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#### blane.c

##### Well-Known Member
HBA Supporter
Can this forum come up with a reasonable EFI for small engines? So software, ardino or appropriate, and common source the bits throttle body, injector, airmass flow sensor, temp, etc. for small engines. It seems a better alternative to have a fuel injection system that compensates for density altitude automatically as a normal function than trying to cob up a carburetor that kinda' works. Maybe the files for an EFI could be filed in a manner for easy access.

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#### akwrencher

##### Well-Known Member
HBA Supporter
Or these.....[video]http://www.ecotrons.com[/video]

#### Hot Wings

##### Grumpy Cynic
HBA Supporter
Log Member
Can this forum come up with a reasonable EFI for small engines?
As with most of these threads - I doubt it. But given the scope of the project is far more limited, and the mission easier to define, it just might be possible. If nothing else it might be able to define the features and sensors that are required, or desirable.

Reasonably priced and probably a very good option for a toy, but not aircraft grade. The integrated triple sensor looks like a single point failure source that could shut the system down completely. For these little industrial engines it would also be nice to be able to hand prop so we could eliminate the weight of the starter. This system probably isn't to user friendly in this regard.

Also a lot of the parts look like proprietary designs. Even if they are produced in significant numbers it would be nice to be able to buy spares from common sources - or build from open source.

#### Tiger Tim

##### Well-Known Member
Can this forum come up with a reasonable EFI for small engines?
Can the forum do it? Of course. We have people here who probably have the know-how AND parts on hand to have this thing prototyped by the weekend.

Will the forum do it? I hate to say it but probably not, and for a variety of reasons. As with every other forum-sourced project it will run off in as many directions as there are posters and a consensus will never be reached. Industrial twins are the hot topic around here these days and if anyone wants one bad enough they’re going to have to stick their own neck out on the project.

#### TFF

##### Well-Known Member
What size engine are you trying to convert? With the intrest, the examples might be worth buying to experiment with. Not going to find a package any cheaper.

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#### pictsidhe

##### Well-Known Member
There are a few Arduino EFI projects already out there on the web. There is also the microsquirt version of megasquirt. If/when I go for EFI, I'd start with one of those and aero mod it as seems fit.
Or, just get one from Ross. But a little pricey for us playing with industrials.

#### Hot Wings

##### Grumpy Cynic
HBA Supporter
Log Member
. If/when I go for EFI, I'd start with one of those and aero mod it as seems fit..
I'd forget the microsquirt as a base. It's more complex than we need for aircraft use and it uses paired injectors (TBI style) so it's not very adaptable to an industrial V-twin. For those we need sequential injection. It would be fine for a 1/2 VW. The source code for these is available to use as a inspiration. It's done in C so it should transplant well to Arduino. I do like the idea of pairing both EFI and ignition control in the same unit, even if some will stick with other ignition options.

The various Arduino EFI projects are probably a better base to use? I've got a Pyboard that I had considered using for this. They are quite a bit faster than the average Arduino but Python is also slower than compiled code.

Of course Python can jump into C where speed or timing is needed. I've never done this so I have some learning to do..........

If anyone is really interested in this kind of project they should probably watch this video of another HBA member that builds and sells kit sailplanes.

#### Vigilant1

##### Well-Known Member
One attribute I'd want for aviation use is a stone-simple backup/limp home mode. It should reduce the number of required external sensors inputs to the bare minimum (redundant RPM and TPS only?) and could depend on manual fine-tuning for mixture control. I'd go so far as to put it on a separate board and use independent code, only a toggle switch connecting the two EFI systems.

If the target engines are sub 30 HP industrials, I'd vote for simplicity and low cost over fuel economy. Improving fuel economy by 10% on an engine that burns 1.5 GPH is not going to be significant. Going open loop with no lambda sensor allows use of leaded fuel (handy on occasion, some folks might want to fly away from their home airport) and eliminates the cost and reliability concern of one sensor.
I am not an expert, but getting the induction beteen the two cylinders on the V-twins appears to be problematic sometimes, maybe because of the uneven induction timing in these engines. The folks using them in airplanes with carbs tend to use two of them, so an independent injector per cylinder probably makes sense (if it is in the budget) and would allow at least partial power with a failed injector. Automobile injectors are quite reliable, I don't have info on smaller injector reliability.
The Micromaster or other twins could benefit from an electronic ignition system that could be sync'ed, but that sounds like a niche application that goes beyond the scope of simple fuel delivery via EFI as you've laid it out here.

#### Tiger Tim

##### Well-Known Member
What are the pros and cons of EFI and how do they stack up in a sub-30hp package? I guess I’m having a hard time picturing the trade-offs being worthwhile but I’m more than willing to learn what can be gained.

#### Hot Wings

##### Grumpy Cynic
HBA Supporter
Log Member
My take on the Pro vs Con:

The only real con is that EFI depends on electricity. That means there needs to be a reliable source on the plane.
Other conditional cons:
It costs money to add to an engine that doesn't already have it. For those of us that grew up with carbs it means learning new things. (It's not hard ) For the purposes of this thread there is no good OTS solution. That means development time and money. If closed loop is used 100LL is a problem.

Neither pro or con:
Failure modes. Both EFI and carbs have them. Obviously they are of different types in some cases but overall I think history is proving that a properly designed EFI is more reliable than carbs.

Pro: (not all would apply to the simple system being proposed)
Automatic altitude compensation is easy to implement.
Better fuel economy is possible due to better control.
More power possible for the same amount of fuel used.
Less pilot interaction needed.
Inverted flight is possible.
Can be designed to run any fuel between 100LL and pure ethanol and in any combination.
EFI starts far better in cold weather.
EFI can be less prone to vapor lock.
EFI is generally less likely to develop carb ice. Yes, EFI can experience intake ice.
EFI is easier to adapt to a turbo than a carb.
EFI software can track trends to help predict failure - similar to progressive failure of a carb.
EFI software can speed repair through the use of trouble codes. Each sensor can be checked statically, and dynamically with an o'scope or a serial interface, like CAN.
For these little industrial engines it might be lighter as well - even considering the fuel pump and filter.
EFI can be directly interfaced with an engine monitor via the software and something like a CAN bus. No need to add sensors just for the engine monitor.
???

#### blane.c

##### Well-Known Member
HBA Supporter
As you go up in altitude there is less and less oxygen available in a given air mass. Going up without leaning the fuel air mix gets more fuel "rich". Aircraft carburetors (generally) are able to be manually leaned for altitude compensation going up and re-enrichened going down. Most other carburetors while they may have a mixture leaning screw are not as adaptable to altitude as a carburetor so designed.

Carburetors also have venturis, under the right conditions moisture in the air will have its temperature reduced to below freezing passing through the venturi and will form and deposit ice restricting the flow of the air mass into the engine.

It falls upon the pilot among other duties to keep the engine properly leaned and to either anticipate or recognize and counter carburetor icing in a carburetor equipped aircraft.

Not a big deal.

Add another engine, and maybe another engine, or maybe an engine problem, and the deal gets bigger. This is among the reasons it is generally considered prudent to have no more than a twin engine arraignment for single pilot aircraft.

A EFI automatically adjusts for density altitude, and while nothing in this world is absolute it is far less susceptible to icing than a carburetor.

#### jbiplane

##### Well-Known Member
Our SmartEMS (digital ignition + EFI) start from 200usd in milled aluminum case and can use remaining hardware available at any shop. We use VW sensors, pressure regulator and filters + Yamaha fuel injectors and fuel pump.
Throttle bodies of 650...1300cc Suzuki cars and chinese 50, 125, 150 and 175 cc scooters.
Dont believe that forum will cheate something robust for similar price. We can fit to this price buying at least 100 sets of electronic components per order. Price could be decreased if use chinese connectors instead of japanese and make plastic case, cheap crap instead of silicon wires... Safety dont worth such economy.

We used before ecotron, but found it non-reliable and non open enough

You can see how work ignition part of this EMS on 18000rpm for 2-strokes (36000rpm for 4-strokes)

We can manage as well by plasma ignition, but plasma ignition coils are expensive

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#### Vigilant1

##### Well-Known Member
Our SmartEMS (digital ignition + EFI) start from 200usd in milled aluminum case and can use remaining hardware available at any shop. We use VW sensors, pressure regulator and filters + Yamaha fuel injectors and fuel pump.
Throttle bodies of 650...1300cc Suzuki cars and chinese 50, 125, 150 and 175 cc scooters.
Dont believe that forum will cheate something robust for similar price. We can fit to this price buying at least 100 sets of electronic components per order. Price could be decreased if use chinese connectors instead of japanese and make plastic case, cheap crap instead of silicon wires... Safety dont worth such economy.

We used before ecotron, but found it non-reliable and non open enough

You can see how work ignition part of this EMS on 18000rpm for 2-strokes (36000rpm for 4-strokes)
$200 (US) seems very reasonable for a controller that can run both EFI and electronic ignition. Do you have estimated prices (or part numbers) for the external parts that would be needed (sensors, coils, etc)? Also, do you have an estimate of when the English documentation of your SmartEMS will be available so customers can understand how it operates in the event of various sensor failures, etc? Selling product to accessorize$1000 engines is going to be a tough biz. As Ross has mentioned previously, owners of $6000 VW engines are reluctant to spend money to buy a top-drawer EI/EFI system. The margins on these engines will probably be much lower. The Chinese CV scooter carbs and the B&S stock EFI will be in the same market space. #### Vigilant1 ##### Well-Known Member Lifetime Supporter As you go up in altitude there is less and less oxygen available in a given air mass. I think you meant to say that the amount of oxygen in a given air >>volume<< decreases as altitude increases. Right? The fraction of air mass that is oxygen doesn't change appreciably with altitude or pressure. The term "air mass" can cause confusion. #### BJC ##### Well-Known Member HBA Supporter Can this forum come up with a reasonable EFI for small engines? I believe that the technical expertise of participants on this forum is more than sufficient to develop an EFI for small engines. In fact, one participant has a business that designs, produces, and supports EFI systems for larger engines. QED. What is not realistic is for “the forum” to develop a “reasonable” EFI for small engines. A devoted effort by an individual or two or three, all with a shared objective and vision for the final product, plus the time, hardware and financial resources, certainly could develop a functional EFI. Then the question would be whether or not it can be produced for a reasonable effort in cost and time. After that, the question becomes, “Who will use one on a minimal aircraft powered by small engines?” Don’t take this as intended to discourage, it is not. Such efforts can be educational, satisfying, and generate other useful ideas. Do take it as one member’s view, based on a long engineering career that included, among other things, development of unique analog and digital control systems. BJC #### blane.c ##### Well-Known Member HBA Supporter I think you meant to say that the amount of oxygen in a given air >>volume<< decreases as altitude increases. Right? The fraction of air mass that is oxygen doesn't change appreciably with altitude or pressure. The term "air mass" can cause confusion. OOPs! #### blane.c ##### Well-Known Member HBA Supporter Our SmartEMS (digital ignition + EFI) start from 200usd in milled aluminum case and can use remaining hardware available at any shop. We use VW sensors, pressure regulator and filters + Yamaha fuel injectors and fuel pump. Throttle bodies of 650...1300cc Suzuki cars and chinese 50, 125, 150 and 175 cc scooters. Dont believe that forum will cheate something robust for similar price. We can fit to this price buying at least 100 sets of electronic components per order. Please clear a couple things up for me? I am confused. So first is this for sale for$200.00 each? Or is this for sale for \$200.00 each based on buying 100 of them at one time?

And second exactly what is included in the purchase?

Thank you.

#### Hot Wings

##### Grumpy Cynic
HBA Supporter
Log Member
question becomes, “Who will use one on a minimal aircraft powered by small engines?”
BJC
This is the underlying limitation.

The market for an aircraft grade EFI is far smaller than the market for industrial/small engine EFI. The other market just doesn't need some of the features we should have. They have no incentive to develop anything more than needed. There is no way we could collectively come up with a system that is price competitive with what is now, or soon to be, on the market.

I'd be willing to be part of a group to develop an aircraft EFI system for 1L class industrial engines - but it would have to be what I want/need.

See post #9