Underdrive pulleys
Safety Car
Joined: Jun 2000
Posts: 4,870
Likes: 25
From: Long Island, NY
Re: Underdrive pulleys (tarheelracer)
On my car, I have the underdrive crank pulley only. It helped performance.
But, at an idle with the headlights on , my voltage drops. The interior lights go slightly dim.
Vic
But, at an idle with the headlights on , my voltage drops. The interior lights go slightly dim.
Vic
Drifting
Joined: Aug 2001
Posts: 1,606
Likes: 14
From: Vacaville, CA
Re: Underdrive pulleys (tarheelracer)
I was running the March brand of performance pully's on my '91. The kit comes with a smaller alternator pully to compensate for the smaller crank pully. Installation of the crank puly is a little trying, but you can fit a long socket extension between the pully lip and the crossmember. I had to find another size belt which required 3-4 trips to the auto-parts store to find one that fits; (Dayco 910K6). The performance increase was quite noticible "off the line" like an increase in torque. One of the best mods for very little cost. :yesnod:
Intermediate
Joined: Apr 2002
Posts: 42
Likes: 0
From: Centreville VA
Re: Underdrive pulleys (BlackRocket)
I think there are better mods out there. If you really want to do this, it is optimal to overdrive the alternater with an overdrive pulley for the alternater. Like someone else said at idle your voltage will drop and the lights can go dim because your underdriving the crank pulley. If you have or are planning any kind of stereo system in your vette be sure to over drive the alternater.
brian
brian
Le Mans Master
Joined: Jul 2001
Posts: 6,252
Likes: 2
From: Silicon Valley Kalifornia
Re: Underdrive pulleys (tarheelracer)
To compensate for the idle undervoltage, you could have the eProm reprogrammed for a higher idle. Instead of 700rpm, maybe a comfortable 950rpm? ...just an idea... :cheers:
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Safety Car
Joined: Mar 2002
Posts: 4,157
Likes: 0
From: Orange County TX
Re: Underdrive pulleys (tarheelracer)
Under drives are a waste of money. Think of it from the standpoint of what they are claiming and what really happens. Take the water pump for instance, its designed for a certian flow at a certian RPM to remove X amount of heat from the motor(granted there is a big plus or minus here). If you start to turn it slower it will pump less coolant. The thermostat is still going to open enough to cool the engine, hence you are still pumping the same amount of coolant. Some folks will say that its no longer deadheading, well with the bypasses and it being centifugal pump, the HP gain is minimal. How about the altenator?? If you slow it down, it has to work harder to keep the same charge going, the regulator will want to up the field voltage, wheres the gain?
Heel & Toe
Joined: Apr 2002
Posts: 18
Likes: 0
From: Milton MA
Re: Underdrive pulleys (Dryseals)
Wait till you install a lumpy cam and TB! Then bump the idle speed up. The new version March pullies (going back a few years alt. and crank) works fine on my 85 at idle. Idle ~ 600-650 ;-)
Phil
Phil