V-TWIN--MAYBE V4

[Brian Rupnow]

I have been so impressed by RReid's build of a v-twin engine on "Model Engine Maker" forum, that I've just had to start modeling my own version. I will use the same cylinder, piston, and cylinder heads (although one of the heads has to be machined "opposite hand") as my 7/8" bore horizontal engine. It is not terribly difficult to design a V-twin engine. However, I'm thinkin' Lincoln,--what if? What if two V twin "stand alone" engines were completely finished then mounted on a common baseplate. Then, with the correct rotational aspect between the two engine crankshafts (using a Lovejoy coupling), wouldn't that make a reasonable v4 engine? I think the second engine would have to be a complete 180 degrees out of phase with the first engine to make this work right, but I'm not totally sure yet. I'm not going to build any engines this summer, but I do love to design.---Brian

[crueby]

Very interesting - looks like some fun in CAD for you this summer!

[Brian Rupnow]

Okay---That's enough silliness for today. The timing gears are just hanging in space for now, not really positioned accurately.

[Brian Rupnow]

Hell, yes!!!--We can do this. All four valves have lifters. I have one idler gear on backwards but that will be changed. Tomorrow I will figure out how to support the idler gears and work on ignition.

[Brian Rupnow]

With all the gears turned to have the hubs facing in the correct direction, I went ahead and designed a gear guard. I'm not sure of the final shape---It currently looks a bit too much like Mickey Mouse ears. I'll worry about that one tomorrow. The endplates for the crankcase are 1/2" thick, so that lets me use two 3/8" diameter shoulder bolts to support the idler gears.

[crueby]

The Mickey-V engine!
You have been having fun on the computer today!

[Brian Rupnow]

Yes Chris, it has been a fun day. It is amazing how quickly it comes, when you have ten or twelve years of "Archive files" to steal parts from and tweak them a little bit to fit whatever engine you may be thinking of.  Fifty years ago when I was working on a drafting board, I would never ever have believed what can now be done on a computer. I've got about seven hours in today on this thing, starting from scratch.

[Brian Rupnow]

With two cylinders, each of which must be timed more or less independently of each other, the simplest way for me to do this is with two sets of ignition points. That doesn't really trouble me, and I've found that by mounting the ignition cams to the camshafts, I can bolt a 1/4" thick flatbar across the back of the crankcase endplate to support them. My original thoughts on this engine was that I would run it with an open crankcase similar to what RReid done on his engine, but I see now that I can run it with a closed crankshaft with splash lubrication for the con rods.

[Brian Rupnow]

I've never had a lot of luck putting tight bends into small tubing without kinking it. So---I'm going to make the intake manifold out of a piece of 1/2" aluminum plate. The carb is my old tried and true Traxxas 4033, same as I've used on my other engines.

[Brian Rupnow]

And of course, being an internal combustion engine, it needs a fuel tank. Fuel tanks are generally pretty boring, but I can fancy them up a bit with a real swoopy support bracket.

[RReid]

My original thoughts on this engine was that I would run it with an open crankcase similar to what RReid done on his engine, but I see now that I can run it with a closed crankshaft with splash lubrication for the con rods

I went the other way with mine. Started out planning on a closed crankcase with splash lube, and decided pretty quickly to go with the open form instead, just because I like to see inside and see stuff whirling around.

[Art K]

Brian,
 A V4 would be cool! The later Saab 96's that had a V4 instead of the 2 stroke triple were based on a Ford V6 and was used for many years in fork lifts. Good start on the V twin.
Art

[Brian Rupnow]

Thanks Art--It's good to hear from you. Hope you and your lady have a great summer coming up. I'm burned out on machine building, but I still enjoy the design end of the business. Hope to get back into building when the fall comes.---Brian

[Brian Rupnow]

I went to bed last night, and as I lay there thinking about this engine, I realized that I had neglected to put a flywheel on it. Okay, that lets me get rid of the Mickey Mouse ears gear guard and put two smaller gear guards on--The rest of the gears are covered by the flywheel. I like this much better.

[Brian Rupnow]

Today I thought about pricing brass to use for my flywheel and gas tank. The one supplier I contacted in Barrie, wants $25 for a piece of 4" round brass 1" long (My flywheel). I then tried to find a piece of 1 3/4" round brass to use for a gas tank. Best price I could get was $40 for a piece 3 1/8" long. Not really complicated parts to make, but I like the color contrast. Okay, maybe I'll try something else.--I did a web search for cans of metallic spray paints that are a close match for brass. A spray can of "metallic brass finish" costs $10.00.  Hot rolled steel for the flywheel and  and thin wall steel tubing for the gas tank are so cheap that they almost give it away. In fact, I have some lying around in my materials bin. So---Use hot rolled steel that is essentially free (because I have it) and $10 for some spray paint, or $65 for material to make flywheel and gas tank. The only thing I gain by using brass is that I find it much easier to machine. Somehow it feels a bit like I'm cheating to make something from steel and then painting it to look like brass, but that's a heck of a big price differential.