Pulleys

[tdy240sx]

Tax returns are coming soon and the itch has got me again! :devil

I am pondering the purchace of a set of Unothodox Pulleys.I would like to know if anyone out there has had any other or new adverse affects (aside from the posts ive already read) from thier install of these pulleys.

any help would be much appreciated!

TDY

[chandler]

ive only seen like a 10 hp increase all over

[slakker]

?ONLY? You guys amaze me. Hello the engine only has about 160. Thats like 8%. Pretty good to me

[180fan]

You may want to wait for the pulleys since UR has sales every so often. I'm waiting for another sale to get my sr's crank pulley replaced (since mine came cracked). Other than the possibility of underdriving too much or them being not so well balanced, it should be all good.

[TwinTurboPoweredZ]

I think UR pullies are a nice gain, my turbo Z gained 18hp just off a pully, but there are consiqeunces of upsetting the harmonic damper of the stock ones. They cause the crank to vibrate alot during higher rpm usage, and from what i hear that could mess up yer crank bearings and other items inside the engine. I have NOT seen hard evidence of that, but it makes perfect sense to me, im just gonna stay away from those for my S13.

[chandler]

I meant that its not gonna give you 20more horses all around, its still a good increase, and it helps in all the gears

[tdy240sx]

I think UR pullies are a nice gain, my turbo Z gained 18hp just off a pully, but there are consiqeunces of upsetting the harmonic damper of the stock ones. They cause the crank to vibrate alot during higher rpm usage, and from what i hear that could mess up yer crank bearings and other items inside the engine. I have NOT seen hard evidence of that, but it makes perfect sense to me, im just gonna stay away from those for my S13.

Can you explain in some more detail?I'm familiar with engines but I'm really more of a layman when it gets that techincal I guess.

[DAEDALUS]

Crankshafts are tuned to minimize the amount of flexing and distortion seen during operation. This includes the use of balance weights on the shaft, and the crank pulley plays a roll too, which is why it's called a harmonic balancer. Part of its job, other than to turn a belt, is to dampen out the deflections of the shaft. It's mass and moment of inertia are optimized for this function. When you go with underdrive pulleys, you decrease mass, which can help acceleration, but you also change the damping characteristics of the OEM pulley. Also, by changing diameters of the pulleys, the accessories don't turn as fast as they were designed for, and bad things can happen. The battery may die faster from a weaker alt, and the car might overheat sooner because of a lower-flowing water pump.How much do UD pulleys affect longevity/reliability and is it worth the performance upper? Impossible to say without testing and the answer is based on personal goals/desires.

[MikeMurphy]

Personally I would grab the ASP one instead of the UR. The price is about 3 times cheaper and you still get much of the performance that the UR provides.

And I have also yet to ever see an unusual trend develop around these pulleys with the KA. I would install with almost complete certainty and definitly wouldnt lose any sleep over it. There are lots of peeps who have gone over 125,000 miles on them with no ill effects.

[TwinTurboPoweredZ]

Crankshafts are tuned to minimize the amount of flexing and distortion seen during operation. This includes the use of balance weights on the shaft, and the crank pulley plays a roll too, which is why it's called a harmonic balancer. Part of its job, other than to turn a belt, is to dampen out the deflections of the shaft. It's mass and moment of inertia are optimized for this function. When you go with underdrive pulleys, you decrease mass, which can help acceleration, but you also change the damping characteristics of the OEM pulley. Also, by changing diameters of the pulleys, the accessories don't turn as fast as they were designed for, and bad things can happen. The battery may die faster from a weaker alt, and the car might overheat sooner because of a lower-flowing water pump.How much do UD pulleys affect longevity/reliability and is it worth the performance upper? Impossible to say without testing and the answer is based on personal goals/desires.

Coulndt of said it better myself, this is the fact i believe in. If you want to put a UD pully you can look for a company called Fisher, they make balanced dampeners for performance without the drawbacks, they make them for 300zx, but unsure if they do for the 240sx.

[karay240]

that's why I'm not putting an under drive pulley on my car. I had one on my last car (altima). I liked it initially, and gave it decent boost in torque, but seemed to drain the battery a little. Nothing severe, but just wasn't too happy w/ it. The AC kinda sucked, too. Living in the south w/out a powerful AC isn't too much fun. lol.I agree w/ MikeMurphy in getting the ASP if you still intend on getting one. They are A LOT cheaper, and, from what I understand, the ASP doesn't underdrive the AC. Of course, this doesn't matter if you don't deal w/ hot summers.As to what DAEDALUS said about the car overheating, it depends on how you drive your car. Stock pulleys are designed w/ the average user in mind. This means normal daily driving. The stock one, although well designed for traffic jams, may have the tendency of cavitation during continuous high rpm usage. This also causes overheating, so it really depends on how you use it. I'll probably think about getting one if I was going to balance the internals, but doesn't seem like the best thing to do on a otherwise stock motor.

[tdy240sx]

First, Thanks alot for everyones help. You've all been educational!

Lemme get a couple things straight.

If I get the ASP crank pulley, I wont have to worry about underdriving my accessories right? I live in the south, so I need to keep my engine cool hence i dont really need to UD the water pump. I am also running a 500 watt amp in back so it's probably not a good idea to UD the alternator. As far as the AC goes I really dont use it that much.

I guess that nixes the set of UD pulleys.

Any ill effects of an ASP crank pulley are speculative at best correct? It could throw off engine balancing but nothing has been proven concrete...

So I've still not ruled out the ASP crank pulley

[MikeMurphy]

I understand the ASP pulley to simply be a smaller diameter hub that goes on the crank. Smaller diameter => runs all accessories slower. Its also very light.

This will be going on my 240 this summer and im not worrying one bit. If you want, just start a new thread with a poll asking who has underdrive pulleys and for how long, and then ask for a general engine history.

[raging panda]

I'm not sure but I don't think the crank pulley is harmonically balanced. You would have to pull it off to check. If it looks like it has some kind of counter weights to it then it is, but if it just looks like a stamped piece of steel then its not. I don't think it has counter balances on it though. The ASP and the UR will underdrive your accessories. The ASP isn't as light as the UR someone said, but its 1/3 the price.

[Ajax]

The ka version of a harmonic damper is a pulley with some rubber solidifying it to the crank if what I have heard is correct. (obviously, this sounds like a very poor way describe what must be a technologically superior design...)In my rebuild which hopefully will happen winter 2005, I will most likely be trying out the Fisher damper. I think it is heavier overall than even the stock pulley, though the way that it works doesn't actually have a heavier effect (read the issue on the 300zx buildup in SCC- not sure the date- for a decent explanation). I plan on the engine rebuild netting me @190 hp at the wheels at least and to last another 200k+ and I think a better built damper will go a long way toward engine longevity. When I try it, I will be sure to update (I might even try this part with a tune-up this next month)

[karay240]

Hey, Ajax, please be sure to post it. I'd be interested in hearing more about it. I read that article you're talking about, but shyed away b/c I figured they'd be a little too proud of them (=$$$). I'd be interested to hear more about them, though. Especially on the KA.

[Ajax]

Yeah, the vg30 was like $325. but hey I've got a real job that pays actual money in comparison to the non-profit theatre job I was working.If it makes the engine smoother and last longer though, I think it will be worth it.