v-12 engine balance

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Kenova
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Re: v-12 engine balance

Post by Kenova » Fri Oct 27, 2017 4:37 pm

SchmidtMotorWorks wrote:
Fri Oct 27, 2017 11:08 am

When the engine is running at a speed that the load coincidently varies at a similar frequency the twisting vibration will increase.
A harmonic dampener (incorrectly called a balancer) can fight that problem, but they are not magic, it is difficult to solve such a large problem with a device attached to the end of the crank.
Does the weight of the flywheel make any difference in the vibration, or does the vibration remain the same and is just less noticeable?

Ken
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SchmidtMotorWorks
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Re: v-12 engine balance

Post by SchmidtMotorWorks » Fri Oct 27, 2017 4:52 pm

Kenova wrote:
Fri Oct 27, 2017 4:37 pm
Does the weight of the flywheel make any difference in the vibration, or does the vibration remain the same and is just less noticeable?

Ken
The mass os the flywheel could make a difference, but you can think of it like a car with bad shocks; you can add weight to the card and it will bounce differently but it will still bounce.

Reducing weight on the crank if it has any useless mass on it will raise the frequency of the vibration.

If you can reduce the mass of the moving parts, then use CAD to estimate the bob-weight of the counterweights, you might be able to reduce the counterweight radius.
http://www.schmidtmotorworks.com Aerospace Machine Work: Prototypes, Tooling, Molds.

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Re: v-12 engine balance

Post by SchmidtMotorWorks » Fri Oct 27, 2017 4:55 pm

Schurkey wrote:
Fri Oct 27, 2017 2:21 pm
jake197000 wrote:
Fri Oct 27, 2017 1:33 pm
they all have the same shake.
Schurkey wrote:
Thu Oct 26, 2017 12:18 am
Is the shake from poor balance, or from uneven cylinder firing?
A 75-degree V-12 is going to shake like an odd-fire Buick V-6 due to the uneven firing impulses--unless it's got an even-fire Buick-style split-pin crankshaft.

Wild Guess: You're dealing with both problems. The engine balance is way off, and the firing impulses make it even worse.
Along those lines, the problem might be reducible with different motor mounts.
I had a 240D Mercedes that would wear out motor mounts when they went bad you would guess that a rod broke, replace the bad one and it was very smooth again.
http://www.schmidtmotorworks.com Aerospace Machine Work: Prototypes, Tooling, Molds.

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