Mark Discusses Advantages/Disadvantages of Different Engine Technologies

I visited the website and found an interesting write-up by Mark, the owner of Aeromomentum. In it he discusses the engineering choices that led him to choose the line of Suzuki engines that he uses for aircraft conversion. Here's a link:

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I believe Aeromomentum is a good option, but find the article lacking.  For example, Mark is comparing his engines against a VVT, but Viking engines use iVTEC.  

The Honda Fit engines in a car may be rated at 130 HP at 6600 RPM, but the ECU controls the iVTEC.  My recollection is that Viking 130's secondary camshaft engages somewhere around 5200 RPM, with full power at 5400 RPM.  This is well below the 6600 RPM in a Honda car, and lower than the 5800 RPM of the AeroMomentum engine.   For this reason we pitched the prop on our Viking 130 so the engine will reach 5400 RPM for take-off and climb, but the normal cruise RPM is below 5,000 RPM.  

As for new, used, wrecked, or totaled, I have a Mercury Mountaineer that the insurance company wanted to total a few years ago because the repair shop could not find a radiator grill after a parking lot fender bender.  There was no other damage to the car or engine, and I'm still driving it.  Here is a common case where the engine was unaffected, but the car was to be totaled.

We look forward to seeing Aeromomentum engines in the tractor configuration, and like our engine, time will tell how good it really is.

Loren, I found the article to be highly informative. I am not knowledgeable enough to address your comments. I would love it if Mark would respond here.

Loren Warner, 

  Just curious, and this is not intent to spark a flame that grows into a fire but I am...curious, what is the horsepower at 5,400 RPM which I am assuming is where the maximum HP is created? Have you seen the numbers at this RPM setting?  Is it 130HP or less or possibly more?

  The topic of VVT that is brought up for comparison has mostly to do with weight savings. Secondly with the RPM range that it is utilized in. 

  Regarding the Mecury Mountineer comparison... what model year was it and what was the year they totaled it? (Or attempted to). A 2019 Honda Fit retails for around $16k (base) and I believe a "considerable" amount of damage is done before an insurance company writes a sizable total loss check. Florida (as an example) has a TLF (Total Loss Threshold) of 80%. Just wanting to keep the apples with apples.

  I think truly and honestly both companies bring something of value to the community. But it is nearly a different business model. One sells "primarily" used at a price point. And the other sells 100% new at a price point. And at this comparison they are competitive in price. I don't know the pricing of a NEW option for the V130 and it isn't marketed much as that is not their model (from what I can tell). "Different strokes for different folks." (quite literally... and PUN intended. 

 2019 is going to be an interesting year for AeroMomentum as there a many airframes about to be completed and then finally flown. 


the Viking 130 HP at 5400 RPM was provided by Viking.  I also believe that all companies do a bit of puffing, so advertised numbers should always be suspect.  But if you're going to compare to the Viking 130, then compare to the way Viking has it setup with the iVTEC for aircraft use, not how it's setup in a car.

My analogy of our totaled car was just to share that even a totaled car can still have a like new engine. Our Mountaineer is still used daily, and oftentimes in extreme conditions.

I also believe Aeromomentum will be a great engine, and wish them well.  


Loren's comments are spot on and go a long way to explaining why this lengthy presentation is not very persuasive.   More suited to engineers than engine owners. 

Ultimately, this overly technical presentation is mostly an advertisement that unfortunately includes a lot of indirect and direct negative criticism of the obviously very worthy competition.   Interesting to read many statements that seem from my reading to present the Viking Honda as a fine engine for aircraft application.  

Like a political argument, much of what is said in this article has been tailored to suit the preferred conclusion.   And it is hard with all the technical jargon to know what is not being said. 

Both are good engines.  Both Aeromomentum and Viking are well proven in high power settings. 

It would be more beneficial to focus on simple objective positives about your product instead of cutting down others.  Show your strengths with hard data and forget the rest.   Negative advertising does not work well.   

The owner's particular aircraft application and preference will ultimately decide.  Virtually all the many positive factors that differentiate the two lines are not resolvable by debate.  They are just differences due to inherent design preferences.    Other factors like fully installed weight (not "stock" weights) with all necessary accessories for flight are objective and can be given as simple facts.

I wish the tit for tat between these two companies would not continue.  Better to focus on full disclosure, straight forward uncomplicated, fact based comparisons and your product's positives.  Owners can sort out the rest.

Both engines are excellent choices.   Choices are good for everyone.   I wish both companies every success.

R Michael Moore, 


  The trouble with wanting TRUTH is the degree of truth one actually wants to accept or take the time to fully understand. I agree with you 100% that what Mark has communicated through his writing this is highly technical and not something you may find on a sales flyer for a product. But it is the truth about how these engines operate and he even takes it a step further in a few areas to reference where the info can be found. Mark is in fact an engineer and very much thinks and operates at that level of thought. This explanation is not intended to belittle the general public or confuse or misguide... but actually to explain the inner workings. Actually the science behind engines is quite amazing at the same time in another way a bit simple...isn't it?  "Overly Technical Presentation." This wasn't a print ad or flashy commercial, it was technical explanation, and attempt to "educate" on the inner workings and technologies of engines and what is needed for our aviation needs. 

 I do agree with you. I want to see positive talk  moving forward from all parties competing or not. Company X makes and brings this to the table and Company Y makes this and brings this to the table and the popularity guides the success. 

It would be really great if there was some third party organization that could independently acquire each and every engine on the market. Then weigh it (dry and installed) and test it (for true HP output at different RPM ranges, put a market value on it and report in their own publication. 

I agree with all of the 'reasons', maybe he could have it proofread for spelling 'wrecks'.  Keep it simple.  I despise Direct Injection.  Performance cars may need walnut shelling of intake valves as early as 15k miles to retain max performance. (WRX).  His competitor's hp numbers have always been suspect to me - for his exact reasons.

I also don't like PSRUs, and I don't like fuel injection on something I wired - where it doesn't have millions of miles of testing behind it (factory built autos).  So, I am using a different '100hp' engine without either that won't quite make 100hp - in low compression form.  

Hi Loren, I think maybe you misunderstood what I was saying about a few things. Sorry for my poor explanation. Please allow me to clarify a couple of points. I used the term VVT as a generic term but included all systems that use variable valve timing and lift. The Honda iVTEC is their marketing name for a system that provides variable valve timing and lift. These systems may use different mechanics and electronics but they all are trying to make for optimum volumetric efficiency over a wider power band. This is not needed in aircraft due to the way a propeller absorbs power as long as the fixed cam is matched for the required peak power point. Yes engines with VVT (including the Honda iVTEC) do have a wide power band. Engines without VVT tend to have a narrow power band. As long as the fixed cam has the correct lift, timing, profile, etc for the intended peak power RPM it works perfectly with a fixed pitch prop. VVT (including Honda iVTEC) is not a problem but at least in aircraft with a fixed pitch prop there is no advantage. And VVT adds weight and complexity that is a major disadvantage.

Honda makes a great motor. The L15b is a better motor for an economy car than the Suzuki G15. Maybe as good as the Suzuki Boosterjet. But what we need in aircraft is not the same as what is needed in an economy car. I was not trying to put down the Honda L15b, Suzuki K series or the Suzuki Boosterjet series. I was just trying to say why as an aerospace engineer I chose the Suzuki G series as the basis for our AM13 and AM15 aircraft engines.

Mark, I was only pointing out what I thought was an inaccurate comparison.  

I believe that aircraft engines do operate more under a variable power band, than at peak power.  Peak power is normally limited to short take-off and climbing.  There is usually a lot of time spent at lower power settings such as idle, taxing, and during normal cruise (typically 75-80% power), and the iVTEC compensates for these variables as well as Peak power.  


Aeromomentum's article does not convince and by taking the negative approach does not serve well.   See my earlier post.

Why not also go after Rotax or UL or Jabiru??   Why Viking should be the sole target?   Interesting question, I think.

One could equally well argue that the Viking Honda is a superior and more modern engine design, coupled with a dual ECU option, a modern redundant fuel system and electrical system all specifically developed around fuel injection, complete firewall forward support, etc.  And already flying in more air frames than I can count. 

The key point here that that it is simply not wise, not helpful and frankly not possible to argue that the Viking Honda conversion is somehow a poor choice.   BECAUSE...The real world facts simply show otherwise.   

The long and rather tedious and clearly biased article would have better stayed with explaining the Suzuki engine's key features and perceived strengths instead of trying to find fault where there are actually simply design differences.   Then there would be no long thread here.   Just good information to help buyers make informed decisions.   

Trying, but actually failing, to disparage only one of many competitors is not what is needed.  Especially when that competition, Viking Aircraft Engines, has a decade of history in providing E-AB owners a proven, highly successful, and progressively improved product.   

Be positive and speak to your strengths.   Buyers are very capable of making informed engine choices of which there are many supported on this forum.

For just such a positive and constructive discussion over just the past week, see this thread on the Zenith forum.

Sorry R Michael Moore but I did not take "the negative approach". On the contrary I provided real facts about each technology and their advantages and disadvantages. I freely admit the Honda L15b is a better economy car engine than the Suzuki G15. I did not say the Honda L15b is bad. I am saying the Suzuki G15 is better in just about every way for aircraft.

I am not being negative by pointing out that lighter weight is better, simple fixed cam is better, port injection is better, new is better and lower piston speeds are better for our aircraft.

The point of the articular that you seem to be ignoring is that I looked at all the available engines and technology and used real engineering reasons to make the BEST choice.

FYI, the Honda L15b does not have a redundant fuel system. There is only the one failure prone high pressure mechanical fuel pump on the Honda L15b engine. The electric pumps do not provide the required high pressure for GDI. They just are to lift the fuel from the tank to the inlet of the high pressure pump. This is another strike against GDI and one of the reasons why we remove the GDI on our AM20T and replace it with port injection.

Sorry that you found my technical explanation "long and rather tedious". I tried to keep it simple and factual. I did write up an even longer technical explanation that included legacy aircraft engine technology like used in Lycoming and Rotax but it was even longer and not really related to why we chose to start with the Suzuki G series engines.

Thanks Mark. I for one appreciate greatly the technical explanation you give for choosing the Suzuki G series. I found it to be highly informative. I'm sure I am not alone.


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