All trash. As a certified powerplant in the power range discussed in this thread Rotax reins supreme. And all of their solutions employ reduction drives. Without meaningful competition, they can charge for these engines whatever they like. The only outlier is Jabiru, who more or less came from no-where. Reason for their existence was basically geographic isolation and rip off import agents for all of the imported engines that more or less resulted in the local prices being double what it was in the US or worse. When the Jabiru engines first appeared on the market they were more modestly priced compared to where they are now. As their market penetration grew, so did the prices. They are no longer inexpensive engines. $15k for 80hp ? I think the Jabiru cost structure is to charge 75% of what Rotax wants for the same power. In the meantime, Rotax is getting close to being on par with the pricing structure of Continental and Lycoming in $/hp.
Those who are making reduction drives are selling at $2400 to $3400 per drive, that covers Rotax E box for $2400 to Skytrax with their cnc from billet 3 gear reduction drives for the Yamaha engines at $3400. The "cost" of the drives is less, if one was an OEM engine builder and was going to integrate them into an engine package in volume. So the cost of the reduction drive is not driving system cost. If one is going the recycle engine route as per Viking, then the engines themselves will range from $600-2000 at most. $2000 being for the turbocharged 4 cylinder engines in the 200hp range. There have not been reliability issues with any of the mentioned reduction drives so far. Viking had an aluminum flywheel/flexplate fail on a couple of occasions so they switched to a CrMo flywheel.
Aeromomentum is taking on the job differently with all the engines starting as piles of new parts and being assembled from scratch. In some cases the parts are modified by CNC porting with hand finishing to improve the flow properties of the new cylinder heads that they buy. Their turbo motor is converted from direct injection to port injection, thus they have to plug the ports for the GDI injectors and add fuel rails that did not exist for the original engine together with new intake manifolds. So Aeromomentum has a pretty big labor charge that goes along with building one of their engines that is simply not the case for Viking at all. Not to mention all of the parts inventory that they have to hold for all of the engine variations. For people who absolutely want to have, and are willing to pay for a zero time engine, assembled by someone in the US, then Aeromomentum is the way to go. They also dyno test every engine before it ships. One just has to remember, these engines are not really close to a factory engine anymore. In some respects like component balance etc, they may in fact be superior. But there have been some problems with some of the custom parts like the new fuel rails cracking, the fuel line connections to the rail being held on with a worm drive clamp instead of something better and other detail issues which they are totally capable of correcting and hopefully will.
But there is a cost. The AM15T is now close to $17k (1.5L turbo 160hp). The "upright" regular AM15 engine is $12k for 117hp
The small 3 cylinder AM-10, which is supposed to be the Rotax replacement, has languished now for many years. In the meantime, Viking has been selling/delivering/installing the 3 cylinder Mitsubishi based engine with 90hp, 159lb and $10k even price tag. Compared to a Corvair, Jabiru 2200 and of course the 912 this is a pretty good deal. Remember those competitors have carbs and magneto's. Its competitive on power, weight and price. Until someone starts selling a 3 gear reduction drive comparable to the one made by Viking, it is going to stay a dream for the DIYers. One could build it with the Rotax E box right now but that being just a 2 gear reduction drive one would have issues with the position of the prop flange relative to the cowling. Aeromomentum has a 3 gear gearbox for their AM-10 engine but development of that entire package has just been too low a priority since customers want engines at the upper end of the power spectrum, or at least those are the more vocal customers SO FAR (in times past one had the HKS option, the 912 and of course 586 and 503 2 stroke options, but many of those are no longer available anymore). So for once Jan has seen the opportunity, developed a solution and has been aggressively marketing it, including installs of the engine at customer sites to get more examples flying. In the meantime, Jans competitors - do nothing.
Picture of the AM-10 reduction drive that so far is not available due to perceived low demand from the market.
