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best 100 HP auto/motorcycle engine conversion?

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TFF

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An A&P has to make a judgement call. Unluckily an A&P is held to two masters. The FAA and the customer. One can take your livelihood while the other hurts you by not using you. The FAA is much more scary. No lawyer would ever sign what A&Ps do. Depending on what it is and the time it might be seen again, the A&P decides if it needs to go or not. I can tell you that if you fly a lot, the parts get to last longer because they get checked more. A&Ps are “ parts changers “ by regulation. Considered unskilled labor by the tax system. Don’t confuse what an A&P is; the rules of the system are the rules of the system. It’s not a boat.
 

Traskel

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Oct 3, 2020
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Maybe my research is not up to par, but I'm not seeing the tremendous value in the Yamaha. Starting with a used engine, I'm seeing parts costs north of 10k for a conversion, or 20k for a ready to run engine. This might make sense if you need 150+ horsepower, but the Aeromomentum comes ready to run at 10k and it's a new engine.
I agree with you - the Aermomentum engines "seem" like the best aero engines currently offered based on power to weight, BSFC, TBO, cost, and rebuild cost,, especially at the upper end of their line.
 

pfarber

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Feb 21, 2019
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Well in my direct experience, A+P mechanics do not buy parts, they are basically parts changers, condemning good, service parts to the scrap bin, then the customer has to buy the parts, mostly.
A&Ps really don't have much authority in FAA land. Given a part, an A&P must have specific authorization to complete the 8313-3. So basically any sort of repair needs to go to a shop with proper certifications to generate a 'this is fixed' paper.

A&Ps can remove/install things, but are very light on the 'fixing' part.

All this really does is add to the cost.
 

120mm

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Oct 13, 2020
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46
Ever regret making a comment on a forum? FYI, I've also owned a couple cubs and a Tri-Pacer, so I know what certified parts cost. This, combined with my experimental spirit is why I'm even looking at auto/cycle conversion engines. Even though an O-200 is the "easy button" for my LSA plans.

But of course, everyone is welcome to continue pole vaulting over mouse turds to their hearts' content.

BTW, a C-17 crash landed at work a couple weeks ago, and in the process of making it flyable, they shipped in new tires, which cost $16,650 each, according to the bar code on them.
 

BJC

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Oct 7, 2013
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97FL, Florida, USA
Ever regret making a comment on a forum?
I’ve been advised, on occasion, that I should.
pole vaulting over mouse turds
New one. Thanks.
BTW, a C-17 crash landed at work a couple weeks ago, and in the process of making it flyable, they shipped in new tires, which cost $16,650 each, according to the bar code on them.
”Your tax dollars at work.”


BJC
 

TFF

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Apr 28, 2010
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Memphis, TN
Fixing is all about liability. People sue you. People with airplanes have lawyers. The parts are expensive because they are sold with the lawsuit payed for. Go to a bearing store and order a bearing. When they make small chat and ask what it’s for, I dare you to say airplane. They will push you out the door like a panhandler. They don’t care what f it’s for a homebuilt. They know that bearing does not have that lawsuit tax on it and are not going to chance it.

Labor rates are lower than car dealerships. The difference is most car places do flag hours. Preset hours. For a mechanic at a dealership to make money, he has to beat the hours. Airplane you pay for what it takes. If it takes 20 hours to fix, you pay for the 20 hours. Some planes are not worth that.

Unless you find someone that you will buddy up to, a regular mechanic with a job doing ok does not want to spoil that to fix your C150 for $100 and you still complain. It’s not that the mechanic doesn’t want to help, they analyze if you are a bottom feeder and act like one or if you go all snooty like you own a king air. It’s usually the person that’s the problem not the plane.
 

Geraldc

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Nov 12, 2011
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448
Location
nz
Go to a bearing store and order a bearing. When they make small chat and ask what it’s for, I dare you to say airplane.
Most people think that anything that goes in an Airplane has to be certified.
When I was looking for a motor I told them it was for a jet boat.
 

TFF

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I have plenty of stories. I started flipping my shirt inside out if I was wearing a tee shirt to look like a fool with his shirt backwards. I went in to buy bearings for a model airplane engine and they almost said no seeing my work shirt. It’s not the guy in the store per say. They were trained for that possibly from up high.

I also have a aquatint that is specialized in aviation law. Top five in the country. He is mostly retired, but he worked either side of some of the biggest aviation cases. Winning side of the radiated dial instruments for one. I know from the stories I don’t want to get involved. Bad day if you are on the other side of him.
 

slociviccoupe

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Apr 1, 2011
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356
Location
Palm Bay Fl.
Yeah never say airplane. Say for airboat. Garrett, tial, and few others prety much refuse to answer emails anymore as soon as experimental aircraft is mentioned.
 

Erik Snyman

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Oct 9, 2019
Messages
74
I know the Yamaha guys or not going to like this, but.......Caviat: I fly GA, but has anyone tried the K series BMW motors? I have a R-series BMW bike, but the K-series engines seem to be going on and on and on...
 

pictsidhe

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Jul 15, 2014
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North Carolina
I know the Yamaha guys or not going to like this, but.......Caviat: I fly GA, but has anyone tried the K series BMW motors? I have a R-series BMW bike, but the K-series engines seem to be going on and on and on...
I believe there have been a few conversions of the triple. They are good, solid engines.
 

Air Trikes

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Dec 21, 2015
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60
Location
Montreal Canada
I know the Yamaha guys or not going to like this, but.......Caviat: I fly GA, but has anyone tried the K series BMW motors? I have a R-series BMW bike, but the K-series engines seem to be going on and on and on...
SPG-4 gearbox installed on one of K-series BMW
 

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Steve C

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Oct 6, 2008
Messages
160
Location
Lodi, CA
I purchased a pair of Honda 750VFR engines a few years ago. They use gear driven dual overhead cams.
I had thought about installing them in either a hovercraft or one of my aircraft projects.
I love motorcycle engines, but connecting them to a propeller seems difficult. Plus theres the extra weight of the transmission. I did see a pic once of a pusher that had a cbr 1000 in it and he used the chain drive.
 

5728950

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Apr 23, 2019
Messages
5
What's the best engine to start with? I don't have an immediate need for this, but I thought it might make an interesting discussion.
HONDA L 15 , SUZUKI 1600 cc . gearbox price 1000- 1300 $

PS
5728950@gmail.com does not work, removed passwor
 

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karmarepair

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Jan 13, 2011
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304
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United States
Greetings,

I've recently been looking at the BMW R1200 conversion. Air Trikes sells a nice gearbox for it, and the engine has a great reputation for reliability. I love the thought of fuel injection rather than carbs, and it would be a fun project to create the engine management system. The engine is really compact, which would make it easier to fit in the cowl as well. The downside I fear would be smoothness, since two big cylinders likely wouldn't be as smooth as 4 smaller ones. As nice as they seem on paper, they sure don't seem very popular here in the US. Is anyone actually running one?

In looking at the Air Trikes site, I see that they sell gearboxes for lots of different engines, but I haven't had a chance to sort through all the various models to figure out what is a good 100 HP option. If you wanted to make a 100 HP alternative to the 912S, using a modern engine. What's the best engine to start with? I don't have an immediate need for this, but I thought it might make an interesting discussion.

Rusty
Corvair. More thrust for less weight and cost than an O-200. William Wynne has the instrumented results to prove it. Not particularly modern though.
 

Daleandee

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Sep 11, 2015
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SC
Corvair. More thrust for less weight and cost than an O-200. William Wynne has the instrumented results to prove it. Not particularly modern though.
3.0/120 HP Corvair works very well on my plane. Smooth, reliable, easy to service, readily available parts,
& a lot of support.

Not for everyone but for a few it’s a great alternative.

FWIW
 

Vigilant1

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Jan 24, 2011
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US
Corvair. More thrust for less weight and cost than an O-200. William Wynne has the instrumented results to prove it. Not particularly modern though.
William Wynne says here that:
Although the Corvair and the O-200 effectively weigh the same, you can’t get the O-200’s CG nearly as close to the firewall.


He also says some O-200s are lighter than some Corvairs, and that a Corvair could be built to be lighter than the lightest O-200.

Installed engine weights seem to be very squishy numbers for some reason.
 
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