1990Z71Swede
I'm Awesome
You don't HAVE to, but you probably should.
A 90 degree V8 is balanced somewhat similar to a single cylinder engine, so in the following example, just think of it as just a single cylinder engine
The idea of balancing is to counteract the g force of the rod and piston changing direction at TDC and BDC to reduce bearing load and engine vibration.
Now if you try to do this by letting the counterweight have the same mass as the piston and rod, it will be perfectly balanced at TDC and BDC but terribly out of balance mid stroke. Thats why Single cylinder engines and 90 degree V8's use a "balance factor" of normally 50%. That means only 50% of the reciprocating weight is balanced out. Making it equally out of balance at mid stroke & top and bottom dead center.
Changing the rod and piston combo will most likely change the balancing, but as long as your new bob weight end up close to that 50% balance factor you are fine... l would assume 48-52% is probably close enough with some margin.. (High rpm engines are sometimes deliberately overbalanced).
A smooth running engine is soooo much more than just a perfect 50% dynamic balance at a constant rpm in a balancing machine.
Just remove a plug wire and see what happens
A 90 degree V8 is balanced somewhat similar to a single cylinder engine, so in the following example, just think of it as just a single cylinder engine
The idea of balancing is to counteract the g force of the rod and piston changing direction at TDC and BDC to reduce bearing load and engine vibration.
Now if you try to do this by letting the counterweight have the same mass as the piston and rod, it will be perfectly balanced at TDC and BDC but terribly out of balance mid stroke. Thats why Single cylinder engines and 90 degree V8's use a "balance factor" of normally 50%. That means only 50% of the reciprocating weight is balanced out. Making it equally out of balance at mid stroke & top and bottom dead center.
Changing the rod and piston combo will most likely change the balancing, but as long as your new bob weight end up close to that 50% balance factor you are fine... l would assume 48-52% is probably close enough with some margin.. (High rpm engines are sometimes deliberately overbalanced).
A smooth running engine is soooo much more than just a perfect 50% dynamic balance at a constant rpm in a balancing machine.
Just remove a plug wire and see what happens
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