running cylinders off rear location of full case?

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revkev6

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Whatever. I was going by the prop being at the front.

On their full VW engines, Great Plains has the option of mounting the prop on either end, with the flywheel drive being a little lighter. It looks like that is what their full-case 1/2 VW is based on. Still, they could not have cut the crank.

By the way, they have a kit of parts for the full case 1/2 VW.

Don't recall if it was them, or someone else, but there was a mention of being able to add the missing cylinders back at a later time. That would be more difficult if the crank were cut. And if the crank were cut, how would it be supported in the middle?
I would venture to guess that pops knows more about building VW engines for aircraft than anyone here... show him a little respect... ;)

there are three bearings that support the crank in a VW... on of which is in the middle between the cylinders.. all you have to do is find a picture of a case to see

851998.jpg
 

Pops

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Pops, whats the lightest practical VW 4 cylinder you come across, not some special big money item, just one that's had attention paid to it.

And/Or would you know the weight of a complete long engine (stock 1600, or 1850), no accessories please?

I have weighed VW long blocks ( no accessories, no intakes, exhaust, prop hub, etc) in 1200 cc, 1600 cc, 1835 cc, 1914 cc and 2180. They all weigh 116 lbs except for the 2180 and its 118 lbs due to the larger stroker crankshaft. The thickest cyl walls is in the 1200 cc, 77 mm dia piston.

The lightest engine installation that I know is the engine in my SSSC. Firewall forward, running and flying, with the prop, engine, intakes and carb and airbox, exhaust system with carb heat muff, Slick mag and mag drive, oil cooler and hoses, engine baffling and 4130 tube engine mount is 141 lbs. I could make it a little lighter because my stainless steel exhaust tubing and intake tubing is excessively thick.
I have been slowly putting together a 2180 flywheel drive engine and thinking about a Carbon Fiber intakes with a short metal section at the head and CF baffling and oil cool shroud, and the correct thickness exhaust pipes.
I believe I can get a firewall forward weight of about 138 lbs and that is without using the aluminum jugs that save 5 lbs.

I have been thinking of building another version of the SSSC but getting serious in getting the EW as low as possible with the light 2180cc flywheel drive engine.
I can use the first wings that I built for the SSSC with the small wing fuel tanks of 8 gal total. But not sure if I would want to use then, might go with a different airfoil .
 

BBerson

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If the prop is mounted on the flywheel end of the case then the crank could be cut off and a straight prop shaft fitted out to the prop.
It would be a bunch of work just to eliminate the weight of two throws.
 

Bill-Higdon

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If the prop is mounted on the flywheel end of the case then the crank could be cut off and a straight prop shaft fitted out to the prop.
It would be a bunch of work just to eliminate the weight of two throws.
The problem with this is the cam drive at the other end of the case
 

BBerson

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The problem with this is the cam drive at the other end of the case
What problem? The cam is either cut off or not, doesn't matter. The prop mounts on flywheel end and the two cylinders are on the pulley/cam gear end which is now near the firewall. So a long pointed cowl can be fitted.
image.jpg
 

N8053H

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Whatever. I was going by the prop being at the front.

On their full VW engines, Great Plains has the option of mounting the prop on either end, with the flywheel drive being a little lighter. It looks like that is what their full-case 1/2 VW is based on. Still, they could not have cut the crank.

By the way, they have a kit of parts for the full case 1/2 VW.

Don't recall if it was them, or someone else, but there was a mention of being able to add the missing cylinders back at a later time. That would be more difficult if the crank were cut. And if the crank were cut, how would it be supported in the middle?
I believe the dude is Leonard Milholand who built the Legal Eagle who makes a full case 1/2 vw.

Tony
 

Pops

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What problem? The cam is either cut off or not, doesn't matter. The prop mounts on flywheel end and the two cylinders are on the pulley/cam gear end which is now near the firewall. So a long pointed cowl can be fitted.
View attachment 61942
I understand you now. So it's just a full case 1/2 VW but the prop driven off the flying wheel end. You can also cut the large flange of the case off the flywheel end for even more pointed cowl.
 

sotaro

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So, if you cut the crank just forward of the center main bearing, the prop shaft replacing the rest of the crank (2 throws) would be supported by the center and flywheel end main bearings. Would this be a substantial improvement on the ability of the engine to withstand gyroscopic propeller forces being transmitted to the crank?
 

BBerson

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The stock crank is stiff enough as is for four cylinders. Certainly strong enough for the 2 cylinder sized small prop.
Would be tricky welding a straight shaft anyway.
 

akwrencher

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I may be understanding the question differently. The way instead it, have wants to do a flywheel drive half VW, which would be fine, except that the oil pump, distributor drive, etc. Is in the other end. Might be tricky to do a cut case that way.
 

BBerson

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The OP wanted to go with full case.
He got the answer in post 7-8.

Other comments are various alternate ideas to cut weight off the crank.
 
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