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EA81 engine

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Weber would be number 1. Two inch exhaust from Y pipe back with a Magnaflow muffler or similar. Also change your thermostat out for a 180 degree, lower if you don't need the heater much. Coolant runs through the intake and heats the air charge. Probably gets you into the high 70's!!!

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You could supercharge it.  All parts are bolt on with some welding here and there.  There are pro's and cons.

 

Two types of SC.  Blow thru and suck thru.  Blow through means air only passes through the supercharger, the common manner that supercharged cars exit the assembly line.  Suck through is an easier method with air and gas passing through the SC.  Hence with suck thru the sequence is carbie, SC then manifold  whereas flow thru is SC, carbie then manifold.  Subsequently the latter needs its carbie to be sealed to stop air escaping.

 

Manifolds before and after the SC need to be made.  Lets stick to suck thru...a method I've tried on my EA81 powered trike.

 

The good-  an increase of around 33% in power output for 74hp to over 100.  Torque increase up by around 30%. No lag like with turboes- power is from idle.  (tune graphs are of the first tune....it had 3 dyno tunes in total but you'll get the picture)

 

The bad- economy.  Expect a drop of around 15-20% after a proper tune.

 

You need to ensure your engine is in top condition.  I geared my supercharger to make 4psi and achieved the above figures on a stock engine (dyno graphs below) and 8psi is ok to but any more and other issues come into the mix because of the stresses involved.  Blow by increases.  A catch can is a must in most cases.  I tried water injection to improve economy but with 4psi it was a waste of money.

 

So what is needed?  A dellorto or weber carbie was easiest to use for my project but it ends up wide.  The carbie should be angled a little towards the SC.  A supercharger.  The most common used is the Toyota units either SC12 or SC14 of the 1980's, the 14 just being longer with more output.  This unit comes with a 5 riubbed pulley so you need to attach another one on your crank pulley. A third pulley needs to be adjustable to allow the belt to be really tight. The belt needs to be lined up correctly.  The original SC pulley has a clutch as OE. However on a suck thru set up this is not possible. Hence that clutch needs to be secured so it doesnt turn.

 

The custom housing  between the SC and EA81 manifold has to have a blow off valve.  This expensive piece is necessary for backfires, to stop the force going thru the SC and causing damage. It proved its worth.

 

A bonnet bulge might be needed. 

 

Mandatory is to not have air leaks.  Dyno tune is a must.  It is difficult to get the right jets to suit all rev ranges.

 

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Edited by tweety

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Hello.

I have in the past posted about "Hot-Rodding" my 1983 Brat.

The subject is a very difficult one, if you have the right perspective.

 

Everyone tells me to get a more modern engine, and mod the hell out of it, major re-working, re-wiring, replacing all kinds of stuff,  and....

NO.

 

I LOVE the EA81 ! I think that that the EA81 engine was a great engine, unique, so utterly dependable, so unlikely to break down, and I personally also love the fact that is is impervious to any possible failure to the timing chain! lol.. Never, ever have to deal with a timing chain on these!

It is also proof, irregardless of argument about performance, that an engine doesn't need a timing chain.

 

Horsepower is the issue, power is the issue, performance is the issue. ONLY real issue as far as I am concerned.

Therefore, I have come to my personal conclusion and answer.

 

I am going to:
Make a better EA81 Engine, rebuilt, and only slightly modified. ( lol )

I. Beefed up

1. Made simply more heavy-duty to survive being forced into high performance.
(A) Not necessarily boring it out, as these engines have not got the block material to allow too much of that, with one exception:
      I want to check out using extra thick Stainless Steel cylinder walls. Yes, I understand the difficulties.
(B) These would either have to be custom fabricated, or there is the slightest possibility that such can be found from another type of engine, and if so, would

      likely not be an exact fit for size, therefore, boring out the cylinder just enough to accommodate that cylinder/wall.
© Thicker, Stainless Steel cylinder walls would enable the engine to take more, make the engine indirectly stronger, and would also allow later to

      re-surface/bore the cylinders if necessary.

 

2. Check into replacing any key engine parts with simply superior parts or materials, even if taken from other types of engines, as there is probably not much

    of a market for actual performance parts for EA81's.
(A) Possibly having a couple things custom machined, and if so, check into using Titanium or other superior materials for smaller key parts if possible.
(B) Same considerations for all gaskets, especially the Head gaskets. Using exceptionally heat-resistant or asbestos-substitute materials.
3. Key parts priority would start with Cylinder heads and arms. These would likely be custom machined, but would double their effective strength, and

(A) The Cylinder heads would be made from stainless steel if possible. This would be a massive improvement as far as being a heavy-duty engine.
(B) If the arms are made of aluminum. they get made out of Aircraft aluminum, if they are already made from aircraft aluminum, then they get made from

      Titanium. If they are normally made of steel, then they get made from either stainless steel, or from alloy, like Cromolly or something.

© Yes, this might add effective comparative extra weight to the engine. I don't care.


II. Give SERIOUS, SERIOUS consideration to somehow installing dual carbs, or some kind of over-sized carb.

1. Yes, I know that you cannot just install a dual carb manifold onto an EA81 engine not originally set up for it without more modification. - I don't care.
     If I can find a dual-carb EA81, as unlikely as that is, I would rather get that engine, but otherwise, it's damn-well going to happen one way or another, with one exception:
2. One absurd option would be a custom adapter plate so that I essentially use a carb from another Subaru or completely different engine/vehicle, so that I

      can install an over-size carburetor, like putting a 4 barrel carb onto a 2 barrel intake in other older vehicles.

(A) People talk about how hard it is to synchronize dual carbs, so that makes using an over-size carburetor a better option, doesn't it?

(B) This option is actually the more likely to be able to do and make work well, with the least hassles for installation and continued reliability with as little
      re-adjustment of fiddling afterward as possible.
3.   I can get blowers that will work with this engine for as little as $150.00 The carburetor to use them would be over $600. Ok. My Brat is worth it, even if it

      mean TWO blowers on a dual-carb system. (This is what made my decision in the end, lol.)

 

III. Use Nitrous.
1. Yes, I know about the various legal implications, and I don't give a sweet damn.
(A) I can hide a nitrous system.

(B) Most law enforcement would not know what the hell it looks like anyway, - and I can hide it.
2. The purpose of the Nitrous is not the usual. This is not about a sudden huge boost of speed. Its about feeding enough to make the difference, when it is

     needed, like going up a steep mountain grade, which has been my main problem. (or when otherwise 'necessary' on RARE occasion, lol)

 

Conclusion:
 

They say this engine can only do so much, you can only force so much air and gas into it, etc.
If the engine can take more, you can do more. It will be able to take more compression at the very least, which also means it is better adapted to use Nitrous, especially with stainless steel cylinder walls.
How do you get more air and gas through the engine - RPM. Volume discounts work for a reason.
Between the Over-sized/dual carbs, the blower(s) and the Nitrous, I have absolutely no doubt that performance will be just fine.


Also, the beauty of this plan is about taking lemons and making moonshine lemonade.
The other option, to put a larger engine from another newer Subaru, would have cost me over $2500.00 minimum, and very likely more."
For that kind of money, I could do this instead - and have exactly what I want, in fact, better, have one HELL of a great engine, that will last a hell of a long time, and and save money as well.


Ok.. Time for people to tell me how this all will never work, all that is wrong with it, etc.... lol...

 

 


 

 

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Hello.

I have in the past posted about "Hot-Rodding" my 1983 Brat.

The subject is a very difficult one, if you have the right perspective.

 

Everyone tells me to get a more modern engine, and mod the hell out of it, major re-working, re-wiring, replacing all kinds of stuff,  and....

NO.

 

I LOVE the EA81 ! I think that that the EA81 engine was a great engine, unique, so utterly dependable, so unlikely to break down, and I personally also love the fact that is is impervious to any possible failure to the timing chain! lol.. Never, ever have to deal with a timing chain on these!

It is also proof, irregardless of argument about performance, that an engine doesn't need a timing chain.

 

Horsepower is the issue, power is the issue, performance is the issue. ONLY real issue as far as I am concerned.

Therefore, I have come to my personal conclusion and answer.

 

I am going to:
Make a better EA81 Engine, rebuilt, and only slightly modified. ( lol )

I. Beefed up

1. Made simply more heavy-duty to survive being forced into high performance.
(A) Not necessarily boring it out, as these engines have not got the block material to allow too much of that, with one exception:
      I want to check out using extra thick Stainless Steel cylinder walls. Yes, I understand the difficulties.
( B) These would either have to be custom fabricated, or there is the slightest possibility that such can be found from another type of engine, and if so, would

      likely not be an exact fit for size, therefore, boring out the cylinder just enough to accommodate that cylinder/wall.
© Thicker, Stainless Steel cylinder walls would enable the engine to take more, make the engine indirectly stronger, and would also allow later to

      re-surface/bore the cylinders if necessary.

 

2. Check into replacing any key engine parts with simply superior parts or materials, even if taken from other types of engines, as there is probably not much

    of a market for actual performance parts for EA81's.
(A) Possibly having a couple things custom machined, and if so, check into using Titanium or other superior materials for smaller key parts if possible.
( B) Same considerations for all gaskets, especially the Head gaskets. Using exceptionally heat-resistant or asbestos-substitute materials.
3. Key parts priority would start with Cylinder heads and arms. These would likely be custom machined, but would double their effective strength, and

(A) The Cylinder heads would be made from stainless steel if possible. This would be a massive improvement as far as being a heavy-duty engine.
( B) If the arms are made of aluminum. they get made out of Aircraft aluminum, if they are already made from aircraft aluminum, then they get made from

      Titanium. If they are normally made of steel, then they get made from either stainless steel, or from alloy, like Cromolly or something.

© Yes, this might add effective comparative extra weight to the engine. I don't care.


II. Give SERIOUS, SERIOUS consideration to somehow installing dual carbs, or some kind of over-sized carb.

1. Yes, I know that you cannot just install a dual carb manifold onto an EA81 engine not originally set up for it without more modification. - I don't care.
     If I can find a dual-carb EA81, as unlikely as that is, I would rather get that engine, but otherwise, it's damn-well going to happen one way or another, with one exception:
2. One absurd option would be a custom adapter plate so that I essentially use a carb from another Subaru or completely different engine/vehicle, so that I

      can install an over-size carburetor, like putting a 4 barrel carb onto a 2 barrel intake in other older vehicles.

(A) People talk about how hard it is to synchronize dual carbs, so that makes using an over-size carburetor a better option, doesn't it?

( B) This option is actually the more likely to be able to do and make work well, with the least hassles for installation and continued reliability with as little
      re-adjustment of fiddling afterward as possible.
3.   I can get blowers that will work with this engine for as little as $150.00 The carburetor to use them would be over $600. Ok. My Brat is worth it, even if it

      mean TWO blowers on a dual-carb system. (This is what made my decision in the end, lol.)

 

III. Use Nitrous.
1. Yes, I know about the various legal implications, and I don't give a sweet damn.
(A) I can hide a nitrous system.

( B) Most law enforcement would not know what the hell it looks like anyway, - and I can hide it.
2. The purpose of the Nitrous is not the usual. This is not about a sudden huge boost of speed. Its about feeding enough to make the difference, when it is

     needed, like going up a steep mountain grade, which has been my main problem. (or when otherwise 'necessary' on RARE occasion, lol)

 

Conclusion:
 

They say this engine can only do so much, you can only force so much air and gas into it, etc.
If the engine can take more, you can do more. It will be able to take more compression at the very least, which also means it is better adapted to use Nitrous, especially with stainless steel cylinder walls.
How do you get more air and gas through the engine - RPM. Volume discounts work for a reason.
Between the Over-sized/dual carbs, the blower(s) and the Nitrous, I have absolutely no doubt that performance will be just fine.


Also, the beauty of this plan is about taking lemons and making moonshine lemonade.
The other option, to put a larger engine from another newer Subaru, would have cost me over $2500.00 minimum, and very likely more."
For that kind of money, I could do this instead - and have exactly what I want, in fact, better, have one HELL of a great engine, that will last a hell of a long time, and and save money as well.


Ok.. Time for people to tell me how this all will never work, all that is wrong with it, etc.... lol...

 

 


 

 

Share this post


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Share on other sites

Hello.

I have in the past posted about "Hot-Rodding" my 1983 Brat.

The subject is a very difficult one, if you have the right perspective.

 

Everyone tells me to get a more modern engine, and mod the hell out of it, major re-working, re-wiring, replacing all kinds of stuff,  and....

NO.

 

I LOVE the EA81 ! I think that that the EA81 engine was a great engine, unique, so utterly dependable, so unlikely to break down, and I personally also love the fact that is is impervious to any possible failure to the timing chain! lol.. Never, ever have to deal with a timing chain on these!

It is also proof, irregardless of argument about performance, that an engine doesn't need a timing chain.

 

Horsepower is the issue, power is the issue, performance is the issue. ONLY real issue as far as I am concerned.

Therefore, I have come to my personal conclusion and answer.

 

I am going to:
Make a better EA81 Engine, rebuilt, and only slightly modified. ( lol )

I. Beefed up

1. Made simply more heavy-duty to survive being forced into high performance.
(A) Not necessarily boring it out, as these engines have not got the block material to allow too much of that, with one exception:
      I want to check out using extra thick Stainless Steel cylinder walls. Yes, I understand the difficulties.
( B) These would either have to be custom fabricated, or there is the slightest possibility that such can be found from another type of engine, and if so, would

      likely not be an exact fit for size, therefore, boring out the cylinder just enough to accommodate that cylinder/wall.
© Thicker, Stainless Steel cylinder walls would enable the engine to take more, make the engine indirectly stronger, and would also allow later to

      re-surface/bore the cylinders if necessary.

 

2. Check into replacing any key engine parts with simply superior parts or materials, even if taken from other types of engines, as there is probably not much

    of a market for actual performance parts for EA81's.
(A) Possibly having a couple things custom machined, and if so, check into using Titanium or other superior materials for smaller key parts if possible.
( B) Same considerations for all gaskets, especially the Head gaskets. Using exceptionally heat-resistant or asbestos-substitute materials.
3. Key parts priority would start with Cylinder heads and arms. These would likely be custom machined, but would double their effective strength, and

(A) The Cylinder heads would be made from stainless steel if possible. This would be a massive improvement as far as being a heavy-duty engine.
( B) If the arms are made of aluminum. they get made out of Aircraft aluminum, if they are already made from aircraft aluminum, then they get made from

      Titanium. If they are normally made of steel, then they get made from either stainless steel, or from alloy, like Cromolly or something.

© Yes, this might add effective comparative extra weight to the engine. I don't care.


II. Give SERIOUS, SERIOUS consideration to somehow installing dual carbs, or some kind of over-sized carb.

1. Yes, I know that you cannot just install a dual carb manifold onto an EA81 engine not originally set up for it without more modification. - I don't care.
     If I can find a dual-carb EA81, as unlikely as that is, I would rather get that engine, but otherwise, it's damn-well going to happen one way or another, with one exception:
2. One absurd option would be a custom adapter plate so that I essentially use a carb from another Subaru or completely different engine/vehicle, so that I

      can install an over-size carburetor, like putting a 4 barrel carb onto a 2 barrel intake in other older vehicles.

(A) People talk about how hard it is to synchronize dual carbs, so that makes using an over-size carburetor a better option, doesn't it?

( B) This option is actually the more likely to be able to do and make work well, with the least hassles for installation and continued reliability with as little
      re-adjustment of fiddling afterward as possible.
3.   I can get blowers that will work with this engine for as little as $150.00 The carburetor to use them would be over $600. Ok. My Brat is worth it, even if it

      mean TWO blowers on a dual-carb system. (This is what made my decision in the end, lol.)

 

III. Use Nitrous.
1. Yes, I know about the various legal implications, and I don't give a sweet damn.
(A) I can hide a nitrous system.

( B) Most law enforcement would not know what the hell it looks like anyway, - and I can hide it.
2. The purpose of the Nitrous is not the usual. This is not about a sudden huge boost of speed. Its about feeding enough to make the difference, when it is

     needed, like going up a steep mountain grade, which has been my main problem. (or when otherwise 'necessary' on RARE occasion, lol)

 

Conclusion:
 

They say this engine can only do so much, you can only force so much air and gas into it, etc.
If the engine can take more, you can do more. It will be able to take more compression at the very least, which also means it is better adapted to use Nitrous, especially with stainless steel cylinder walls.
How do you get more air and gas through the engine - RPM. Volume discounts work for a reason.
Between the Over-sized/dual carbs, the blower(s) and the Nitrous, I have absolutely no doubt that performance will be just fine.


Also, the beauty of this plan is about taking lemons and making moonshine lemonade.
The other option, to put a larger engine from another newer Subaru, would have cost me over $2500.00 minimum, and very likely more."
For that kind of money, I could do this instead - and have exactly what I want, in fact, better, have one HELL of a great engine, that will last a hell of a long time, and and save money as well.


Ok.. Time for people to tell me how this all will never work, all that is wrong with it, etc.... lol...

 

 


 

 

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I think you are going to struggle for anything significant in improvement relating to bore. That said, Darton would happily make you a set of custom sleeves...for a price.

 

The thing to look in to would be stroking. The EJ family really didn't increase the bore that much from the EA (92mm) - EJ20 is also 92mm but is 11% bigger in capacity due to stroke of 75 vs 67mm for the EA. I would think at best you might squeeze out a bore of 96mm using custom sleeves and a lot of machining but that will only take you up to 1.94L (up 8%). The main issue would be clearancing the block (less of an issue if you are boring as well), and of course Subaru made a few changes to the block design when they went to a higher stroke/bore ratio!

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I think you are going to struggle for anything significant in improvement relating to bore. That said, Darton would happily make you a set of custom sleeves...for a price.

 

The thing to look in to would be stroking. The EJ family really didn't increase the bore that much from the EA (92mm) - EJ20 is also 92mm but is 11% bigger in capacity due to stroke of 75 vs 67mm for the EA. I would think at best you might squeeze out a bore of 96mm using custom sleeves and a lot of machining but that will only take you up to 1.94L (up 8%). The main issue would be clearancing the block (less of an issue if you are boring as well), and of course Subaru made a few changes to the block design when they went to a higher stroke/bore ratio!

Thanks for the input.

 

No this will not make it a racing car, but there can be no doubt that doing half of what describe will drastically improve performance nonetheless.

 

What I would really like to know is the potential for mounting/adapting any larger-than normal Carb to the engine as opposed to dual carbs.

I read how people say they are difficult to keep properly matched and tuned. But One carb, even if its not a subaru but a close enough match might make a big difference in itself.

 

Otherwise, I think I will definitely have to go with a super-charger and matching carb.

- any thoughts anyone?

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