VW Based Twin?

[Driven5]

All questions of sanity aside, if someone wanted to build their own basic (easy to maintain) air-cooled parallel twin engine from as many readily available off-the-shelf components as possible, are there any technical concerns that would prevent using the Type I engine as the foundation? Maybe I'm just missing something that should otherwise seem entirely obvious. But after spending a considerable amount of time thinking and researching about it, the glaring issues would be the custom built case and custom (modified?) fully counterweighted crankshaft. But beyond that, what would be the main hurdles?

The biggest unknown that jumps to mind is that oil drainage in the head could be an issue. With Rabbit valve seals and keeping it slanted at least somewhat towards the pushrod tubes might that be enough to mitigate any potential problems? Worst case scenario I would think the head could be tapped for additional drainage plumbing. Is there anything else about these engines that would prevent half of one from being tipped up at a 60* or 75* angle?

Also, what if the phase angle of the crankshaft was revised from 180* to 360*? Are the lobes on the cam blanks full circles, such that any 'custom' cam grinder could rephase one to match?
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"I couldn't find the sports car of my dreams, so I built it myself" -Ferdinand Porsche

[Juanito84]

You would have to block off the oil passage that goes to the right side lifters and tip up the left side.
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If a water cooled engine cools its water with air, isn't it just an overcomplicated air cooled engine?

[Boolean]

A parallel twin should have a 180 degree crank - otherwise it would just be two singles coupled together.
Use the left side of the case, make a girdle or something to keep the bearings in place, and bolt an oilpan to the case split bolts. A piece of cake.
Note that oil drainage from the head is a very small issue compared to the amount of work needed to make it all work.
Something has to be done with crankcase breathing, oil system, cooling, and other bits I forget right now.
It will surely work, and with a stock crank too. (It may have to have counterweights matched to the missing rods)
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I strive for perfection. Excellence will not be tolerated!
Build thread here:
http://www.thesamba.com/vw/forum/viewtopic.php?t=529379

[Driven5]

Thanks for the replies! I know that these kinds of questions can seem outlandish enough to rational people that they are often not given much consideration.

I believe the 'traditional' parallel twins actually used the 360* crank, even if the 180* crank has better balance and eventually became more popular because of it. Technically a parallel twin should probably have a 270*, or maybe even ~285* crank, but that's neither here nor there. A stock crank may work to get it running initially, but I wouldn't automatically count on it being ideal in the long run either. So assuming a cu$tom crank may eventually get thrown into the mix anyways, the main additional concern I can see at that juncture with changing the cylinder phasing to anything other than 180*, would be the cam lobe phasing. Thus my interest in finding out if the standard blanks used by most VW cam grinders would allow for otherwise standard ground cam lobes to be rephrased to compensate, or if they too would have to be completely cus$tom from scratch.

I do realize that the amount of work to do this would be pretty immense. There would obviously be many more concerns needing to be addressed, but right now I'm mostly looking for anything (obvious big bits or unsuspecting little bits) that could potentially be a show stopper. It would be better to find as many as possible now, during the initial investigation, rather than after diving headfirst into such a project.
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"I couldn't find the sports car of my dreams, so I built it myself" -Ferdinand Porsche

[miniman82]

[Boolean]

I heard about a guy who put a Citroen aircooled opposed four Visa engine in a bug. It had one hp less than the 1300 it replaced. When asked about WHY?!, he replied:"Basic hot rodding. It hadn't been done before"
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I strive for perfection. Excellence will not be tolerated!
Build thread here:
http://www.thesamba.com/vw/forum/viewtopic.php?t=529379

[Boolean]

Besides, a well tuned 1166 cc twin should deliver 75 hp without much trouble.
_________________
I strive for perfection. Excellence will not be tolerated!
Build thread here:
http://www.thesamba.com/vw/forum/viewtopic.php?t=529379

[Driven5]

[miniman82]

Please, I spent 4 years in that hellhole they call Chicago and Hampton Roads isn't much better. GRIDLOCK is a daily occurrence.
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Build thread: http://www.thesamba.com/vw/forum/viewtopic.php?t=212747

[Matthew]

It can be done I'm sure. It has been done before keeping the engine horizontal and just using 1-2 cylinders and head. The other side gets the cylinder spigots and pushrod tube holes blocked off.

What is the intended use?
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[Driven5]

[Oldfart]

They have been converting Vdubs to two cylinders for mebe 40 years?
http://www.flyhummel.com/hummel-bird

[Boolean]

[Driven5]

And the easy path does you no good, if it does not lead to where you are going. It is then that the more difficult path may actually be your easiest option.
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"I couldn't find the sports car of my dreams, so I built it myself" -Ferdinand Porsche

[SBD]

[mondshine]

How about a water cooled twin?

[Driven5]

[Quokka42]

If simplicity were the name of the game, just leave one side off, make up a cam to suit and cut up and weld the original crankshaft to provide a 360 firing arrangement. You could slant it up about 30-45 degrees and still fit it under the hood would be my guess (just move the pickup and add a new drain plug. Use the right side and you won't need to worry about the left filling with oil.
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