do underdrive pulleys really help? Options

[nate95]

Just curious if any body had put an underdrive pulley on there car, and how much of a difference it made, or how much HP you gained,, thanks.

[Bitter]

pulleys need to be balanced as well, not to mention that most crank pulleys have a rubber dampener that helps to absorb vibrations so you dont get erroneous misfire codes.

its about DSM's but can be applied to most any other motor http://www.machv.com/tip11cranpul.html

This post has been edited by Bitter: Aug 11, 2006 - 1:16 AM

[Kwanza26]

pulleys need to be balanced as well, not to mention that most crank pulleys have a rubber dampener that helps to absorb vibrations so you dont get erroneous misfire codes.

its about DSM's but can be applied to most any other motor http://www.machv.com/tip11cranpul.html

All gospel... at least when it comes to toyota engines. Those "rubber damners" do absorb vibrations... but it's nothing more than glue for the most part. If it were such a big deal, little things like over tightened drive belts, slightly overtorqued/undertorqued pressure plate bolts, grease build up... would all upset the crank balance. I've run underdrive pulleys on damn near every performance engine we've built at my shop... and never had a problem for 8 some odd years. Myth. There's a lot more needed to upset the crank balance than a crank pulley weighing a few pounds less. Hell... driving the car hard upsets the crank balance more than an underdrive pulley...