Underdrive pulleys with a system?

[aesic]

I'm thinking about getting underdrive pulleys but I'm wondering how they will work with my system. Its nothing big but after searching and reading it seems like people suggest that you don't have systems with underdrive pullies. I have a 4x45w Sony deck with 4 - 4x6 Infiniti Kappa's and a JL 12W0 powered by a RF 250W amp (yes, I take the sub out when I go driving). Any ideas on if the underdrives will work with this setup? I have an S13 if that matters

-aesic

*I'm not sure if this fits better under the KA forum or the Stereo forum so if its in the wrong place, please move it.

[corn322]

I say just bump the idle up to like 800 rpm

[Thee 240sx Owner]

I could have sworn that most underdrive pullies don't come with one for the altenator... but it should be that bad... UDP are a waste of time in my opinion...

[Veriest1]

Unorthodox Racing has a nice FAQ about such as this... but I can't find the link at the moment.

Quote »UDP are a waste of time in my opinion...[/quote]Why do you consider lowering rotating mass to be a waste of time?

[Thee 240sx Owner]

Because you are sacrificing one thing for another... to gain hp you loost the torque... not to mention how efficient are they really...Theres a reason for a Harmonic Balancer..

[Veriest1]

The KA is balanced internally and thus have no harmonic balancer. From what I've read few if any inline motors have an externally counterwieghted pully.

Underdrive pulleys and lightwieght flywheels don't effect the amount of torque or horsepower the engine makes. It just effects how much gets to the ground.

What you may be thinking of is how fast the revs fall off and go up once the rotating asymbly is lightened. I know on my neighbors dirtbike with a lightwieght moto-x flywheel he has a hard time climbing hills and traveling at low speed because the motor is easy to "kill." A heavier flywheel would solve the problem due to the increase in rotating mass providing more momentum and the illusion of more torque.

[Thee 240sx Owner]

http://www2.nisspartswholesale...ulley

http://www.replacementautopart....html



That is the stock CrankShaft Pulley of a KA24E motor... Complete with Harmonic Balancer
Modified by Thee 240sx Owner at 4:29 PM 8/3/2005

[240marcuSX]

im thinking about renting a billboard or a pilot with a scrolling message that says

"NISSAN KA'S HAVE NO HARMONIC DAMPENERS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!"

do you think the pilot will charge extra for all the exclamation points??

oh, and those arent really nissan affiliated sites, so just because they say "harmonic dampener", doesnt actually change what they are.

look in your fsm and find the words "harmonic dampener"

[InsanityInc]

Because you are sacrificing one thing for another... to gain hp you loost the torque... not to mention how efficient are they really...Theres a reason for a Harmonic Balancer..

Uhhhh. No.

You can't lose torque and gain horsepower at the same RPM level. It's literally impossible. Horsepower is an expression of torque over time, specifically torque*rpm/5252. An underdrive pulley increases both your torque and power across the entire range of the engine.

And that pulley doesn't have a balancer on it, just look at it for christs sake. I have no idea what you're smoking.

[JimmyMethod]

Heh heh heh...

The only issue with underdrives, is that you won't be able to compete in audio compitions...but considering the system you have, I don't think that's your focus, so you should be cool.

[nyckanny]

on my friends mx-6 he had a subwoofer, and a whole bunch of audio upgrades. he was stuck in nyc traffic at night with the windshield wipers and heatslights and radio on. he had a pully, lightened flywheel, and optima battery. during that ONE time in the nyc traffic at night, the lights started dimming. besides that, hes never had any electrical issues.

so, i think a little pully is ok.

[aesic]

I could have sworn that most underdrive pullies don't come with one for the altenator... but it should be that bad... UDP are a waste of time in my opinion...

Well I never thought of or heard of underdrive pulleys till recently. Then I came upon a link from another thread that had dyno's of before and after install of underdrive pulles (http://www.importtuner.com/tech/0210it_powerpages/). I was very supprized when the dyno said that underdrive pullies gave the car an extra 8.4 max hp and 5.1 max torque (since numbers for the 2nd dyno results are cut off, you have to open both the pully dyno and the pully+intake dyno to compare stock vs. pulley). That much gain for ~$200 seems WELL worth it, and thus, if it works with my system, I will be getting them.

(sorry about the delay in reply, work got busy)

-aesic

[Veriest1]

Keep in mind that there are different types of "underdrive pulleys." Many use a smaller crank pulley to underdrive everything and stock sized aluminum and lightened pulleys everywhere else. Some are just alminum stock sized pulleys everywhere and some use larger pulleys on the accessories to slow them down.

Know what kind you're buying. If I remember correctly UR sells a pulley set designed for sound systems. The big question is do they make it for the KA.

8.4 and 5.1 are some good gains for the price. Keep in mind that the gains from car to car may be different and when upgrading components external to the engine a new fancy unit may yield little or no gain. It just depends on how bad the factory unit is versus the new unit.

[prexcelon000]

just my 2 cents. I have steeda underdrives on my mustang and i have a near 2000w system with a 130 amp alternator, and it works just fine. however i did need to replace my belt to another stock one as it had streched out a bit. I know the engines are different but the idea is the same. so you should have no prob with a system. use a power cap if your not sure though.

[Dattebayo]

look in your fsm and find the words "harmonic dampener"

Yes, there maybe no dampeners on a KA, but the FSM does not label alot of parts that do exist and have actual names. Sorry I had to say so, but this is a bad example.

[Thee 240sx Owner]

Yes, there maybe no dampeners on a KA, but the FSM does not label alot of parts that do exist and have actual names. Sorry I had to say so, but this is a bad example.

Finally someone said it... sorry i haven't been able to post but i have an FSM thank you and i i agree with ^^^^^ for saying it... it list alot of stuff but doens't give a name for it... i can bet you that every stock oem pulley you take off has a harmonic balancer in it....

[InsanityInc]

Finally someone said it... sorry i haven't been able to post but i have an FSM thank you and i i agree with ^^^^^ for saying it... it list alot of stuff but doens't give a name for it... i can bet you that every stock oem pulley you take off has a harmonic balancer in it....

You completely missed his point, and no it does not have a harmonic balancer, nor do many engines. His point was that while a KA doesn't have a harmonic balancer, it's lack of inclusion in the FSM is not indicitive of that. Seriously, go look at your damn crank pulley, it doesn't have a balancer.