Underdrive pulley

jdeaton · #1 (**permalink**) 03-06-2008, 06:50 PM

do they reduce the alternator output? If it does do you think i will have problems if i get one... i have the 130A alternator, and my stereo is 1250 watts RMS.

zero_chances · #2 (**permalink**) 03-06-2008, 06:54 PM

I havent talked to anyone that put them on a tundra, but i know many people have put them on mustangs. They do reduce alternator output, but on stock equipment, it usually isnt noticeable. But with your setup, i really dont know. You have one powerful audiosystem, and im not sure how much your alternator is putting out. Could probably work with a high output alternator.

GORILLA · #3 (**permalink**) 03-06-2008, 07:01 PM

i can't do it either, i have a 1800rms, plus piaa lights ,air horns, and several other gagets.
and i do have the bigger alternator 150amp.for a sequoia 4x4 with the trailer hitch.
2 batterys and a power cap,etc.
so i need ALL the amp's i have.
it would have been a good idea.
maybe i could cut out the floor board and use my feet for extra speed, like fred flintstone. just making a funny.
but thanks
gorilla

DH · #4 (**permalink**) 03-06-2008, 07:37 PM

I installed one and it only reduces the output below 1,000 rpm. At 1,000 rpm and up it is just like factory. Not sure how many amps your stereo draws but my electric fan mod draws 20 amps to cool the radiator. No problems and mo power.

Hugemoose · #5 (**permalink**) 03-06-2008, 07:55 PM

I also have the underdrive pulley on my truck. When I am sitting in traffic and the truck is at idle I will notice my lights dim. But, the second I put my foot on the gas and start moving the light immediately come back to their normal selves.

You may have an issue with giving the battery more work to do with your stereo system when sitting in traffic. But otherwise during normal driving it makes no difference.

jdeaton · #6 (**permalink**) 03-06-2008, 08:09 PM

well watts/v=I so 1250/14= 89 amps, but its probably 75% efficient so the current draw is 119 amps... well crap i guess i shouldnt get one then

gorilla, what type of audio setup do you have?

Burger Steak & Eggs · #7 (**permalink**) 03-06-2008, 11:41 PM

Go with LED bulbs on all the external bulbs (except headlights). They take a fraction of the current of a normal bulb, so the current savings will add up if you swap all of them. That should be enough to relieve the "brown out".

jamesjr4750 · #8 (**permalink**) 03-07-2008, 02:18 AM

Yup Switching to LEDs is nice, but also Expensive. Did it. I wrote a whole reply but this F'in site in screwing up at the moment ... again. And it lost it

So yeah. I've got the 1200 RMS Kenwood at 2 channels. Aftermarket Deck: 80Watts x4 with Aftermarket speakers. I switched to all LED's all around the entire truck. It looks good too. I'm running the IPF Fog lights with 55 watt bulbs. 2 KC lights with now 55watt replacement bulbs over the 130watts. And IPF X4: 60/80 headlamp H4 Bulbs now. So running all this at idle I don't see any dimming in the 770 CC Battery until I turn on the winch under at 2000 lbs of load which is drawing about 175 amps according to the WARN site and their manual. It can draw up to 480 Amps on the 9.5XP winch under full load. Alternator is 130 AMP. I don't have any underdrive pulley but I hope that can explain some draw on a system.

GORILLA · #9 (**permalink**) 03-07-2008, 05:09 AM

hi , here is some of what i have:
eclipes avn30d with all the bell & whistels CD,rear camra,HD,sirous radio,etc200watts
4 jl audio amps,500/5,500/1,300/2,300/2
3 sub's -all jl audio- stealth box 10w3-2, 10w6-2,10w7-3
3 sets of jl audio 6 1/2 dual speakers XR
1.5 capasitor
kenitik 1800 battery for system help ,i do have another battery for the vehicle
i'm sure there is more i'm forgetting, i had it installed professionaly.
everything i has a fuse to protect each item.
if you seach my post post's it's in there.
i have taken long ride's and my system has never ever shut off.
nor has the truck ever died when i was rolling.
the sound is amazing, so clystal clear.
gorilla

MKYOTA · #10 (**permalink**) 03-07-2008, 08:23 PM

Yeah the smaller pulley makes the ACC belt go slower (which is where the added power comes from) so it can be an issue especially if you have an older battery. Best thing to do is get a really good battery (Optima or something that puts out the same amps) if it actually does cause a noticable drag on your truck (I was always told that if I wanted more power than I should just disconnect the A/C instead of getting an underdrive pulley but who wants to drive around without the A/C)....oh and don't let it idle for a long time with the radio on, you will be fine as long as your driving around I am pretty sure.