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Old 02-06-2001, 02:51 PM   #1
Jonnathan
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Post Pulleys ?

I've heard a bit about gaining so-called "free-power" by changing my underdrive pulleys.
Possibly around 2 or more HP per lb saved from the weight of the pulley ?
But I also heard that a slight diameter decrease sends less power to be used by other driven devices such as the air-con.

So which do I want ? reduced weight or diameter, or both ?
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Old 02-06-2001, 04:39 PM   #2
gavin
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An under-drive pulley should only rob power at idle. You should not see any power drain at speed. That's the beauty of an under-drive.

You can get a pulley that under drives even further, but there isn't really any reason too. If you want to go to that extreme, you should just get rid of the accessory pullies altogether.
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Old 02-06-2001, 05:02 PM   #3
Jonnathan
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what about weight reducing pulleys, vs. smaller diameter pulleys ?
whats the difference ?
I'm guessing smaller diameter saves power lost to air-con etc, and less weight means less rotational inertia for the engine to overcome.
So where can I buy a reduced weight, reduced diameter pulley ? I guess I'll have to buy new pulley belts too
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Old 02-06-2001, 08:16 PM   #4
suby ej25
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you can check teague's auto, cobbtuning, flatline motorsports...basically any suby specializing place will have the unorthodox racing underdrive pulley(both reduced weight and diameter)..some places will sell it with the new belts..should run about $180

[This message has been edited by suby ej25 (edited February 06, 2001).]
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Old 02-07-2001, 04:55 AM   #5
suby ej25
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i was just browsing the private classifieds board...if you still want a pulley...someone is selling their's
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Old 02-07-2001, 05:56 AM   #6
Rich L
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Jonnathan,
Do other mods (swaybar,intake or exhaust) before you buy the unorthodox racing underdrive pulley.

IMHO It is simply is not worth the money.
-some people will disagree with me-
but they are wrong

Good Luck
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Old 02-07-2001, 08:04 AM   #7
Jonnathan
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Thanks Rich L, I allready have P1 suspension, 20mm sway bar and ScoobySport Exhaust mods : )
I'm was gonna do the intake and underdrive pulley at the same time. Why don't you think its worth it ?
The shops claim up to 2.7 hp gain, per lb lost from the pulley. ? is this not so ?
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Old 02-07-2001, 09:20 AM   #8
Matt Monson
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Jonathon,
The Unorthadox pulleys are both lighter and smaller. The weight reduction is 2 lbs. I believe. I got mine for $125 from SPO with belts. I did notice the change in throttle response pretty immediately, but I don't have an intake, just a K&N panel filter. My point? Someone with a true intake is less likely to be able to feel the difference and not think it is worthwhile because they have already gained 10-15% power from their intake.
As for the impact on the accesories? Zero. Well, the power steering belt squeks when cold, but goes away after 5 minutes. But otherwise, nothing noticeable.
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Old 02-07-2001, 02:10 PM   #9
Rich L
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Jonnathan,

I dont think it is worth it because the performance gain is not noticable. I think people "perceive" an improvement, but in all honesty, I think this perception is due to actually knowing the mod was done.
I would recommend getting a test drive in similair cars with and without the pulley.

My butt dyno is not that perceptive to notice the 2-6hp claims, but I noticed better performace gains through an ECU reset. I really cant recommend it to anyone.

Not to mention there is dimming as a side effect. (I havent had any belts slipping/squeeking though). The dimming becomes even more apparent with added accessories (I have airfuel/boost/oil temp gauges).

Use you money to enhance other mods. With the extra $200... get a better intake, or put it toward a lighter flywheel, headers, or tires. (or a digital camera for internet pics)

Anyway you spend it, the $200 better off being put to good use someplace else.
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Old 02-07-2001, 02:37 PM   #10
Jonnathan
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Is doing an ECU reset risky in any way then ?

Is an ECU reset done by disconnecting the battery for half an hour or so ? , then restart car, and let it adle and warm up ???

Does that make your Mileometer readings dissapear ?

Does it make any difference what gas you have in your tank when you do an ECU reset ?
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Old 02-07-2001, 02:44 PM   #11
Jonnathan
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Yes a digital cam would be nice : )
I have a few pics on my website ripped off from other places, but need to get some of my own done : )
there is a link to my crappy website on my profile : )
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Old 02-07-2001, 04:49 PM   #12
Matt Monson
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Jonathon,
All your ECU questions are covered in the new FAQs section in detail.
As far as the pulley question, in his last post, Rich mentions his "boost" gauge. This leads me to believe "turbo", and if anyone is running a turbo, I don't think the pulley is really worth much either. It is with milder NA mods it will have an impact. I would not have bought one if i didn't have a gift certificate about to expire and a Cobb intake already ordered. Otherwise my money would have gone towards an intake.
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Old 02-07-2001, 05:41 PM   #13
Rich L
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Jonnathan,

An ECU reset is recommended at each oil change. Try to put in an octane booster at that time, you will notice a differance. That will give you 5 good hp! (or preserve 5 hp)

Matt,
yes a turbo is a worth wild mod!
it is worth every penny and guys in z-28s learn to respect you! Anyway it is good that someone cares enough to give you a gift certificate for any mod!

Make sure you guys go to the KC event, we can tech talk and talk mods. Hopefully see some good Scooby action.
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Old 02-07-2001, 05:58 PM   #14
ice
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So for those of us that are still N/A, that have already done and intake and exhaust, this is a noticable mod? I've been considering a pulley set, and I would really like to know if it is worth it or not.
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Old 02-10-2001, 09:11 AM   #15
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We have a lightweight pulley that is the same size as stock for $137.95. We also carry the UD pulleys for the same price (belts are additional)
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Old 02-10-2001, 03:13 PM   #16
adamsrs
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I just ordered the Unorthodox racing pulleys form Cobb Tuning. He carries only the best stuff!
adamsrs www.unnatural.org
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Old 02-11-2001, 12:19 AM   #17
Jonnathan
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KC event ?? whats that ? where and when ?
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Old 02-11-2001, 12:37 AM   #18
ImprezaRS dot com
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I just had the lightweight N1 pulley installed at JCS today - it is about 3lb lighter than stock, and uses the stock belts.

Either Grassroots Motorsports or SCC magazine in the last issue stated that 85% of the gains from a pulley were from weight loss, and the UD pulley with smaller belts is only about 1 lb lighter than this one. They said it was a 2.7hp gain per 1 lb lost. I could tell an immediate difference in free reving the motor and spooling of the turbo. Most notable was the hwy acceleration seems stronger in 3rd and 4th gear. I am very happy with it, although it was not as dramtic as going to a 12lb flywheel. And, in the summer I will still have full AC power.

Larry www.ImprezaRS.com
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