AK 670 Powered Kitfox on Barnstormers

[EDMO 1078]

Please don't quote this to the FAA or your IA: Experimentals don't come under the same rules as certified - A certified would probably require you to buy an STC, or if in Alaska, and NOT in Missouri, you might get a field approval for a certified mod. AND, it would require a form 337 signed by an IA and approved by the FAA.

The best rule I have ever heard is: "It never happened if you don't report it". !!!!

You will need to do new W&B for your bird, but you can do that anytime you want to without any major changes - You don't need an IA at all - Just an A&P for conditional inspections every 12 months. And, you can remove wings, repair fabric, other maintenance, repair, rebuild, recover...etc.

ED

After thinking for a while - which is difficult at my age - I believe the newer operating limitations allow you to make a logbook entry for a major change, but you may have to put it back into Phase I for at least 5 hours.

I'm sure someone knows about this.

EDMO

[Mendlerr 4]

Just thought I would update this thread with some information I found.

Rotax Rick now has the Rotax 670 "Blue Head Edition". 97hp for takeoff, 70hp roughly for cruise and 5gph fuel burn. Price is the same or just slightly higher then the original 670

Trade in your 582 and the 670 is $3,400 with all new parts and an addition $700 or so for the tuned exhaust for the kitfox

Edited 12 Aug 2013 by RMendler

[lv2plyguitar 172]

Does the c drive bolt onto that engine?

[Mendlerr 4]

Of Course!

 

The 670 is almost identical to the 582, other then it is 1/4" Taller.  The early model 670's were all predrilled for the Rotax "C" and "E" Gearboxes.  I think Rotax Rick machines his cases out though, he does a lot of custom work to these engines.  They are not your run of the mill 670.  I know he machines out the bearing races and goes to a larger "caged" bearing as found in a more modern engine.  This supposedly improves the reliability over the "standard" 670

Edited 13 Aug 2013 by RMendler

[lv2plyguitar 172]

So I am assuming it has the dual ignition.  Sounds pretty good.  How is the power band.  Is it steady throughout or does it suddenly produce power at certain rpm's.

 

Thanks

[Mendlerr 4]

yes it uses the 582 dual ignition head.  you do not have to change anything electrical, everything 582 works with the 670.

 

from what I have been "told" if you use Rotax Ricks exhaust then the powerband is smooth, designed for your aircraft respectively and he has a lot of avidfox experience..  If you use a 582 exhaust then the powerband is very smooth but the engine only makes about 66hp, not really any gain over a 582.  If you make your own exhaust you can make power in the 105hp range but the powerband is going to be snappy like a dirtbike or high strung snowmobile and the engine life is greatly reduced.

 

With his Kitfox/Avid exhaust you can make a minimum of 87hp, 97hp on the new version apparently.  The engine TBO is 450 hours.  Total overhaul cost is $1,175.  Fuel burn is between 4.5-5GPH in Cruise, upwards of 6.5-7GPH on takeoff.  Still better savings then the 582, well my 582 anyway.  My last email conversation he explained the rods and pistons he uses are not run of the mill cast pistons, they are supposedly much nicer, like a high end racing set.

Edited 13 Aug 2013 by RMendler

[C5Engineer 1170]

I've been watching this thread closely http://ppcflyingforums.com/forums/showthread.php?t=9503

[Mendlerr 4]

Good find ther C5Engineer. Seems he is very happy. Only time will tell how it works for him though. If I had the money I would probably do it right now.

[lv2plyguitar 172]

I will be ordering soon.  Cant have to much power in Alaska.

[akflyer 1427]

Jeff,

 

I would be thinking about the power valves and the upside down engine install!!  That is why I am mounting mine right side up.  I think Bob has one of his 670's that he was not going to use, you may be able to get it from him or work out some sort of swap for the 582 and some $.  Worth talking to him anyways. 

 

In any case, I would REALLY think lang and hard before putting a power valve engine in Avid inverted.  Your talking about ALOT of mods to get that exhaust in the cowling too.

 

The best performance upgrade you can do right now is to put gas in the tanks and REALLY learn your airplane and the different techniques to get you in and OUT of those small places.

 

[lv2plyguitar 172]

Your ruining my day Leni but you are probably right. 

[akflyer 1427]

I didn't mean to ruin your day, and it may very well work out, however, based on the experience I have with RAVE in snowmachines, I would be hesitant to install them inverted.  If you do install one inverted, your looking at having to pull and clean the valves probly every 5-10 hrs to assure smooth operation of them.  I thought of 100 ways to modify the housing for the "power Vales" (the arctic cat equivalent) and each one led me down the path that it would be better to just install the engine upright and not have to worry about them.

 

I would bet that the new engine mount I come up with for the Avid to mount my 800 upright, will work just fine with the 670 also, so then it is a matter of exhaust.  There are lots of guys using this engine in the Rans S-9 and a quick search will come up with some do's and don'ts that they have found to work.

 

As far as wiring the valves shut, well you just gave away your low end grunt to get that prop swinging, or you gave away the power on the top end to take that pitch load at climb and cruise.  Some of the 670's opened up at 4500 some at 6500 depending on the spring installed in the RAVE valve.  A lot depended on the application for normal riding or for drag racing.   I am the last person to tell anyone to NOT use try or modify and engine to try and get better performance, I am doing that very thing myself however, I am just saying to think it through, do some research, and talk to the guys that have been FLYING this engine.  Don't take and engine builders word that his engine is the best thing since sliced bread... We have seen dozens of these claims and dozens of guys close up and fade away as the latest greatest engines failed and planes were destroyed and people were killed.

 

http://www.bwid.net/S9/670.htm   This guy has been running his on an S-9 (I want one bad) and went through the trials and errors to get the 670 to stay running and not melt down.. As you can see in his post, one of the fellows he knew took that final flight West due to a failure of the 670. 

 

In defense... I know a lot of people have died flying behind a 582, AND the rotax 912 (for you two smoke haters)   No engine is impervious to failure.  I have had my 582 fail on me, but it was due to something besides the engine (faulty thermostat and radiator cap) as well as the placement of the radiator.  It is not the engines fault that we do something stupid and melt down the engine.  I have had failures with Lycoming engines that were more likely to kill me, and it hurt a lot worse when I hit the dirt with that plane versus my Avid.

 

I would love to see the 670 perform in the Avid as I think it would be a very nice flying plane, but I would not just bolt one on and go, hoping for the best.

 

[Johnnyboy 0]

 I am installing a 670 in an Avid Mark IV that previously had a 582. The 670 was acquired from Rotax Ron. The problem I have encountered is mounting the supplied exhaust. It is an elongated muffler that does not fit beneath the engine as the 582 round exhaust did. I have tried several ways to mount it but ultimately the pipe hits the cowling on the left side and the muffler is to close to the firewall and/or cowling at the bottom. This is an inverted engine mounting. Has anyone installed a 670 in an Avid Mark IV? Any help would be appreciated. My phone is 509 793 6043. As it is now, the cowling would have to be modified to allow the muffler to hang below the engine, and even at that it would be protruding out.

[C5Engineer 1170]

I think I have some pictures of a 670 install at home on my computer that Larry sent me. I'll check tonight. Looking your area code what part of WA are you in?

[tbucket 2]

Ed, I got a picture a couple days ago of the almost completed adapter plate for the 800. As soon as Dave completes that and gets the fly wheel machined, I can start the engine mount and exhaust mods.

 

akflyer

what engine are you talking about I might have ask this before.....I don't remember.... I have been looking at the Arctic cat engines.they have a Suzuki engine that they came out about 2010 I believe it  is a cf 800 ho engine the later engines has 2 plugs per cylinder it is fuel injected with an ecu the engine looks real promising if I was to use this engine I would have to go the route that you are doing making an adapter plate  and dealing with taper on the crankshaft but I believe that it would be worth it because  the engine is still in production and you can get parts for it.There is a guy on the gyro site that is using a arctic cat 500 on her gyro and it seems pretty impressive the engine she is using has a smaller crankshaft I believe it is a 30 mm taper similar to the rotax sized crankshaft are you keeping notes on what you are doing to fit the gearbox up?

thanks Bob

Edited 29 Oct 2013 by tbucket

[tbucket 2]

correction on the arctic cat 500 it is an1998 arctic cat zr 600 efi engine here is the link for this

 

http://www.rotaryforum.com/forum/showthread.php?t=33990

 

thanks Bob

[SkyPirate 8]

doesn't the Happi conversions use a tapered prop hub? I wonder if this could be adapted to fit if its the same size taper,..for a belt reduction

[tbucket 2]

doesn't the Happi conversions

 

they did make a conversion that used a tapered prop flange but I don't know if they are still in business i found some pictures of the conversion that I posted I am not sure about the box she used looks like a b box  looks like she split the gear box in half and drilled 4 mounting holes to mount to the engine  and then installed the pinion gear to the shaft with a bolt I am not familiar with these types of setups

[SkyPirate 8]

thinking your right on the B box Tbucket

[Trackwelder 12]

How much trouble is it to build a mount to turn the engine right side up in an Avid, I am not sure why it was originally turned upside down, but I am planning on a right side up installation, Is there anything I should be looking out for, when I bought this plane the first owner had mounted a firewall and had about 2 inch spacers between the mount and firewall, I had originally thought it was for Balance, are they needed or should I just bend up the firewall to fit the engine in the proper place.

[SkyPirate 8]

the only advantage of mounting the engine upside down that I have seen is routing the exhaust and upside down the cowl can be 1/2" from the engine to top cowl

Edited 24 Oct 2013 by SkyPirate

[SkyPirate 8]

but in my mind heat rises,..so an upside down engine isn't using the fins on the head to cool much heat,..its going into the block

[akflyer 1427]

I think the original inverted engine was like Chase said.. to clear the exhaust and to get the trust line where Dean wanted it, yet keep the cowling low.  The visibility is MUCH better over the cowling on an Avid verus a Kitfox because of the inverted engine and the cowling clearances.

 

I think with my conversion due to the lay down design of the engine, I can get it all stuffed in the cowling with the engine right side up and maybe only lower the thrust line about 1/2"  I can live with that!

 

As far as the year range of engines for conversion... 06-09 on the AC 800 engine.  This has the larger crank in it that is oh so smooth.  The 10 and up have the lighter crank that gives you the "Harley" shake and you have to run premium gas in them.  I do remote flying where there is no premium gas for 100's of miles, and adding octane boost to an unknown rating already is a crap shoot on keeping it from burning down.

 

[akflyer 1427]

but in my mind heat rises,..so an upside down engine isn't using the fins on the head to cool much heat,..its going into the block

 

That would only kick in when you shut the engine down and don't have any airflow.  The ducting routes cooling air through the fins whether its right side up or upside down (on an air cooled engine)

 

[SkyPirate 8]

gotcha..most of my 2 cycle rotax were free air,..I only had one inverted mount on a quicksilver that had the fan and duct work