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Author
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Topic: Underdrive pullies
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hilltim54
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Member # 10655
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posted
 
 
How do they actually wrk?? Ive seen reports that they free up 15hp on average at the rear wheels... Is this true??
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Just bcuz you lived a long life dont mean it cant come to a short end old ass nigga.
Thugnificent
Posts: 1971 | From: Oregon | Registered: Feb 2011
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Blind
2.3L
CAFords OG
Member # 3052
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posted
maybe 5hp, they do what the name suggests and make things driven by the belt spin slower, in theory reducing the amount of hp it takes to spin them especially at higher rpm's.
in real life, they make the waterpump and alternator spin slower so they both don't work as well.
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89 LX Notchback ex 4cyl, 14psi
02 Harley F150, 15psi
Posts: 8521 | From: Fairfield | Registered: Jul 2003
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hilltim54
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Member # 10655
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posted
are they even worth buying??
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Just bcuz you lived a long life dont mean it cant come to a short end old ass nigga.
Thugnificent
Posts: 1971 | From: Oregon | Registered: Feb 2011
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MauriSSio
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Member # 9943
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posted
depends on the car but i dont think theyre worth it on a high powered street car. you give up some cooling efficiency and tax the alternator more. I think the only underdrive pulley worth getting would be the power steering one.
Posts: 503 | Registered: Apr 2010
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warhorse58gt
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Member # 7702
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posted
yes they are worth it.. ![[patriot]](graemlins/patriot.gif) still one of the cheapest mods you can do.. even if it's only 5hp. you get 5hp for what $60 bucks.. that is a damn good $ per hp..
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WOLFPACK RACING
With guns, we are 'citizens'. Without them, we are 'subjects'.
83gt 354ci sbf 9.40 @ 143
77 cobra 2 171ci 97hp of pure fury!
Posts: 4200 | From: 209 | Registered: Jun 2007
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Blind
2.3L
CAFords OG
Member # 3052
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posted
I wouldn't run them on a foxbody with over 300hp, a stock h/c/i bolt-on foxbody? for sure go for it, helps get every little bit out of it.
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89 LX Notchback ex 4cyl, 14psi
02 Harley F150, 15psi
Posts: 8521 | From: Fairfield | Registered: Jul 2003
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phildog
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Member # 1214
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posted
The only underdrive pulley with which I have had problems was an underdrive pulley on a stock 5.0 alternator. It would not charge at idle. And I have never had a cooling system that was so on the ragged edge that spinning the water pump slower made any difference to coolant temps.
Why not put u/d pullies on a high power motor? Parasitic drag is a constant enemy, so I fail to understand why I would want u/d pullies on a 200hp snoozer but not on a built race motor? A racier motor is gonna be spun higher in the rpm band, so I would want to run u/d pullies to avoid over spinning the accessories.
Posts: 1554 | From: 510 | Registered: Apr 2002
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Blind
2.3L
CAFords OG
Member # 3052
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posted
personally I want the waterpump to spin as much as possible, I see foxbodies overheating at the (open) track all the time that have a ton of bolt-ons and a stock cooling system.
for a straight line car, doesn't really matter. But for something with sustained high load running...I want that waterpump and alternator to spin as fast as possible.
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89 LX Notchback ex 4cyl, 14psi
02 Harley F150, 15psi
Posts: 8521 | From: Fairfield | Registered: Jul 2003
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MauriSSio
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Member # 9943
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posted
quote:
Originally posted by Blind:
personally I want the waterpump to spin as much as possible, I see foxbodies overheating at the (open) track all the time that have a ton of bolt-ons and a stock cooling system.
for a straight line car, doesn't really matter. But for something with sustained high load running...I want that waterpump and alternator to spin as fast as possible.
+1 i agree. also on a high hp build thats driven on the street, you dont want to hinder the alternator thats trying to keep your high flow electric fan on while its pulling all those amps at idle. same with the water pump.
Posts: 503 | Registered: Apr 2010
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phildog
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Member # 1214
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posted
I can see both of ur points, but from a stock component standpoint. That was the question of the op, so I'm just gonna leave it at that.
Posts: 1554 | From: 510 | Registered: Apr 2002
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ddarkslayer
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Member # 10688
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posted
I wouldn't run them period. If I did I would keep the stock alternator pully.
Posts: 307 | From: Folsom | Registered: Feb 2011
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MauriSSio
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Member # 9943
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posted
quote:
Originally posted by phildog:
I can see both of ur points, but from a stock component standpoint. That was the question of the op, so I'm just gonna leave it at that.
true, but you know how all this starts!!!
Posts: 503 | Registered: Apr 2010
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phildog
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Member # 1214
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posted
Ok, ![[Big Grin]](biggrin.gif) I'll play along then.
If we are stuck with low-buck stock junk, aka 60amp alternators and stock water pumps, then yes, spin the beegeezus out of them with stock pullies to keep the electrical and cooling systems alive. But you do know that these systems should be upgraded BEFORE the motor.
Now on a built motor that is gonna be rung to 7k on a regular basis and that rpm maintained for extended periods, aka open track, then I want to slow down my 140amp Alternator and Eddy water pump, but I know that past their efficient rpm ranges, I am only burning up bearings and cavitating the cooling system. High output parts are designed to be more efficient, and do not require the bearing-killing rpms and power loss due to the lack of under drive pullies.
So I am going to keep my u/d pullies on the car.
[ March 23, 2011, 05:43 PM: Message edited by: phildog ]
Posts: 1554 | From: 510 | Registered: Apr 2002
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Blind
2.3L
CAFords OG
Member # 3052
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posted
you need to shift up to the next gear if you're buzzing along at 7k all day long
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89 LX Notchback ex 4cyl, 14psi
02 Harley F150, 15psi
Posts: 8521 | From: Fairfield | Registered: Jul 2003
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warhorse58gt
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Member # 7702
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posted
quote:
Originally posted by Blind:
you need to shift up to the next gear if you're buzzing along at 7k all day long
lol nope.. i spin mine to 7k all day.. last build i was shifting @ 8k.. but i guess if you got a pos stock motor you won't even run under drive pullies on.. i guess you should shift it..
i run under drive pullies on all my cars.. even my dart block race motor.... hell if i could find a cheap set.. i'd put them on my 97hp 77 mustang..
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WOLFPACK RACING
With guns, we are 'citizens'. Without them, we are 'subjects'.
83gt 354ci sbf 9.40 @ 143
77 cobra 2 171ci 97hp of pure fury!
Posts: 4200 | From: 209 | Registered: Jun 2007
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racsirx
CAFords OG
Member # 1710
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posted
Underdrive pulleys work great, but I do recommend to upgrade to a 130amp alternator, even with a smaller than stock pulley on a stock 75amp alternator, it doesn't charge well.
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88 Saleen #564
88 GT 331 NOVI2000
88 Coupe TURBO 9.75@142
95 Cobra R #75-SOLD
06 F250
13 BMW AH3
17 GT350 #5556
GOD'S NOT DEAD
Posts: 20750 | From: Concord & Pittsburg, CA | Registered: Aug 2002
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Egocentric
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Member # 9529
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posted
I would get an oversized pully for alt & UD crank and call it a day.
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08 G37S
72 C10 Custom
R6
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ain't no one tell me what to do. - NEIGHT
Posts: 1712 | From: NoOneTellMeWhatToDo-Neight | Registered: Oct 2009
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