Undredrive pulleys
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: Undredrive pulleys (JPLT1)
Pros:
-less parasitic drag on the crank
-quicker spin up
Cons:
-lower charging, if overdrive is not used on alternator pulley
I have the March Power & Amp set with only the crank pulley installed. Charging is OK with accessories on. I didn't measure any HP gain but was having troubles with false knocks pulling timing when this mod was done. However, the motor does seem to rev up faster.
-less parasitic drag on the crank
-quicker spin up
Cons:
-lower charging, if overdrive is not used on alternator pulley
I have the March Power & Amp set with only the crank pulley installed. Charging is OK with accessories on. I didn't measure any HP gain but was having troubles with false knocks pulling timing when this mod was done. However, the motor does seem to rev up faster.
Drifting
Joined: Aug 2001
Posts: 1,979
Likes: 0
From: Portage Mi
Re: Undredrive pulleys (65Z01)
I've heard about this under charging issue, but I'm wondering how it relates
to what kind of gear you're running. It just seems like a car with a 2.59 would
have more trouble than one with a 3.07 or an even taller gear like a 3.73. Can
anyone confirm this?
to what kind of gear you're running. It just seems like a car with a 2.59 would
have more trouble than one with a 3.07 or an even taller gear like a 3.73. Can
anyone confirm this?
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: Undredrive pulleys (Black 'n Blue)
I don't think gearing is an issue here (I have 2.59 gears). At, idle with accessories on, I get about 12.0-12.5Vdc; once up to 1k RPM charging is back up to 13.5Vdc.
Le Mans Master
Joined: Oct 2001
Posts: 5,302
Likes: 2
From: Atlanta GA
Re: Undredrive pulleys (JPLT1)
Personally, I would not do it, as I have a 400 + watt (continuous) stereo system (see sig). Driving around Hattiesburg (home of USM) there is quite a bit of stop and go (especially w/ all the god forsaken lights here - I have never seen so many). During the day it is not a problem. Night is a different story. As I do not have a capacitor, my healights dim noticeably and if I have my wipers on, they operate slower. This is w/ a stock pulley/alternator. I dont' think the slight if any gain in underdrive pulleys would be worth driving w/ candle lights for headlights at night. Just my $0.02. :cheers:
[Modified by dtorc4, 7:11 PM 10/14/2001]
[Modified by dtorc4, 7:11 PM 10/14/2001]
Instructor
Joined: Sep 2001
Posts: 128
Likes: 0
From: Pittsburgh PA
Re: Undredrive pulleys (JPLT1)
JPLT1
Nice car!!! When you you upgraded your stock foglights what fuse did you replace? And where is it located? I've been trying to figure it out and nobody has been specific about which fuse they replaced. I have a 91 and I'm pretty sure our fuses would be the same. Also what bulb did you replace the stock ones with?
Nice car!!! When you you upgraded your stock foglights what fuse did you replace? And where is it located? I've been trying to figure it out and nobody has been specific about which fuse they replaced. I have a 91 and I'm pretty sure our fuses would be the same. Also what bulb did you replace the stock ones with?
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Racer
Joined: Oct 2000
Posts: 476
Likes: 0
From: Socorro New Mexico
Re: Undredrive pulleys (JPLT1)
I've been running the MAD 22% underdrive crank pully for a few years now and have not experienced any problems (~50K of driving with it). I picked up about two miles per gallon, that must translate into something. The water pump, alternator, ps pump, AC and idler pully are all spinning slower. I have not experienced any overheat or under charge problems. At idle the voltage output is down, but I do not idle for long (stoplights, etc). Once the rpm is up to about 1000, everything is nominal. I do not think the alternator pully is necessary based my prolonged experience.