Mounting 618 and 670 to KF-IV

[rdooley79]

Hey Guys,

Haven't made as much progress as I would have liked. Went to Costa Rica for 10 days. Wife graduated College just prior to that and yard work for the party was necessary. Needless to say I got side tracked for about 2 weeks.
Today I pick up the engine hoist to help me plant the new engine. I almost dropped the 618, twice, when I was trying to lift it myself. Needless to say I don't want that to happen at all! I'll start mounting the 670 on the KF this week.



I was able to 'fit' the exhaust with the 618 and get everything shimmed to have it fit, snug, but very nicely.


I've attached pics of the 618 mounted and the cowl modification I needed to do to have it fit in the cowling. I think it turned out very well.





Also you can see the head that Rotax Rick modified for dual plugs. This is the stock 670 head that has the recirculator just like the Blue Head but provides a bit more compression. Rick estimates it bumps the 670 up to 95hp!

[rdooley79]

ok guys, Tonight was the first true flight of the 670!

The summary of below is; WOW, it's an awesome upgrade! Rotax Rick's 670 is a real performer.

So you all may know that I fly out of Boulder CO, where field elevation is a mile high. Density altitude was at 6800 this afternoon.

Take off distance was about 30% shorter and climb rate was about 30% better as well. Now I'm still getting used to the plane so results may vary but it was very apparent that the 670 gives a lot more power than the 582. It's truly a new airplane and performs much better than before. Since I have the prop set up for climb especially with summer here and density altitude getting worse every day. Cruise was right about 74 indicated. I'll have a gps next flight to get some better numbers. Fuel burn seemed noticeably less but I need more time to see what the fuel burn will be like. I was just so happy to be flying again with a much better performing plane. I'd recommend the 670 if you have a 582 on your KF and want more power.

I have her set up with;
Rotax 670
Dual Ignition
Custom 670 purple head, giving an estimated 95hp (at sea level)
C box 3:1 w/ Clutch
Warp Drive 3 blade 72" straight blade, pitched for 64000-6500rpm on climb out max throttle.
Rotax Rick 670 exhaust made for this type of installation.
Electric Start
Amsoil Interceptor pre-mix 40:1

I'm comparing it to previously;
Rotax 582
Dual Ignition
Grey Head
C box 3:1 w/ Clutch
Ivo Ultralight 3 blade, pitched for 64000-6500rpm on climbout max throttle.
Stock 582 exhaust.
Electric Start
AV-2 oil pre-mix 50:1


Doing the runup's the last week I have noticed that the 670 likes to be warmed up correctly. It just sounds right when it's nice and hot. The main thing with these larger motors is keeping the head as hot and therefore expanded as possible. Rick has a runup procedure that works great. I use Amsoil Interceptor pre-mix at 40:1. Using good automotive fuel.

What I liked about this is that it's a "bolt on" upgrade. You can re-use everything from your 582, keep it, mostly in place and just swap it out. You don't need to shim the motor mount or add the spacers to raise the engine up like the 618. It fits better than the 618. The rear bell housing is smaller on the 670 and that makes it fit without needing to add washers to move the motor mount slightly forward. You also don't need to add the shims to raise the motor up, it just fits on the 582 motor mount. The cooling system if working well before will be good for the 670. I have the larger belly radiator and it kept the 670 right at 164 degrees at cruise. Climb out it was 168 degrees, perfect. EGT's were at 1180 in mid range cruise flight and max power was about 960. That's with the carbs set up from Rick.

I wish I didn't need to cut the cowling so much to fit the exhaust. But I wrapped it with exhaust wrap and that worked well. A ton of trimming little slivers off until it fit just right. In the future I'd like to get the cowling re-glassed to fit the exhaust and have it look right. For now though it's not that bad actually and works.

[SkyPirate]

Just changing drom an ivo light to a warp will make a big difference, the warp will out pull the ivo easily

[rdooley79]

True, that's why I changed to the Warp Drive. It's a much better rough field and climb prop.

However the change would not be accountable for anywhere near the performance difference, in my humble opinion. I've swapped props on my trike and saw a slight performance increase but nothing close to what the 670 performed increase experienced.
I just want to be clear as this engine is a new contender for people needing more power than a 582 but don't want to swap everything out.
Keep in mind that this was the first real flight and results may vary.

One additional detail that I failed to mention is that there was about a 3 knot tailwind for the first takeoff and I still experienced a conservative 30% shorter roll. I chose the tailwind takeoff as the terrain was more of a concern than a slight tailwind in this case. Once I get a better feel for this engine and how it performs these estimates will harden in to actual performance numbers but right now it's annecdotial and "seat of the pants" statistics. I do know that when she lept off the ground I was all grins!

[Aker]

Good info video footage would be great if you can.

Thanks.

[Aker]

Any more updates?

[rdooley79]

It's been a while. Life happened but I've been working on the bird in general. There were other things that needed attention. Since I've bought this bird it's been a much bigger project than I anticipated. The plane had more issues than I thought. I had a failure that really made me pause and very closely look at the plane. Flew for a couple hours and the plane was working great. I was taxiing out after filling up at a close airport. As I was lining up on the center line the throttle cable snapped. Right where it attached to the bell crank it had abrated and the cable had failed right at the barrel end. Very good timing I wasn't even moving but could have been a very bad day if it failed a couple throttle adjustments later. PHEW!
This made me take a long harder look at the plane and decided to do a few things I knew needed some love.

I've ended up;
Rebuilt throttle assembly from carbs to dash.
Re-wired the rats nest behind the dash and labeled everything.
New Odyssey 625 battery and relocated to behind the passengers seat.
Ran 4ga wire and replaced the solenoid.
Zip-Tied and organized all connections.
Replaced the starter motor with a new one.
Removed the halogen landing/driving lights.
Flushed and cleaned the radiator.
New coolant lines with less connections and better routing.
Ran all new fuel line and fuel filter, cleaned the gascolator.
Rebuilt Mikuni fuel pump
Reinforced the seat pan with cables/turnbuckles, keep from rubbing control rods.
Added foam to the seat bottom and back.
New bolts for seat belts.
Rebuilt the flaperon handle friction plate with new leather
Fabricated new exhaust mount.





The day after Thanksgiving I'm planning on running it up and checking everything out.

[rdooley79]

Alright Guys,

I wanted to give you all some close up pics of a 670 installed on a Kitfox 4.

Just had the annual inspection done and she passed. I had no doubt especially after the work just done.

First pic is my favorite!


Second one is a good one too. This is the High compression head. No it's not a bluehead from a 582. It's the 670 head that's made for the 670! Then Rotax Rick has a shop put in the dual spark plugs. Notice that it has the recirculator hose just like a blue head. It's just as good as the blue head but it's made for the 670 AND has dual ignition. BONUS!

If you're wondering what's on the sparkplug, It's some rubber to make a solid positive contact with the cowl lip. Without the rubber it vibrates just barely touching. In this case it's better to contact it solidly. Works nicely actually. Simple solution.



In hindsight, I wish I would have put the exhaust probes coming in from the top. If you have any exhaust splatter, cut up some exhaust gasket for washers around the probe between the clamp and the y pipe. Or weld on some bungs, that would be the best.


The exhaust is wrapped with Titanium Exhaust Wrap! Yes I said TITANIUM EXHAUST WRAP!!!!! It's super light and helps your exhaust retain a uniform heat profile. It doesn't add any power but it does look nice and keep heat off of the components.

Also notice the simple yet strong bracket. That was a good buddies design and it turned out very nice!

This exhaust was made specifically for the 670. It's what makes the engine have a nice flat power curve and perform at 90h+hp. A key to this engine is the Exhaust.



The cowl did need to get trimmed quite a bit.


One of the modifications done when the battery was located behind the passengers seat was to install a charging connector. The connector has 8ga wire that goes directly to the Odyssey 625 battery. That battery then connects to the solenoid with 4ga wire. The connector sits just under the passengers seat frame crossmember. I've wired up a battery charger/maintainer to connect to this SB15 connector. I used all together 3 SB15 connectors to make a splice with the clamp cables that come with the charger and one for the plane. I can also use this for a booster battery connection as well. BTW, you can get all of these that you want at batteries plus. Their used in APC UPS units.


Stubby nose, needs a spinner. That'll come soon enough.

[t j]

Thanks for the update. I've got a 96 Ski Doo Summit with the 670. That thing pulls like a freight train

[LSaupe]

If I can ask what is your max power RPM and cruise RPM. Did you need to change the port timing at all? I had a 670 on an MXZ and was thinking max HP was up around 7800 RPM.

What gear box ratio are you running?