use for an engine anyway?

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The 2.5 dohc blew headgaskets a lot. There is a lot more info and details in the newer generation sub forum. I never had one, so what I have picked up came from those threads. It's nearly unanimous to stay away from ej25s.

 

The mod I have considered is swapping an ej 2.2 into a Loyale ea82 which is a 1.8. It's something like a 50% HP increase. It's been done. More power upgrade than that, you'll just spin tires all the time and /or blow the rest of the driveline. Somewhere I had found a list of Subaru engine models and thier HP ratings that made it easy to compare. The SPFI ea82 is noticeably more power than carbed ea82. Iirc the main difference between EA81 and ea82 is the overhead cams. Some have put the SPFI onto ea81s.

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I was guessing about the redline on my tach, and I was WAY off - its redline is actually at about 5500 rpm.

I juist cant get past that aweful feeling when I hear the RPMs high, since I have an older engine in not prime condition that it will throw a rod or something. If I get up to even 4000 RPMs it sounds like I'm pushing it too far.

It is probably just me,  So just to re-orient myself, with an older EA81 in 75-80% condition and a tach that starts the red at 5500, just how high can I safely take the RPMs ???

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I was guessing about the redline on my tach, and I was WAY off - its redline is actually at about 5500 rpm.

I juist cant get past that aweful feeling when I hear the RPMs high, since I have an older engine in not prime condition that it will throw a rod or something. If I get up to even 4000 RPMs it sounds like I'm pushing it too far.

It is probably just me,  So just to re-orient myself, with an older EA81 in 75-80% condition and a tach that starts the red at 5500, just how high can I safely take the RPMs ???

 

 

Just pretend it's not yours and you just stole it.

Get out there and beat the snot out of it.

You'll be surprised at how well it will like that.

 

I've ran a few of my EA81's up to 60 mph in 3rd, that's spinning things pretty good.

 

Keep oil in them, and keep coolant level good, and these little engines will run a long time.

Good solid lower end in them.

 

Yes, there's been a few what threw a rod, but that is as rare as hen's teeth.

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