Although I have been on this planet for quite some time and have seen a lot of things and done a lot of things, I have never set up a multi-engined car. It has rattled around in my brain for 60-odd years though and perhaps before I am recalled by my Maker, I will have the opportunity to jump in on such a project.
As a techinspector at the drag races, I have seen my share of dual-engined cars and have talked with the owners/builders. One of the main things that crops up is how are we going to phase the motors to each other.
A 4-cycle motor goes through 4 different cycles to make one power pulse........ intake, compression, power and exhaust. Each of these cycles are 180 degrees in length, so 4 of them add up to 720 degrees (two complete turns of the crankshaft) to make one power pulse to the tires. If we connect the motors both at 0, then both of them will be in unison and will double the forces that they exert on components. The first problem will be starting them. With two cylinders on each motor firing at the same time, that will be a tremendous load on the starter motor of whichever motor you hang the starter on (probably the rear motor would be the one with a starter ring on the flexplate or flywheel), so it makes sense to me to phase the second motor a ways off from the first motor, like maybe halfway between the front motor #1 and #8 cylinders. Tied together and firing number one on the front motor and number one on the rear motor at the same time, for instance on a 350 Chevy, you would have this.....11-88-44-33-66-55-77-22. If you phased the firing so that the rear motor fired halfway between 1 and 8, you would have this......1-1-8-8-4-4-3-3-6-6-5-5-7-7-2-2. You can see how the power would be spread out over the two crankshafts, so that instead of having a power pulse every 90 degrees, you would have a power pulse every 45 degrees. This is how a factory would do a V-16, a power pulse every 45 degrees. It would not only be easier to start, but the flow of power would be more gentle on the parts that come after the motors (clutch, transmission, driveline, differential).
This might be a good place to enter the sound of a Harley-Davidson 45 degree motor. Here'why they sound like they do....
The Harley Sound
So, a dual-engined setup with odd timing might sound almost as strange if you were to time them, for instance, 10 or 20 or 30 degrees apart instead of 45.
Here is a detailed thread from the H.A.M.B. that may offer some enlightenment. If not, come back and let's talk more. Use all the links that are provided in the discussion on the H.A.M.B., because some of it applies to coupling systems too.
Twin Engine Coupling (How Do You Get Two V8's In-Line?) | The H.A.M.B.
P.S. When I began typing, nobody had answered yet, then when I posted, I was amazed to see all the fellows who had posted while I was typing. This thread has struck a nerve.....
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