Crankshaft weights?

[ItsVince725]

I heard something from a friend about cars having extra weights added to the crankshaft to make the engine smoother, and that these weights apparently rob the engine of power.

Is this a thing, and if it is, does my 3100 SFI have them?

[pocket-rocket]

Every engine has counter weights on the crank. If they didn't, your engine would shake itself to pieces. If you want your engine to run smoother (and it already has a clean bill of health) have the rotating assembly balanced if you have plans on a rebuild. Not only will this make your engine run smoother, but it will free up a little horse power and allow your bottom end rev higher safely.

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[caffeine]

I've heard of knife-edging the counterweights as well but I have no idea what kind of a difference it makes.

[pocket-rocket]

Knife edging is to help the counter weights slice through the air/oil mist to reduce drag and pick up a little power by reducing parasitic drag.

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[ItsVince725]

I see my friend was full of crap. XD

Well, thanks anyway.

[caffeine]

Maybe he was talking about balance shafts?

[pocket-rocket]

Not totally.

Sometimes when a crank is balanced weight has to be added in spots to balance out.

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[ItsVince725]

Maybe he was talking about balance shafts?

Could be...but I didn't think you could even remove those.

[caffeine]

I think you can on certain engines. I've heard of removing them on later quad 4s and other 4 cylinders.

[ItsVince725]

I think you can on certain engines. I've heard of removing them on later quad 4s and other 4 cylinders.

My friend did once have a DOHC Dodge Neon R/T, so perhaps with the Chrysler DOHC four you can actually do that.

But probably not with a 60 degree V6.

[caffeine]

60 degree V6s don't have balance shafts

[ItsVince725]

60 degree V6s don't have balance shafts

Wow, I didn't know that.

[robertisaar]

60V6: naturally smooth.

90V6: naturally unbalanced.

the LQ1 has an intermediate shaft, but i wouldn't call it a balance shaft. seems to be more for driving the oil pump than anything.

the newer DOHC (high feature) 60V6 MAY or may not have them, i haven't looked at them in a while.



also, removing weight from the crank(without considering inner-engine aerodynamics) will essentially be the same as lightening the flywheel/flexplate. it's just taking weight out of the rotating assembly.

[pocket-rocket]

the LQ1 has an intermediate shaft, but i wouldn't call it a balance shaft. seems to be more for driving the oil pump than anything.

And drive the timing belt.

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[robertisaar]

ehh... i forgot that the LQ1 has the crank drive the timing chain, which drives the int shaft which drives the cams...

i'll learn of the LQw1n soon enough.