Electronic Fuel Injection for recreational engines

[facthunter]

Diesel

 

Fuel for diesel engines used to be called distillate. It is a Refined product from crude oil that suits the higher performance engines used in road transport.It is much denser than say, avgas, so the extra weight of the fuel for the same No.of litres should be taken into account when making comparisons with petrol.(and calculating your aircraft weights) It has a low octane number so it readily ignites under pressure =(heat),when fuel is injected (in a highly atomised state, at the right time for the engine operating conditions) into a hopefully turbulent combustion chamber full of atmosphere compressed to at least 18/1.This is the essential characteristic of a compression ignition (Ie. Diesel) Engine. (2 or 4 stroke). Initially I thought the Diesel might be the big answer,but I feel hasten slowly might be appropriate. I have heard of cyl head failures at pretty low hours. Has anyone got factual data on this?

 

 

[Guest bazdavis]

The big advantage of a spark ignited high compression engine ie:14/1 is the use of a much higher calorific fuel resulting in less fuel needed per Kw developed. Weather distillate or jet a are used they would both require direct injection into the combustion chamber to maintain good atomisation for rapid ignition and proper and complete combustion. the use of spark ignition reduces the crankcase masses required withstand the forces that would be developed by a compression ignition engine. being an old mechanic one of the pranks we used to pull on new apprentices was to show them how to set up and test injectors with a hand crack tester and then watch them jump back a meter with startled looks on there faces when the injector was shot past an oxy flame the fireball is very large and the heat intense :big_grin:

 

 

[Guest pelorus32]

Some of the advantages of the newer compression ignition aero engines:

 

1. They are rated to operate at max power all day...so unlike most spark ignition aero engines their max power = their continuous power;
    
    
   
2. They are turbocharged so the power output tends to be flat-rated to 8 or 10,000 feet;
    
    
   
3. They have inherently greater reliability because they are using traditional and proven diesel engine technology;
    
    
   
4. Diesel and other similar fuels have a specific energy about 30% greater than petrol/avgas etc. Their weight is about 12.5% greater so you end up with more bang for your kg;
    
    
   
5. They are FADEC controlled so you can have more efficient fuel/engine management and single lever control;
    
    
   
6. I think finally we are learning how to put them on a diet so power/weight ratios are level pegging with things like the Rotax which is a pretty mean performer in its own right.
    
   

 

This analysis BTW from a person who has been into print on these forums saying that the diesel offerings didn't cut it for our applications. Times move on quickly in some areas. Diesel technology is moving very rapidly with lots of R&D by the big car and truck manufacturers, pushed in no small part by upcoming EU pollution regs.

 

Regards

 

Mike

 

 

[facthunter]

Engines-New Diesels.

 

The big problem limiting aero-engine output & reliability was detonation as compression ratios rose in the 20's. Tetra-ethyl lead additive alleviated this engine destroying phenomenon to a certain extent. but the potential for the fuel to ignite prematurely is always there, EXCEPT when it is not introduced into the cylinder to be combusted till the piston is nearly at top dead centre, as in a diesel,( or a direct injected spark ignited petrol engine ).

 

Once we put spark plugs in diesel, and put precisely timed direct injection in petrol engines, the distinction becomes blurred, But what can be achieved in both cases is high compression (safely) no detonation.

 

giving high combustion temperatures= high efficiency (specific fuel consumption )

 

With boosting (supercharging) we can achieve high pressures after combustion which will give high torque even at low revs, and compensate for reduced cylinder filling(& power loss ) as we climb & experience reduced atmospheric pressure.

 

This all seems fine & dandy, so lets get on with it. The difficulty is to get the engine internals, which we have subjected to enormous loads/ pressures ,light enough, and still remain reliable over a reasonable time and keep the costs to something that suits the market The purpose built engines are very expensive( & it's hardly likely to be otherwise,given the level of engineering required ) & I note ,the euro.auto engine adaptation, the engine is not overhauled, but discarded at a specified time. This is not as outrageous as it might seem because the source is relatively cheap & it is probably not economically viable We will see as time moves on ...N...

 

 

[Guest micgrace]

Hi

 

There is a very high level of research into the areas relating to controlling detonation in spark ignition engines, namely devices ie shape of piston/combustion chamber/port entry angle/size of ports/ 3d ignition/injection timing, even plenum chamber volumes/resonance devices/exhaust etc relating to detonation control and efficiency.

 

This sort of development is probably far beyond what is possible for an aero engine. ($$$$) The internal combustion engine is not a simple thing to develop.

 

Possibly the biggest current breakthrough in improvement was variable vavle timing (computer controlled) along with variable lift (still experimental). Time will tell.

 

However, some things that can be done to any engine is the use of ceramic barrier coatings ie less heat to the parts = more hp.

 

By the way. there is a trend in engine manufacture to use prelapping of rings on assembly. This has the unfortunate result of the engine actually producing less power if overhauled. Nasty.

 

Micgrace

 

 

[TechMan]

Continental are supplying their 0-200 engine with the FADEC (fully automated digital engine control - or something like that) and have removed magnetos and carburettor. They have aimed this at the LSA market in the US. The FADEC allows plug and play for fault and maintenance management with an upload facility to the factory for analysis, results being emailed back.

 

Wont be long before we see it on the other engines out there.

 

Chris

 

 

[facthunter]

Aircraft Engines Fuel Injection.

 

To Techman- Chris, have you got a site where more information can be obtained on the 0-200?

 

Micgrace, The process of lapping rings in prior to engine assembly is not new, though perhaps not widespread.

 

Royal Newcastle Aero Club had their own engine shop where this was the normal practice. A purpose-built hand operated device moved a used piston ,on which the new rings were installed, up & down as well as imparting a slight rotary motion, which seemed to be satisfactory. This was in operation in the early 60's.

 

N......

 

 

[Guest micgrace]

Hi

 

As you say, never stop learning. I didn't realize someone had actually beaten the major manufacturers to it in Oz. Wonder what else is in the backyard?

 

Micgrace

 

 

[TechMan]

To Techman- Chris, have you got a site where more information can be obtained on the 0-200?

Sorry Nev, not on me. The 0-200/Continental 'sales pitch' was part of the Avtech 2007 industry presentations run by CASA.

 

Their Aplha engines also make for interesting developments, as it seems that gone are the days of being able to fit a round plug in a square hole and space it with rings. Their accuracy is increasing down to even 'thousands' (be it inches), they are buying British made pistons that weigh up to 2grams of each other and they are streamlining air intakes and matching flow through rate of cylinders to each other and bolting them on engine cases.

 

Unfortunately, I still reckon that as soon as the apprentice swaps a barrel, all the technological advantage disappears with each click of the torque wrench ;-)

 

Chris

 

 

[facthunter]

Continental 0-200s etc

 

I have a lot of time for these engines. Everyone says they are heavy but they don't weigh more than a VW .The c-90 which is still 200 Cu in is listed as weighing 167 lbs, significantly less than the Lycoming 0-235. The problem with the Continentals is that most of them are a bit long in the tooth, and are therefore a bit of a liability to recondition. If they are becoming available as a noncertified new engine, all that changes. If you want 70 plus horsepower out of a VW you would need a reduction drive so you can run a decent sized propeller on it, and get some take -off performance out of it. I'm not trying to knock the vw as the development of the later version seems to have some promise, JUST MAKE A COMPARISON. The Continental will run a 72" prop, direct drive. N...

 

 

[Allan 601XL]

Hi

 

I wishing to use a plenum camber on a corvair motor with 40mm bing carby.

 

Is there a ratio or formula on how to work out the volume of the chamber?

 

Any other info would be a help

 

 

[Guest micgrace]

Hi

 

Plenum chamber volume should be about 80% of engine capacity. However runner length is more important for power (torque) purposes. From end of plenum to intake vavle measurement taken, then tune for 2nd or 3rd or 4th or 5th reflected pulse length. 2nd length (inches), 108,000/rpm desired, 3rd, 97,000/rpm, 4th, 74,000/rpm, 5th, 54,000/rpm. It will depend on size constraints. If done right, same as low boost turbo!! and 100% volumetric efficiency!!

 

Then theres runner diameter, say, engine has 80% efficiency

 

(.8 x eng. cap. Litres x desired rpm)/3300, take sq root of answer = runner diameter in inches.

 

Hope that's not too confusing, Micgrace

 

 

[Guest Lucifer]

EFi vs Carbs

 

Hi Roger,

 

I guess your query as to why we don't have EFI on aircraft engines is valid, in the same way it was valid when asked of the motorcycle manufacturers some years ago. And the answer, as I see it , is that we don't need it. Cars went for EFI as a way to minimise pollution and improve economy. Motorcycles went for it as a marketing ploy. With the exception of Ducati, not too many bikes gained anything from going over to EFI. With regard to carb icing, yes, that could be eliminated but how many Rotax 912's have you heard of that suffer from carb icing ?

 

Like I said, it is a valid query, but I don't feel that our fairly simple aircraft engines stand to gain much by going to EFI. You only need to look at the slow development of FADEC systems to see that this technology is not being universally embraced. Or at least, no one wants to pay for it...

 

Cheers

 

Martin

 

 

[facthunter]

EFI for Aircraft engines.

 

The criteria that I apply to an aircraft powerplant is that it will be reliable. To me generally, that requires it to be simple.

 

I don't believe that means that it has to be crude & inefficient except that the upper limits of compression & RPM have to be kept away from for longevity & reliability,& variables in operator technique so there is some sacrifice there. It has to be as light as possible also, cheap & easily serviced, but I believe it must also continue to run without external electrical power,to cover the circumstance where the battery must be isolated in flight for a suspected electrical short etc N...

 

 

[skootaroo]

Why do you see a difference between external and internal power? Doesn't that sugest your battery is necesary equipment?

 

Does anyone make a dead loss system anymore as any other system does keep the engine running without the battery.

 

 

[Guest micgrace]

Hi

 

So long as you use some sort of magneto, either points based or solid state, can then disconnect power ie battery/alternator if required.

 

The vw conversion, for example, can use a vertex magneto plugged into the normal distributor hole, along with a backup magneto at the "rear" ie flywheel side of the engine, provided that the heads have been drilled and tapped for dual plugs.

 

That would be my definition of internal power, as such, could be prop started without any battery at all. To make even more reliable, could use a gravity fed Aerovee carb. (no fuel pump required)

 

I'm surprised not more of these engines are in use especially considering the wealth of components available and, with the right capacity, increased hp.

 

Micgrace

 

 

[facthunter]

Magnetos

 

My external power reference may be ambiguous, I meant external to the engine, ie A/C battery, as Michael has explained. I would like to see a low tension magneto system ,at engine speed, with double firing high tension coils (that is a dead spark on the cylinder not firing) This is common usage on motorcycles & eliminates the need for rotors & distributor caps.The HT leads are quite short & straight with the coils situated on top of the motor. If it could be arranged without points, all the better. The reference to engine speed only relates to a four cylinder configuration. The coils in this instance, do not have any end of the HT winding earthed, they are both attached to a HT. terminal and to a plug and the circuit is completed through the engine. This is probably the simplest ,lightest system available, and could be home-made. Nev...

 

 

[TechMan]

For those interested in more info about fuel injection can view:

 

http://www.experimentalfuelinjection.com/default.html

 

Chris

 

 

[ZULU1]

HKS efi

 

We are currently installing a basic efi unit on my HKS 700e, the cast manifolds and tuned exhaust are all complete and will be doing a similar mod to the 912 when completed. This is for a trike crop sprayer.

 

Will keep forum posted.

 

Paul

 

 

[Guest MundooTriker]

Hello,

 

I am considering a trike with a HKS 700e. I notice however there are no Australian distributors for this motor.

 

Has anyone got any comments regarding TBO, service, parts supply & maintenance in Australia. I don't like to be a guinea pig.

 

Thanks Andrew

 

 

[eastmeg2]

Put in an order with Airborne for an XT-700 - yeah right ! . . . LOL.

 

Or,

 

Maybe that's the only thing that might make Rick & Rob seriously consider it, if they get firm orders for trikes on the proviso that they are fitted with the HKS motor.

 

 

[eastmeg2]

The only trike I have personally seen with the HKS motor was a nice black Pegasus Quantum, from Bright in Victoria if I remember correctly.

 

Seemed to run quite well.

 

Rgds,

 

Glen

 

 

[Guest MundooTriker]

At present I'm more likely to get one from Sth Africa.

 

 

[Admin]

MundooTriker

 

Which of the South African trikes do you feel would be a good match for the Airborne XT912?

 

 

[ZULU1]

Aquilla Sizing

 

Mundoo triker, you wont be sorry, the Aquilla has possibly the most comfortable seating arrangement that I have ever been in. The XT, Quiks and so on rear seats are compact. The Aquilla was designed for our large countrymen !!

 

The Aerotrike Cobra 912 (Mike Blythe Coast to Coast) is a suitable comparison to the Airborne XT912, the Aquilla is slightly more of a bush type of trike, closer to a DTA than a XT as the under carriage is not unlike a Toyota Bakkie !!

 

I have done over 300 hrs with zero hassles on the HKS and the SA team has three machines, these have been seriously "tweaked" with mega time thrown at them for fuel economy etc. not missed a beat. There are many flying in the USA also with no reported problems. Its a simple engine.

 

Just decide the colour ! See pic of my HKS Aquilla.