Underdrive Pulley

[SuperStock96]

I realize that installing an aftermarket underdrive pulley lightens up the load of the flywheel, but what all does it do? What is underdrive, is what I am trying to get at, I guess. Does it affect other aspects of the car? ie. Air Conditioning or the alternator

[4DSC]

"underdrive pulley systems increase engine horsepower by reducing the amount of power required to drive external accessories. For example, the alternator, power steering, water pump and air conditioner all rob horsepower from the engine. By replacing factory-sized crank and accessory drive pulleys with a resized pulley, the accessories are slowed, resulting in more horsepower available to drive the rear wheels. Typically, a set of Auto Specialties street pulleys will increase output by 12 to 15 horsepower, resulting in quarter mile time improvements of .2 to .25 seconds."

http://www.4dsc.com/articles/drivetrain/udp/udp.shtml

You may also experience a small loss of power from those accessories mentioned above. You may not. Some have, some don't know the difference. In theory, you should.

[SuperStock96]

I think I can live with that. Thanks. I guess I have something else to add onto my 'to do' list.

[4DSC]

I hear it's not a bad mod. A bit pricey for the gains in my opinion, but when your an NA Maxima, you could use all the help available. Im actually very close to getting one for my 92' VE-5spd since my crank seal has been leaking for awhile.

[SuperStock96]

I run an amp for my interior speakers and plan to add a 150W Sub soon. You don't think there will be any effect on the battery, do you? I don't run it too loud. Like I say, it is only one 150watt 10" sub.

[4DSC]

Unfortunatly I suck at electricity so I wouldn't be able to help you out with this question. Which Maxima do you have? Im guessing you have a 4th gen? You can just go to the Maxima.org forums and you will learn a million tons more about your car then you will ever learn here, trust me.

[Nahkapohjola]

Originally Posted by SuperStock96

...any effect on the battery...

Any effect: sure is.

Smaller crank pulley dia drops alt rpm. This affects alt capacity at idle: with all appliances ON, plus audio, your battery gets less charge. Is it critical, dunno. U have to calculate your loads with your utilization:

1. Seek the manual and your alt output - at different rpm's.
2. Think what is YOUR typical utilization (=rpm). Refer to 1...
3. Calculate what appliances sink: each and ALL of the Amps the car uses starting "from seat heater to fog" lamps.
4. Measure the actual Amps your addon devices drain.

- Calculate all these drains together in Amps. Deduct this from your batt 60Ah -value (Amps hour = Amperes consumed durin one hour).
- Also calculate 5A off from batt Ah -value for each startup (depends on startup lenght)
... ...during one of YOUR typical car utilization hour.

If Amps drained is more than Amps gained, you'll end in dead batt. Take also into account that during winter the COLD battery will receive only fraction what your alternator can charge. At the same time, at freezing point, the COLD battery output start-capacity has been halved, at -40 its only 10% of nominal value (depends on battery type).

When figuring these out, its essential to define how/where the car is used: worst case is when it sits out in subzero conditions without any heating, is driven short distances with all possible electrical device on full blow. On the other end of this scale, most Mexicans have none of these problems...

OTHER:
I would not seek power by changing crank flywheel or pulleys. The engine designers have gone to great lenghts in calculating & simulating the rotatin masses & crank counter weights, pistons etc with their harmonic vibration dampening properties etcetc. The tuneup parts may work well, but if not, I dont want to be near such a car as parts start to fly through the hood.

Opinion: In audio issues, I bet youre better off on some car audio page than with maxorg instant experts...

[mikedizzle]

there should be no problems unless you play it for a long period of time without the car running. My friend has two 750 watt rms pioneer premier 12's with two 800 watt amps and no problems

[4DSC]

Originally Posted by Nahkapohjola

OTHER:
I would not seek power by changing crank flywheel or pulleys. The engine designers have gone to great lenghts in calculating & simulating the rotatin masses & crank counter weights, pistons etc with their harmonic vibration dampening properties etcetc. The tuneup parts may work well, but if not, I dont want to be near such a car as parts start to fly through the hood.

The new pulleys do come balanced and sleeved. I don't know about the VQ, but on the VE, I have never heard of any problems, ever. They've been used for many years.

Originally Posted by Nahkapohjola

Opinion: In audio issues, I bet youre better off on some car audio page than with maxorg instant experts...

[Ceasars Chariot]

had mine for years, not a moments trouble, wouldnt expect a .2 out of maxima, not even a .1 with the 4th gen.

[Nahkapohjola]

Originally Posted by 4DSC

...I have never heard of any problems, ever. They've been used ...

I've read also about exploding cases, cut crank end. Cannot argue this or that way, cause no experience ...I dont think its a common problem, but has to be noted as any hazard.

Dead batt happens. I installed digital temp/Volt gauge, still happens. (And my max has 'no audio', silence is the hi speed soundbite.) When batt is dead, THE click is most annoying sound. If/WHEN mama or me leaves cabin light on for two days; then noclick: stupid nissan, why have special daylight electronics box if it cannot guard against humanity?

.

[SuperStock96]

Thanks, I just saw that Unorthodox makes a lightweight pulley that is the stock diameter and weighs 3.00lb compared to the underdrive version that weighs 2.00lb. Isn't the equation something like 5hp at the crank for every pound lost there?