Track Tommorrow! Proof underdrive pulleys make a difference

Daniel50 · May 20, 2005

well going to the track again tommorrow. my first time out i went 14.2@97mph. My only mods since then are mac underdrive pulleys, a/c delete kit, and smog pump by pass. the 50 resto off road accesory kit. lets see what it does. ill post results tommorrow night.

Philstang · May 20, 2005

I'll hold you to that...

Blakthorn · May 20, 2005

interested to see if theres any change as well, dont forget to post

Maryland Stang · May 20, 2005

I'll bet that you pick up a tenth or two. I put full exhaust and a K&N panel in my car and felt nothing. That was 500 bucks to make it sound nice. Then I spent 60 bucks on MAC underdrives and got a nice little "seats of the pants" kick.

millhouse · May 20, 2005

Keep in mind too that changes in weather can make just as much of a difference in et as those pulleys.

stang22 · May 20, 2005

This is subject to criticism though. I could see it if you had it strapped down on a dyno, do your mods and then dyno again, but hopefully your time slip will tell. Good luck!

Tim

Aliate X · May 20, 2005

millhouse said:
Keep in mind too that changes in weather can make just as much of a difference in et as those pulleys.

Agreed, I think theres just too many variables to accurately show that underdrives cut a tenth off your quater.

Curse · May 20, 2005

Good Luck

mackey · May 20, 2005

U/D pulleys help alot. Especially if you have the right ones. I gained quite a full with my ASP pulleys. The difference is I dont' have a full charge on my battery until 950RPMS.

Aliate X · May 20, 2005

mackey said:
U/D pulleys help alot. Especially if you have the right ones. I gained quite a full with my ASP pulleys. The difference is I dont' have a full charge on my battery until 950RPMS.

so they really do make that much of a difference? you just have less of a charge on your alt, which isnt a problem unless your running a big sound system, right? Im not sure how much power my 255lph pump sucks up.

Daggar · May 20, 2005

The MOST I've seen pullies make on an ACTUAL dyno test is bwtween 3 and 8 HP. Your money is better spent on an electric fan (the stock fan in combination with underdrive pullies is where the majority of the HP comes from when installing under drive pullies). If you've already got an electric fan and decide that you still want to do pullies then your HP increase will be negligible and you'd still have to overdrive the alternator in order to keep up with the electric fan to offset the under drive pulley.

What a waste.

D347643 · May 20, 2005

"""you'd still have to overdrive the alternator in order to keep up with the electric fan to offset the under drive pulley."""

I totally disagree with that daggar....overdriving your alt to keep up with an elec fan? unless its something like a mk8 then the black magic fan or the flex fans can be used with a stock alt and underdrive pulleys and have no charging probs at idle. (uless you are rockin the 3inch crank pulley from ASP) I know this because ive been through 2 dif elec fans and 2 dif sets of pulleys with different underdrive percentages but never an overdrived alt. I wouldnt even know where to get an overdrive alt pulley let me know though cause my buddy needs one.

Daggar · May 20, 2005

You must be one of the lucky few who have not had charging problems resulting from underdrives. Smack an increased electrical load on top of an already diminished power supply and whaddya get?

Speeds8erM-1 · May 21, 2005

Put a real alternator on and dont use the underdrive alternator pulley. The big gains come from the crank pulley and some from the water pump pulley, the alternator pulley isnt doing jack, unless it's aluminum and lighter, even still, easy way to avoid alot of charging problems is dont underdrive the alternator.

shonoff · May 21, 2005

Daniel50 said:
well going to the track again tommorrow. my first time out i went 14.2@97mph. My only mods since then are mac underdrive pulleys, a/c delete kit, and smog pump by pass. the 50 resto off road accesory kit. lets see what it does. ill post results tommorrow night.

Someone didnt post their results as promised

sn9550 · May 21, 2005

Daggar said:
The MOST I've seen pullies make on an ACTUAL dyno test is bwtween 3 and 8 HP. Your money is better spent on an electric fan (the stock fan in combination with underdrive pullies is where the majority of the HP comes from when installing under drive pullies). If you've already got an electric fan and decide that you still want to do pullies then your HP increase will be negligible and you'd still have to overdrive the alternator in order to keep up with the electric fan to offset the under drive pulley.

What a waste.

My opinion exactly! Be careful with the alternator pulley.

Maryland Stang · May 21, 2005

Well fellas, I have been using my underdrives for over a year now on an old battery. The charge voltage goes to about 8 volts at idle and picks up to 14.3/6 volts at 1,200 RPM. I guess I haven't had any problems because I don't let my car sit and idle for hours on end. I start it, roll the power windows down and drive it. In the winter I start it, turn on the defroster at full blast, wait for the windshield to clear and drive it. I'm guessing that if you are having charging issues with underdrives then you would have probably had issues with the stock alternator anyway. The couple of minutes it sits with a low voltage charge isn't going to kill a good battery. Pulling 250+ amps out for 5 seconds by turning the starter will pull more reserve than letting it idle for 5 minutes at 8 volts.

Daniel50 · May 21, 2005

results! http://forums.stangnet.com/showthread.php?t=547545

Track Tommorrow! Proof underdrive pulleys make a difference

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