Crank Pulley
03-01-2007 | 06:22 PM
#1
Thread Starter
Member
Joined: May 2006
Posts: 32
From: Arcadia, CA
Crank Pulley
Hi guys whats up? I am looking into putting a Perrin Crank pulley on my box. Now my question is since its a different pulley would I have to get a different size belt to make up for it? thanks!
03-02-2007 | 12:53 AM
#6
Senior Member
SL Member
Joined: Aug 2005
Posts: 144
Over 5 years of use in real world applications from street to road course to rally to dragstrip, Unorthodox Racing lightened underdrive crank pulleys on average can provide gains of 5 to 12 HP and 4 to 8lbs.-ft. on normally aspirated engines and 8 to 16 HP and 8 to 18lbs.-ft. on forced induction engines. These are average gains. Power gains are obtained in two ways. First is the weight loss. An average of 2.7 HP is gained from every pound lost off the crank shaft. 85% of UR gains are from weight loss. The rest of the gains are from underdriving, which accounts for about 15% of the total gains. All of UR underdriving is done with the crank pulley, not the accessory pulleys. This is done so maximum weight loss can be achieved at the crank where most of the horsepower gains are found. Ultra Street lightened underdrive crank pulleys provide excellent power gains for little investment.
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