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Fuel injection for the Rotax 912

D

Don at Airflow

Well Known Member
We are looking at installing one of our fuel injection systems that we have developed for the Rotax 912 engine on a Vans RV-12.

Here is the deal. To do the first installation I will need an airplane at my shop to make the intake manifold design, do the airframe fuel system plumbing and document the installation. The airplane does not have to be in flying condition, but the engine must be installed in the airframe fuselage along with the complete engine cowl. We would have to be able to run the engine after the installation is complete.

The time frame to do this project is 6 to 10 weeks. The cost to the customer is the use of their airplane for the said time and payment of the fuel injection system components at a discounted price (I?m guessing $3200.00). Current Rotax 914 kits we have developed to date cost $3700.00 to $4200.00. We would be supplying the labor to install the system, airframe fuel system and boost pump plumbing, mixture control cable, pump switch/s, engine compartment hoses and control system brackets and air inlet. This would be at no cost to the customer.

If this interests you, you can email me at [email protected] or call me at 864-576-4512. For those of you that don?t know, our shop is located at the Spartanburg Downtown Airport (KSPA) Spartanburg, South Carolina.


Don
 
Rotax FI

Most of you already know the benefits of multi point fuel injection, better fuel distribution, no carb icing, smoother operation, better throttle response, aerobatic operation, and so on.
Based on the engine that we developed the system on (Rotax 912 S in stalled in a Just Aircraft Highlander) we saw an 8% to 13% increase in horsepower. This was climb performance, top speed increase and fuel flow calculations as compared to the plane with the carburetors. Granted we have not done dyno testing but the customer had previously flown the same airplane for over 800 hours with 3-4 trips to Florida and one trip to Idaho. Fuel burn was %4 to %6 better than the carbs with the plane at the same power level. (Again flight test data as compared to flying with other like aircraft on a trip. In addition there is no carburetor synchronization as there is only one fuel control unit. Fuel consumption will improve over the carburetor the higher you fly as you can manually optimize the mixture. EGT information is required to correctly set the mixture. In addition, this system is completely mechanical, so if you choose the mechanical engine driven fuel pump option the engine would run with out any electrical power once it is started.

So the reason to install fuel injection on this engine is pretty much the same reason one would install fuel injection on a Lycoming powered aircraft.


Don
 
Don, the RV12 is an LSA airplane. As such we are limited to a top speed of 120 kts. Furthermore we are not permitted any aerobatics in the 12 so the carbs are not an issue. Given the limit on speed the value of additional HP is pretty moot. Actually the carb. equipped 912uls is a very nice performer in this airplane. Lastly I suspect such a mod might have a bearing on the Rotax engine warranty. Your proposal may very well have benefit for such an engine, but I suspect you should be looking for a different airplane to match it up with. I am speaking only for myself here, but the above comments make sense to me for the RV12. Anyone else out there have an opinion?
Dick Seiders
 
Fuel Injection

Don at Airflow said:
Most of you already know the benefits of multi point fuel injection, better fuel distribution, no carb icing, smoother operation, better throttle response, aerobatic operation, and so on.
Based on the engine that we developed the system on (Rotax 912 S in stalled in a Just Aircraft Highlander) we saw an 8% to 13% increase in horsepower. This was climb performance, top speed increase and fuel flow calculations as compared to the plane with the carburetors. Granted we have not done dyno testing but the customer had previously flown the same airplane for over 800 hours with 3-4 trips to Florida and one trip to Idaho. Fuel burn was %4 to %6 better than the carbs with the plane at the same power level. (Again flight test data as compared to flying with other like aircraft on a trip. In addition there is no carburetor synchronization as there is only one fuel control unit. Fuel consumption will improve over the carburetor the higher you fly as you can manually optimize the mixture. EGT information is required to correctly set the mixture. In addition, this system is completely mechanical, so if you choose the mechanical engine driven fuel pump option the engine would run with out any electrical power once it is started.

So the reason to install fuel injection on this engine is pretty much the same reason one would install fuel injection on a Lycoming powered aircraft.


Don
Click to expand...

Yes this sounds Like a Viable Improvment to the Rotax 912 engine I Look forward to seeing an Installation fitted and Resulating Improvments!
 
Me Too...

I am very interested in a fuel injected option. Carburetors are so 20th century (especially multiple carburetors). Since I am at near the polar opposite side of the country mine is not a candidate for prototype, but depending on the increase in complexity, weight, and head scratching, I will be watching closely. If you find your victim, er.. I mean volunteer, please post pictures of the progress.
 
I'm curious to see how this works out, although don't think I would go down this track personally - certainly not during the warranty period on the engine. How would this mod affect the Rotax TBO and general maintenance recommendations/requirements. I assume you would be on your own.

Still, in Australia we don't have a 120kt speed limit on LSA aircraft, so a little more performance and improved economy on long trips could be useful.
 
dick seiders said:
. . . "we are limited to a top speed of 120 kts." . . . "Given the limit on speed the value of additional HP is pretty moot."


Two things well worth considering:

1) A better rate of climb to cruise altitude.

2) 120 kts at a lower engine throttle setting and slightly lower fuel consumption.
Click to expand...
 
20th Century!

No comparison to carbs....heck, fully tunable cylinders via 1/2 thousandth increases or decreases in injector orifices? Can you say smooooth?

My -10 went to Don for massaging:)

Best,
 
RV-12 FI

Hey, what a better way to do a market study than put this out on the VAF.:) We figured with the popularity of the RV-12 the FI option would be a good match. But may be not. In any case I would like to hear comments from all you out there good or bad. We certainly do not want to sink a bunch of money and effort on this project if there is only a market for two or three units. Been there done that to many times. Hey anyone want multi point fuel injection for a P&W R-1340?

Keep the comments coming. We have to be smart in what projects we get involved with these days.

Don
 
Don, with the shear number of 912s out there the market will be good for FI. Slow at first, but if the HP increase is close to what you claim (and I am sure it is) you will have a winner on your hands.

FYI, Rumor has it Rotax is working on a factory installed FI also, but it will not be a retro fit kit. You would have to buy a new engine to get a FI system from rotax. With your system it is an after market add on. Kewl!

Good luck.
 
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Pros & Cons

There might not be much of a market for fuel injection on the RV-12 because the majority of builders in the U.S.A. are registering their aircraft as E-LSA. In order to do that, every part must be purchased from Van's Aircraft and the plane must be built exactly according to plans. Once the plane is flying, changes may be made. But will the builder want to pay more money and endure more down time to install fuel injection? Or will he want to fly and enjoy his new RV-12? Who knows? Some builders want the best of everything and are willing to pay. The question is, how many?
Saving money on fuel is not a reason to install fuel injection. 100 Hours/year x 5 Gal/Hour x $4/Gal (unleaded) x 0.05 (five percent) = $100 saved per year. $4000 (fuel injection cost) / $100 per year = 40 years pay back period. Double that to 80 years for a plane that flies 50 hours per year.
The need for a mixture control is a disadvantage. I like not having to deal with that on the RV-12. Does fuel injection add weight? It does add complexity.
It would be nice not to have to balance the carburetors. And it would be great having a smooth running engine with a perfect fuel-air mixture delivered to each cylinder.
I am taking a neutral position and wish Airflow success.
Joe Gores
 
Hi Don,

I hope you are a success with the project, as I see it hear are the good and the not so good:

Good

Eliminates the dual carb issues
Eliminates the spring pull on the throttle
more power
less fuel
I like a real mixture control

not so good

cost of system (not saying it is not right but it is 5% more for a RV-12)
Question of long term parts and system support
Lack of trained (knowledgeable) maintenance people
May lower perceived value of a particular RV-12 as buyer may not see the value and prefer to have the original carbs

Questions

Are the parts like injectors off the shelf so that we can plan on long term availability if your company is gone or no longer supports the system?

Are there any parts in the system that only your company makes and will you make full details of these parts available so that if your company is no longer supporting the system we can continue to make critical parts instead of removing the system for one failed and unavailable part?

Is a second fuel flow sender required and included for the return fuel line?

How will installing your system effect Rotax warranty?

Will your system be STC'ed on any of the certified applications of the 912 (this would give buyers the confidence that the product was at least in one application reviewed and approved by the FAA)?

Again good luck, it sounds like a good way to go if it works as well as you say and it is not to hard to install.

Best regards,
Vern
 
FI ! yes

I will definitely add this to my -12 if I get the rotax engine at all.

One of the main reasons I am looking at alternative engines is because of the carbs on the rotax.

I hate carbs.

my ideal engine
Electronic FI.
Turbo.
Dual ignition, including dual sparks per cylinder.
Water cooled.
Self powered after start (no external battery/electric system required)
engine driven fuel, water and oil pumps.
40+ Amp alternator.

Rotax is getting close to that list...
Viking is pretty close too.
and there's others, this is going to be a hard choice !
 
vernhendershott said:
Hi Don,

I hope you are a success with the project, as I see it hear are the good and the not so good:

Good

Eliminates the dual carb issues
Eliminates the spring pull on the throttle
more power
less fuel
I like a real mixture control

not so good

cost of system (not saying it is not right but it is 5% more for a RV-12)
Question of long term parts and system support
Lack of trained (knowledgeable) maintenance people
May lower perceived value of a particular RV-12 as buyer may not see the value and prefer to have the original carbs

Questions

Are the parts like injectors off the shelf so that we can plan on long term availability if your company is gone or no longer supports the system?

Are there any parts in the system that only your company makes and will you make full details of these parts available so that if your company is no longer supporting the system we can continue to make critical parts instead of removing the system for one failed and unavailable part?

Is a second fuel flow sender required and included for the return fuel line?

How will installing your system effect Rotax warranty?

Will your system be STC'ed on any of the certified applications of the 912 (this would give buyers the confidence that the product was at least in one application reviewed and approved by the FAA)?

Again good luck, it sounds like a good way to go if it works as well as you say and it is not to hard to install.

Best regards,
Vern
Click to expand...

Are the parts like injectors off the shelf so that we can plan on long term availability if your company is gone or no longer supports the system? Our injectors are interchangeable with Precision nozzles, although we modify the nozzles for the Rotax installation.

Are there any parts in the system that only your company makes and will you make full details of these parts available so that if your company is no longer supporting the system we can continue to make critical parts instead of removing the system for one failed and unavailable part? So you want all the manufacturing drawings of the proprietary components for our fuel injection system if we decide to go out of business. Humm not likely. I will say we have been in business since 1984, I do not think we will be closing our doors very soon.

Is a second fuel flow sender required and included for the return fuel line? No. If you put a fuel flow transducer in the system a single transducer would be installed in the metered fuel line which runs from the fuel control to the distribution block.

How will installing your system effect Rotax warranty? Knowing Rotax, they would not approve of this modification.

Will your system be STC'ed on any of the certified applications of the 912 (this would give buyers the confidence that the product was at least in one application reviewed and approved by the FAA)? If you think $3700 is a lot of money for this system just figure what it would cost if it was STC?d. There would have to be some SERIOUS COMMITMENT to go through this process. There would have to be a GUARANTEE of at lease 200 units per year to make this a feasible venture. We learned this the hard way when we certified our FM-250 Fuel Injection system for Lycoming. Nuf said.

Keep the comments coming



Don
 
Is it possible to uninstall the system an reinstall the carbs.

I am thinking that, if, unlikely though it might be, you go out of business and the parts and servicing are not available for the FI.
then at least I could go back to the carbs instead of ending up with a $30000 paperweight.
 
Hi Don,

Thank you for your clear and candid answers that is a very positive sign for you and your product.

Sadly far to many companies have prospered in aviation and are now gone even after having been the market leader for years like NARCO and even when the company continues if they just stop supporting a product with parts the customer may be out a lot of money, I had this happen with Boeing on one of their few bad ideas involving "Live TV" on aircraft so it can happen to any company and for want of an injector the entire system would have to be removed and the old carbs reinstalled or a new kind of engine found.

In any case please keep us informed and the very best of luck.

Best regards,
Vern







Don at Airflow said:
Are the parts like injectors off the shelf so that we can plan on long term availability if your company is gone or no longer supports the system? Our injectors are interchangeable with Precision nozzles, although we modify the nozzles for the Rotax installation.

Are there any parts in the system that only your company makes and will you make full details of these parts available so that if your company is no longer supporting the system we can continue to make critical parts instead of removing the system for one failed and unavailable part? So you want all the manufacturing drawings of the proprietary components for our fuel injection system if we decide to go out of business. Humm not likely. I will say we have been in business since 1984, I do not think we will be closing our doors very soon.

Is a second fuel flow sender required and included for the return fuel line? No. If you put a fuel flow transducer in the system a single transducer would be installed in the metered fuel line which runs from the fuel control to the distribution block.

How will installing your system effect Rotax warranty? Knowing Rotax, they would not approve of this modification.

Will your system be STC'ed on any of the certified applications of the 912 (this would give buyers the confidence that the product was at least in one application reviewed and approved by the FAA)? If you think $3700 is a lot of money for this system just figure what it would cost if it was STC?d. There would have to be some SERIOUS COMMITMENT to go through this process. There would have to be a GUARANTEE of at lease 200 units per year to make this a feasible venture. We learned this the hard way when we certified our FM-250 Fuel Injection system for Lycoming. Nuf said.

Keep the comments coming



Don
Click to expand...
 
duel redundant EFI

Don... are you using a dual redundant EFI system like the HKS 700T?
 
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Rotax FI

rschy said:
Don... are you using a dual redundant EFI system like the HKS 700T?
Click to expand...

No. Our system is completely mechanical. It is a multi-point system that meters fuel to the engine based on the air flow consumption of the engine. So like a Lycoming FI system there is one fuel control unit and one injector nozzle at each cylinder that sprays the fuel into the intake port. No electronics.

Don
 
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