Roee Kalinsky's RV-7A Project

2009.01.14: (0.0) Early in the project I made some basic decisions about my choice of powerplant for the airplane, which I will explain below.  But in summary, I decided to go with a non-certified clone of a Lycoming parallel-valve IO-360, featuring an Aerosance (now part of Teledyne Continental Motors) PowerLink FADEC in lieu of the traditional magnetos and mechanical fuel injection.  Mattituck, an engine shop that also happens to be owned by Teledyne Continental Motors (TCM), has been selling exactly such an engine to the experimental market: the TMX IOF-360.  Sadly, TCM, who bought out Aerosance some years ago, has recently decided to no longer offer this FADEC system to the experimental market, nor for Lycoming-style engines at all.  TCM cites lack of sufficient demand from the experimental market, and their need to focus on the certified market.  I doubt that this is the whole truth (Lycoming recently announced their own FADEC in the works), but in any case, TCM has made their decision.  TCM has also recently moved the FADEC group from Aerosance's original home in Connecticut to TCM's home in Mobile, Alabama.  In the process, no surprise, they lost the key people who developed the technology at Aerosance.  So the whole future of this product may now be in jeopardy.  I have to say I am very disappointed, but to some degree also relieved, at the timing.  Had I already purchased my engine, say a year ago, I would now be stuck with an "orphan" product, and a dubious future for support and spare parts.

So I'm back to the drawing board.  I'm still planning to go with a Lycoming clone parallel-valve IO-360, but I'm back to evaluating my options for ignition and fuel metering.

Anyway, just for fun, I will document my engine selection process here, including both past and present evaluations and decisions.  This is an interesting and hotly debated topic, and one that people often ask me about (both pilots and non-pilots).  So here it goes, from the ground up.

AIRCRAFT ENGINES VS. AUTOMOBILE ENGINES

There have been quite a few people who have installed auto engines in their aircraft.  There are reasons why this seems enticing.  Firstly, auto engines are far less expensive than aircraft engines.  A new Lycoming engine costs more than a brand new Subaru -- the whole car I mean, not just the engine.  Secondly, auto engines are generations ahead of aircraft engines in technology.  Because of regulatory and other obstacles in the aviation industry, we're still flying engines that essentially haven't changed in 50 years.  While the auto industry on the other hand, blessed with a free market business environment, intense competition, and high production volumes, has moved forward in leaps and bounds.  Auto engines are also designed to burn auto gas, which is cheaper and has a less uncertain future than leaded avgas.

But there is a dark side.  The best auto engine in the world still makes a poor aircraft engine.  An engine in an aircraft is subjected to operating requirements that are very different from the operating requirements for an engine in an automobile.  Naturally, automobile engine designs are optimized for their intended application: operating in an automobile.  Many of these design optimizations make them unsuitable for aircraft use.

1. Automobiles require short bursts of relatively high power output for acceleration, and then only modest power output for steady state cruising.  It is very unusual for an auto engine (other than in a race car) to operate anywhere near its "red line" RPM, or anywhere near its max rated power output.  Aircraft operations normally consist of takeoff and climb at near "red line" RPM and 100% power output, followed by steady state cruise at 80-90% of red line RPM and 75% power.  Aircraft engines are designed to sustain that sort of operation reliably over a 2000 hour service life.  That same profile of operation would be incredibly abusive to an auto engine, and would be detrimental to its reliability and service life to an unknown degree.

2. Light aircraft engines are generally designed to spin a propeller via direct drive, i.e. the prop is basically bolted to the crank shaft.  Now, propellers operate most efficiently, and produce less noise, when the blade tips are well under the speed of sound.  The tip of a 72" diameter prop (typical for an RV) traces an arc of approximately 18.85 feet per revolution.  The speed of sound at sea level, dry air, 20°C, is approximatel 1,125.79 feet per second.  So the blade tip will be traveling at Mach 1 when rotating at 59.7 revolutions per second, or 3583.5 revolutions per minute (RPM).  Typical aircraft engines for this class of airplane are designed to produce peak power outpout at a red-line 2700 RPM.  Compared to auto engines, these aircraft engines produce lots of torque at relatively low RPMs.  Auto engines, typically, produce very little torque at those RPM settings, and are designed to produce their peak power at RPM settings as high as 7000.  This is well suited for automobiles, producing smooth efficient operation when coupled with an appropriate transmission and drivetrain.  But in order to use such an engine to spin a 72" prop, a reduction drive -- a transmission of sorts -- becomes necessary.  This constitutes extra weight, extra friction and heat, an extra critical failure point (and a highly significant one as shown by the accident statistics), and extra cost that often far exceeds the cost of the engine itself, thereby nullifying the cost advantage over a traditional aircraft engine.

3. Aircraft engines are designed with certain measures for mission-critical reliability, such as dual redundant ignition systems, and independence from failure of the airframe's electrical system.  Auto engines, while generally very reliable, do not posses this level of fault tolerance.

And more...  Most auto engines are water-cooled, whereas most aircraft engines are air-cooled.  Water cooling is not necessarily a killer, but does present some practical challenges in aircraft: more weight, more failure points, etc.

There are a number of vendors out there selling kits to convert various auto engines for aircraft use.  Some even specifically for the RV.  Some do a decent job under the circumstances.  But when all is said and done, they have no performance advantage over traditional aircraft engines, no major operational advantages, distinct operation disadvantages outlined above, and ultimately cost at least as much when all the associated conversion and installation costs are taken into account.

My bottom line: Shoe-horning an auto engine into an airplane can be done, but ultimately is not a good fit.  No thanks.

OTHER ALTERNATIVES TO TRADITIONAL AIRCRAFT PISTON ENGINES

How about a diesel?  Several companies have or are in the process of developing and marketing diesel engines for light aircraft.  There are certain benefits to diesel, including the fact that they can burn Jet-A or a variety of other suitable kerosene and bio diesel fuels, which will likely remain available long after traditional avgas (i.e. 100LL) is history.  These diesel engines have seen some limited commercial success, especially in Europe, in experimental as well as certificated aircraft.  However, they do have some major downsides.  The diesels are generally bigger and heavier for a given power rating compared to traditional aircraft piston engines.  As these are new designs, there is still not a lot of history on any of these engines, so their long term reliability remains to be seen.  The future of any specific engine and its manufacturer is also quite uncertain, as we've seen with the recent collapse of Thielert, which was one of the most promising players. 

How about a turbine?  Turbines have certainly proven their worth in larger and higher-performance aircraft.  Their power to weight ratio is superb, as is their reliability and service life.  However, they present some practical limitations for my class of aircraft.  They are not very available, not well supported, and still too expensive to put in a little RV.  Their fuel efficiency is also abysmal compared to piston engines, making the aircraft's operating costs (predominantly fuel costs) much higher.

How about electric?  I wish!  An electric powered airplane could be far more reliable, more energy efficient, and far less noisy than piston power.  This IS coming, but it's not here quite yet.  There are a few concept prototypes of electric airplanes out there, but they are basically underpowered motorgliders with very limited performance, range, and endurance.  The biggest obstacle right now is lack of a battery technology that has sufficient energy density to even come close to that of petroleum-based fuels.  I'm sure we will have this some day, maybe even within the next few years.  But the technology will likely be driven by the auto industry as it pushes toward electric cars, and then we can adopt the technology for aircraft use.

TRADITIONAL AIRCRAFT ENGINES: LYCOSAURUS REX

They are certainly outdated in comparison to the state of the art of piston engines outside of aviation, but the venerable Lycoming engines are still the industry standard for this class of light aircraft.  These are available in various displacements and configurations, but for the RV series basically all are horizontally opposed, normally aspirated, air cooled engines that will spin a propeller in direct drive.  In their stock configuration, they employ dual magnetos for redundant, electrically independent ignition, and either a carburetor or mechanical fuel injection servo for electrically independent fuel metering.  The throttle control in the cockpit directly controls an intake air butterfly valve, and a mixture control in the cockpit is used to adjust the mixture for atmospheric and operating conditions throughout the flight.  Optionally, these engines also have provisions for a hydraulic constant speed prop, also via a dedicated control in the cockpit.

These engines, if treated right, are fairly reliable, and have a TBO of approximately 2000 hours.  However, their primitive design does require a fair amount of knowledge and attention from the pilot to keep the engine happy.  This is not a "turn the key and go" engine like we've become accustomed to in our cars.

These engines are also not cheap.  A certified Lycoming IO-360 for example can cost in the neighborhood of $30K to $40K new.

Update 2009.04.17: One of the issues currently facing these engines is that they were designed to burn high-octane leaded gasoline.  Their favorite blend, 100LL avgas, has been widely available for decades, but may disappear within the next few years due to increasing economic and environmental/regulatory pressures to eliminate the use of lead additives.  Tests have shown that most of these engines (except for high compression and turbo-charged variants) can operate just fine using various high-octane unleaded fuels.  But contemporary auto gas is not an option due to the now mandatory inclusion of some fraction of ethanol in the blend (thanks to the corn growers' lobby masquerading as environmentalists... argh!).  Ethanol is a poor automotive fuel, and even more problematic for aviation use for several reasons, but that's a whole other discussion.  Anyway, currently there are several different fuels being proposed as replacements for 100LL avgas, but it remains to be seen which will emerge victorious, how available it will be, and how much it will cost.  The best bet for now is to try to make choices that will support the broadest spectrum of possible fuels in the future.

TRADITIONAL WITH A TWIST: LYCOSAURUS CLONE

In the experimental category we are not required to use certified engines, and so most opt for a slightly cheaper and less restrictive alternative.  There are several engine shops out there that build "experimental" Lycoming-clone engines, meaning ones that have not been blessed by the FAA.  In most cases, these engines are built from all or most of the same FAA-certified parts.  In some cases these engines are totally identical other than a piece of paper and/or data plate.  In other cases, modifications are made to the builder's needs, or to alleviate known deficiencies in the certified engine that have not been remedied due to the excessive regulatory burdens associated with design changes to FAA-certified equipment.

Among the more common modifications in these Lyco-clones are improvements in lubrication, alternative cam profiles, roller tappets, and electronic ignition.  And yes, a somewhat lower price (but not much lower...).

For me, the Lycoming clone option represents the best compromise among what's currently available, so that's what it'll be.

ENGINE CLASSES AND VARIANTS

Van's designed the RV-7A to accept a range of Lycoming-style engines with displacement between 320 and 360 cubic inches, and between 160 and 200 horsepower.  This effectively translates to one of three major engine classes: the 160 HP parallel valve (I)O-320, 180 HP parallel valve (I)O-360, and 200 HP angle valve (I)O-360.  The parallel valve 320 and 360 are very similar in design, size, weight, and cost, with the 360 just being a little bit bigger and more powerful.  The angle valve 360 is a distinctly different design from its parallel valve cousins.  The angle valve 360 puts out 20 horsepower more than the parallel valve 360, but is somewhat larger, significantly heavier, and significantly more expensive.  Van's website shows performance data with each of these three engine classes.  This data is reasonably accurate according to other builders who have completed and flown their RV's.

For my airplane, I have decided on the 180 HP parallel valve IO-360.  This represents a good compromise between performance, range, fuel economy, weight, and cost.

IGNITION AND FUEL METERING TECHNOLOGIES

Back to the topic that sparked this write up.  Traditionally, these engines have used dual magnetos for ignition, and either a carburetor or mechanical fuel injection for fuel metering.  The biggest advantage of these devices is that they do not depend on the aircraft's electrical system to operate.  Historically, aircraft electrical systems were known to be highly unreliable (same technology as automotive electrical systems of the 1950's), and so making the engine's ignition and fuel metering independent of the electrical system was vital.  Mags and mechanical fuel metering fit this requirement.  But the disadvantages of these ancient devices, however, are many.  Firstly, they are themselves fairly unreliable by modern standards, being finicky mechanical contraptions with moving parts that regularly wear out or go out of adjustment.  Secondly, even at their best, these devices perform their jobs in a fairly crude manner, lacking sufficient accuracy or intelligence to operate the engine at its best.  As a result, engines using these devices can be difficult to start, run rough at some power settings, produce less peak power than they otherwise could, and burn more fuel than optimum at all power settings.  Thirdly, most of these setups include a manual mixture adjustment that the pilot must manipulate during different phases of flight to adjust for altitude and other operating conditions.

At the opposite end of the spectrum is an alternative known as FADEC (Full Authority Digital Engine Control).  This technology uses computer technology to continuously adjust fuel injection and ignition timing based on the engine's current operating parameters as measured through an array of sensors.  A FADEC engine effectively monitors and manages itself, far better than a human ever could, and the pilot is mostly out of the loop other than selecting the power setting with the throttle.  Better-running engines and reduced pilot workload -- I love it!  We have taken this for granted in our automobiles for some time, but general aviation has been slow to adopt this technology.  There are many reasons why, but most are not technical.  Rather, many are simply paradigm paralysis or resistance to change in one form or another, both institutional and individual.  Anyhow, the biggest technical implication for an aircraft builder installing a FADEC system is that it does make the engine electrically dependent.  That means that sufficient safeguards must be designed into the aircraft's electrical system such that the probability of total electrical failure which leads to loss of engine power becomes negligible.  This is not difficult to accomplish, but does require a level of electrical system redundancy that traditionally hasn't existed in single-engine GA aircraft.  There are well known electrical system architectures that meet these needs and have been in use on twin engine aircraft for some time.  It is now time to bring them to the singles.  Incidentally, the GA market is now finally moving toward glass cockpit technology in lieu of traditional flight instruments, which brings forth the same requirements for electrical system reliability.  So FADEC and glass cockpit technology naturally go well together.  Good riddence to the magneto, mechanical fuel servo, and vacuum pump!

There are also a variety of products out there that are not quite full FADECs, but somewhere inbetween, mostly in the form of stand-alone electronic ignition systems.  Electronic fuel injection systems are still not nearly as common.

Following is a review of several products currently on (or off) the market.

AEROSANCE/TCM POWERLINK FADEC

The Aerosance PowerLink FADEC was my solution of choice until Teledyne Continental Motors pulled it from the experimental market.  This appears to be a well designed system, is field proven in over 100 installations and many thousands of flight hours over several years, and for what it's worth (not much) it's even FAA certified on certain engines.  The system is fairly sophisticated, implementing variable ignition timing and closed-loop pulsed fuel injection, individually per-cylinder.  People flying with this system report smooth, reliable, fuel-efficient operation.  I'm sorry to see it go.

Update 2009.08.27: Continental's presence at Oshkosh 2009 was conspicuously meager.  They had their usual large tent, but it was mostly empty space.  That's curious, and a bit disconcerting.  Anyhow, speaking briefly with a couple of the TCM representatives, they made it quite clear that they have no intention of making the FADEC available again for the experimental market any time in the foreseeable future.  Not surprising, but confirmation.

LYCOMING iE2 INTEGRATED ELECTRONIC ENGINE

Lycoming announced in 2008 that they're working on their own FADEC system named iE2 ("Integrated Electronic Engine").  The system's capabilities, from the info released thus far, will be even more comprehensive than the Aerosance product, including its own electrical power generation, knock detection, prop control, and turbo control.  But unlike the Aerosance product, the iE2 will not be a bolt-on solution, but rather an integral component of Lycoming's new engine designs.  In other words, it will not be retrofittable to legacy engines.  Lycoming is initially targeting the iE2 technology at a 350 HP turbo-charged TEO-540-A engine for the piston version of the Lancair Evolution, and a 116 HP IO-233-LSA engine for the light sport market.  No word yet on when/if Lycoming may produce an iE2 version of an IO-360 class engine, which would be suitable for use in an RV-7.  I will be watching the iE2 system with great interest, but I'm going on the assumption that it will not be there in time for me to use on my airplane.  I suspect that it will also be VERY expensive, at least initially.

Update 2009.08.27: Lycoming's overall presence at Oshkosh 2009 was far more dominant and impressive than Continental's.  Also, Lycoming seems much more interested in getting a piece of the experimental (i.e. non-certified engine) market.  I attended a technical presentation on their IE2 system, which was very informative and interesting.  The system is quite sophisticated and capable, well beyond even the Aerosance system.  It looks promising technically.  But unfortunately for me, application of this system to the 360-class engine is still likely years away, and even then it won't likely be made available for customers like myself.  The Lycoming folks insist that the system doesn't just need to be adapted to the engine type, but also needs to be integrated and tuned with the specific airframe.  Their intention is to accomplish this by working with the airframe OEMs, developing standard installations for the aircraft types, which can then be made available as complete packages to customers through the airframe OEM's (the Lancair Evolution is the first example of this).  So in theory the same could be done with Van's, and in fact one might think that with the size of Van's market this would be a high priority for Lycoming.  But it doesn't appear to be.  And furthermore, given the penny-wisdom and resistence to new technology that's prevalent at Van's and a good portion of the RV community, I suspect that there won't be much "pull" for that either.  So I won't hold my breath.

PRECISION AIRMOTIVE EAGLE EMS

I first learned of the Precision Airmotive Eagle EMS (Engine Management System) at a presentation held at Oshkosh Airventure 2007, while the system was still under development.  Like the Aerosance product, the Eagle EMS impelements computer-controlled electronic fuel injection and ignition, although it is more rudimentary in its operation than the Aerosance product.  The Eagle EMS uses fixed ignition timing just like a magneto, and controls the mixture in open loop.  The system hasn't yet gotten much test time in the field as far as I know, but I look forward to pireps when it has.  It is currently priced somewhere between (formerly) the Aerosance product and a traditional setup.  If it proves to be a solid reliable product, it may very well be the best offering available to the RV market, now that Aerosance is out.  I'll be watching the Eagle EMS with interest.

Update 2009.01.27: I've learned some more about the Eagle EMS, and it's a mixed bag.

The good: There are currently 14 of these in the field, at least 2 of which are flying in RV's.  These systems are now available through Aerosport, a highly reputed engine shop.  And the Eagle EMS has been receiving increasing levels of attention in the RV community, so hopefully this will help break "the FADEC barrier".

The bad: There are some technical aspects of the Eagle EMS that I really don't like.

1. They are now shipping with a manual mixture adjustment knob (a potentiometer in the cockpit wired to the ECU) and have the pilot tweak it for different phases of flight.  That seems to defeat one of the main advantages of EFI.  I interpret that to mean that this system just doesn't do as well as it should without pilot intervention.  If that's the case, that's a deal breaker for me.

2. The physical architecture of the system includes too many "boxes", some of which are rather large, which makes for a cumbersome installation.  On the forward side of the firewall there is a very big ECU box, two boxes containing the coils, a power management box, and a dedicated battery (more on this later).  That's just a lot of "stuff" on the firewall, taking up space, adding weight, and requiring a vulnerable wiring harness to connect it all up.  I would much prefer a system that would fit within the physical confines of what it replaces, i.e. just bolt on to the magneto pads (E-Mag did this nicely!) and intake.  The number of separate "boxes" should be kept to a minimum, and especially any extra "boxes" on the firewall should be kept to a minimum.

3. The Eagle EMS was originally designed to drop in to a traditional certified airframe (Cessna 172) with only a single electrical system, so a dedicated backup battery was designed in as an integral part of the Eagle EMS.  This makes it a poor fit for an airframe like mine, which will already have dual indpendent electrical systems in order to support an all-glass cockpit.

4. Precision Airmotive apparently is not developing or testing the ignition and fuel injection maps to be used on any particular class of engines.  Rather, they leave it up to the engine shop and/or the aircraft owner to "calibrate" the maps for that particular engine (not just that type of engine, but each individual engine!).  So even if the system hardware and software were well designed and tested, the maps may not be.  That may also be a factor in Precision's inclusion of a cockpit mixture adjustment knob, if they're expecting that people will be running with poorly calibrated mixture maps.

Update 2009.08.27: Attended a technical presentation at Oshkosh 2009 on the Eagle EMS.  No news and no new details that I didn't already know.  The only new development that they're working on is adapting the system to a six-cylinder engine.  Still sending mixed messages about the necessity the manual mixture adjustment knob.

LIGHT SPEED ENGINEERING PLASMA CD IGNITION

The Plasma II Plus and Plasma III Capacitor Discharge Ignition systems from Light Speed Engineering are standalone electronic ignition products that implement high spark energy and variable ignition timing to provide increased engine performance in comparison to a magneto.  This product line has been around for many years, and is available through most of the major experimental engine shops.  Pilots who use it report that it indeed delivers the performance it promises, and many are very happy with it.  However, there have also been a significant number of reports of failures associated with heat or vibration damage.  From others' descriptions (I haven't had the chance to see for myself), it sounds like the component selection and industrial design of these units is just not up to par.  For example, it uses DB-9 connectors and household wiring in the engine compartment to connect to the hall-effect crank position sensors on the magneto pads, which has been the source of many reported problems.  Also, the method of mounting the circuit board inside the main box allows the board to vibrate within the enclosure and damage the connectors and other through-hole components.  If these descriptions are accurate, then I'll have to write this product off as too much of a tinkerer's radio shack project and not a robust design.  Bummer.

Update 2009.08.27: Stopped by their booth at Oshkosh.  No new development taking place.  Just selling more of the same.

E-MAG

A relative newcomer, E-Mag is another standalone electronic ignition product that takes advantage of a strong spark and variable ignition timing to improve engine operation.  The E-Mag concept has some distinct advantages over the Light Speed product though, most notably in form factor.  The E-Mag is completely self-contained in an environmentally-sealed enclosure that sits right on the magneto pad of the engine, whereas the Light Speed product has several components spread across both sides of the firewall and connected with cables of dubious quality.  E-Mag also has a model known as the P-Mag that incorporates a small built-in alternator giving it an independent power source, while it can still also run from ship's power as a backup.  There were some problems reported with early versions, but it sounds like the company has been responsive in incorporating design changes to correct the problems.  I haven't closely followed the field reports on E-Mag lately, so it remains to be seen if it ultimately proves reliable in the field.  I hope so.  E-Mag is also planning to certify their product, with all the good and the bad that that entails.

Update 2009.08.27: Visited their booth at Oshkosh 2009.  A certified variant is now going into Lycoming's new IO-233-LSA engine.  It has a different form factor, puts two channels into the same box, uses more rugged environmentally-sealed connectors, and uses discrete logic instead of a microcontroller (to alleviate certification requirements).  On the non-certified side, the 114-series P-Mags seem to be past their growing pains and are accumulating significant flight time in customer aircraft (including many RV's).  Studying the unit up close, I'm again a bit disappointed with the choice of connectors.  They are screw terminal type connectors that are not environmentally sealed and have no provision for strain relief (what's with these electronic ignition guys and their choice of connectors???).  [Update, Oshkosh 2010: There is now a provision for a cushioned clamp on the chassis for strain relief of the wire harness.]  They reassured me that the electornics are potted to prevent moisture intrusion, and that they've never had problems with the connectors, although they admitted that other customers have expressed the same concerns.  So why not just fix it?  I'd be happy to pay a few more bucks for the good connectors they used on the certified unit.

SIMPLE DIGITAL SYSTEMS EM-4

Simple Digital Systems makes electronic fuel injection systems for a variety of engines, both aircraft and automotive.  I don't know much about this product line yet.  As far as I know, all their installations use the same core hardware, which is highly field-proven in cars but less so in aircraft.  And of their aircraft installations, most are auto conversions or other "alternative" engines.  They have had the system set up on a Lycoming, but it sounds like this presents a more difficult case for them, and has not been a popular choice (and therefore has not benefitted from much refinement or test time).  Unofficial rumors are that one of SDS's customers has developed a kit for installing the system on a Lycoming and is now starting to test it.  We'll keep an eye out for that.

2010.08.05: (0.0) My mission at Oshkosh this year was to finalize my engine choice down to the details and select the engine shop.  It took many hours of discussion with the various vendors over a span of 3 days, but I was able to get all my questions answered to my satisfaction, and arrive at a clear winner.  The following week I placed the order.  Note that I placed the order now in order to take advantage of the good deals offered at the show, but I'm scheduling delivery for later in the year, around mid-November when I expect to be ready for the engine.  I'll summarize the details of the engine below:

Engine shop: Aero Sport Power

Aero Sport Power (Kamloops, B.C., Canada) is an engine shop that specializes in the experimental market, and has earned a solid reputation among their customers in the RV community.  Engine guru Bart LaLonde and sales manager Sue Gregor were both at the event, and I had the pleasure of speaking with them at length.  Both are very knowledgable and helpful.  In choosing their shop it came down to having the right offerings at the right price, having the willingness to work with me to meet my specific requirements, and that I can see that they take pride in their work, will stand behind their product, and provide good support when needed.

Note that the first runner up was Teledyne Mattituck (Mattituck, NY), which is also a highly reputed engine shop with similar offerings and competitive prices.  I think Mattituck would also have been a fine choice, but a few details ultimately gave the edge to Aero Sport.

Base engine configuration: IO-360-B1B

Fundamentally this is a non-certified clone of the certified Lycoming parallel valve IO-360.  The parallel valve IO-360 is a long-time work horse in the general aviation fleet, and is a good reliable engine.  This particular variant is configured for constant speed prop, vertical ("updraft") induction, a compression ratio of 8.5:1, and is nominally rated at 180 HP.

Flat tappets

There has been much talk over the past couple of years about roller tappets.  Although commonplace in auto engines, roller tappets were first introduced into aircraft engines a few years ago by the now defunct Superior Air Parts, and later by Lycoming.  The roller tappets are meant to alleviate cam lobe spalling problems that historically have affected these engines.  Sounds like a good idea, but comes at a hefty premium (>$2k).  Most of the engine shops now offer both the traditional flat tappets, as well as the new roller tappets as an option.  But the feedback I had gotten from all of them without exception was that the roller tappets really only add benefit to engines that sit for long periods of time (months) without flying, therefore being much more prone to accumulation of corrosion.  Otherwise, there is no performance gain associated with roller tappets, and flat tappet engines that are flown regularly don't tend to experience any significant cam lobe corrosiong and spalling.  So I decided to stick with the flat tappets and save some money.

ECi Titan nickel carbide cylinders

The Titan nickel carbide cylinders from ECi have better corrosion resistance, faster break-in, and lower cost than Lycoming's nitride cylinders.

Note that some ECi cylinders were affected by mandatory service bulletins and ADs issued in 2008 and 2009 for a problem with potential cracking at the cylinder head to barrel interface.  The issue has since been resolved, and cylinders now being produce and installed on new engines are not affected by this issue.

Other major engine components: ECi

The engine shops tend to build the entire engine from either ECi or Lycoming parts (although this is not strictly a requirement, since they are interchangeable).  ECi components are generally a bit less expensive than Lycoming, and by all accounts just as good in quality, so that's what it'll be.

Fuel injection: Precision Airmotive Silver Hawk EX

The certified ancestors of this engine use the venerable Bendix RSA-5AD1 fuel injection system.  This system is currently produced by Percision Airmotive, and continues to be used on certified Lycomings.  Precision Airmotive also produces the Silver Hawk EX, which is a non-certified clone of the RSA-5AD1.  Physically, the Silver Hawk differs from the certified RSA-5 in its method of manufacturing.  The main housing of the certified RSA-5AD1 servo is cast aluminum, whereas the non-certified Silver Hawk's servo (known as model EX-5AV1) is machined from aluminum billet.  According to Precision, modern CNC technology makes the latter no more expensive than the former, and eliminates the RSA-5's problems with casting porosity.  There is also another superficial difference in that the certified RSA-5 is black anodized, where as the Silver Hawk EX is clear anodized (hence the silver appearence).  And that's about it.  Otherwise they are identical in operation, and their parts are interchangeable.

The variant of the Silver Hawk EX that I am getting actually has one more difference.  In the standard variant of the Silver Hawk (as well as the RSA-5), the mixture lever is oriented downwards and swings below the bottom of the servo, which is known to interfere with Van's standard airbox.  A common solution that is now available as an option from Precision is an "alternate rotation mixture" variant, where the mixture lever is oriented up instead of down, and rotates in the oppositve direction so that it is still rich-forward / lean-aft without having to use a bellcrank or other mechanical contraption to reverse the direction of the control cable.  Reportedly, with this option, Van's standard airbox can be used without modification, as well as Van's carburator mixture bracket.  The alternate rotation mixture variant for my engine is kit # EX360-3 (whereas the standard kit is # EX360-1).  The physical differences are limited to a couple of internal parts, and the servo could be converted back and forth if needed (by Precision, not in the field).  So the part numbers are as follows:

Kit # EX360-3:
1ea Servo p/n 3015010-1 (model EX-5AV1 with alternate rotation mixture)
1ea Flow Divider p/n 3015004-1
4ea Nozzle p/n 2524864-2

Regardless of the mixture rotation option, the fuel inlet fitting can go either on the left next to the mixture lever (typical) or on the right next to the throttle lever.  The fuel outlet fitting of the engine-driven fuel pump is on the left side, so it probably makes for more direct routing of the fule hose to have the fuel inlet fitting of the FI servo on the left side as well.

This fuel injection system is relatively low-maintenance.  The only scheduled maintenance items are to clean out the inlet finger screen and replace three o-rings in the inlet cavity at each annual.  The only other field-adjustable item is the idle mixture.  And otherwise it is expected to be maintenance-free until overhaul, which is specified at the engine's overhal (2000 hour TBO) or 10 years, whichever occurs first.

All "rubber" components (o-rings and diaphragms) are now made of fluorosilicone, which is compatible with all known fuels, including ethanol.  A good thing as a contingency, looking pessimistically into the future of aviation fuel availability.

Note that I had also considered some newer fuel injection systems from Airflow Performance.  These are still continuous-flow all-mechanical systems, but claim higher performance than the older RSA-5 style systems.  By all accounts the Airflow Performance FI's are good systems.  However, the performance gains are minor, the installations more complex, they are more expensive, have less of a service history, have single-source parts, and are unfamiliar to most A&P's in the field so they can only be service by Airflow Performance.  For those reasons I decided to stick with the RSA-5 based Silver Hawk.

In the past I had also considered the Aerosance FADEC and other electronic fuel injection solutions.  I still believe that EFI is a better solution in principle, and I hope that solid viable products will emerge in this space in the future.  But to face facts, I have to say the the EFI products currently availble for this class of engine are just not quite there yet.  So, sadly, the prospect of EFI will have to wait, perhaps until my first engine overhaul.

Ignition: Dual P-Mags

The P-Mag (form company E-Mag) is a self-contained electronic ignition system that fits into the form factor of a traditional magneto.  These deliver a stronger spark than magnetos, support variable timing advance as a function of MAP and RPM, and should enjoy a long maintenance-free service life with no mechanical wear (no "points").  This product has had its growing pains when it first arrived on the market, but has since proven itself to be reliable and robust in the field over the past couple of years (even Lycoming is now OEMing it on their new light sport engines).  The P-Mags, as opposed to the original E-Mags, are also self-powering above idle RPM via a small internal alternator.  Ship's power is only used for start-up, at very low RPMs (lower than flight idle), and as a backup in case the P-Mag's internal alternator fails.  In my case, I will have dual electrical systems anyhow, and so each P-Mag will receive its ship's power from a different electrical system for added redundancy.

Automotive spark plugs, aviation bosses, adapters

The P-Mags support either traditional aircraft spark plugs or automotive spark plugs.  The consensus seems to be that automotive spark plugs are the best choice all around.  Having been designed with modern automobiles in mind, they are designed to support a stronger spark, and therefore don't erode as quickly as aviation plugs when using electronic ignition.  Automotive plugs are also available in more heat ranges.   And as an added bonus, as anything automotive vs. aviation, the automotive plugs are far less expensive.  To their credit, aviation plugs are RF-shielded, whereas auto plugs are not.  But with modern resistive plugs and modern avionics (anything newer than ADF...) this doesn't present any problem with RF interference.

Aviation plugs have 18mm threads, whereas auto plugs have 14mm threads.  As an available option, the bosses on the cylinders can be threaded for 14mm so that automotive plugs could be used directly.  But although I plan to use auto plugs, I opted for the bosses to be threaded for the standard 18mm aviation plugs, and I will then use 18mm-to-14mm adapters along with the auto plugs.  That gives me the flexibility to use either automotive or aviation plugs in the future without having to re-machine the bosses.

Starter: Sky-Tec 149-NL

Sky-Tec model 149-NL "High-Torque Inline" starter is reputed to be strong, durable, and reliable, and is a popular choice on these engines.  It also has a unique feature called the "Kickback Protection System", which is essentially a field-replaceable sacrificial shear pin that is meant to fail before damage could be done to the engine's ring gear in case of kickback.

The other common choice is Sky-Tec model 149-12LS "Flyweight" starter, which is both a pound lighter and a bit less expensive.  But this model is reputed to suffer from occasional problems with cracking and deformation of its housing, which can also lead to damage of the engine's ring gear by engaging it off-axis.  So in this case I decided to go with the more reliable solution at the expense of an extra pound of weight and a few bucks, and chose the NL.

Straight spin-on oil filter adapter

Several styles of spin-on oil filter adapters are available for these engines, including straight and right angle variants.  While the right angle adapters look like they may make it easier to remove the filter, I've been advised that the straight adapters actually make the job easier and less messy.  Just slip a "bread bag" over the filter when you remove it, and the bag will capture any oil that may drip out.  According to Bart, the right angle adapters are the only choice for Cubs due to the limited space between the engine and firewall, but RV's have ample space and so a straight adapter is possible and preferred.  So a straight adapter it is.

2010.11.02: (0.0) The engine shipped from Aerosport!

2010.11.04: (0.0) The engine cleared customs (entering the U.S. from Canada).

2010.11.10: (0.0) The engine arrives.  What a beautiful beast!