As I've been building I've also kept my eyes open for the latest and best possible engine for the plane. I have definitely tried to steer clear of the demanding two stroke engines. I am also trying to get around the very expensive Rotax 912. So, I need between 100 and 120 HP to feel good about not under-powering the plane. A builder's plane is almost always heavier than the prototype and I think mine is no exception. I looked at the VW based engines as well as the Subaru and Corvair based engines. They have good power and pricing, but are just too wide for the nice lines of the P-40 cowl.
When RotoMax came on the scene it was like manna from heaven. It had 120 HP, was 17 1/2 inches in its widest dimension, and weighed the same as a two stroke. Unfortunately, RotoMax went out of business following a mishap that resulted in the loss of a Sadler Vampire aircraft but no fatalities.
Now I started looking at the Jabiru 3300 with the possibility of adding a variable pitch propeller to it. I'd get my needed 120HP and I could lose a little aesthetics at the very front end as a trade-off.
Tied with the Jabiru is the new Eggenfelner Viking HF-110 engine. It can produce 115 HP for take-off and produce a continuous 110 HP in flight. I don't have the exact dimensions on it, but from the videos on the web it looks like the reduction drive gearbox will place the prop well forward enough to keep the cowl lines intact. This engine is setup pretty much on its side. It might fit even better in the P-40 rotated to a more upright position. The only thing is, that this engine does not have the track record that the Jabiru does.
At one time I was seriously considering the liquid cooled, two stroke International brand, model 808L-100. If you haven't already guessed, that's an engine specifically designed for small aircraft. It's a 100 horse power engine. It has three cylinders with two spark plugs per cylinder for added reliability. It will come with a gear box for the propeller, and it's completely ready for aerobatics. Unfortunately, they stopped making light aircraft engines!
So now I'm looking at a VW engine again. I have my eye set on a VW 2700 cc, 107 HP engine. It needs a belt reduction drive from Valley Engineering. The Great Plains Company has a VW kit that you can buy. You essentially have to build the engine from the ground up with all of the specialized aircraft safety and reliability parts. Right now it's going for about $3000 plus shipping. I already bought the series 3 belt reduction drive for about $1500.
I finally made the decision to go ahead and purchase the VW engine conversion kit! Here it is. It's an out of production Volkswagen type 1 engine that I got from Great Plains Aircraft Supply Company. It came with the Aero-Conversion kit. The engine is bored and stroked to 2276 cc for use with the reduction drive that I already bought. It still has the 107 horsepower at takeoff with a continuous power output of 75 horsepower.
This is a highly customized crankshaft with the (from bottom, up) No. 4 main bearing shown. The cam timing gear, spacers, brass ignition timing gear, and snap rings are also highly customized for this aircraft engine. The camshaft and gears are meshed with the cam timing gear on the crankshaft. Every item was checked for free rotation independently and with each other. The nose of the crankshaft is poking out the front and is waiting for the lower pulley to be attached. The piston connecting rods protrude out the sides, and the cylinder studs have been attached to the case halves.
This engine takes 92 octane fuel. The specific fuel consumption rates are yet to be determined in this very unique aircraft. The total weight of this engine when complete will be 181 pounds. The total engine length will be 30 inches.
The original spinner back-plate has a bowl shape to it that makes mounting a flat, straight-across, two blade, wood prop impossible. On a smooth flat board I sealed the holes with thin brown packing tape and filled the bowl with liquid Plaster of Paris. The Plaster of Paris surface was sanded smooth with very fine grit sandpaper. Ten coats of Carnuba wax were applied and buffed. Three coats of PVA mold release were misted on with a small spray bottle. Six layers of modified twill "E-glass" were applied one day at a time, and two more strips of glass were applied around the flange area to ensure the angle didn't change.
This shows how the outside dimensions of the back-plate were preserved. With the back-plate remove we now have an 18 inch diameter mold with the proper flange angle, but with a nice flat surface for the prop to rest on. This is a good view of how the fiberglass-carbon fiber-fiberglass sandwiched final part will look with the spinner.
