[grandville455]

Originally Posted by slowbird

My rods weigh around 850g, crank weighs a ton, don't worry to much about weight. Use the K.I.S.S method! Imo there is next to nothing in reducing crank, rod, piston weights as far as performance goes.

Have u tried lighter stuff Brian? To me anything that helps lighten the assembly the easier to turn n less wear n stress?

[PAUL K]

Originally Posted by grandville455

To me anything that helps lighten the assembly the easier to turn n less wear n stress?

Generally that's how it starts out, the lighter the better. As you make more power you need heavier parts to stand up to the additional load. Next you have to pay the big bucks for stronger lighter parts, like ones made out of titanium.

[slowbird]

Originally Posted by grandville455

Have u tried lighter stuff Brian? To me anything that helps lighten the assembly the easier to turn n less wear n stress?

Ive had lighter rods and crank, no performance difference, in another engine we went from alum rods to steel, no performance difference. The lighter rotating assembly seem to rev quicker in neutral but that's it.

[PAUL K]

Originally Posted by slowbird

Ive had lighter rods and crank, no performance difference, in another engine we went from alum rods to steel, no performance difference. The lighter rotating assembly seem to rev quicker in neutral but that's it.

When you switched to the aluminum rods and saw no difference, were the counterweights turned down or drilled?

[slowbird]

Originally Posted by PAUL K

When you switched to the aluminum rods and saw no difference, were the counterweights turned down or drilled?

We've never had counter weights turned.
FWIW Chris U on yellowbullet has a 9000+rpm record setting bbc with 800+g rods

[PAUL K]

Originally Posted by slowbird

We've never had counter weights turned.
FWIW Chris U on yellowbullet has a 9000+rpm record setting bbc with 800+g rods

When switching from a steel rod to aluminum rods you want to turn the counterweights down rather than drilling holes when balancing the crankshaft. Any gain you might of seen from the lighter rods may have been absorbed in windage losses due to the holes machined to balance the crank. You'll also benefit from the shorter counterweight.

[slowbird]

Originally Posted by PAUL K

When switching from a steel rod to aluminum rods you want to turn the counterweights down rather than drilling holes when balancing the crankshaft. Any gain you might of seen from the lighter rods may have been absorbed in windage losses due to the holes machined to balance the crank. You'll also benefit from the shorter counterweight.

If that balance hole offsets the gains from the alum rods, then the gain was so small it wasnt going to be noticable.
Besides that how does lighter rods increase performance?

[PAUL K]

Originally Posted by slowbird

If that balance hole offsets the gains from the alum rods, then the gain was so small it wasnt going to be noticable.
Besides that how does lighter rods increase performance?

The gains or losses from different reciprocating weights are usually small but real. Manual trans guys have played with flywheel weights for decades to increase their cars performance. It's kinda like the difference between power producing atmosphere and warm temperatures with lots of humidity and low barometric pressures.