What size pulleys for endurance racing?
Printed From: TheAMCForum.com
Category: Competition
Forum Name: Autocross, circle track
Forum Description: Ralleys, autocross, non-drag racing events and conversations
URL: https://theamcforum.com/forum/forum_posts.asp?TID=36573
Printed Date: Apr/18/2024 at 6:35am
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Topic: What size pulleys for endurance racing?
Posted By: Hurst390
Subject: What size pulleys for endurance racing?
Date Posted: Feb/04/2012 at 3:16pm
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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 ------------- SC/Hurst Rambler 11.62 120 100% Street Legal |
Replies:
Posted By: His68Hers71
Date 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. |
Posted By: amcglass
Date Posted: Feb/05/2012 at 8:06am
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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 thought ------------- Javmanpres BBG Mark Donohue 401 74 Jav/AMX 71 Matador 2dr sedan delivery wagon 1902 Rambler Runabout 70 T/A Javelin |
Posted By: Hurst390
Date Posted: Feb/20/2012 at 4:45pm
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Thanks for the replies..I Spoke with Barry and he gave me a baseline to start with... ------------- SC/Hurst Rambler 11.62 120 100% Street Legal |
Posted By: 74Bubblefender
Date Posted: Feb/20/2012 at 5:56pm
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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 |
Posted By: Hurst390
Date Posted: Nov/23/2018 at 10:14am
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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 ------------- SC/Hurst Rambler 11.62 120 100% Street Legal |
Posted By: 304-dude
Date Posted: Nov/23/2018 at 11:28am
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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. ------------- 71 Javelin SST body 390 69 crank, 70 block & heads NASCAR SB2 rods & pistons 78 Jeep TH400 w/ 2.76 Low 50/50 Ford-AMC Suspension 79 F150 rear & 8.8 axles Ford Racing 3.25 gears & 9" /w Detroit locker |