Light Weight pulleys for an SR20DET

[jr_ss]

You're not getting the point... Using anything other than an OEM, ATI or equivalent crank dampner will destroy your internals over time... Moral of the story, don't use anything but what was stated above.

[positron1]

Dinan BMW - The Dangers of Power Pulleys and Understanding the Harmonic Damper http://www.dinancars.com/bmw/t...amper

[Didderson]

Replacing your main crank pulley with a lightweight one isn't as bad as you'd think.Based on that diagram from the BMW website, most of the dampening needs to happen because of the stock flywheel. Once you replace it with a light weight flywheel, you're in way better shape to replace the front crank pulley. We know this because an unbalanced flywheel will try to put a moment or torque on the axis of the crank. This diagram from one of my mech engineering books shows the direction torque is applied by an unbalanced flywheel: (I can't find a diagram on the internet so here lol) As you can see, the moment isn't being applied around the cross sectional circle of the shaft, just making sure we're clear.

The greater the unbalanced flywheel and rpm, the greater the forces, and also, because torque=force * distance, the greater distance from the flywheel, the greater the force amplified by the unbalanced flywheel. That is why you see this graph has more amplified forces at the bearing near the crank pulley:

Nissan flywheels and crankshafts are internally balanced also, not perfectly balanced, but still it's not like an old V8.

Quoted from rogoman on nissan forums .com:"However here's a caveat to the story. Both the OEM flywheel and front pulley are designed to act as harmonic dampers. Lightened flywheels and lightened pulleys will cancel much less harmonics causing 'possible' vibrations at certain RPMs. It all depends on how well the motor is balanced; OEM balancing will always have some degree of compromised tolerance because of mass production techniques compared to a custom balance. Some OEM balanced assemblies may be better then others."

the entire thread link cannot be posted because NICO pansies don't want internet traffic to leave. go to those forums and search for 240sx has a harmonic dampener, or google it.

Basically if your front engine pulley has metal drilled out in some spots (like the flywheel or crank does) then it is balanced and shouldn't be removed until a lightweight flywheel is installed. That lightweight flywheel better be well balanced!

Arguably the stock flywheel is balanced, so I wouldn't fight too much over this topic guys .
Modified by Didderson at 7:58 AM 4/9/2009