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best 100 HP auto/motorcycle engine conversion?

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13brv3

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Joined
Feb 14, 2018
Messages
122
Location
Tellico Plains, TN
How much can a Onex take? A 912 is going to make it a rocket off the bat.
The Onex was originally intended for the 80HP Aerovee, but they also allowed the 100HP turbo version. They appear to support the UL350 which is up to 130HP. Sonex does support the 912 for some models, but they don't make a mount for the Onex. Prop diameter is a significant limitation.

I'd hope my 80HP 912 will be better than the average 80HP Aerovee, but it would be nice to have more power I bet.
 

stanislavz

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HBA Supporter
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Aug 21, 2016
Messages
738
Location
Lt
80HP Aerovee, but it would be nice to have more power I bet.
Buy used rotax, with good bottom end, and give him a new set of high compression pistons. 750usd i think. All else same, gives you 90-95hp.
 

120mm

Active Member
Joined
Oct 13, 2020
Messages
41
How does it look ? I have seen hill-climbing, it was kind of high tuned ones, and some do not survive..
Hours and hours of high load on rough surfaces at low speeds (mostly). I imagine the stresses are similar to WWI dogfighting.
 

AIRCAB

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Joined
Feb 6, 2015
Messages
89
Location
Vancouver Island
It sounds like a good deal if I needed the power. But I don't, and the AM13 appears more sorted. Still thinking a used O200 is a better deal, though I'm a sucker for an auto conversion
Have you ever had to buy certified aero engine parts ? You wont be happy !
 

120mm

Active Member
Joined
Oct 13, 2020
Messages
41
Have you ever had to buy certified aero engine parts ? You wont be happy !
I'm an A&P, so yeah.

Plus parts availability of that 1.3L engine is pretty amazing. Truly a global engine
 

sotaro

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Joined
Feb 26, 2011
Messages
141
Location
San Francisco
Yamaha Apex is about 170 lbs complete, with oil, radiator, exhaust, electric start, EFI gear reduction ready to run with more than 100 hp. Turbo versions are flying with much more power...The Yamaha Phaser is about 135 lbs same as above, ready to fly, 80 hp.

The Apex has about a dozen flying with cumulative (all examples) about less than a thousand hours in planes and trikes. Yamaha engines are flying, the RX-1, an older version of the Apex (both 4 cylinders), and the 3 cylinder version, mostly in trikes "With approximately 150 Yamahas out flying (as of 2019), some dating back 10 years now, we conservatively have 15,000 to 20,000 cumulative hours on Yamahas in the air, a number that is growing rapidly..." This was written July 2018 Facebook Groups The Phazer has a few flying with s few hours. Look on Facebook for more info
 

Mitchell

Member
Joined
Jan 1, 2019
Messages
17
Location
Shakopee MN
I’m putting a yamaha Apex in my project. I should have everything firewall foward done for about 10 grand. I looked at about everything before deciding to go with the Apex. The big reasons that stood out to me was the base engine is as bulletproof as they get in the snowmobile world. I also personally prefer yamaha engines over anything BRP makes including the 912. I wanted efi, liquid cooled “I live in Minnesota and want a good heater”, and light weight. I oversized the engine mount quite a bit but should still have a flying engine for under 180lbs installed. I also really liked how I could throttle back to still make that 100hp. Vs. a lot of the other options which make 100hp max
 

rv7charlie

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Joined
Nov 17, 2014
Messages
997
Location
Jackson
The Onex was originally intended for the 80HP Aerovee, but they also allowed the 100HP turbo version. They appear to support the UL350 which is up to 130HP. Sonex does support the 912 for some models, but they don't make a mount for the Onex. Prop diameter is a significant limitation.

I'd hope my 80HP 912 will be better than the average 80HP Aerovee, but it would be nice to have more power I bet.
Aren't you going to have the same prop dia issues with the 80hp 912?
 

sotaro

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Joined
Feb 26, 2011
Messages
141
Location
San Francisco
I’m putting a yamaha Apex in my project. I should have everything firewall foward done for about 10 grand. I looked at about everything before deciding to go with the Apex. The big reasons that stood out to me was the base engine is as bulletproof as they get in the snowmobile world. I also personally prefer yamaha engines over anything BRP makes including the 912. I wanted efi, liquid cooled “I live in Minnesota and want a good heater”, and light weight. I oversized the engine mount quite a bit but should still have a flying engine for under 180lbs installed. I also really liked how I could throttle back to still make that 100hp. Vs. a lot of the other options which make 100hp max
Would love to see your build blog when you can.
 

Iwerk

Active Member
Joined
Aug 27, 2014
Messages
28
Location
Irricana
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.
Honda VFR750F Engine.jpg
 

slociviccoupe

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Joined
Apr 1, 2011
Messages
314
Location
Palm Bay Fl.
All the guys screaming rx-1 please check and or replace the rod bolts. If they share same rods as the mr-1, or the r1 engine they like to sling rods from failed rod bolts. Yes i know there are many flying with no issues but you dont want to be the one that does. Ive seen engines go 2500 hours in a ski and ive seen one go at 100 hours. Ive never personally had one fail on me but have worked on enough of them that its worth rolling it over and checking torque or just replacing the bolts.
 

AIRCAB

Well-Known Member
Joined
Feb 6, 2015
Messages
89
Location
Vancouver Island
I'm an A&P, so yeah.

Plus parts availability of that 1.3L engine is pretty amazing. Truly a global engine
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.
 
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