# Non- Biased Engine Reviews -Viking

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#### wsimpso1

##### Super Moderator
Staff member
Log Member
Actually the BD-4C does use a fiberglass main gear. I believe it's made by Grove.
Grove makes gear legs of 7075 aluminum alloy, bent and heat treated. If the BD-4 is using fiberglass, I strongly suspect a different maker...

#### Alessandre

##### Well-Known Member
Bringing back this discussion, there is engines like viking (or similar), but not truly cheap if you need high power (I'm talking about the 195HP), for other side could be considered cheap if you think this is a brand new engine and there is in this market "smart guys" that sell only the PRSU for equivalent price, is very confuse to decide because also there is used Lycomings or Continentals from 8k that I think opening and change the bearings, clean the cylinders and change the gaskets could work very well, but they need to use avgas (the more expensive fuel of the world), that make the operational cost much more expensive. I think the advantage of these auto converted engines is because the price of the parts and fuel economy, but they aren't cheap if compare with used direct drive engines, they can work very well or be a true head ache. My observations about these auto converted option until now are:

1- I think Jan solved the issues with torsional vibration, I think Aeromomentum too, there is no cases of broken crankshaft that I know.
2- The engine can use avgas with additive and mogas ($cost economy) 3- The engine core once well cooled can operate in max power climbing better than any air cooled engine. 4- There is a case of prop strike with 500h of operation where the engine still well and only the gears and bearing was changed. 5- The weight of these engines are very similar with the direct drive air cooled equivalents. 6- We need to have alternatives for scape from the cage of these 2 big brands that sell their parts for almost the same price in silver. If we think rationally and if the supply of parts is not interrupted, these engines could be operated for 1000 hours and then replaced almost all the components and would still be cheaper to operate than the traditional ones, of course it is estimated that they can last longer. But they do not fail to offer buyers risks. But to sum it all up, to solve the cost problem in aviation I see only two alternatives, either some high production car or motorcycle adopts the Lycoming engine or we adopt the engine of some high production vehicle for our use. One of the reasons of the existence of the homebuilt aircraft is because there is no much people with money to buy a brand new GA and operate with the costs of GA, we don't see a lot of people building cars in their garages because car is cheap. If turboprop was cheap I think all the projects would be turboprop, the reciprocation engine would be retired. That is cost matter. Last edited: #### BJC ##### Well-Known Member HBA Supporter One of the reasons of the existence of the homebuilt aircraft is because there is no much people with money to buy a brand new GA and operate with the costs of GA, we don't see a lot of people building cars in their garages because car is cheap. I think that there are many parallels between homebuilt aircraft and homebuilt cars, especially wrt kit planes and kit cars, which, in both categories account for the vast majority of completed machines. Neither is cheap. Mass produced vehicles are cheaper. Neither has to meet the most stringent (in the USA) government standards. Both are intended to perform and handle in ways that government approved vehicles do not. Eack can be taylored to the personal whims of the builder. BJC #### rv6ejguy ##### Well-Known Member Lycomings and Contis run just fine on mogas. Lots of folks been doing that for years. #### PagoBay ##### Well-Known Member My observations about these auto converted option until now are: 1- I think Jan solved the issues with torsional vibration, I think Aeromomentum too, there is no cases of broken crankshaft that I know. Viking's rubber torsion damper is easily inspected in a very few minutes and replaced if needed. Multiple videos of owners / operators commenting on how smooth the engine is at all RPM settings idle / takeoff / cruise. See Here: #### Alessandre ##### Well-Known Member Weak points of used Lycoming/continental: catastrofic failure Weak points of viking auto conversions? Electronics? Fuel system? I saw a lot of posts where rv6ejguy posted that the brake specific fuel consumption of the lyco are better than any auto engine, in this case using mogas looks the used lyco/continental wins. But these engines brand new still very expensive. #### rv6ejguy ##### Well-Known Member Frictional losses at high rpm generally hurts the BSFC of geared auto conversions but if you're burning Mogas and the engine is a lot cheaper to buy, I don't think this is a big concern. You need to look at initial costs and operating costs to work out a cost per flight hour. You don't see many catastrophic failures on Lyconentals which have been properly cared for and flown fairly frequently. Infrequently flown ones sometimes get bore, cam and lifter corrosion which can be expensive to fix. #### Alessandre ##### Well-Known Member Frictional losses at high rpm generally hurts the BSFC of geared auto conversions but if you're burning Mogas and the engine is a lot cheaper to buy, I don't think this is a big concern. You need to look at initial costs and operating costs to work out a cost per flight hour. It make sense, the friction grows a lot with the speed, there is an old relation between rpm and lifespan where low rpm=high lifespan that justifies the long lifespan of the locomotive engines and ships, but they also have a good liquid cooled system that keeps the temperature constant, I think the low RPM is another point for the lyconentals, but themselves are going to way of liquid cooled auto conversions with their new diesel engine series. Including Porsche all the automotive brands no longer are using air cooled engines. That's why I think aircraft engines seem stuck in the past, that's works, but the 6 cylinders of Porsche 911 air cooled also worked very well, but it's no longer available. #### akwrencher ##### Well-Known Member HBA Supporter It isn't just RPM though, its that and piston speed. Shorter stroke engines designed to run higher revs can have similar piston speeds to larger slower engines. #### TFF ##### Well-Known Member I think the missed point of the Lycoming being old tech is wrong, it’s best tech. As direct drive, an engine is never stressed enough to move away from air cooled. You want it smaller with the same amount of horsepower, you have to add complication to make it work. Prop reduction to convert high RPM horsepower to prop speeds. That’s a pretty big complication. Of course doable with millions. Higher horsepower needs better cooling. Liquid cooling is great, cut running temperatures in half easily, but it adds complication. You have added two failure points to equal one with neither. A new design engine will not revive GA. A new engine will not retrofit without an overhaul of either the system or a giant influx of money. Enough money to buy all of GA airplanes. A total reset. We complain about spark plug cost. The trickle down will take either 60 years or everyone buys a million dollar airplane. That’s business models. Which one does a company today want to work with? Everything is niche at best. Some is just less so in relatively. You have to ask yourself, fresh technology or best technology for the money. The 911 based airplane engine almost bankrupt Porsche. They could have stuck with it but it needed lots more development. The cost becomes useless when one has one in the market that still works without the trouble. #### tspear ##### Well-Known Member @TFF Depends on how define best. As you have chosen to define it, based mostly around certified used airplanes, then yes. Not much has a chance of beating or radically overhauling Lycoming or CMI. What used to drive costs for aircraft of yesteryear compared to today has changed. If instead you define best as most fuel efficient, most cost effective, and stay in the experimental space, there are many other choices. And as a result, neither Lycoming nor CMI have fair well. Where they continue to do well in experimental has more to do with local tribal knowledge about the engines, not because they are the best at any one thing. Tim #### Alessandre ##### Well-Known Member For curiosity this is my cost estimation for build an almost brand new Lyc O-360 (I think there is some itens missing). Obs: Before questions I'm a mechanical engineer and I did training in engine repair and I have some experience with car engines rebuilding an 4 cylinders and recently an GM V6 modern engine that is working pretty well and smooth in my car. I have never opened or even loosened a bolt on an aero engine, but I think I can learn. In my case an O-360 could work, but I'm seeing also continental O-470 and seeing the car converted options. My options to try to keep the budget bellow 20k are there: 1- Buy an used Continental O-470, open and rebuild it; 2- Build an O or IO-360 buying the parts and join (maybe get a good core for start) 3- Buy one of these brand new auto-converted engines. Of course there is a lot of personal choice in each situation, but all opinions and arguments are very welcome, I want to know what to expect from each choice. Last edited: #### rv6ejguy ##### Well-Known Member I'd stick with a timed out or half time Lyc 360. Lots of support and clone parts out there. The 470 is really old and a bit of a boat anchor. The 470 has more power but is a lot heavier. #### tspear ##### Well-Known Member @Alessandre The advantage of an O-360/470 is there is a lot of experience (e.g. tribal knowledge) about the pitfalls and problems. Depending on the plane you are building (I missed it, if you posted it earlier) there are a few auto based conversions which have a good track record. Otherwise, you will do a lot of "design" work on your own to solve many problems. If however you want to split the difference, talk to Ross on here and install one of his EFII systems on a Lycoming/CMI engine and call it a day. Tim #### rv7charlie ##### Well-Known Member You're probably over-estimating the cost of the cylinders and a couple of other items (check other suppliers), but vastly underestimating some other costs and not accounting for many thousand$ in other needed items to build a complete, working engine. For instance, the magneto gears (not included with the mags) are hundreds of dollars each. You'd need connecting rods, of course. Nuts & bolts could easily run over a thousand $(rod bolts are big buck, single use items). And you're without doubt rolling the dice on an ebay crank and/or crankcase. I'd be shocked if you were lucky enough to build a reliable Lyc from collected parts for less than a mid-time 'runner' from someone you trust. Actually building one is relatively straightforward (it's basically a big VW Bug engine), except for all the little 'bite you in the butt' items you need to know that will only come from working with someone who's done it, or *very* careful research & following the overhaul manual (and all updates) to the letter. The Lyc 360 & Cont. 470 live in different universes, purely in terms of weight. Airframe choice pretty much dictates picking one or the other. #### Alessandre ##### Well-Known Member You're probably over-estimating the cost of the cylinders and a couple of other items (check other suppliers), but vastly underestimating some other costs and not accounting for many thousand$ in other needed items to build a complete, working engine. For instance, the magneto gears (not included with the mags) are hundreds of dollars each. You'd need connecting rods, of course. Nuts & bolts could easily run over a thousand $(rod bolts are big buck, single use items). And you're without doubt rolling the dice on an ebay crank and/or crankcase. I'd be shocked if you were lucky enough to build a reliable Lyc from collected parts for less than a mid-time 'runner' from someone you trust. Actually building one is relatively straightforward (it's basically a big VW Bug engine), except for all the little 'bite you in the butt' items you need to know that will only come from working with someone who's done it, or *very* careful research & following the overhaul manual (and all updates) to the letter. The Lyc 360 & Cont. 470 live in different universes, purely in terms of weight. Airframe choice pretty much dictates picking one or the other. This is the first estimate, providers usually don't show prices on the internet, to find out the actual prices I would need to make some phone calls, not yet. I'm going to seriously think about the next year or 2 years ahead, for now I'm deciding which direction to take. I'd stick with a timed out or half time Lyc 360. Lots of support and clone parts out there. The 470 is really old and a bit of a boat anchor. The 470 has more power but is a lot heavier. Yes, is almost 130 lb of difference, in this point the auto conversions and O-360 are almost similar. @Alessandre Depending on the plane you are building (I missed it, if you posted it earlier) there are a few auto based conversions which have a good track record. Tim, I'm doing my own project, is a 4 seats low wing all metal airplane, I have worked in this concept last 10 years and I started the build this year, I have the background of 20 years working in automotive industries how design engineer and worked for different car brands in a lot of projects, then I decided to take this adventure using the knowledge that I got in CAD/CAE for my own airplane. Someone can say I'm crazy, but the raptor designer was a TI guy and his airplane flew (not as well as predicted, but...), maybe I being an mechanical engineer I can humbly got a good result. #### TMann ##### Well-Known Member I had a IO-360-1C that I took off of a plane/project that had been sitting in a hangar for 11 years. It had 85 hours on it since it was rebuilt (very poorly.) Unbeknownst to me (at the time), at about 25 hrs a rod cap came off and the rod struck the crankshaft. The owner of the plane, at that time, contacted the rebuilder and told him what happened. The rebuilder came out, pulled the engine, fixed it and reinstalled it. In reality, he was covering his tracks. He took the crank to a auto machine shop and ground most of the damage to the journal out and replaced that bearing before bolting it up. My guys found the crack in the crankshaft as well a other wear/damage throughout the engine. They started with my core and added a new crank, pistons, machined the cylinders, new fuel pump, oil pump, mags etc. and it cost me around$17K for parts and labor.
Add to that their national reputation for quality work and you have a solid engine.

#### Arkan

##### Well-Known Member
Basic economics are at play here. Traditional Aviation engine manufacturers are limited to a small customer base in comparison to the automotive industry.

World wide, Anyone of the major auto manufacturers will produce more new cars in a day, than all of the small aircraft manufacturers together produce planes in a year.

Aviation is a limited customer base and restricts the Aviation industry as a whole. Research and Development comes slower, not only because the funds are limited, but because retooling costs of machining equipment could sink anyone of the larger aviation engine manufacturers if they made a drastic change in design.

Multi port fuel injection in the automotive industry has been around for decades, we are just beginning to see this innovation in Small craft aviation, and let's face it, the auto industry has already proven it is more efficient than carbs and manually adjusting the mixture.

I am new to Aviation, and by no means have the money to throw away on high operating costs. So I look at the auto conversion engines as an alternative to traditional engines, 10 to 15 thousand dollars for a new engine, and I am flying. Parts and repair costs are lower since most of my maintenance items are readily available at the local parts store or some online auto parts supplier if I want to wait a couple days.

Reliability of the PRSU's is my largest concern, they are the weak point in the conversion. I predict one day though, someone will engineer a PRSU that will either use a torque converter or some other means to lower engine RPM in cruise, lowering operating costs even further. (Just a personal thought).

I read recently Yamaha has entered into partnership with a Japanese Kit plane manufacturer to produce engines for their kit planes, and I think advancements will come from this partnership and you will see more partnerships develop like this with other auto/ motorcycle engine manufacturers.

Ultimately for my build, I have decided on an auto conversion engine and have researched which one I plan on buying based on cost and reliability. For now I will go back to my little design cave, and the "much I have to learn."

#### Alessandre

##### Well-Known Member
Reliability of the PRSU's is my largest concern, they are the weak point in the conversion. I predict one day though, someone will engineer a PRSU that will either use a torque converter or some other means to lower engine RPM in cruise, lowering operating costs even further. (Just a personal thought).
I think Rotax did it very well. The 9xx series are high RPM engines with no complains about reliability and very fuel efficient, light weight, but low power (max 150hp) and equal expensive. But they are the proof that PRSU can also work very well.

#### TFF

##### Well-Known Member
Best does have different definitions, but first best is reliability. Let’s make reliability a fixed point. All contenders need that to be the same footing. Complexity, efficiency, cost, weight are the floaters. Cost becomes almost fixed. You might be willing to pay a little more, but if costs strays from best average, you start thinking about value in it. That leaves weight and efficiency which is in essence complexity.

An all new design has to amortize out. If it’s someone talented in a shed doing their own thing building one, time and ideas are free. If it’s for sale in the wild, it has to be developed. If you are independently wealthy, and spent your days making twenty prototypes to get the design along, it’s a cheap test program. Pay people, tooling, buildings, subcontractors, minimum orders, raw materials, along with new ideas, and where is break even to a developed product? Break even to development is not break even to production. That’s where the Delta Hawks, Dyna Cams got stuck and where Rotax got it right. Mechanical things break, can you cover that and move on? That’s where better stops if it can’t get past that. Which means it’s not better.