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Harley-Powered?

xl1200r

Member
Okay, so I got turned on by an idea i heard in another thread.

For those that don't know, there's a company called HogAir that modifies Harley-Davidson v-twins for small airplane service. The only problem is they the highest HP rating is 108hp with a 95CID engine.

Has anyone heard of, or used themselves, these engines? 95CID is no where near the limit of displacement for a new HD Big Twin. There's an engine builder in Colorado (NRHS) who sells kits up to 127CID. I've sent an e-mail to them asking how much HP you get get out of a STONE DEAD RELIABLE setup - nothing outrageous.

Also, with weight savings around 100lbs versus a Lycoming, how much less horsepower would be acceptable to run (i.e., if one was planning on using a 180hp Lyc, would a 150hp engine that weighed 100lbs less be comprable?)

I'm a total newbie to anything about this, so if i'm being retarded just let me know. I'm not usually a fan of using non-aircraft engines in and airplane, but this just sounds like a readlly cool concept.
 
That's not a valid option for most of us due to CG. We'd have to add the weight back to the front. Might work in the 12 though.

I've seen pictures of a bike with a radial engine, so anything is possible.
 
Interesting idea!! I hear HD parts are readily available... all up and down the road side.
 
Paul Thomas said:
That's not a valid option for most of us due to CG. We'd have to add the weight back to the front. Might work in the 12 though.

I've seen pictures of a bike with a radial engine, so anything is possible.

I actually though of that after my post. At first glance it seemed cool since most everyone on here says they want a lighter, more powerful engine option. I guess that's just too light.

And why does everyone on this forum feel like HD engines haven't changed since 1913 and fall apart all over the side of the road? I'll have to watch what I say on here...
 
xl1200r said:
I actually though of that after my post. At first glance it seemed cool since most everyone on here says they want a lighter, more powerful engine option. I guess that's just too light.

And why does everyone on this forum feel like HD engines haven't changed since 1913 and fall apart all over the side of the road? I'll have to watch what I say on here...
Because most of us base our opinions on some measure of truth. The truth is the Harley engines and the Lycoming engines, actually every internal combustion engine, have changed very little since they were originally developed. There have been a few minor tweaks with secondary components but for the most part IC engines have changed very little since they were first developed.

Now as far as the statement about finding parts all over the road, well, I have no first hand experience with Harleys per se but I do know that since the design is set up to specifically run inefficiently so that it can have that distinctive "Harley sound", I for one wouldn't want to have it shaking my plane to pieces just so I can say "Yeah but doesn't it sound sweeeeet!"
 
xl1200r said:
I actually though of that after my post. At first glance it seemed cool since most everyone on here says they want a lighter, more powerful engine option. I guess that's just too light.

And why does everyone on this forum feel like HD engines haven't changed since 1913 and fall apart all over the side of the road? I'll have to watch what I say on here...
The ;) means it was a joke. HD's are nice bikes. If I was given one, I'd be very grateful. Just probably would not buy one for myself. 1/4 the money for a HD knockoff rice-burner Virago with "immitation HD sound" worked OK for me. ;) ;)
 
Having owned three Harley's over the years and having spent many hours either standing beside my broken down pride and joy waiting for a tow truck or pushing it down the road. there is no way in **** I'd trust my precious butt to one in anything I fly. Now I realize the newer stuff is much better, but.... Nuff said?
 
A reminder from one of the moderators...

Let's all take a deep breath, exhale and think before we post. I don't see any objectionable posts in this thread yet, but I must remind you this is an RV forum, not a motorcycle forum. I like to ride cycles, too, but let's not get into a "which motorcycle is better" discussion. I see the potential for this thread to veer off the RV path. Nuf said?
If in doubt... read the rules. Doug has the link in the middle of the first page of the forums.
Thanks and keep on posting...about RV stuff. :)
Don
 
rv7boy said:
Let's all take a deep breath, exhale and think before we post. I don't see any objectionable posts in this thread yet, but I must remind you this is an RV forum, not a motorcycle forum. I like to ride cycles, too, but let's not get into a "which motorcycle is better" discussion. I see the potential for this thread to veer off the RV path. Nuf said?
If in doubt... read the rules. Doug has the link in the middle of the first page of the forums.
Thanks and keep on posting...about RV stuff. :)
Don
Don -

Respectfully (so please don't ban me or anything), I see nothing inflammatory. A little very light-weight smack and some discussion about use of an alternative engine choice. This discussion about using an HD engine on an RV, how reliable or not they are, *is* alternative RV engine discussion.
 
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rv7boy said:
Let's all take a deep breath, exhale and think before we post. I don't see any objectionable posts in this thread yet, but I must remind you this is an RV forum, not a motorcycle forum. I like to ride cycles, too, but let's not get into a "which motorcycle is better" discussion. I see the potential for this thread to veer off the RV path. Nuf said?
If in doubt... read the rules. Doug has the link in the middle of the first page of the forums.
Thanks and keep on posting...about RV stuff. :)
Don

I think this came from another post on RV12 alternative engines. http://www.hog-air.com/hogindex.htm

This company is providing Harley aero engine conversions for other LSA type airframes at the moment and it may be applicable to the RV12. I am always interested in others experiences with powerplants- especially from a reliability standpoint. Yes, threads drift a bit but the other motorcycle thread is far less RV related in my view.
 
HD engines aren't really inefficient by design in order to get "that sound". While in some applications, the 45* common crankpin v-twin is less than optimal, there are advantages to be found. For instance, a common crank v-twin in a 45* config will make more tourque than one of the same internal dimensions in a 60* or 90* configuration.

As for the reliability, there have been quite a few trouble free miles on modern HD twins. Now, AMF days are not included with this obviously, and anything before 1968 can hardley be called reliable. Not to say that other engines aren't equally (dare I say more? Nope.....) reliable, I wouldn't think twice about putting one in an airplane provided proof that the engine would tolerate that kind of use (abuse), as I would with any non-aircraft engine.

Actaully, come to think of it - I wonder how the Honda flat-6 that's used in the Goldwings and Valkyries might far for RV duty???
 
xl1200r said:
Actaully, come to think of it - I wonder how the Honda flat-6 that's used in the Goldwings and Valkyries might far for RV duty???
I think these would work very well if the weight were not too much of a problem to overcome. I would be curious about what the weight is for those engines.
 
RVbySDI said:
I think these would work very well if the weight were not too much of a problem to overcome. I would be curious about what the weight is for those engines.

I'm having a hard time finding weight figures. The best I can find is the 1800 is 1kg lighter than the 1500. There are some issues though - they are a six, which means less room for a redrive - is this a problem with the Egg H6 mills? They also only make 118hp. That leaves a lot to be desired for RV apps, though I'm not sure the how the aftermarket is for these engines either.
 
xl1200r said:
There are some issues though - they are a six, which means less room for a redrive - is this a problem with the Egg H6 mills?
The Subaru engine is a boxer instead of straight six so they are going to be more compact than these engines.
 
While I realise that this is a little off-topic, there are some points regarding H-D power that I wish to make. Harley engines are not 'designed' to be inefficient - they are designed to chug along without using a lot of revs, just like any big ol' Lycoming.

Work out the hp per cubic inch - the Harley TC88 puts out around 40 hp per 44 ci cylinder, the Lyc O-320 puts out 40 hp per 40 ci cylinder. The Harley revs more to make the power though.
An interesting aspect of the H-D bottom end is the knife and fork con-rod set up, similar to the RR Merlin V-12, and allows the cylinders to be set inline with each other, rather than offset like the Lycoming. This reduces the 'rocking couple' - a cause of secondary vibration. The 45 degree layout ensures the mill vibrates regardless.

The bottom line is that the H-D engine will shake all your rivets loose anyway, though it could be mounted like in the Buell, but I just don't think the engine will take to running hard like it would have to in the aviation environment.

Martin
 
RVbySDI said:
The Subaru engine is a boxer instead of straight six so they are going to be more compact than these engines.

The Goldwing is an H6 as well. I don't know of any Inline-6 engine in a bike - there's just no room for it.
 
Red Voodoo said:
"I don't know of any Inline-6 engine in a bike - there's just no room for it."

Depends on how you orient the mill. Gone but not forgotten:

http://www.motorcycle-usa.com/Article_Page.aspx?ArticleID=822&Page=1

http://www.motorcyclespecs.co.za/model/kawasaki/kawasaki_z1300 84.htm

I stand corrected:
Honda%20CBX%20portrait%20-%205b.jpg


Though I think we can all admit that was about as much overkill as trying to get a Chevy 725hp 572cid crate strapped to the front of a -3 ;)
 
xl1200r said:
Okay, so I got turned on by an idea i heard in another thread.

For those that don't know, there's a company called HogAir that modifies Harley-Davidson v-twins for small airplane service. The only problem is they the highest HP rating is 108hp with a 95CID engine.

Also, with weight savings around 100lbs versus a Lycoming, how much less horsepower would be acceptable to run (i.e., if one was planning on using a 180hp Lyc, would a 150hp engine that weighed 100lbs less be comprable?)

I'm a total newbie to anything about this, so if i'm being retarded just let me know. I'm not usually a fan of using non-aircraft engines in and airplane, but this just sounds like a readlly cool concept.

Ok...you asked so I'll just blurt it out.

You're being retarded :) There, can we stop this ridiculous thread about using a 2 cyl Hog engine in an place of a 180 lyc?!?!

Sorry for being blunt, but it's kind of a waste of time to even discuss it. Not wanting to burst your bubble, just trying to keep you from wasting much more time on it! Alterntives are fine....but this one....well, it's crazy for this application. I'm afraid even a hog with lipstick won't do!

Cheers,
Stein
 
Not really.

RVbySDI said:
I do know that since the design is set up to specifically run inefficiently so that it can have that distinctive "Harley sound

Not really. The reason Harleys sound so good is that both pistons run on the same crank pin, causing them to fire 90 degrees apart instead of 180 degrees. The reason it was designed that way (about 90 years ago -- before anybody cared how they sounded), and the reason for the whole V-twin arrangement, was to create a narrow bike that's easy to straddle. The great sound was a side effect. And by the way, it's not inefficient if you're after low-end torque. But you're sorta right -- they couldn't change the design now if they wanted to. Nothing else would be a Harley. If I you want smooth, quiet, safe, and reliable -- buy a Miata.

All that said, I wouldn't fly behind a Harley engine on a bet. I owned one particular '76 Ironhead Sport for over 20 years and, although it only left me at the side of the road once (broken clutch cable), I probably spent about an hour working on it for every 5 I rode it. I loved every minute of it and I'm in the process of rebuilding a '74 now. But there's a big difference between the level of reliability I'll accept 22 inches off the ground vs. 2200 feet.
 
SteinAir said:
Ok...you asked so I'll just blurt it out.

You're being retarded :) There, can we stop this ridiculous thread about using a 2 cyl Hog engine in an place of a 180 lyc?!?!

Sorry for being blunt, but it's kind of a waste of time to even discuss it. Not wanting to burst your bubble, just trying to keep you from wasting much more time on it! Alterntives are fine....but this one....well, it's crazy for this application. I'm afraid even a hog with lipstick won't do!

Cheers,
Stein

The bluntness is appreciated, but the logic in the beginning was looking to see if it was reasonable to deal with less hp if it meant losing a lot of weight with it.

BTW - I heard back from the build shop, and they told me that 124CID Twin Cam would be able to put out 160-200hp, but it would be a rather extreme engine and it would be at the top of the rev range. Anyways, the weight is just TOO light for it to matter anyways.
 
Mike S - you are right. I knew it didn't sound right, and realise I substituted 160 hp for 320 cubes. Yes, the ol' O-320 puts out approx 40 hp for each of its 80 cubic inches, or about half of what a Harley cylinder produces.
My experience with big capacity Harleys ( 124 ci) is that they are great for posing, but are not long-lived, and certainly not for any serious aviation work.

Oh, and there is a few other bikes that had 6 cylinders : Factory Honda racer as ridden by Mike Hailwood and a Benelli roadbike to name two inline layouts, then there is the Laverda V6 and the Guzzi V8, as well as Glenn Curtis's V8 racer.

Forget the idea of using a Harley engine in anything more than an LSA, but has anyone considered the 9-cylinder Rotec radial with 150 hp in say - an RV4 ?

Cheers

Martin
 
Harvey said:
Forget the idea of using a Harley engine in anything more than an LSA, but has anyone considered the 9-cylinder Rotec radial with 150 hp in say - an RV4 ?

Cheers

Martin

Umm...pleae post a link or a photo or something...sounds interesting.

Edit: I found it. Looks very cool. They're guessing 150+HP with that, but haven't tested it yet. Looks to use a reduction unit as well...i wonder where the revs are. 150hp and 270lbs...not to shabby. Big cool factor with that one!

R3600Large.jpg
 
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KTM520guy said:
A radial would be extremely cool.

:)
Yes they are cool but I just have a hard time thinking about all of that oil oozing out of them onto the floor of my hangar. If they can just figure out how to keep the oil in the cylinders where it can do some good.
 
Back in my younger days I worked as a mechanic at a Honda dealer and had the oportunity to build a few of those from the crate and test ride before delivery. Talk about a smooth machine!

-Jeff

xl1200r said:
I stand corrected:
Honda%20CBX%20portrait%20-%205b.jpg


Though I think we can all admit that was about as much overkill as trying to get a Chevy 725hp 572cid crate strapped to the front of a -3 ;)
 
RVbySDI said:
Yes they are cool but I just have a hard time thinking about all of that oil oozing out of them onto the floor of my hangar. If they can just figure out how to keep the oil in the cylinders where it can do some good.

Radials don't leak oil, they mark their territory. :D
 
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