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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Your writings are not technical.  They are for sales.   You can not provide "real facts" when you are selling something.  Nobody are stupid here.  

How many rubber cam belts does the Suzuki  engine have hidden under the plastic cover? 

It is a single belt.  Ready to fail way before a 2017 Honda fuel pump.  And yes, the pump can be replaced every 5 years if anyone is worried about it.  

Point is, every engine has failure points.  Everyone knows car engines have become more and more reliable every year.  

As long as you keep writing negatively about our company (because clearly you are)  we will defend ourselves.

Hi Loren, You may want to check out how the Honda iVTEC system works. There are 2 sets of cam lobes. At low RPM one set of cam lobes are selected. At higher RPMs the other set of cam lobes are selected. Either set of cam lobes would work but one set gives better power at low RPM and the other set gives better power at high RPM. Since the propeller can not absorb added power at low RPM there is no reason for an aircraft to have or use cam lobes that are best at lower RPM even if you operate some of the time at low RPM. Please see the propeller absorption curve on the graph on my web site.

Problem with this statement is that the low lift setting is perfect for cruising and the high lift setting perfect for additional takeoff power. Why this is so is technical but Honda is not stupid and the switch to high lift is at the perfect RPM for aircraft usage.  The high lift and variable cam timing is on the intake cam only and offer the possibility to have max power and great torque / efficiency and long lasting valves.  

To say "I am better" is a negative approach by definition.   Interesting that we never see any other highly successful engine company taking this approach in an effort to win customers.   That is worth noting clearly because it should guide the proper formula for success.   

Selective use of engine "facts" that don't match the actual real world application should be avoided.   The Viking Honda certainly offers a redundant dual pump fuel system.   Same for the electrical system if desired with two lithium type batteries. 

All the while targeting just one competitor and ignoring a decade of successful application of the Viking Honda to E-AB aviation in hundreds of aircraft of various sizes and missions.  This fact plainly defeats the good vs bad approach.   

The remainder is not proof of "better" but rather engine design preferences that do not provide a compelling argument that your Suzuki engine is the better.   

There are EIGHT excellent engine options supported on this forum.   You have a good engine.  Stay on track.  Avoid the negative arguments.   Buyers are fully capable of sorting out their ultimate preference be it Corvair or UL or Jabiru or Viking or your Aeromomentum.   

Hi R Michael Moore, I have to disagree. Just about every company says their features or technology are better and this is not at all a negative approach. I am not even saying the technology Suzuki uses in the G series is better for economy cars. Just better for our aircraft in the real world. I backed up every technology and choice made with real world hard facts that positively show what technology and choices are better.

If any of the "facts" I use are selective, incorrect or omitted please feel free to point them out and I will correct them.

The Honda GDI does not have a redundant high pressure fuel pump. There is only one, it is mechanical and on the engine. It produces the 2000+PSI needed for direct injection. The relatively low pressure (under 100PSI) electric lift pumps do not provide any redundancy for the high pressure pump even if there are 2 of them. If the single high pressure mechanical pump fails the engine will stop. Sorry.

Again, I never said that the Honda L15b is bad! It is a great economy car engine! But for aircraft the design choices Suzuki made with the G series are better. I am also not trying to pick on the L15b. Suzuki also makes long stroke DGI engines with variable valve lift and timing. Again these are better for economy cars but not better for aircraft so that is why I chose the G series.

Why then did you choose here to use negative language like "failure prone" when referring to the Honda high pressure fuel pump?   Is that really accurate and fair?   I seriously don't think so.

BTW.. I have a flying friend who is seriously considering an Aventura II.   I am encouraging him to use the Aeromomentum engine and the Viking designed fuel system.   Because that fuel system was designed by Viking to work well with most fuel injected engines.    

I also note that Aventura (Aero Adventures) is now offering Viking aircraft engines in addition to your Aeromomentum.  See Alex Rozinski's January 2019 newsletter.  Not sure if this is the newer 90HP or the heavier 130HP.    Obviously Aero Adventures recognizes that Viking is also doing things right.    

Go high.  Be positive and constructive at every step.    I sincerely wish you every success.

I don't think anyone would argue seriously about the clear advantages of a direct injection fuel system on an aircraft engine, or modern variable intake valve / lift systems.  But rather than discussing any of this, you are all in for a treat.  The latest Aventura will fly with a Viking 130 engine.  So, it will just be a good American race :)  

Hi Jan, Please tell me how the Honda iVTEC system changes the power/torque absorption curve of the propeller? Please look at a propeller absorption curve and compare it to the engine power curve. Where the engine curve is higher than the propeller curve the propeller can not transfer the power/torque to thrust. So while iVTEC provides more area under the power curve and this is very useful in a car it is not at all usable in any way in an aircraft. Honda is not stupid and put a lot of effort into making the engine better for accelerating a car but they also did not design the power curve for aircraft. What makes a better economy car engine is not necessarily what makes a better aircraft engine.
Hi Jan, I will certainly and have provided technical reasons why variable valve timing, lift and duration and direct injection are not a good choice for the way we use an engine in our aircraft. Please see the propeller power absorbing curve for the total uselessness of variable valve timing, lift and duration.

The five main issues with GDI for use in aircraft are the lack of a redundant high pressure (about 2000+PSI) pump, the known issue of carbon build up on the intake valves (google this common issue), no need or possibility for stratified charge at the RPM and useful power settings in aircraft, added weight and added complexity.

I love direct injection and my (Diesel) truck has it. I also love the most of the forms of variable valve timing and lift. They are both great in cars and trucks providing low power economy and low RPM power. But useless in our aircraft.

I am very much looking forward to the race of the Aventuras! Your 130hp against my 117hp!
Hi R Michael Moore, Sorry but Honda had a rash of high pressure fuel pump failures where gasoline went into the oil and caused fluctuating power and engine stoppage. Most happen around 50K miles but some as low as 10K miles. Honda is very proactive so maybe they have or are working on a solution to these failures.

The one Viking 130 is being installed on the Aventura at the request of the customer to replace his Viking 110. The customer needed better performance than the Viking 110 could provide.

I agree that I should be more positive! The issue is I am an aerospace engineer and like many engineers I am not very good at public relations and marketing. I will try to work on being better and more polite.
Hi Jan, Sorry but I am providing real facts and actually I have been accused of being "too technical".

Again, if there is any errors, or omissions in my statements and web site please let me know and I will correct them! But please do not say that "You can not provide "real facts" when you are selling something" without pointing directly to something that is not a "real fact". As an engineer I deal in real facts.

Yes every engine has some single point failures. Modern cam belts now last well over 100,000 miles. Ford went back to a cam belt on some of their engines and with the modern belts available they no longer have or need a replacement interval. Cam chains also are a single point failure. So far our longest cam belt went over 4000 hours and did not fail! We recommend replacement every 1500 hours or 10 years, they are $43 on our parts page and take about 2 hours to replace if you have never done it before. The Suzuki G series is a simple engine to work on. How much is the high pressure fuel pump on the Honda that you just suggested be replaced every 5 years?

FYI, while a belt or chain failure will stop both the Suzuki G series and the Honda L15b, the Suzuki is a non interference engine so there will be no engine damage. The Honda is an interference engine so not only will the chain failure cause engine stoppage it will also do major internal damage to the engine.

I have not said anything negative about you or your company! I have only talked comparatively about Suzuki G series, Suzuki K series, Suzuki M series, Suzuki Boosterjet, Honda, Subaru, Kia, Hyundai, GM, VW, Toyota and many more engine technologies. The WHOLE point of what I have said is about why I chose to use the Suzuki G series as my starting point and provide real facts both good and bad to back up these technical choices. I choose the Suzuki G series for solid technical reasons. I did not choose the Suzuki K series, Suzuki Boosterjet, Honda L series, etc for technical reasons. All I did was provide the technical reasons for my choices. Of course you are free to and do promote the technology of your choice.

Why do you think your negative comments about cam belts, port injection, "old technology", etc are positive but then say my technical and factual explanation of various engine technology is negative?

For you to say that a can belt and it’s greased ideler pulleys are superior to the lifetime chains now used in the Honda’s  and Mitsubishi engines together with hydraulic tensioning is exactly the reason that this kind of discussion is useless. 

The technology will speek speak for itself as far as if  one 1.5 is more powerful than another 1.5. That is the only question. Honda reliability is not on the table to be discussed. 


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