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Janus Engine Concept

Mating two engines the simple way.
  (+4, -2)
(+4, -2)
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In response to a recent idea involving mating together two four cylinder motorcycle engines it occurred to me that many of the problems posed by this idea could be resolved if we abandoned some of the traditional notions about engine design and instead looked to minimize the redesign factors. An F1 engine program on the cheap, so to speak. In concept I recommend that the engines to be mated be left essentially alone thus minimizing the need for non-stock extra capacity oil and water pumps, custom cranks, new camshafts, etc. Instead the two engines should be mounted facing apart with water and oil pumps on the front and the rear, a good sort of redundancy. To accommodate this a custom Janus bell housing would bolt the two engines together. Between them a special damping flywheel with herringbone gear drive around the outer edge. This flywheel/gear would be where the engines would mate to the transmission. This obviates the need for stronger cranks and reduced engine speeds as the motors are exposed to the same stresses that they were in stock configuration.


1) Very cheap, now 80% off the shelf parts

2) Engineering, testing and development at a bare minimum

3) Increased flexibility as to engine position, crankshaft can be offset from drive shaft to a limited extent

4) Engine can be positioned beside or above transmission allowing for simpler mid engine AWD layouts

5) Redundancy is a good thing.

6) Utilizes the development program for the unmodified engine


1) Needs a novel transmission linkage

2) Extra gear linkage is going to eat some power

3) Unconventional engine placement requires a re-think

4) Overall package will be slightly heavier.

I would love to see more unconventional teams hit the tracks and compete. It would be far more appealing to me than watching the current Formula racing events which come across as, well, formulaic.

WcW, Jan 19 2009

Cizeta V16T http://en.wikipedia...Cizeta-Moroder_V16T
Wiki Link to Cizeta V16T, which used this exact idea. [Skrewloose, Jan 25 2009]

Tiger Z100 http://www.tigerracing.com/z100.php
A current implementation. [Skrewloose, Jan 25 2009]


       This would be pretty heavy, wouldn't it?   

       edit: The above was in response to an earlier revision.
Spacecoyote, Jan 19 2009

       Rather than the crazy extra flywheel, why not have a diff between the two engines (taking power out from the crown wheel, or equivalent)? You would want some crafty comms to link the two throttles though, or run an LSD.   

       If it was locking, you could deactivate one and pull in the clutch to give a 'pootle' mode, and you could 'bump-start' the other engine for instant extra power.   

       Not sure whether this has been baked in your form though - as a 'V16' supercar (on Gran Turismo 4 I believe, it understeered a lot) that had 2 V8s mated flywheel-flywheel (see link).
Skrewloose, Jan 19 2009

       link makes no indication of a mated engine, only of a v16 engine with a common crank. Also, why differentiate the engines? We want them locked together for reliability. Furthermore for weight two bike engines still weigh less than one conventional SBC.
WcW, Jan 19 2009

       How about having one engine run the left wheel and the other run the right? I guess left and right pedals would be more difficult to handle than a steering wheel.
Spacecoyote, Jan 20 2009

       Further reading following some of the further links reveals that it was made up of 2 x Ferrari 3 litre V8s, and they mated flywheel to flywheel (hence the super-wide car) with the gearbox Ting off backwards (hence the V16T naming).   

       Apologies for the less than thorough linking, there's notvery much on the car, spread over too many places.   

       My idea with the diff was to allow each engine it's own flywheel to deal with the harmonics in the crank. True it probably adds more complexity than it's worth, but hey, this is Halfbakery after all. Running on a single engine (if road-going) would allow better fuel economy if driving 'less enthusiastically' than the Stig.
Skrewloose, Jan 20 2009

       Are we on Stig III yet? I'm not sure that this sort of engine (low fuel economy) would be a good platform to practice fuel economy measures. Please re-link, I'm not finding anything but I am very confident this has been done at least once. (do it more!)
WcW, Jan 21 2009

       Quite reminds me of the 24 cylinder Allison V-3420, which was basically (80% by interchangeable parts) a pair of twelve cylinder V-1710s snuggled into a common crankcase (two 60-degree Vs with a 30-degree gap between them). It was the designated engine for Lockheed's XP-58 project, among others; none of which reached production.   

       Most of the problems seemed to stem from getting it sufficient air to run with. At 56 liters displacement, perhaps it just needed a Bussard ram-supercharger.
lurch, Jan 21 2009

       What's a "Janus bell housing"? Google returns exactly one result - this idea.
spidermother, Jan 25 2009

       I think [WcW] is making reference to the Roman deity Janus, who is characterized as two-faced, or looking in two directions at once; hence, a double-bell housing with the bells facing opposite directions.
lurch, Jan 25 2009

       I managed to get a reasonable link for the Cizeta. Not sure how they mated the two flywheels to the gearbox.   

       My point about the 'eco mode' was that if you were running a little kit car with this in, you'd be able to commute to work on a single engine, then fire up the second plant to get the full performance.   

       Tiger Racing (see link) have also been running twin motorbike engines for a few years now. I'm not sure how they mate them, but I seem to remember you have two motorbike gearboxes going into a transfer case, so you run each system independently, and then link their speeds through the transfer box.
Skrewloose, Jan 25 2009

       [lurch] Also the god of gates and doorways; I've always disliked the stereotype of janitor as cleaner, as the name suggests doorkeeper. I guessed at the meaning you suggest, I just wanted to be sure he wasn't referring to an existing concept of which I wasn't aware.
spidermother, Jan 27 2009


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