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| MikGan |
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yeah maybe theres difference sizes in underdrive pulley setups, some save more than others the trade off being the reduced effectivness of accessories.
_________________ I couldnt fix your brakes so I made your horn louder
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| bigbeard |
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wat sorta price they go for?? ...rnt the pully's lighter to??
_________________ brett<a href="http://photobucket.com/" target="_blank"><img src="http://i101.photobucket.com/albums/m41/public_animal_au/MEandFRIENDS/me.jpg" border="0" alt="Photobucket - Video and Image Hosting"></a> |
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| XH5LWEPN |
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Scaffy wrote: XH4LWEPN - which set are you using and is there a noticable difference?
I went for the race kit. I certainly did notice a difference, even if it was just a little. You will notice them most from bout 2500rpm to redline, you can just feel it revs up there quicker and smoother. Definately a worth while mod being cheap and easy to install, i would recommend them as a first mod to do to any pre AU windsor. Also havent had any problem with alternator charge or water flow. You can see the volt guage sit slightly lower on idle but once revs go up past about 1000rpm its charging fine.
_________________ STREETBUILT RACING |
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| raiki |
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I don't think most people here understand why under drive pulleys were developed. An alternator, water pump etc are designed to run in a particular RPM band. When a race engine is built, it is designed to run at higher than stock RPM which drives your accessories outside there designed band. Underdriver pulleys were developed to bring back into there design spec.
If you put these on a stock motor with stock RPM, you drive them slower. A slower turning waterpump will use less power (and this is what you guys are looking at). The reason it uses less power is becuase it is pumping less water. Less water = hotter motor. Your alternator will also not be efficient becuase it is turning too slowly. I'd be interested to see before and after dyno charts, and I'd be suprised if you gained more than a few kW. If you ask me the dangers involved in using them and the cost don't make it good value for the small performance increase.
_________________ Adrian
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| vik351 |
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raiki wrote: I don't think most people here understand why under drive pulleys were developed. An alternator, water pump etc are designed to run in a particular RPM band. When a race engine is built, it is designed to run at higher than stock RPM which drives your accessories outside there designed band. Underdriver pulleys were developed to bring back into there design spec.
If you put these on a stock motor with stock RPM, you drive them slower. A slower turning waterpump will use less power (and this is what you guys are looking at). The reason it uses less power is becuase it is pumping less water. Less water = hotter motor. Your alternator will also not be efficient becuase it is turning too slowly. I'd be interested to see before and after dyno charts, and I'd be suprised if you gained more than a few kW. If you ask me the dangers involved in using them and the cost don't make it good value for the small performance increase. Right on the money bloke You gain lighter wallet vik...hence a power gain...
_________________ [b]BANNED[\b] |
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| 4.9 EF Futura |
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Yes, i understand that the alternator is typically underdriven to a point where the battery wont be taking on charge at idle.
_________________ I promise..... I will never die. |
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| Happy |
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ahh interesting, so on a stock car they would be pretty much a waste of time then...
_________________ Owning 1 of 67612 EF GLi Sedans made
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| Kilma |
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MikGan wrote: I had heard that they actually change the turn ratio so that the accessories turn slower and in some cases too slow. Any truth to that?
I'm pretty sure TerroristGHIA (Brett) had troubles with the one he was provided on his alternator due to a large stereo. That is the only problem I have heard of. The alternator may be underdriven so that it doesn't take any charge at idle, but really... how long does your car sit at idle for?? The only reall time I can think of is at lights, or those with a turbo timer.
_________________ The fast fun: Suzuki GSXR1000
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| kato |
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After I fitted mine, I noticed at idle the voltage gauge read at 14v rather than 16, and the motor can get a little warmer in heavy traffic, never getter much over half though, overall I would recommend them to anyone, It made a noticable difference to my car.
_________________ EF XR8 5spd: 302ci /178rwkw |
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| raiki |
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If your volt gauge ever read 16V your charging system is stuffed. The regulator limits you to 14.4V, but generally aims for 13.8V.
As for a "noticable difference", it's amazing what your brain will think after you have spent hundreds of dollars. If it's what you guys want, go for your life. Personally, I am not going to waste my money.
_________________ Adrian
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| znipa-x |
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raiki wrote: If your volt gauge ever read 16V your charging system is stuffed. The regulator limits you to 14.4V, but generally aims for 13.8V.
As for a "noticable difference", it's amazing what your brain will think after you have spent hundreds of dollars. If it's what you guys want, go for your life. Personally, I am not going to waste my money. hey raiki, have you tried them, cos if you haven't, the old saying goes "if you haven't tried it, don't knock it", underdrives were one of my very first mods on a very stock donk, and it did make a difference, the engine revved up that little bit quicker, but the main thing I was after was fuel economy, and anything that reduces load on an engine is going to aid that, sure there are trade offs as outlined in this thread, but they are minor and managable, there are also the benenfits as those that have them have highlighted.
_________________ former FORD V8 owner |
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| MuzzaXR8 |
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I thought underdrives were just hot air on a Windsor.
But I took the plunge and brought BPT race series with 3 pullies. Made heaps of difference, really happy with the purchase. I'm now a believer in the underdrives ! |
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| raiki |
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znipa-x, don't get your undies in a twist. In a previous post I did say that they reduced loads, it's the loads that they do reduce which I have a probelm with (low cooling water flow).
Like everything they are a compromise, and in this particular case I errr on the side of caution. Scaffy asked for our opinions and I have given mine, and that is all I have given. Ins't the internet wonderful, we all have different opinions and are free to voice them.
_________________ Adrian
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| Timmeh |
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The alternator may or may not charge at idle depending on the condition of it. The water does pump less water however the pulleys where designed to still turn the water pump and alternator at acceptable levels. Since I've had mine on the temperature needle has not moved up at all even in hot weather with the air con running.
I have had no problems at all with the alternator. Both the alternator and the water pump have larger pulleys fitted. The crankshaft pulley is a smaller pulley under driving the rest of the accessory's (power steering and air con). The power steering is no heavier than it was before and the air con no warmer. If your accessory's are in poor condition then get them checked and sorted prior to fitting under drives. Otherwise all is good. Engine is quicker to rev and there is a small gain to be noticed in power. Best value for money modification. ~$250 for about 7-11 rwkw. |
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| znipa-x |
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Timmeh wrote: The alternator may or may not charge at idle depending on the condition of it. The water does pump less water however the pulleys where designed to still turn the water pump and alternator at acceptable levels. Since I've had mine on the temperature needle has not moved up at all even in hot weather with the air con running.
I have had no problems at all with the alternator. Both the alternator and the water pump have larger pulleys fitted. The crankshaft pulley is a smaller pulley under driving the rest of the accessory's (power steering and air con). The power steering is no heavier than it was before and the air con no warmer. If your accessory's are in poor condition then get them checked and sorted prior to fitting under drives. Otherwise all is good. Engine is quicker to rev and there is a small gain to be noticed in power. Best value for money modification. ~$250 for about 7-11 rwkw. absolutely agree 
_________________ former FORD V8 owner |
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