1/2 VW Airplane Engine

[Alex Westling]

Well since this is really not a Cal-Look question or a drag racing question I thought I would put it the off topic section. I am building a ultralight airplane that I am going to put a 1/2 VW engine in. Bacisicly it is just the front two cylinders. I will cut the back half of the case ,crank, and cam off. The prop is then attached to the pulley end of the crank. Heres a picture to get an idea of what I am talking about.


Heres a list of parts I have so far
84mm Crank
Stock Length Rods
94mm Nikasil Cylinders
Two crank trigger ignition systems(Two plugs per Cylinder)
2 32mm Mikuni Carbs

So my question is what would be the best valve size, and camshaft to use for this thing. It will need to make max torque around 3000-3300. I can adjust the prop to make it rev faster or slower but I dont want to have to rev it much over 3500. The cylinder heads are factory head cut in half so I will put in what ever valves will make the most power. Compression will be around 10:1. Any suggestions would be appreciated. Keep in mind I dont want to make any modifications that will compromise longevity.

[martin]

I know a guy who built a Type 4 motor for a hydroplane that would tool around the coastline water, and used by cops on patrol. The engine had problems lasting and he was tempted to put in a Berg Type 1 motor. He put Honda motor in it eventually, but the motor turned the wrong direction for the prop, and I think they had to redo that prop too. Sounds like a learning experience for him. I would give Berg a call and ask them. They have such a long history in building and recommending parts that last with a proven record. This is not to be taken lightly with aircraft. Someone flew a VW powered plane over a bug show years ago, and the announcer asked the people there how many of the show goers would trust their engines in that craft and there was a sudden hush over the crowd.

[mcmark]

What are ya building Alex? I've flown a couple of ultra-lights and survived . Low and slow is a wonderful way to fly, but I prefer being inverted. Makes my world look right. Like to see your progress.

Thx

Mark 

[Alex Westling]

I am building a Legal Eagle. (http://www.betterhalfvw.com/). I have never been a huge fan of the "Flying Lawn Chair" ultralights. Just somthing about using standerd aircraft manufacturing techniques that I like better. I will have complete confidence in my engine when it is done. It should in fact be superior to many of the engines flying today. Take a look at the engine in some of the older aircraft. You will find two old magnetos very similar to what is used on an old tractor. And many of the carburators where made by Marvel which where also on old tractors.

I will take some pictures. I only have one of the wings built so far.

[mcmark]

I'm glad you said it, "flying lawn chair". Having flown a Kolb that was supposed to be powered with 27hp, that had been repowered with 58hp, you start to question your sensibilities. I like a high horsepower to weight ratio, but that was almost beyond control. Full power on takeoff roll, I could not hold it with rudder. I have looked at the Legal Eagle and read a bit in Sport Aviation, looks like a strong bird. It would not take much to improve on the original VW aircraft engine. Aircraft engines still operate on 1940's tech, but you new that. Experimental aviation is pushing forward with FI and Electronic ignition and it's forcing the Feds to take notice. Keep the rest of us airplane nuts updated. If I could find an aerobatic capable redrive, I'd build a turbo stroker to run. That HP to weight thing again.     

[turbo_bob]

I would guess 40 x 35 valves. Low RPM's, high torque, 84 x 94, 1/2 engine.

[Alex Westling]

Thanks Bob. I was thinking the same thing on the valves. I was thinking about going with a Web Cam #111. I think it will make tons of torque but I also now that cam is really aggresive and I am a bit conserned about longevity with it.

[bo]

i am a huge fan of vw powered planes i have a quickie a volksplane and an ultra cruzier i also had a varieze all of these planes are fun but all ended up with a rotax minus the volksplane

[turbo_bob]

I think a good cam choice would be a stock cam with 1.4's, low RPM, high torque.

[blue manx]

 ;DI helped building one of these years ago and we made a 1/2 1776 90.5 x 69mm stroke I think we used ported stock heads with 1.25 ratio rockers on a stock cam because you could not rev it past 3500! The guy who flew it really liked the combo.

[wilbur]

The pic of the green eng shows the carb feeding through an exhaust port, i dont think any vw cam is gonna work for that setup

[bo]

those are aircraft heads made specifically for that setup

[Alex Westling]

Those are just stock heads cut in half with a welded on intake port. Heres a better picture.


Looks like I will either go with the stock cam with ratio rockers or the Web Cams #111. I think they should both give plentey of torque.

[bo]

^ ultra cruiser ?

[markhuebbe]

Talk to Steve at Great Plains.  He is very knowledgeable with VW conversions.

http://www.greatplainsas.com/

My dad and I have a 2276 direct drive VW conversion.

[KAFUR1]

i like the intake manafold's  add some injectiors and tb and a turbo