What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Fuel Injection 101

vic syracuse

Well Known Member
Advertiser
Mentor
In the spirit of "never too old to learn" I participated in the Fuel Injection 101 class delivered by Don Rivera at Air Flow Performance in Spartanburg, SC this weekend. I have to tell you that you only think you understand injection systems until you take this class. Of course, Don probably forgets more in a day than I will ever learn in a year about injection systems, but I found his transfer of knowledge and experience to be absolutely fantastic! You not only get a half day of theory, with lots of diagrams and very interactive presentation from Don, but the following half a day in the lab REALLY drives it all home.

Seeing first hand why different springs may or may not be used in various parts of the system, and how they actually impact the flow curves was fascinating. That coupled with seeing failure modes really leads to a deep understanding of the advantages and limitations of injection systems.

It was also cool to be in the class with 6-7 other RV builders and pilots, some of whom I already knew and some of whom became new friends. Lots of great discussions both during the class and afterwards.

By the way, Colleen (Don's wife) actually provides home-cooked meals for the weekend that were absolutely delicious.

Many of us take classes during our original build to learn how to rivet or wire or weld. This is one of those calsses that will really help you understand how to better operate your engine, along with understanding why it might behave a certain way and how changing various components can improve the operating efficiency. I found it very valuable and would encourage those of you with injection systems, or considering injection systems, to take the class.

I know some of the classmates took pictures and they may post some here.

Vic
 
Fuel Injection

Hey Vic

Sounds like a great class. I am in the process of building a 10 and probably a few years away from ordering an engine but am definitely interested in some of the electronic direct fuel injection systems (such as EFII or SDS)

Without getting into any discussions of the specific products or companies, you just finishing this course and you having quite a bit of experience, would very much be interested in your thoughts\perspective on pros\cons of traditional fuel injection system vs new electronic controlled system from a perspective of system management while flying reliability, serviceability and maintenance?

I am definitely interested in the new technology but not sure if I have justified rationale for wanting to go in this direction beyond just liking the technology.

Would appreciate your perspective, thoughts

Steve
 
Well, you are asking me to opine on something that is probably akin to the primer wars. :)

First, let me make it clear that I am really glad that Experimental aviation exists and we are allowed to "experiment." The results of our progress in this facet of aviation are nowing showing fruits in the Certified world, one example being the approval of Dynon D-10's for use in a whole bunch of aircraft outside of the Experimental word. Personally, I think it is also bringing a better level of safety to aviation.

That being said, I, too am watching the progress of elctroninc technology being applied to integrating the fuel & ignition systems. By that I mean the ignition system and fuel system are more linked than what we currently have today. We seen a lot of development on electronic ignition systems such as Light Speed, Electroair, PMag, etc., but they are independent systems for the most part.

A long time ago the automotive industry tied those two systems together (of course EPA emissions and mileage requirments helped to push them along). Some of them started with just throttle body injection, but now we have pretty sophisticated systems giving us mileage and horsepower unheard of when I was a kid. Of course progress didn't come without some failures. I once heard a comment that if our airplane engines had made the same progress as the automotive industry did we would be flying our airplanes to the moon today.

Back to the sytems you mentioned----- I think they are making progress but I am not ready for them on my airplane yet. That doesn't mean they are bad. MY mission is reliability and minimizing the risk. You asked for my opinion. :)
Even if one airplane were to run for 2 years with no problems, I personally don't think that is a large enough sampling to insure the system will work trouble-free under all conditions. I think the Certified fleet is a good example here, as we still see AD's issued against engines, airframes, and accessories that are 50-60 years old and in a fleet with millions of hours.

Our fleet is quite young right now. I even see some pushback when I post on really poor riveting that "hey, they haven't crashed yet, how good does it have to be?" My opinion is that 200 hours on an aircraft or subsystem still doesn't mean it won't fail at some time in the future, as oblong holes and poor rivets will eventually work loose. Some failures take time to show themselves.

Each of our airplanes are built so differently, even the match-drilled kits from Van's. I know, as I get to see A LOT of them every year. So, it is going to take some time to get good field experience from some of these systems across a variety of installations.

I think a real win would be to see an engine actually designed from the ground up to use the integrated systems, or at least begin to see the Lycoming and Continental guys do some testing and start to offer integrated systems on their engines. Perhaps with the new fuel requirements we will start to see some advances here. I know we have seen some FADEC systems, but they haven't seem to have lasted.

I know I certainly hope progress continues. As much as I do like my injection system, it has limitations and quirks (hot starts and idling problems come to the mind of anyone with an injection system). But, for now, I do like the reliability, and will put up with the quirks.

I hope that answers your question. Would I talk you out of one of the systems you mentioned? Not now, since you said you are a couple of years away. I think the landscape could change by then, so no need to make any decisions now.

Thanks for asking. :)

Vic
 
I attended the class this weekend as well, and thought it was well worth my time and the cost. Vic says everything in his post and I agree on each point. I have one of Don's FM-200A injectors on my -8 and after doing the deep dive on how it all works, and how to troubleshoot it, I came away very impressed and confident in his product. It's hard for me to imagine that there's anyone in the industry that understands fuel injection better than Don Rivera. Highly recommend that anyone attend to get a better understanding of the subject regardless of which injection system you decide to buy.

And to top it off, there's all that home cooking, beverages and lots of comradery. :D
 
Another happy, more educated FI 101 class mate here. I've been having some performance issues with my newly finished -7A and wondered if my FM-150 was part of the problem. After going through the class and talking to Don, Vic and others, I was confident that the issue was not FI related. Both suspected a timing issue and Vic felt it was likely the P-Mag.

Upon arriving back at home base, I retarded the timing on my P-Mag a couple degrees and went flying. CHTs dropped about 70 degrees over the last flight where one cylinder hit 450 (OAT was about 20 degrees cooler yesterday too).

Now to put the rest of my new knowledge to work and tune the injectors so I can better lean the engine in cruise for improved economy and smoother operation.

I highly recommend the class and you might be lucky enough to run into folks like Vic, Mark and others that have great stories to tell and advice to give.
 
AGREED!!!! I took Dons course in 2015, and was impressed! Gee everyone needs flow bench, right? Theory and practical application is one of the best parts of this course. I mean, you can read it in a book, but do you REALLY get it? With the AirFlow course, you get to apply what you learn, AND understand why things work. I highly recommend this to anyone that is using mechanical injection.
Don---you need a FI 201 course for those of us that have FORGOTTEN alot of the little things.

Tom
 
Carb loss question?

Any current Kitplanes subscriber may click here for a past article, written following a trip to the Airflow Performance school:

http://www.kitplanes.com/issues/33_3/builder_spotlight/Bendix-and-Beyond_21479-1.html
Great article, Dan!

One question that is perhaps answered in the class, and I didn't quite get from the article, is what is the relationship between the "carb loss" and either power or efficiency of the engine?

For example, you show:
Code:
RSA-5  12.75 inches
FM-150 10.0  inches
FM-200  4.0  inches
RSA-10  4.9  inches
FM-300A 2.6  inches

What would be the difference in "performance" of an io-360 with a FM-150 and a FM-200 or a FM-300?

Thanks!
 
Last edited:
What would be the difference in "performance" of an io-360 with a FM-150 and a FM-200 or a FM-300?

Thanks!

From what I learned in the class, my understanding is that larger engines pump more air and therefore need a larger fuel servo/regulator to provide more fuel at higher RPMs, which translates to more HP.
 
One question that is perhaps answered in the class, and I didn't quite get from the article, is what is the relationship between the "carb loss" and either power or efficiency of the engine?

Carb loss is simply a reduction in manifold pressure. All things being equal, replacing an RSA-5 with a FM200 would increase manifold pressure by 12.75 - 4 = 8.75 inches of water, or 0.64359 inches Hg.

Things are not always equal. For example, a different manifold may be necessary to get a larger mounting flange diameter.
 
Back
Top