Balance shafts

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ema1, Feb 13, 6:33am
This will explain it all with 4cyl inline engines.
https://www.youtube.com/watch?v=hwigSbyQ7AI

ema1, Feb 13, 6:35am
Horizontally opposed does that also.60degree V6 & V12 also.
A 90degV6 with paired journals are odd firing engines but later revised ones with off set journals a 90degV6 is even firing.
A la the difference between the Buick 3.8 V6 early editions compared to the later GM Buick and Holden /Buick derived 3.8 V6 with offset crank journals.
90 deg V6 were cheap adaption design of what essentially began as a V8 but with 2 cylinders chopped off.
Same thing was done with the PRV 2.8 litre V6 as in B28 odd fire and B280 even fire Volvo V6 engines.
Douvrin engines originally designed the the PRV V6 as a V8 but revised it to a V6.

tintop, Feb 13, 6:45am
Go Ducati !

ema1, Feb 13, 6:49am
The balance dynamics of the Lancia narrow V engines
(around 12.5-13 degree) would be an interesting study as would the weird W design engines from VAG Group?

mechnificent, Feb 13, 7:00am
Interesting Ema ?

It would give me a major headache.

ema1, Feb 13, 7:00am
This will explain the V angle engine design implications.
http://www.caranddriver.com/features/the-physics-of-engine-cylinder-bank-angles-featureThis link explains the forces and dynamics of engine balancing. http://www.tonyfoale.com/Articles/EngineBalance/EngineBalance.pdf
Some folks will understand but there will be those who can't get their heads around the above theory facts. at all.

mechnificent, Feb 13, 7:08am
Ha. I'm not even going to try.
I am an automotive engineer, and I was taught about balance. never needed to know it yet though. And I think I'll keep it that way.

That smooth running Roller that Sr was describing. it will be so smooth because the crank weighs about three hundred pounds and the pistons and rods only weigh fifty. and the whole motor weighs a half ton and absorbs the rest of the vibration.

The theories are only half the story.

ema1, Feb 13, 7:12am
Mathematics applied to the " balancing of inertia forces" it's even more complicated in internal combustion engines considering all the various designs out there.
I studied a lot of the design and dynamics of engine design theories years ago to a fairly advanced degree but . that was years ago and the memory has to be jogged considerably which I'm not about to do now again to regain what I had on board way back.
Did a lot on steam & gas turbine design + by pass turbine design study theory stuff back then too.
http://www.codecogs.com/library/engineering/theory_of_machines/balancing-of-inertia-forces.php

mechnificent, Feb 13, 7:29am
Ahhh

Stop it Ema. stop it .

twincam1, Feb 13, 7:36am
5 cylinders inline are smoother than a six. Perfect balance.

tintop, Feb 13, 8:39am
Um - good, but not perfect.

http://www.academia.edu/4682393/Dynamics_3_Assignment_Balancing_inline_5_cylinder_engines_Contents

An interesting read, a wee bit technical without having to stop and think though.

And a not unsurprising conclusion at the end :)

sr2, Feb 13, 9:49am
Easy to understand article on crankshaft design.
http://www.e31.net/engines_e.html

gsimpson, Jun 19, 6:48pm
It is the 4 stroke six or 2 stroke three that has inherent balance.
I have a 5 cylinder car but it has a counter rotating shaft (very smooth too)