Electronic Fuel Injection for recreational engines

[River]

G'Day 'team',

 

I’m been to pondering as to why the recreational aviation engine manufacturing industry or third party companies have not produced an electronic fuel injection (EFI) system for either the Rotax 912’s or Jabiru engines. These engines have by far the most popular engines used throughout most of the world and yet, here it is 2006 and with the approaching fuel usage and supply crises plus that very well known old bogie – carburettor icing, it would seem that EFI would be a most desirable option.

 

I would put forward to say that EFI has been for quite a period of time now and highly reliable and very fuel/engine efficient contributor. It’s my personal belief that we should be using this system to both benefit ourselves and that of the planet.

 

Look at how the automotive car industry, the motorcycle industry, the recreational and professional boating industry with both two and four stroke engines all producing excellent and highly reliable engines with superb fuel economies using EFI.

 

The other major advantage is the removal of the serious and on-going problem of carburettor icing.

 

Surly with the use, success and reliability now of EFI everywhere else it’s time both the engine manufactures and third-party companies to begin serious development and sale of these units. I’m talking though with recreational and experimental aircraft, where certification costs are not part of the process, though reliability and safety are of-course a genuine must!

 

I can remember when disk brakes where considered ‘too technical’ and that the use of hydraulics’ was going to be far-to-complicated with them for use on motorbikes… To-day - totally a standard item. When EFI was first introduced the same concerns were raised along with computer controlled engine management systems too… again to-day in many engines, computer controlled engine management systems are standard.

 

With all the experience gained by all the various automotive manufactures and third-party companies and that of motor racing there would have be to highly reliable information and data available to greatly assist in producing an EFI unit for recreational aviation engines.

 

Yes, the costs may be more for their implementation but I believe the added costs will be totally outweighed by the major benefits of engine efficiently in improved reliability, superior fuel usage and engine performance and removal of that serious carburettor icing problem which has caused far too many aviation incidents and accidents.

 

Fuel prices can only go up and in my personal opinion, aviation based fuel will be ‘skyrocketing’ sooner than later and we’ll all be wishing for better fuel economy with the fuels we will be using down the track. Unless there is a miracle of massive proportions fuel pricing alone could easily see us all paying $5 or $6 a litre with-in the next five years, ouch. A quick look at fuel prices, say currently at $1.50 per litre and a 60 litre fuel tank comes out at $90. At $5 per litre, that’s $300! Not counting any other expenses.

 

Taking the 3 to 5 hour cross country recreational flight would see you looking for a financial planner to arrange your flight planning . Remember, I’m talking recreational aviation here, not a commercial operation and as quite a few of us are either semi-retired or retired every litre one can save is easier on the wallet and allows for more flight time.

 

The other major benefit of using both EFI and an electronic computer engine management system is that the system gives the user excellent detailed and usually highly accurate engine analysis both in real time and history wise. This will lead in turn to longer engine life and the ability to be warned, usually in advance, of an impending malfunction or component failure, hence being able to ‘save’ the engine by catching the occurrence early and saving further damage, etc.

 

I realise that many of us (recreational aviators) are quite happy with current engine arrangements and I’ve no problem what so ever with that. It’s a case of 'horses-for-courses’ where-as most users with older engines, etc may be either happy with their present set-up or maybe, they (you?) have had an interest in improving the fuel efficiencies and endurance of their engine but have been unable to find or source reliable systems.

 

I would be interested in you’re constructive thoughts towards EFI and computer engine management systems in our recreational aircraft and if anyone knows of any of the above mentioned system in use to-day or under development.

 

Yours in recreational aviation,

 

 

[Guest danda]

Hi Rodger

 

I'm told that in Europe they are doing just that, having never been OS I am unable to confirm this but that's what I have been told from someone who should know.

 

Don

 

 

[Matt]

Interested in what they're doing with Rotax engines around the world, check out this story on how NASA has modified a Rotax 914 with triple turbochargers and EFI to operate at altitudes up to 90,000 feet

 

http://www.designnews.com/index.asp?layout=article&articleid=CA151154&cfd=1

 

 

[Admin]

Interested in what they're doing with Rotax engines around the world, check out this story on how NASA has modified a Rotax 914 with triple turbochargers and EFI to operate at altitudes up to 90,000 feet

http://www.designnews.com/index.asp?layout=article&articleid=CA151154&cfd=1

- Is this for the new Space Shuttle ;) - geez Rotax are good arn't they

[Galpin]

You may care to look through the B2 website at

 

http://www.b2engines.com/

 

It may well be advantageous for someone to keep an eye on items relating to engines at Oshkosh. I think that commences in about a week.

 

Can anyone give a listing of engines under development in Australia/New Zealand?

 

 

[Guest micgrace]

Hi

 

Not particularily difficult to do a efi conversion. Crankshaft position sensor. Temp sensors (air, oil, tp sensor). MAP / airflow meter plus programmable computer.

 

Not to forget, lift pump plus high pressure pump.

 

BUT, this will cost a hell of a lot more than simply putting on a carby or two.

 

e.g. a proper efi computer (say Motec), $3,000 all up be looking at a bill of around $10,000 (mainfolds, fuel system custom machining etc)

 

That's one reason why efi is notused. Cost.

 

But, I'll bet if pollution laws applied to a/c engines you would see them. This is the main reason all new cars have efi NOT performance advantages. They cannot comply without.

 

Just some thoughts, Micgrace

 

 

[pylon500]

bill of around $10,000

I think the above may apply to someone doing a home, high performance conversion to a 912 or Jab motor, but using ultralight homebuilders enginuity, (ei; go down to the local wreckers and rip all the bits out of Subi or something..) EFI could be fitted for less than $3,000. ;)

As for Rotax or Jabiru doing it themselves, because they mass produce, the whole system might add $1,500 to the price of an engine! :ah_oh:

 

Naturally they would only use pre-existing hardware from some auto manufacturer, who because of the size of their production numbers, probably fit it to their cars (at a cost to them for about $500.

 

A lot of it probably comes back to the buyers (Us) and whether we want to pay $3,000 for non icing fuel injection,,, or just pull the carbi heat knob!

 

Besides, Hirth has been offering fuel injection on two strokes for a while now, and the price difference between the injected and non injected 3203 is about $1,500.

 

See; Hirth Engines

 

this is not a plug!

 

Arthur.

 

 

[Guest micgrace]

Hi Arthur

 

The price tag of $10,000 applies only to using someone to do it with necessary skills and hand fabricating everything required plus all new top range equipment.

 

For those with skills a rather ancient camira mpi actually has the computer required, reprogrammed using kalmaker software. Use the full lot of sensors and computer out of. Use a VL commodore hp pump and some sort of electric lift pump. Also need some sort of throttle body with a on off tpi switch preffered rather than variable resistor type.

 

Naturally a manufacturer will tool all this up and spread the tooling/design cost over many thousands of engines for a greatly reduced cost.

 

This is something you can't do for a onceoff.

 

My preference is actually for a microtech computer (has a in dash display available as well as a programming handset rather than other types that use a laptop. And simple to use, plus change tune while you fly possible (cost $1000, less for fuel only, but why bother with fuell only, take full advantage)

 

One drawback would be the use of AVGAS leaded kills oxygen sensor. Unleaded Mogas only for auto tune,fuel/air meter

 

I,ve used this on numerous engines and is incredibly flexible. But note: absolutely NOT CERTIFIED at all under any circumstances use at your own risk.

 

There is a website (I'll try and find it again) where a guy converted his o360 to efi. The sticking point was choice of computer. The rest is not that hard.

 

Micgrace

 

 

[Yenn]

The current state of the art with fuel injection doesn't inspire confidence in me. They do break down especially in extreme weather conditions and I have trouble just pulling over when my plane engine falters. For the slight saving in fuel there is a too great a risk factor.

 

 

[Guest micgrace]

Yeh

 

And might as well go back to using points as well so there's no electronic components at all.

 

You could use a mechanical fuel injection system. They were used on some earlier european cars in the 1970's. As well as by BMW during WW2 and other manufacturers.

 

Or to increase safety use a duplicate system for everything.

 

I suspect if emission standards were applied fuel injection would become standard plus other changes. It's a wonder governments haven't applied this to aero engines yet.

 

Micgrace

 

 

[River]

Re... I suspect if emission standards were applied fuel injection would become standard plus other changes. It's a wonder governments haven't applied this to aero engines yet.

 

Dont 'speak too aloudly' as there appears to be some dust rising just over the horizon on this subject if one looks at events elsewhere both in the US and europe... rats

 

 

[Guest Kitfox 4004]

Hi ! Rodger,

 

Very interesting post. I like the idea of fuel injection. I am a retiredelectronics guy and have played with injection troubles on two of my cars fixing what the experts couldn't. To do this I've worked out the basics of EFI but not the computer programming on the later stuff. I'm hopeless on all that unfortunately. I have also made and designed several types of CDI ignitions and reliabillity has been excellent so I see no reason to believe EFI should be feared on reliabilitty grounds. I don't like the idea of the old mechanical set ups though.

 

My reasons in favour of EFI are efficiency. the chance to easilly control mixture and automatic altitude compensation. This also encompasses protection from high EGT and burning holes in pistons. Yes I run a Rotax Blue Head 582 two stroke andI love it. Incidentally out of interest it's in a MKIV Kitfox that I bought in Perth and flew home to the Riverland in South Australia. It took 14 hours flying time.

 

I have thought about converting from carbs to EFI myself but on second thoughts I think it's wiser to just run with what's proven in a plane.

 

Thanks for your post and let's hope we soon get this option from the manufacturers. Really I think those that would rather not see this happen are just wary of change although I would agree there is some instances of troubles in automobiles. However surely we can expect better examples in aircraft engines because we are definitely capable of doing so.

 

Kind Regards,

 

Rex Shaw.

 

 

[Yenn]

I am waiting for one of our newer members to describe how he runs EFI on his Jabiru engine.

 

Personally I like the proven capability of a carbie, even with the icing problem. I have seen EFI cars break down and there is nothing you can do about it on the road.

 

I wouldn't touch mechanical petrol injection. I worked on it in the army in 1956, without a workshop manual because it was top secret!!

 

Ian Borg

 

 

[facthunter]

Fuel injection, /carbies etc.

 

We all acknowledge the need for sophisticated engine management on motor vehicles from the polution aspect .One feature of road use (particularly in city situation) is the wide operating range the engine is subject to. Most car owners are incapable of tuning their engines and the vehicles are only serviced at about 20,000 Km intervals these days, or if the car comes to a standstill. Aircraft engines are somewhat different.

 

An aircraft engine spends most of its time at cruise power in a very close rev range. It is monitored by the pilot far more than any car driver. A carefully designed inlet and exhaust system will give very even fuel mixture distribution with either a carburettor or a single point fuel injection system. If manually leaned in either case, it will equal the efficiency and pollution requirements obtained any other way, (without going into the direct injected stratified lean burn technology) The problem with fuel injection ( and I'm not trying to knock it ) is that it requires electrical power to a critical pump as well as the management electronics. If you have a battery failure or have to isolate the electrics where are you then? I'm a little surprised that manual carburettors are not available more widely. Its hard to beat a gravity fuel system for reliability. N....

 

 

[Smokey]

....Its hard to beat a gravity fuel system for reliability. N....

What I really love about these systems is that if the fuel pump fails you don't have to worry about landing.

 

:big_grin:

 

 

[Guest neal]

interesting engine .......rotax alternative perhaps??

 

This engine caught my eye as I trawled the aviation world online.

 

http://www.ulpower.com/

 

 

[facthunter]

NEW Engine.

 

Thanks for that Neal I will follow that up N...

 

 

[BigPete]

Hmmmm.....

 

Nice engine - it reminds me of something......

 

Ahhh YES -

 

Lets say that Jabiru "chopped" their 5100cc eight cylinder in half...

 

Four cylinders with a capacity of 2550cc and around 95/100 Hp at 3300 RPM - with all up weight of around 62 kg's.

 

NOW bung it in my J160 with a prop of around 48 inches and ...

 

SHASAM! - Super Jabby lives - Yay!

 

Today's dreams are Tomorow's reality.

 

regards

 

 

[facthunter]

Follow up

 

The website has a Q&A which covers the situation regarding operating without alternator functioning etc. The battery will provide power to the fuel pump till the voltage drops, somewhere between 30 & a max of under 60 mins provided you know the state of charge, otherwise it would be a matter of landing fairly quickly to be prudent.( My words )

 

The older fuel injection systems on the certified engines are essentially mechanical "dribble" systems to each cyl port. Can be tuned by jetting each nozzle, are manually leaned by fuel flow figures to horsepower tables or by response to exhaust gas temp readings. Done properly,the optimum fuel/air ratio wil be achieved for that particular engine,as well as the electronic control would do ( I would suggest ) Interesting subject N..

 

 

[Guest micgrace]

Hi

 

I am of the opinion a properly designed electronic fuel system is superior in nearly every way to carby, apart from using magneto and hand swinging (no battery required) But they still have parts to fail.

 

Need at least some sort of throttle position sensor, vacuum manifold sensor, air inlet temp, intake manifold temperature, knock (detonation sensor) engine temp. Also fuel/air (O2 sensor) but cannot use with leaded fuel.

 

Many aftermarket efi computers are made (not certified) that can be easily tuned to suit any type of operating condition you care to think of.

 

Sensible design of the fuel system with appropriate micron filtration using a lift pump from tank to efi pump ( or 2 in parrallell for added safety) Also sensible placing of injectors in intake manifold, as close to vavles, but firing against prevailing air flow the best.

 

Also a suitably large plenum chamber helps. Another benefit, direct fire with one coil per clyinder. No more distributor.

 

Unfortunately expensive to set up compared with carby but the tech exists.

 

Micgrace

 

 

[Galpin]

Rod at Jabiru employs engineers who work on engines. Is it possible that a DIESEL fuel injected engine is in the works? I am not the first to ask that question. Several aviators of my aquaintance have asked the same question. I put this to the forum as a FWIW.

 

 

[Guest micgrace]

From my understanding of aerodiesils they are not compression ignition in the first place. More like a very high compression petrol engine that uses injection to deliver the kerosine jet a or whatever to the combustion chamber then uses spark ignition to ignite the mixture.

 

Weight will be the issue for compression ignition. (True diesil)

 

Micgrace

 

 

[Galpin]

Some new aero diesel engines in the pipeline are supposed to be common rail. Would that make a difference?

 

 

[Guest micgrace]

Hi

 

If commonrail injection diesil, that would make a huge difference if you like electronics akin to petrol efi. Overcomes disadvantages of mechanical injection as applied to diesil. These being flexible timing issues and rpm range.These are compression ignition but vastly more flexible than traditional diesil, along with modern (but expensive to machine) materials may go some of the way of cutting down weight eg 4140 (not 4130) conrods, titanium retainers etc Still not convinced on aerodiesil.

 

Micgrace

 

 

[Yenn]

So someone has redefined the word diesel. It is a con trick to call spark ignition diesel. The term does not come from the diesel fuel, but from Rudolf Diesel who invented the compression ignition engine and the fuel it used was called after the engine in British speaking countries.

 

The common rail diesels are still diesel because they are compression ignition.

 

Are aero diesels direct injection into the cylinder head or are they injected into the manifold or a pre combution chamber?