Supercharger for EA81

[DaveT]

From the EAVS super charger link - the model for a 1.4 liter engine uses a 4KW motor to drive the supercharger.  That's a little over 5 Horsepower, so a 1.8L will need a bigger one.

[skishop69]

From the EAVS super charger link - the model for a 1.4 liter engine uses a 4KW motor to drive the supercharger.  That's a little over 5 Horsepower, so a 1.8L will need a bigger one.

 

Yes, and as I stated before, you have to be able to produce high voltage three phase power to run it. Not safely feasible on an EA81.

[DaveT]

I didn't see an easy way to get to the detailed specifications for the EAVS.  5HP electric motors don't have to be 3phase.  240VAC 5HP motors exist, but are not common.  The Eaton page  I got to states that it uses a PM motor, which means permanent magnet - normally implies a DC motor.  I have a continuous duty DC motor sitting a few feet away that is good for 4KW drawing a bit over 110Amps at 36V DC.  They may have chosen higher voltage, because there are optimum size / efficiency / materials trade offs.

[iceageg]

From the EAVS super charger link - the model for a 1.4 liter engine uses a 4KW motor to drive the supercharger.  That's a little over 5 Horsepower, so a 1.8L will need a bigger one.

We use a 15HP Briggs and Stratton motor to bench test all of the superchargers we sell.  Depending on the model and application they must draw no more than 5-8 HP to make 3-4psi to be considered in-spec.  If you are going for a mild boost system that is about the draw you are looking for off your crank, via exhaust pressure (for a turbo), or from an electric motor.  That is simply the amount of power it takes to compress that volume of air.

 

We did use an electric motor once to do endurance testing where we kept one "over sped" (way under design but over what our application requires) for 48 continuous hours.  We used junk parts to put the bench together so it may have been overkill but the electric motor was about the size of a breadbox.  I don't remember where it even came from.  Good chance it was some sort of commercial HVAC component.  Fun fact, on a cold winter day in eastern Oregon, the compressed air from that blower warmed an oversized 3 car garage up to about 85° pretty quickly and kept it there for 2 days.  Ahh memories.

[iceageg]

. . . Now for your control issues. The EDF's themselves would have to be tied to a TPS that would control their speed in proportion to the throttle blade opening so that airflow out of them (IF they could compress which they can't) would stay within the correct flow ratio . . .

 

For full disclosure a TPS is not only one way and it would probably not be enough by itself.  I have used vacuum actuated valves and cam systems attached directly to the throttle to modulate static flow systems based on throttle position.  Both of these simple (for a car with no TPS) solutions work exceptionally well but have one fatal flaw that the TPS would also have.  When you tune them they are altitude (ambient conditions) specific.  If you gain or drop a few thousand feet of altitude you need to re-re-re-re-adjust them every time.  This would not be as much of an issue if you lived in Florida, Iowa or Nebraska but in places like California, Colorado or Oregon you will need to find a way to actively adjust where the boost modulation occurs based on ambient pressure and temperature.

 

Trying to stick to my cliff notes theme this is because the change in ambient conditions is not linear.  The compressor map of various blowers are different and none of them are linear.  Your suction of your engine (essentially a vacuum pump) is not linear either.  So if your static boost system is running 3psi on a given day at a given altitude it is fairly easy to tune that to run very well using a mechanical linkage and tear rump roast around your own property or a track most of the day.  However, if the weather changes significantly or you trailer it up to your favorite camping spot in the mountains it will run like crap and you will have to adjust the manual linkage.  Thus the TPS/MAF solution is the only one that I would consider "daily driver" to the standard of letting my daughter drive away in it.

 

So to skishop69's point if you wanted an electric blower that would be turnkey and go driveable you would need to set up a system that was tied to a TPS and MAF and made adjustments to either the speed of the electric motor or a valve to modulate the boost getting to your carb/throttle body.  It can be done without it but in mountainous country you can count on doing some roadside tuning.

Edited September 13, 2016 by iceageg

[subarubrat]

To put a nice bow on this, the end result is that your life gets much simpler when you replace the entire battery, controller, and electric motor system with a simple belt and use the built in bypass valve on the SC to modulate when boost is made. All you really need to do to supercharge an EA81 is make a manifold adapter, nose brace, carb adapter and a drive pulley. That will give you the simplest, most reliable, and least expensive supercharger system. There are quite a few different inlet manifold castings for the Eaton SCs that one of them would likely be a good candidate to re-purpose for this application. Used M62s in good or rebuilt condition are out there for $400-600, if you are handy at aluminium welding or have a buddy who is you can probably pull it off for about $800ish, dirt cheap for an SC system. I would advocate for adding in a fuel injection system but that is a discussion for another day.

[iceageg]

Another option would be one of the small centrifugal units on the market today.  Procharger has a few marketed at the motorcycle/ATV market and the C-2 model specifically performs very well for the volumes you are considering.  Some of the tuner companies like Greddy have even smaller units that use a planetary gear set (instead of a single gear reduction like the Procharger).  You will likely spend quite a bit more on these because they are more difficult to find used but they do offer more mounting options for fitment under the hood.

 

As I mentioned before, do some research on draw-through and blow-through systems and make sure you pick one that is appropriate for your goals.  Depending on your desired boost level you could be in for a tuning nightmare with the wrong setup.

[Bantum]

This might be worth a look at :

 

Found here : http://www.ft86club.com/forums/showthread.php?t=39719

 

If your more adventurous, could even do a twin system based on rare Webber dual manifold ...

 

Cheers, Bantum ...

[iceageg]

Without reading the entire thread it looks like they overcame the static boost feeding a variable throttle problem by only engaging the blower at wide open throttle.  A very simple solution to get around a complex problem.  The big difference though . . . the FA20 is fuel injected with the computer compensating for the extra air.  I'd venture to guess that the sudden change of the blower turning on would present some interesting tuning challenges for a carbureted motor.

 

I still love the innovation though.  Good find.

[skishop69]

I didn't see an easy way to get to the detailed specifications for the EAVS.  5HP electric motors don't have to be 3phase.  240VAC 5HP motors exist, but are not common.  The Eaton page  I got to states that it uses a PM motor, which means permanent magnet - normally implies a DC motor.  I have a continuous duty DC motor sitting a few feet away that is good for 4KW drawing a bit over 110Amps at 36V DC.  They may have chosen higher voltage, because there are optimum size / efficiency / materials trade offs.

 

I based it on industry standards I see in the picture for it. Orange cables are high voltage, 100v or higher, typically 150v, 240v or 360v and these are DC (as in D Ceased if you touch them live) though the connector and number of cables indicates a three phase motor. The amount of current at 12v needed to supply a 5hp DC motor at the max RPMs to run a SC could not be produced by a typical automotive alternator. Calculations would vary, but as an example, you would need to add two batteries and a 200A aux alternator to your current charging system to come close to powering it in a continuous mode.

[DaveT]

I agree, trying to get 5HP with a 12 volt system is pretty impractical. 330 amps at 12 v not allowing for efficiency losses.

[RAD]

This is fast becoming a situation where I may have to put my subaru in storage for the expense of fixing or improving it. Any engine swap will likely cost more than $2,000.00 to even think about it.

There must be a better answer....

[iceageg]

I avoid paying others to work on my car unless it is absolutely necessary, but $2,000 to do an engine swap seems like a pretty reasonable deal to me.  The only way to reduce that would be to do the work yourself or source the parts yourself and find a mechanic who will use your parts and only charge for the labor.  This will likely still be over the $1,000 mark.

 

I don't know what your urgency is or what the issue is with your existing motor but the cheapest way would be to find another EA81 that will bolt directly in to your

Brat.  My local pull-n-pay hard charges $160 for a long block.  They can be difficult to find and are always in questionable condition but you can rebuild it casually while still using your car.  When it is time to do the swap you can swap over pieces you want to keep from your existing motor to the new one.  Depending on how you want your engine to perform you can accomplish this for well under $1,000 for a casual daily driver or several thousand for a crazy custom setup.

 

You could also try to source a running engine on ebay/CL/here/etc.  With a bit of searching you could probably find a solid engine with some life left in it for $300-$600.  In a weekend you could swap it in and swap over whatever you want to keep from your existing motor.  Just to keep the car running you may be able to do this for $400 with just a few gaskets.  The result probably would not have the same long term reliability as a complete rebuild but it could keep you on the road.

 

You have no options for a "cheap" swap to a new engine format.  Adapter plates, custom fab, etc. will make it more complex, expensive and time consuming guaranteed.  The cost savings is to do it yourself which can be daunting without a well provisioned shop and the experience to use it.  Those skills can certainly be learned during the project but re-work and acquiring new tools will drive up cost and you can forget any thoughts of a quick turn around or being able to use your car during the project.

 

Personally I LOVE these types of projects and it is one of the reasons I love older cars so much.  Resources like this forum will prove invaluable sources of information and allow you to prepare with a little research that will save you a great deal of heartache and help you through an issues you run into.  If you don't have the time and money to finish it though, it would be best to delay the start.  Especially if you need the vehicle being worked on.  If you do prep, prep, prep before getting started to minimize the inevitable downtime.

 

Cheers

[TomRhere]

Yeah, there is no cheap...

You can go for easy, fast, reliable. But you have to pick just two of those, ain't getting all three.

And the more reliable you want it, the more it will cost.

 

Plain simple truth, regardless of what vehicle make you're wrenching/spending money on.

[RAD]

All brings me back to original premise, I prefer the EA81 engine, what to do with it to get more horsepower - how much can the cylinders be over-bored, to what approx. C.C.?

[MR_Loyale]

MCM did the experiment.

 

 

[iceageg]

If you are trying to stay under the $2,000 mark you are looking at a Delta cam, Weber carb and an MSD while doing all the work yourself.  Then source a solid block and do a slow build for future install as funds present themselves.

 

There is limited support for these engines and I don't know if you will find any direct replacement pistons for a bored out cylinder radius.  You would probably be looking at a set of custom pistons at that point which is going to drive your cost up significantly.  You would need head work, probably EFI and associated tuning to make 115-130 horsepower.  I'm not sure what your end goal is but once you start spending that amount of time and money on an EA81 the EJ22 swap gets you more for less.

[DaveT]

There is not a whole lot of metal between the cylinders. I doubt that the can be bored out enough to make a noticeable difference in power. There is enough for .02 or .03 oversize for rebuilding due to wear, iirc.

[skishop69]

There is no piston other than EA81/EA82 that you can put in. The killer on these engines is airflow in the intake and heads. To make power gains, you need to install EA82 SPFI pistons which will bump compression to 9.5:1. Then, you need to do serious porting work to the heads and install bigger valves. As it happens, certain Harley Doucherson valves have the same dimensions except they have a larger face diameter. Along with that goes a custom intake to allow for more airflow into the heads. Now you need to retrofit Chevy small block roller rockers to the head using the 1.6 ratio rockers. Computer modeling shows this will net almost 200HP with EFI. I've posted this before and of course, I always get, "It's not possible." RAM engines has gotten 200+HP out of a turbo'd EA81, but they are constrained by safety factors since their engines go in experimental aircraft. Fact is, a usable, long life EA81 will never make more than 200HP without turbocharging due to original design constraints. Is it worth it? Depends. EJ swap is certainly cheaper and in the long run, probably more dependable. However, if you can do it yourself and you just want to be able to say you did it and you have the only 200HP NA EA81, it MIGHT be worth it.

[sparkyboy]

Wow! Have you considered a draw through? The gas is compressed with the air and since the carb isn't under boost, you don't have to wongleflute around with a blow through carb, in fact the carb should be tuned the same way as N/A. It's probably the cheapest too, you just need carbon seals

[sparkyboy]

Oh yeah just slap it on if you want, if you blow something up then do an ej swap! If you have enough to spend on boost then you can do the swap. Buy a used nitrous kit, I have seen them for $700 on CL. I saw one for $400 once! You can easily resell a kit like that

[RAD]

And thus, the circle always comes back to the same conclusion... Engine swap with an EJ2000, 2200, 2300 (?) or EJ 2500, or to the extreme, an EJ2500 with 2200 heads for more compression.

It will cost me at least $2,500.  Is it worth it? Of course the already super cool and sexy Brat is absolutely worth it, but ouch! lots o'money !!!

[subnz]

Agree;   Engine (heads / manifolds) design limits  EA engines ability for  boosting potential.  eg the modest power increases  in factory turbo EA81/82  engines  - for example.

 

Head and manifold design  (ability for airflow increases / boosting)  small  2 port heads / 2 valves per cylinder / shared port - inlet - exhaust manifolds,    limit airflow.

 

EJ engines with 4 valves per cylinder (instead of 2 for EAs)  4 port heads / 4 branch manifolds (inlet / exhaust) have more power to start off with and are   far better suited to being boosted (turboed / supercharged) as they flow better so will  get better power gains if wanting to go that way / spend more, and  also have the advantage of being fuel injected as well in most cases.

 

The only advantage of EA81 engines is their bomb proof simplicity  / reliability of the valve train  (gear driven cam and OHV) suitable for small light (kitset) aircraft applications etc.

Edited October 10, 2016 by subnz

[crazyhorse001]

I've seen video of an electric supercharger. A high torque brushless motor turning the impeller of a turbocharger. These people are having positive results, when its not eating itself from imbalance and poor clearances.

To play devils advocate, brushless electric motors that spin in excess of 11,500 rpm are considered low end in today's radio control market. Mind you these run at 11.4v with 4600mAh lipo batteries. Imagine that at 13.7 with a 60 amp reserve. Throttle it with a tps signal, and you're butter!!

[DaveT]

Up higher in this thread, there is a real electric one mentioned. If you are talking about a 4-5 HP motor with a proper compressor for an engine about the size of 1.8L then it's a real thing. An electric motor of that HP takes about 4-5 kilowatts. 4KW at 12 volts means you need 333 amps. Of course, this scales up and down with engine displacement.