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Ok, the V12 crankshaft has come to 698.8mm, with 4 main bearings. There is no definition of counter-balancing elements right now, and the default crank will be quite heavy at first. The idea is, as I said, to get a working unit, and refine it over time.

Block should be ready later today. I've all but settled on a V4 to test.

Which makes sense. Test the unit with the fewest cylinders to keep work loads down and then IF it works as you like you can always build one with more cylinders when you have it as you like it.

How about a twin to begin?

I was originally thinking a twin, but after careful thought it struck me that the twin would have too many differences from the main design to be as good a test as the V4 would be. The bearings (which, incidentally, I am designing it to use the same bearings you'd find on the 426 Hemi, in order to add plenty of margin for strength) have to support two rod throws each, four pistons. A v-twin would only have two, which means you'd still not know if the crankshaft is strong enough because it would have half of the number of pistons per bearing. The dry sump oil pump is tied to the crankshaft as well, with the number of collectors being tied to the number of rod-throws. But with a v-twin, you'd have to design a different oil pump arrangement, not enough throws. With the V-twin and V4 you'd still need a balance shaft, so no advantage to the twin there. I just cannot find a real advantage to the twin beyond needing 35% less metal to make it.

Ok, taken some time to study balancing for the V4. Because of how the oil pump is being arranged, I can combine that pump with the balance shaft I think, which should allow some weight savings.

But now am looking at how to connect it to the rest of the world, the transmission. In the open source world there exists already a Honda B-engine transmission mount that would be quick and cheap to adapt, but it would not fit quite right (it is very obviously for an inline-engine). Alternatively, I also have both a Nissan 71C transmission here and have access to a Type 2 VW transaxle. Or I could make a custom mount and push a custom transmission later on (which if I did would be using a chain drive and not gears, fan of the Nash chaingang transmission).

Yup, that's it. Although, not talking the whole rear-end drive system like on the Nash, just that the use of chains over gears for most 'gears' save Reverse, which would use a normal gear setup. Chain drive transmissions in my experience are a lot less painful to repair, and cheaper to build. Off the shelf motorcycle drive gears should do, attached to dog engagement gears.

Have not forgotten, instead found a tutorial describing just how to build a V12 engine, which I have been following to make sure I did not fall over any pitfalls.

You can find it here:

http://grabcad.com/questions/tutorial-h ... gine-final

I hope I didn't mention this one before. Anyway its worth to share, I can see big advantages in cost power & reliability with this example and it sure has still been a good amount of work to do and makes the owner proud with large parts of it being homemade.

http://translate.google.de/translate?sl ... 2F&act=url

I've had one rough year, but have not forgotten about this. I've been working on the aircooled jugs some more, and hit upon a novel solution to the lubrication issue I was running into. With the fork-in-blade design, lubricating the piston was turning into a problem. Difficult to align the lubrication holes in the crankshaft, and the casting for the shaft was more difficult due to the lubrication channels.

Then a bit of serendipity struck, and I'd found my old Suzuki GT380 manual (long lost the bike). The GT380 was an interesting engine in that instead of feeding lubricant through the crankshaft, it used direct oil injectors inside the engine cylinders themselves. I could accomplish this because the pistons were just a bit longer than the stroke of the engine. So, I looked at the pistons I'd designed, and if I extended them by 2mm, they'd also fit the same bill. Simplifies the casting of the crankshaft, while retaining strength.