Kitfox 4 with greatplanes - VW 2180

[rogerh12]

Nope, wish it was true that air ducting alone would solve the VW high power setting overheating problem at low air speeds. But, as Geowizt pointed out, the real issue is that there is simply not enough fin area on the VW stock heads to dissipate the waste heat at high engine power settings with a low air speeds (on 2100CC engines and larger, geared down motors are even worse). That’s why planes that work best with the VW are fast, like the Sonerai, Sonex and KR-2.

However, with careful ducting, a large oil cooler (VWs are also oiled cool to a large part), and the right prop, you can still run full power in a slow’ish climb with 2100 cc and larger engines, but not with Geared down engines producing 100+ HP. And, if it’s a hot day it won’t be for long if your climb speed is much below 90 mph. On my VW powered Zenith 601 HDS, even a 5 mph increase in climb speed made a noticeable difference with the oil temperature on a hot Kansas summer day.

Still, there are ways to cool the VW better: Thicker and larger heads are now available with better fin’ing and Aluminum cylinders to replace the standard cast iron, which help cool the heads as well. But the real fix to running high power settings on a VW at low air speeds is to install Water-Cooling heads (I had these on my Zenith for a while). Unfortunately, the special aftermarket aircraft water cooled heads I used are no longer available, as the designer made only a single run of castings, 80 sets total. And, despite out right begging by Steve Bennett at Great Plains VW (and offering to buy the rights and making them himself), the designer just won’t make more or sell the design (he is a Ford cylinder head engineer).

Anyway, all this is what I have learned over the last 10 years playing with VW’s and talking to other builders. My Model Kitfox 4-1200 is getting one installed this year. It’s a large 2300 cc engine with the new heads and aluminum cylinders, but will only produce 75 HP as the compression ratio will be reduced to allow car gas to be burned.

I just need it to outfly a Cessna 150 and I will be happy!

[lakeflyer]

WOW, Just want to thank every one for the great input on the VW powered KF-4 I saw on barnstormers, again it looked great and I'm sure it is well built and flys just fine but I don't think it would be a good floatplane based on all the great advice= wrong engine / short wing. I know from experience floatplanes can spend a lot of time trying to get off the water with full tanks, two people, gear, 85 degrees and no wind. the last thing one would want is to have a engine that isn't strong enough or getting all the cooling it needs. THANKS AGAIN p.s. I'll keep looking

[av8rps]

Keep searching for the right airplane and engine combination if you want that floatplane...the combination is critical when it comes to flying off water. Your decision to pass on the VW plane for a floatplane was a good one. The airplane was a beauty, but the combination was wrong for water flying. I have a 912ul powered Kitfox IV on amphibs and love it. It performs very well, burns very little fuel, and all the girls just love it because it is so cute .