Author Topic: Big Bang Camshaft  (Read 1079 times)

Offline Deuce

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Big Bang Camshaft
« on: October 01, 2013, 08:44:17 pm »
Ever heard of a "twingle" camshaft. ie: 1&4 cyl fire at same time and then 180 degrees later, 2&3 cyl fire. A big bang would have all of the engines cylinders firing at different time, rather close together, as to allow for staggered power impulses to happen vs even firing of a 90 degree, 180 degree or 360 degree engine.
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Offline IanC

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Re: Big Bang Camshaft
« Reply #1 on: October 02, 2013, 08:55:08 am »
Not sure I see what the point would be. Ignition at or near the top of the stroke is the most efficient way to make power in a combustion engine that I know of. Seems like the Big Bang idea would be a huge waste of energy. 
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Offline Deuce

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Re: Big Bang Camshaft
« Reply #2 on: October 02, 2013, 02:58:29 pm »
I took it to mean that normally when 1 is on a compression stroke 4 is on its exhaust stroke. And, likewise with 2 and 3. The big bang cam would put 1&4 and 2&3 on the compression stroke at the same time. Granted I only read a tiny bit on it while looking for a track master style tank. But, it seemed to me it would be like some sort of dual twin or something. I don't know what the benefit might be. I did however find it interesting.
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Offline 8Ball

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Re: Big Bang Camshaft
« Reply #3 on: October 05, 2013, 08:34:17 pm »
The theory behind "big bang" firing orders is that the tire gets a chance to recover between pulses.  Where an inline four has firing pulses evenly spaced, a V-twin or V-four has pulses closely spaced then a longer dead space.  Twins and V4's do not tend to spin up tires like a screamer inline 4 because of this.  The "big Bang" engines made their debut back in the 90's on the 500 GP bikes to try to tame the 2 stroke 4 cylinder monsters.  Yamaha has done something similar with the R1 with its "cross-plane" crank.  That groups the firing pulses unevenly and creates more low end torque without shredding tires.

I assume that the cam shafts that you mention do exactly what you think they are doing Firing 1-4, and 2-3 cylinders at the same time.  That would give the engine the same power characteristics as a parallel twin.
« Last Edit: October 05, 2013, 08:34:57 pm by 8Ball »
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Offline Deuce

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Re: Big Bang Camshaft
« Reply #4 on: October 05, 2013, 10:43:58 pm »
Yeah that's about what I thought. But, that article I found by accident was the first I remember hearing of it. Thanks for the explanation. That article was pretty vague.
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Offline 8Ball

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Re: Big Bang Camshaft
« Reply #5 on: October 06, 2013, 09:02:29 am »
The only "twingle" set up I have ever heard of is a parallel twin that fires both cylinders at the same time, like a single.  Thus the name twin-single...."Twingle".  I have never heard of an I-4 set up to fire like a twin, although the theory would be the same.  As I mentioned before, Yamaha went to a cross plane crank to spread out the firing pulses, but I assume they didn't go with firing two cylinders at once so that they could get a compromise between low grunt and high end HP.  But that requires a completely different crank shaft, as well as cams.  The set up you are talking about would only require different cams.

I have never heard of anyone actually using this set-up, but as an engineer and mechanical enthusiast, I am intrigued. :21
Quote from: jeff5150
just follow 129 on the map towards nc til it looks like a kid drawing it had a siezure
Quote from: Tomsljr
Know the difference between crack heads and Gap addicts? I have heard of people quitting crack.

I find a Soap Box comes in handy when getting on and off my High Horse!