I'm somewhat hesitant to respond to your post, since I joined the forum just recently and don't want to come across as somebody who joined only to trash talk AeroMomentum.
I also wanted to make it clear that I still think that Mark is a nice guy and that the engine itself is probably fine.Deleted... Info provided in Oliver's attachment.
I'm in Novi, Michigan, USA.I see the pdf read like a for sale ad.Where are you located?
I build Suzuki G10, then G13 from 1998. I sold 80+ G13BB engines for different aircraft, hovercraft and airboats, more than 300 conversion kits. Not too much maybe but enough for some statistics. I know at least 3 companies started to convert Suzuki G series engines looking at my results (from China, USA, Russia). Unfortunately it is not easy to find "made in Japan" engines and components now. I'm not very optimistic yet about using Chinese engines, gearboxes or other components. This is first hand experience. More info Air Trikes: Engines and Conversion Kits.
Mark, I usually agree with what you say here but this is just wrong. We have sold over 10,000 ECUs with collectively something over 20 million hours on them over 27 years. Zero D sub failures in that time. A bunch used in multiple Baja 1000/500 and SCORE race trucks and buggies which can pound you so hard, people have broken ribs. This is a FAR more extreme G and vibration environment than aircraft ever see.One of the main reasons we chose this ECU is the high relaibility Amp Seal connector. Most of the other aftermarket ECU's use mush less reliable D connectors.
I very much could be wrong. My understanding of D-sub connectors is based on information told to me back in the 1980's and maybe was from a biased source and could now outdated. I would also think that even slight differences in the wire strain relief method could have an impact. It is hard to disagree with 20 million hours without failure!Mark, I usually agree with what you say here but this is just wrong. We have sold over 10,000 ECUs with collectively something over 20 million hours on them over 27 years. Zero D sub failures in that time. A bunch used in multiple Baja 1000/500 and SCORE race trucks and buggies which can pound you so hard, people have broken ribs. This is a FAR more extreme G and vibration environment than aircraft ever see.
You can't get any more reliable than that...
Our 6th generation ECU, under final development now, will also use the same D subs for the main, Hall sensor and programmer connections that the current EM-5 does.
Yup strain relief is 90% of the battle for reliability. As another data point, our main test bench finally had the female DB25 wear out after 15 years in 2009 after an estimated 15-20,000 connect/disconnect cycles. It was certainly never designed for this but shows how robust they actually are.I very much could be wrong. My understanding of D-sub connectors is based on information told to me back in the 1980's and maybe was from a biased source and could now outdated. I would also think that even slight differences in the wire strain relief method could have an impact. It is hard to disagree with 20 million hours without failure!
I am sorry but this is not true for a number of reasons. First, at high power and high RPM the GDI is also injecting during the intake stroke and has the same near homogeneous air and fuel mixture so when the piston is approaching TDC you would have the same conditions for detonation with both GDI and MPI. This would be true even if the fuel was being injected only during the compression stroke since max pressure happens near TDC. The real reasons that modern engines can run higher compression are valve timing, squish, quench and knock sensing. Also compared to legacy engines the lower cylinder head temperature, smaller bore and higher RPM help. This can and has been done with both GDI and MPI. Especially if you know that the engine will never be required to produce high power at lower RPM you can tune to prevent detonation very simply. When used in a car, the valve timing also helps with this.The comparison between GDI and port injection is relevant. Unless I am mistaken, the base Viking engine on at least one model is a stock Jazz/Fit Motor.
View attachment 111611
This motor has a compression ratio of 13.5:1 which simply cannot run in an aircraft with port injection without detonation. If port injectors put in the full fuel charge prior to the compression stroke then a high compression ratio will increase gas temperatures. Boom. Detonation.
Not so much with direct injection. With GDI the fuel is injected during the compression stroke and can be timed not to meet combustible stoichiometry until the spark triggers the flame front. And even during combustion, with GDI more fuel can be added to increase/decrease/time optimum PCP.
All good stuff for cars, however I cannot think of a single successful aircraft motor that runs 13.5:1 and successfully maintains detonation margins even with GDI. Certified engines require 12% fuel margin from detonation on a standard hot day across all throttle settings and at coolant temp limits. With 13.5:1 that would require a lot of fuel ROP. I believe Jan programs well ROP across most power settings however I have never seen a test to AC 33.47-1 so its hard to know. In fact I have never seen ANY tests from Jan except static thrust. However the unofficial GPH numbers I have seen all point to BSFC numbers >.45/lb/hp which is rich, rich, rich but with 13.5:1 probably needs richer still. So much fuel probably kills any efficiency benefit of GDI and probably robs power too. So the temptation for Jan is not to do it, and hence get closer to detonation margins from such a high compression engine. Made worse particularly if run on Mogas which has way too low octane for use in the air.
Of course if the original Honda programming and knock sensors were installed then the issue can be avoided however O2 exhaust sensors are not compatible with leaded fuels so Jan removes them. No Lambda monitoring. I believe Jan also removes all the knock sensors too. No knock monitoring either. So the detonation margins are blind and rely on Jan's fixed programming of the ECU. Across the huge variety of engine operating conditions, if the needed generous ROP limits are ever wrong or too fine, overheating and engine destruction from detonation can result. All without anything on the panel to alert except strangely high coolant temps, excessive PCP and PSRU harmonic issues thereafter.
their own boats or were the customers testing the un-tested products?
from Aeromomentum website."their own boats or were the customers testing the un-tested products?