Converting the CC340 to fuel injection

[randylervold]

Could someone from CubCrafters or ECI comment about whether this conversion can work in the Carbon Cub. I would be inclined to do it on my E-LSA if it appears feasible.

Bob, the CC340 is not fuel injected for one primary reason... weight. Fuel injection would require an engine driven fuel pump, an aux fuel pump, a filter, and a servo (which is heaver) in place of the carburetor. What would those weigh? I don't know but I think it would be in the ball park of 8-10 lbs.

That might not seem like that much but you need to understand that in order to get an entire aircraft of the size and performance of the Carbon Cub to make the LSA max empty weight there had to be a mindset that was fanatical on weight awareness. That mindset had to manifest in every single aspect of the aircraft, if we hadn't then the Sport Cub / Carbon Cub wouldn't exist as an LSA. Yes, certain compromises in the interest of reducing weight had to be made, anyone who has taken all the screws out to remove the cowl is aware of one of them, and reverting to an old fashioned carburetor was another. As with all things in aircraft design compromises are required.

No question a fuel injection system would provide better fuel distribution, improved LOP operation, and probably a small bit of extra power. Yes, it could be retrofitted if one had the time, determination, and willingness to solve some potentially difficult problems on his/her own. Are you up for it? Having built two aircraft myself the conversion would be attractive to me and I wouldn't be afraid of the challenge, only the weight. Still, with my company hat on I'll neither encourage or discourage the idea, it's your aircraft and it's already been converted to an ELSA so it's entirely legal.

Now, in terms of fuel injection systems, you really have three choices:
1. The ECi system (newly available)
2. Silver Hawk EX from Precision Airmotive (the experimantal version of the original Bendix design)
3. Airflow Performance (very popular with homebuilders but it requires a return fuel line)

Once the F.I. system is installed the airflow still won't be even to each cylinder, that's a function of the intake tubes which are too space constrainted to be optimized, but you can adjust the size of each fuel injector to get the fuel/air ratio right and to peak at almost the same time. I've played with this myself a fair amount, click here for the story of what I did on my RV-3B.

Hope that provide some perspective.

[randylervold]

Further comment on the idea of converting... especially if you go with the Cold Induction system, you'll need to deal with inlet air plumbing. There should be enough room there to fab something, but this will be one of the hurdles you'll need to overcome.

[turbopilot]

Bob, the CC340 is not fuel injected for one primary reason... weight. Fuel injection would require an engine driven fuel pump, an aux fuel pump, a filter, and a servo (which is heaver) in place of the carburetor. What would those weigh? I don't know but I think it would be in the ball park of 8-10 lbs.

Hope that provide some perspective.

Thanks Randy, that is helpful. I do understand the weight issue and the chicken/egg problem of being an LSA before you can be an E-LSA.

I have built two homebuilts as well, so I am up to the challenge. Right now I am just trying to determine if it is worth the trouble. The one area where I have no experience is optimization of air fuel mixtures in carbureted engines. I know there is a great deal of experience with folks who like to tinker with old automotive engines.

Roughly a 1 gph spread between peak TIT's for #1 & #2 versus #3 & #4 cylinders is pretty big. It creates all sorts of second order problems with engine temperature and performance management. Is this spread typical of carbureted aircraft engines? As I said in my first post all of my experience with carbureted aircraft engines predates the use of engine analyzers and even the routine use of EGT, so I may just be discovering the obvious as I return to the world of carburetors.

Any ideas from CubCrafters or ECI about reducing this spread?

[Chris]

I am building an EX and would love to push this fuel injected Carbon Cub ball down the road.
I don't need to deal with conversion of an already installed engine as I'll be building an engine from scratch and realize this is my best chance to optimize it.

Sounds as though compromises were initially made by the factory to meet certain weight constraints for LSA qualification and market placement. My plane will be EAB, so I am not battling a hard empty weight stop and I can consider the design and function of the machine in a broader manner. For me, installing a carburetor just doesn't seem appropriate.

I understand the empty weight issue, but when actual function is considered, I think an injected motor wins easily. The additional weight of fuel injection, if any, equates at most to 1 or 2 gallons of fuel load. One would burn 6-12 lbs less fuel weight every 1-2 hours of flying with an injected engine cruising LOP. I consider that a performance wash. Also the owner will enjoy large fuel cost savings and perhaps a longer lasting engine.

I'd like to learn what we know about using fuel injection in Carbon Cubs.

Is anyone running a fuel injected set up in a carbon Cub? Which one? How do you like it? How did the installation go?

Can we get some support from the factory regarding a fuel injection set up?

[randylervold]

I am building an EX and would love to push this fuel injected Carbon Cub ball down the road.
I don't need to deal with conversion of an already installed engine as I'll be building an engine from scratch and realize this is my best chance to optimize it.

Sounds as though compromises were initially made by the factory to meet certain weight constraints for LSA qualification and market placement. My plane will be EAB, so I am not battling a hard empty weight stop and I can consider the design and function of the machine in a broader manner. For me, installing a carburetor just doesn't seem appropriate.

I understand the empty weight issue, but when actual function is considered, I think an injected motor wins easily. The additional weight of fuel injection, if any, equates at most to 1 or 2 gallons of fuel load. One would burn 6-12 lbs less fuel weight every 1-2 hours of flying with an injected engine cruising LOP. I consider that a performance wash. Also the owner will enjoy large fuel cost savings and perhaps a longer lasting engine.

I'd like to learn what we know about using fuel injection in Carbon Cubs.

Is anyone running a fuel injected set up in a carbon Cub? Which one? How do you like it? How did the installation go?

Can we get some support from the factory regarding a fuel injection set up?

Chris,

Unfortunately there have been no fuel injection installations yet that I'm aware of, and you are absolutely correct that weight is what has kept us from going down that road. I have personally spoken with at least a few builders about it, and encouraged them, but breaking trail on a project like that is not something to be taken lightly.

All that said, it's only a matter of time before some creative and enterprising builder makes such an installation. They will be rewarded with all the benefits that accrue from fuel injection and have the appreciation of all who come behind. Of course documenting such an installation here on the forum for others to benefit from would be especially appreciated.

Lastly, what do you mean by "support form the factory"? I will do what I can, and be candid about what I can't do and why.

[Chris]

Chris,

Unfortunately there have been no fuel injection installations yet that I'm aware of, and you are absolutely correct that weight is what has kept us from going down that road. I have personally spoken with at least a few builders about it, and encouraged them, but breaking trail on a project like that is not something to be taken lightly.

All that said, it's only a matter of time before some creative and enterprising builder makes such an installation. They will be rewarded with all the benefits that accrue from fuel injection and have the appreciation of all who come behind. Of course documenting such an installation here on the forum for others to benefit from would be especially appreciated.

Lastly, what do you mean by "support form the factory"? I will do what I can, and be candid about what I can't do and why.

I have realized that I believe my wonderful and high end Carbon Cub should be able to run LOP. This seems particularly appropriate in light of the factory recommendations for cruising at very low power settings. If I don't set up my engine for LOP operation now, it's not likely to happen for a very long time until the engine is overhauled.

I was/am hoping I can collect enough information to make installing FI on my plane a reasonable endeavor. But there does not seem to be much information out there. Knowledgeable folks I have spoken with seem to think it's a good idea but no one seems to have any specific information. Of course, it's a good thing people are reluctant to provide advice without experience to back it up.

The engine builders are easily able to build an engine with several well vetted FI systems. The main problem seems to be lack of information regarding what is compatible with the Carbon Cubs firewall forward pieces.

I am a first time builder and not an engineer. I wanted to find out if someone knows enough about doing this for me to reasonably move forward and to install FI on my project. I seem to be finding the answer is no, and that's a disappointment.

Now I am thinking the company really should seriously consider development of a FI system for the CC.

The CC is highly engineered, high performance and high end with a number of options available. Seems like one option really should be FI.

If the original engineering goals excluded development of FI, maybe the time is now considering the product has matured and expanded.

The Company has added a number of other relatively heavy options such as the extended fuel, extended baggage etc, which are chosen by many buyers. To me fuel injection seems overdue.

Please get going fast as I need to get my engine ordered!

Chris

PS For my purposes, just a bit of R&D confirming basic mechanical compatibility of the plenum and cowling with a combination fuel/ignition EFII system would be great.

[randylervold]

PS For my purposes, just a bit of R&D confirming basic mechanical compatibility of the plenum and cowling with a combination fuel/ignition EFII system would be great.

We can likely provide that confirmation if we could get some parts here to take a look, but for obvious reasons with no guarantees that anything will fit or work. The ability to cruise LOP would be important to me too and I'm more than happy to share what we've learned here at CC about it with the CC340. With recent work on sump neck inserts and perforated nozzles in the carbs we've managed to even out the fuel flow a bit. Still not to fuel injection levels where you can balance each individual injector, but it does bridge the gap to the extent that most CC340 aircraft can be cruised LOP. Unfortunately I've also found variation from plane to plane, something we just can't explain -- some are simply better than others, go figure.

BTW, there's a thread in this forum on that topic HERE.

[Treetopflyer]

Chris,
I'm using the EFII system on the RV-7 that I'm currently building and I also plan on using it on the CC that I hope to start building in the very near future. It's a very easy system to install (a lot of plug and play) and I think that it really brings any aircraft that it's installed on into the 21st century. The throttle body is much shorter than a typical aircraft carburetor so if it were to be mounted in a vertical orientation that there would be ample room for it to be mated up to the CC air-box......(although I've never had the opportunity to study a CC air-box). The only other small obstacle that may need to be overcome is modifying the fuel lines a little bit and installing an Andair duplex fuel selector valve. As you probably already know the EFII system uses a high pressure fuel rail along with a fuel return line. By using the duplex fuel selector valve all of the unused fuel is just returned back to the same tank that it was drawn from. A very nice benefit of this kind of system is that you always have cool fresh fuel being delivered to the engine so the chance of vapor lock is practically non existent. It would be interesting to see a horizontal forward facing cold air intake manifold installed on a CC. I have a Superior cold air manifold on my RV and I really like it. It wound be great if factory wound give a little support and maybe design a cold air intake manifold adaptor so that if a builder were installing a forward facing cold air induction that the adaptor wound make it easy to adapt to the existing CC air-box and filter. Another benefit to the EFII system is that you also get all of the advantages of the current light-speed ignition system that's currently being used on the CC. So, you kind of get a two for one.....a modern electronic fuel injection system along with a modern electronic ignition. I think that the EFII system is a win win setup and it'll definitely be going in my CC, even if I have to make a few small modifications myself.
Mark


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[randylervold]

I don't know much about the EFII system as it came on the market after I stopped building RVs, but it looks most interesting. I wouldn't make an F.I. choice without thoroughly investigating it. Jim Richmond, our owner/founder who loves to tinker, is quite interested in it as well. Who knows, you might see a factory project with that next year some time with that system, or a derivative of it. That said it won't be something we offer, just a prototype or "proof of concept".

I suppose this is as good a time as any to give some insight as to why we at CC can't just snap our fingers and do a project like that. We now have an engineering staff upstairs of 15 people, plus another half dozen or so DERs we use. All projects we undertake, both Part 23 Certified and ASTM certified (LSA), require all sorts of time consuming design, testing, and documentation. Bottom line, it is EXPENSVE and we have to prioritize our projects carefully -- we simply can't take on all the projects Jim and I might want even if we KNOW they will sell. I'm sure this is hard to understand from the outside looking in, but when you sit in my chair it is reality.

All of that said, you will see CC continue to innovate and bring new concepts to market. I think our track record is pretty good so far and I don't see that changing, but it will never be fast enough to keep some of us happy (including me!). ;-)

[Treetopflyer]

Thanks for the reply Randy, and I certainly understand your position. I really hope that you guys do take a good hard look at this system as I think it would be a fairy easy system to integrate into your current format. As a side note, which you probably already know, ECI has been running some pretty extensive testing on the EFII system and are very happy with their findings.

Mark


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