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Forum Index : Other Stuff : 6 cylinder engine balance

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isochronic
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Joined: 21/01/2012
Location: Australia
Posts: 689
Posted: 06:42am 12 Jun 2018
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???? just a thought bubble -
If a six cylinder in-line engine has good mechanical balance -
will it run on 3 cylinders with the other 3 not firing ? Can they then
be used for other things like compressing etc

ed - My family had an old Toyota Crown six. The engine was so
smooth at idle it was hard to tell if it was running or not, prompting
ghastly noises from the starter motor trying an unneeded restart
(and even worse from the driver with three-on-the-tree )Edited by chronic 2018-06-13
 
Boppa
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Joined: 08/11/2016
Location: Australia
Posts: 814
Posted: 10:37am 12 Jun 2018
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Not sure about the 6 (yeah those old crown motors were tough as guts werent they, had a 69 crown 6, 3 speed with electric overdrive, it was the limo of the toyota fleet, even had volume and tuning from the back seat!)

I know the 2 cylinder conversion has been done many times to vw flat fours, where 2 cylinders run as the motor, and the other two are used as a air compressor, but never seen a six done

I spose if you had one running, you could try pulling the appropriate sparkplug leads off and see how it ran???
 
George65
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Joined: 18/09/2017
Location: Australia
Posts: 308
Posted: 11:47pm 12 Jun 2018
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Kubota and yanmar do a lot of 3 Cyl Diesels.
Cant be too bad to balance unless they have inbuilt balance shafts or counterweights in the flywheel.

Tell you this much, My listerioid single Cylinder is a jackhammer. Thing is so badly balanced I can't run it unless it is well and truly secured to a concrete slab and even then it tears free after a while.

Have to get to pulling the flywheels and balancing it one day.... or just get a better engine and be done with it.
 
Warpspeed
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Joined: 09/08/2007
Location: Australia
Posts: 4406
Posted: 04:54am 13 Jun 2018
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Should work, but you will probably need to keep the original cylinder head for the compressor half of the engine.
A much better bet might be a V6 of some description.

That would give you much more freedom to adapt a proper "flat" compressor valve plate with reed valves for the compressor half.
Cheers,  Tony.
 
Gizmo

Admin Group

Joined: 05/06/2004
Location: Australia
Posts: 5078
Posted: 05:33am 13 Jun 2018
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A 4, 6 or 8 can run with a few cylinders down, the resulting vibration will depend on how the missing "bangs" are located in the full sequence. A 4 cylinder with a firing order of 1342 could run happily at 1_4_, or _3_2. At high RPM it will run smooth, but lower rpm will have some vibration. A 6 cylinder would be better, and a V8 would barely have a rough idle.

Back in our youth, a mate of mine had a Holden Gemini with the little 1.6L 4 cylinder. It was stuffed, rings gone, and would constantly foul one plug. So he took out the rockers for that cylinder, figured it would save fuel as a 3 cylinder, no point sucking in air/fuel if its not going to fire. It was rough around town, firing miss bang bang bang. On the highway the vibration was ok. A month later a 2nd cylinder needed the same treatment, out came the rockers. His firing order was miss miss bang bang! That was bad, car was shaking itself to pieces, but he drove it like that for another month until he had the money to rebuild it.

Glenn
The best time to plant a tree was twenty years ago, the second best time is right now.
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isochronic
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Joined: 21/01/2012
Location: Australia
Posts: 689
Posted: 10:17am 14 Jun 2018
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There are net descriptions of "linear generators" - so the idea was,
put three into the three blank cylinders - conserving the same masses
should retain good balance and the whole should be vibration free.
Output would be 3phase, I guess 50 Hz at 3000 rpm. Don't know if
permanent magnets are ok with constant SHM stress though. (Mainly
an idea for an old engine reuse )
 
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