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What size pulleys for endurance racing?

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Hurst390 View Drop Down
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    Posted: Feb/04/2012 at 3:16pm

 What size pulleys do you guys run on your AMC engines for cooling...stock? underdrive? tell me what works in road race or circle track..Thanks

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Post Options Post Options   Thanks (0) Thanks(0)   Quote His68Hers71 Quote  Post ReplyReply Direct Link To This Post Posted: Feb/04/2012 at 6:46pm
There are many people with more knowledge than me on this form. But I stay stock had a underdrive once and kept eating up water pumps. Don't understand why maybe to much torque even though it was turning slower. Run factory 71 pulleys no problem at 5 plus grand.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote amcglass Quote  Post ReplyReply Direct Link To This Post Posted: Feb/05/2012 at 8:06am

not trying to be a smartie pants here but eating up waterpumps  could be in the tightness of the belts.    Ive seen it many times if the belt is TOO TIGHT plus the torque causes issues

just food for thoughtSmile

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Hurst390 Quote  Post ReplyReply Direct Link To This Post Posted: Feb/20/2012 at 4:45pm
Thanks for the replies..I Spoke with Barry and he gave me a baseline to start with...
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 74Bubblefender Quote  Post ReplyReply Direct Link To This Post Posted: Feb/20/2012 at 5:56pm
From what we have sold in the last 10 years, 20% crank seems to be the norm on guys who are street racing. I would say maybe 80 racers out there in the world that have ordered 20% just for endurance.
We are just about to forge new AMC V8 crankshafts.. please check here
http://www.bulltear.com/forums/showthread.php?19564
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Hurst390 Quote  Post ReplyReply Direct Link To This Post Posted: Nov/23/2018 at 10:14am
Several years later....I tried a reduction crank pulley and it ran cool at WOT but on yellow flag's it heated up. I found using chevy 1-1 pulleys is the best all around set-up for cooling. It runs 190 all the time
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 304-dude Quote  Post ReplyReply Direct Link To This Post Posted: Nov/23/2018 at 11:28am
oddly enough pulley sizes are scattered on who uses what on their engines.

NASCAR R07 engines from ECR used a dual stage 6.4" water pump pulley with a 7.4" diameter for steering pump drive.

Assuming 8k to 9k RPM ranges are 85% of operation during a race,  water pump will be not over driven. Most race power steering pumps have variable pressure settings.  So no need to under drive with a 5.5" pulley.

Most NASCAR Ford engines use 5.5" or abouts, on the water pump pulley with the second stage to the power steering pump of the same diameter. Assuming an aluminum C-III pump is used or they are using lower pressures on their steering pumps, and sticking with It. 

For myself, I am under driving a police alternator which at stock will produce 100A @ 1500 RPM.  Being under driven 80A should be at 1500 RPM.  An alternator will always need under driven if going all out above 80% of the time.

Water pump can be 1:1 as there is a limit to flow effecting pump spin. Once RPM is too great pumping effect is wasted into force against ability to spin, thus effecting engines efficency. 


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