LYC 4AO84 ??

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mogren

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Jul 18, 2003
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Has anyone used this 4AO84 in an aircraft?? it seems to be about 40hp or more .. Where might I find some specs, weights,etc, parts ??
Thanks. MM
 

mogren

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Jul 18, 2003
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Is there a site with specs Or someone flying this critter??
I cant get that link to go. MM
 

wassbiplane

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Apr 1, 2003
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Location
Oklahoma
84 in3 engine

Well I dunno what happened to 1st reply, mebby it'll show up--here's smaller pic.

Jerry
 

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wassbiplane

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Apr 1, 2003
Messages
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Location
Oklahoma
84 in3 engine

Dear Mogren

The article you should read is in the August-Kitplanes issue, pg-21.
The mans name ,Address & phone # are there.

If you're not subscribing to Sport Aviation--
( it comes with EAA membership), a sister
publicatiuon The Experimenter-- and Kitplanes

YOU SHOULD BE !!

You would save yourself and others a lot of time.

Jerry
 

mogren

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Jul 18, 2003
Messages
43
!!!

Thanks, W-ASSBiplane I have not found a Kitplanes on the shelves here in redneck FL. I did call a friend and found the name and number for the gent that put it in a flying critter.
I still dont have a weight. I have a target weight of 85# or less for my ultralight/floats. I need a large prop to jack it off of the water and it seems that the 84 cid will pull a 54-56in prop. That should be near 45-55 hp at MSL and plenty for my needs. I like it a lot better than the 1/2VW, having built and raced those for a while.
Im sure the .5- VW is 80#+- and might work also. @ 35hp
I will get KP sent to me so as not to bother you in the future !!!
):> MM
 

Cy V

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Jul 1, 2008
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Location
Virginia
I'm bumping this old thread to see if more people have info on this engine.
 

Dan Thomas

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Sep 17, 2008
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5,230
The surplus info says it's a Teledyne engine. Teledyne owns Continental, not Lycoming. What's with that? And it's an 84 cubic inch engine; the Cont A-65 is about 170 cubes, twice the size, and produces 65 hp at 2350 RPM. You have to run the surplus engine at very high RPM to get much power out of it.

I'm wondering about that 20 hp "USG" rating. Is that a different scale than the hp scale we use? (33,000 ft-lb/minute). 20 hp sounds rather anemic for that many cubes, at 3600 RPM.

Dan
 

bmcj

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Fresno, California
The surplus info says it's a Teledyne engine. Teledyne owns Continental, not Lycoming. What's with that? And it's an 84 cubic inch engine; the Cont A-65 is about 170 cubes, twice the size, and produces 65 hp at 2350 RPM. You have to run the surplus engine at very high RPM to get much power out of it.

I'm wondering about that 20 hp "USG" rating. Is that a different scale than the hp scale we use? (33,000 ft-lb/minute). 20 hp sounds rather anemic for that many cubes, at 3600 RPM.

Dan
And did you catch that those 20 hp were put out by a 265 lb engine?

Bruce :)
 

Dan Thomas

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And did you catch that those 20 hp were put out by a 265 lb engine?

Bruce :)
Yeah. And it amounts to less than 1/4 hp per cubic inch, at a high rpm. Something's wrong, there. That engine should be capable of more than 1/2 hp per cube at that RPM.

Dan
 

bmcj

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challenger_II

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Location
Fisher County, Tx. USA
I stumbled across this thread by accident, and, now, ya'll have caused me to enroll in another discussion group!!! :p

Ok, regarding the Military Standard 4AO-84 engine, it is rated at 20hp, by the U.S. Government (that 10,000ft item, as mentioned earlier), 35 hp Factory, at 3600 rpm. As it comes out of the crate, she's a heavy beastie, and, with some minor unbolting of unnecessary items, drops to 145#, with oil.
I have set up, and flown, several of these engines, and, in the stock configuration, it will turn a 54x26 Tennessee prop at 3150-3200 rpm (resultes differ, with different engines). This is the same prop a Rotax 377 with a 2.2:1 drive turns at essentially the same revs. This pretty well dictates that the engine is making 30 hp, at this rpm.
Turning the engine up, to make more ponies, isn't recommended above 3600 rpm, as you will generate a lot of heat the heads can not dissipate. The same is true, for loading the engine up with a prop to less than 2800 rpm.

There have been some interesting claims for some interesting hp outputs, but the only mods I have seen to be of any use are electronic ignition, and fuel injection. One fellow experimenter did a LOT of extensive work to set an engine up with these, and dyno'ed the engine at 50 hp. But, it did add a good bit of complexity to the FWF.

Hope this helps.
 

TreeTopPilot

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Aug 8, 2011
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Location
Eastern US...for now
OK...new here...just really wanting to see if anyone has been seccesful with these. I am looking at purchasing one with "0" hours....NIB manu date in 1999. Have plans to attach it to the front of a N3 Pup. I think this engine has a great sound and can be made quite...and if it will make 45HP with a SU HS-4 carb I will be one happy camper. Also noticed one guy removed the 11 ld. cast oil pan and fabbed one up out of .080" T-6 and lost 9 lds.! Please help me here as I am not so certain this is a good idea as of now...just terribly enamored with that little engine. I am sure it would be very safe and reliable with a little safety wire and some TLC before the install. Thoughts/Ideas? Thanks in advance
 

TreeTopPilot

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Aug 8, 2011
Messages
14
Location
Eastern US...for now
OK I have secured an engine. Now that some research has been done...I really think this is going to work out well. I plan to make a lighter oil pan assembly, replace the rotator retainers on the valve springs with titanium units, Tig up a nice , light stainless 4 into 1 exhaust, and replace some of the fasteners with safety wire being applied as needed. Now that the nasty state of affairs with perceptor aircraft have surfaced......now what airframe do I consider building? Really liked the design except the ribs and lift strut to fuse attatch point location. Guess I will order a prop tonight and contemplate a test stand being needed soon. Maybe time to finally finish my 3/4 Champ drawings. I also plan to make J-3 style eyebrows for cylinder cooling...and employ a quad CHT guage on the panel if I don't run it in a pressure cowling. Wish I could get my paws on a set of N3 plans.....

I have read all the posts mentioned above...seen a ton of airboats on youtube.....and one flying vid. So I take it that there is nothing being done to the thrust bearing the way it is? No one porting the heads a bit to clean the flash up? I may have a good thing going here....tube engine mount in the works with Lord type mounts. This should be a good project and I will document as things are built....like to be able to replicate parts if needed. Even seen a 2 cylinder flying pretty well!
 
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