Underdrive Pulley Queston
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Junior Member
Joined: Aug 2001
Posts: 9
Likes: 0
From: Kingston,Ontario Canada
Underdrive Pulley Queston
I've heard stories about under-drive pulleys causing charging and cooling problems on daily drivers. But they were from using 2 and 3 pulley systems.
What effect would, using only, an under-drive crank pulley have on the alternator and water pump operation?
And could you expect any performance gains?
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1985 Z28
305 LG4/700R-4
bone stock right now
What effect would, using only, an under-drive crank pulley have on the alternator and water pump operation?
And could you expect any performance gains?
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1985 Z28
305 LG4/700R-4
bone stock right now
Supreme Member
Joined: Jun 2001
Posts: 1,522
Likes: 0
From: Indianapolis IN
It doesn't matter wheather you increase the accessory pulley size or decrease the crank pulley size. The end result is that the accessories spin slower. This is where the power gain comes from. It takes less torque to turn the accessories.
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iTrader: (4)
Joined: Dec 2000
Posts: 861
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From: ILL
Car: 1986 Pontiac TA
Engine: 383
Transmission: 700R4
Axle/Gears: 3.70
I had charging problems with my original March pulley set. I have since switched to their "Power and Amp" pulleys and have no charging problems any longer. What they did was change the diameter of the alternator pulley that allows the alt to spin faster.
www.geocities.com/dzperf
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D&Z Performance
"Putting Power to the Pavement"
www.geocities.com/dzperf
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D&Z Performance
"Putting Power to the Pavement"
Senior Member
Joined: Mar 2001
Posts: 953
Likes: 0
From: LONGVIEW TX . USA
IMHO underdrive pullys are a waste of money and time. Do some reserch and talk to people with the third gens and most can tell you the best bang for the buck mods on the market.
good luck.
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97 formula w/6speed,cags skipshift eleminator, hurst billet pro shifter, 30#injectors,adjustiable fuel presure regulator,Moroso cold air induction,ported mass air sensor,accell300+ ignition box, accell 9000 wires, bosch platnum4 plugs,flomaster crossflow muffler,Lingenfiter 52mm throttle body,TPIS L98 SuperProfile cam,Crane 1:6 full roller rockers,Edelbrock subframe connectors,Edelbrock strut tower brace.
Other car is a 89 GTA w/700r4w/stage 2 shift kit, corvette servo, B&M mega shifter, TPIS bigmouth intake, TPIS large tube runners, TPIS 52mm throttle body,Edelbrock ported centerbolt heads,LT1 24# injectors,GMPP LT4 hotcam,CompCams Pro magnum roller rockers,Edelbrock headers, flowmaster crossflow muffler,MSD 6A, accell coil, bosch platnum plugs, this car is currently under rebuild and restoration.
good luck.
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97 formula w/6speed,cags skipshift eleminator, hurst billet pro shifter, 30#injectors,adjustiable fuel presure regulator,Moroso cold air induction,ported mass air sensor,accell300+ ignition box, accell 9000 wires, bosch platnum4 plugs,flomaster crossflow muffler,Lingenfiter 52mm throttle body,TPIS L98 SuperProfile cam,Crane 1:6 full roller rockers,Edelbrock subframe connectors,Edelbrock strut tower brace.
Other car is a 89 GTA w/700r4w/stage 2 shift kit, corvette servo, B&M mega shifter, TPIS bigmouth intake, TPIS large tube runners, TPIS 52mm throttle body,Edelbrock ported centerbolt heads,LT1 24# injectors,GMPP LT4 hotcam,CompCams Pro magnum roller rockers,Edelbrock headers, flowmaster crossflow muffler,MSD 6A, accell coil, bosch platnum plugs, this car is currently under rebuild and restoration.
Joined: May 2001
Posts: 5,244
Likes: 14
From: Sac, CA
Car: '89 GTA
Axle/Gears: 3.27/9-bolt
I took out a 305 camaro the other day. He probably needed a tune-up though, heh.
-88-v6-k&n-flows-jet chip-cam
Poncho - any idea how fast you are with all those mods on your GTA? I have an 88 gta along with my 6'er and i want to mod it up too. Thanks~!
-88-v6-k&n-flows-jet chip-cam
Poncho - any idea how fast you are with all those mods on your GTA? I have an 88 gta along with my 6'er and i want to mod it up too. Thanks~!
Thread Starter
Junior Member
Joined: Aug 2001
Posts: 9
Likes: 0
From: Kingston,Ontario Canada
The reason why I'm asking is because I just bought an underdrive crank pulley off e-bay because it was cheap, $8 bucks. And I don't know if I want to install it or not.
Thanks for the replys, though.
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1985 Z28
305 LG4/700R-4
bone stock right now
Thanks for the replys, though.
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1985 Z28
305 LG4/700R-4
bone stock right now
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Senior Member
Joined: Mar 2001
Posts: 868
Likes: 0
From: Randleman,NC,USA
Car: 91 Camaro RS Convertible
Engine: 385ci LT1 cnc ported heads big cam
Transmission: 4L60E automatic
Axle/Gears: 3.42 Zexel posi 7.5" rear
If your just running 2.73 gears your car might not turn enough RPM to keep a good charge going. If you your running in the 3.x's you should be fine. I ran my car 6 months with just crank pulley and it was fine. Thought motor reved faster with pulley.
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91 Camaro RS 5.0L Black Convertible 700R4
** Added so far **
*GM Wonderbar,Alston SFC's,spohn LCA's and Panhard rod
*Turbo City Inj Spacer
*Dual Snorkel Air Filter
*March Performance Pulleys
*GM 3.42 Gears with OEM Zexel POSI
*Edelbrock headers
*3" High Flow Cat
*3" Dynomax Exhaust
*Walbro 255 lph Fuel Pump
***Future 330hp Vortec Crate with LT4 hotcam and 454 TBI
<p><img border="0" src="http://www.bharris.org/images/smcamconv.jpg" width="200" height="73"></p>
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91 Camaro RS 5.0L Black Convertible 700R4
** Added so far **
*GM Wonderbar,Alston SFC's,spohn LCA's and Panhard rod
*Turbo City Inj Spacer
*Dual Snorkel Air Filter
*March Performance Pulleys
*GM 3.42 Gears with OEM Zexel POSI
*Edelbrock headers
*3" High Flow Cat
*3" Dynomax Exhaust
*Walbro 255 lph Fuel Pump
***Future 330hp Vortec Crate with LT4 hotcam and 454 TBI
<p><img border="0" src="http://www.bharris.org/images/smcamconv.jpg" width="200" height="73"></p>
Supreme Member
Joined: Jul 1999
Posts: 1,431
Likes: 1
From: Huntsville, AL
Car: '00 Chevrolet Corvette
Engine: LS1
Transmission: 4L60E
Axle/Gears: 2.73
You should be alright. The two pulley sets slow down the crank and the alternator, so just a crank pulley shouldn't give you any trouble...if it does, swap 'em back.
-Mark W.
'88 SC Camaro w/ 305 TBI
-Mark W.
'88 SC Camaro w/ 305 TBI
Senior Member
Joined: Aug 1999
Posts: 950
Likes: 0
From: This spot right here --->*
Car: 2002 SOM z28
Engine: LS1
Transmission: T-56
I got a 25% underdrive crank pulley and I really don't have too many charging problems. Besides, who stays at 1000 rpms for any great length of time while driving anyways?
My main problem is the cooling problem. I have a Stewart pump, a monster Griffen radiator, and a 160F thermostat and it goes through the roof on hot days in traffic. On the highway, absolutely no problems, but if I sit for more than 10 minutes I will be at 260F and beyond! I seriously fear gridlock and rush hour traffic...
It was worth maybe a little SOTP difference at the upper rpms.
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1984 z28 w/ a 357 cu in. monster engine which is looking like the posterchild for Edelbrock with the exception of the Holley 750vac... all the suspension stuff... 9-bolt posi disk is in...
-=ICON Motorsports=-
My main problem is the cooling problem. I have a Stewart pump, a monster Griffen radiator, and a 160F thermostat and it goes through the roof on hot days in traffic. On the highway, absolutely no problems, but if I sit for more than 10 minutes I will be at 260F and beyond! I seriously fear gridlock and rush hour traffic...
It was worth maybe a little SOTP difference at the upper rpms.
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1984 z28 w/ a 357 cu in. monster engine which is looking like the posterchild for Edelbrock with the exception of the Holley 750vac... all the suspension stuff... 9-bolt posi disk is in...
-=ICON Motorsports=-
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