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Discussion Starter #1
Hi guys.....here is another question to the ever bright and talented people in this forums.....

I have read from other RAV fanatics websites that lightening the crank pulley does some good to the performance of our rav's....

has someone here in RAV4WORLD has installed a light weight crank pulley???

below you will see an article from RA4Expedition, about light weight pulleys...some of them did this mods on their RAV's and claimed that it worked for them....better performance....

i just hope one of us guys did install this and could give us some insight......



Pulleys, the unsung heroes of internal combustion engines. Yeah, pistons and valves get all the glory, but without pulleys, a lot of really important stuff wouldn't get done. The alternator, power steering pump, water pump, oil pump, cooling fan, and air conditioning compressor all rely on the humble crank pulley to do their work. Let's take a closer look at what actually goes down on the pulley end of the engine and learn how to make it more efficient.

The crank pulley is coupled to the front end of the crankshaft. A "fan" belt rides on grooves cut into the pulley, and loops round smaller pulleys attached to other engine components mentioned, forcing them to turn as the crank pulley turns. In essence, whole lot of extra load is added on the crankshaft; not only does it have to turn the wheels, but it also has to recharge the battery, cool the engine, and so forth.
So, what can be done to lighten the crankshaft's job? Replace the pulley, of course! Like most stock engine parts, the pulley is engineered to cost as little as possible, and work reliably for a long time, economy and reliability is primary. For this reason, most stock pulleys are made of cast iron, which is rather heavy. For a ride worthy of praise, a good, modern pulley should be made of lightweight aluminum.

A performance pulley is milled from lightweight billet aluminum and weighs only a fraction of the stock pulley. Less weight means less force is necessary to turn the pulley. Moreover, its width and groove pattern are designed to maximize efficiency without creating extra friction on the belt. A lightweight pulley will allow your engine to reach high RPMs sooner, helping the engine climb smoothly into its powerband. You can expect about 6 to 10 additional horsepower and 7 to 12 more foot-pounds of torque after installation. Still not convinced? Well, I've got one more reason to upgrade; aluminum pulleys look real cool! Most are shiny silver, like the B & D series pulley from SRD, but some brands like Unorthodox Racing, and AEM offer anodized pulleys to match whatever other under-the-hood accessories you may have on your ride.

Notes :pulleys create horsepower at the wheels by lightening the load on the driveshaft, and are straightforward to install, relatively cheap, and make a noticeable difference.

http://www.rav4expedition.com/modules.php?name=News&file=article&sid=85

Underdrive pulleys — underrated upgrade
Note: submitted by "globe"
extracted from article by "Kid Turbo",
www.sportcompactonly.com
 

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I haven't installed one of those, but that won't stop me from offering some comments.

Lightening the drivetrain or any so called "unsprung weight" will provide a performance improvement. I have added billet alum underdrive pulleys on other vehicle and there is an improvement but mostly from the reduction of drag on the crank and not as much as from weight alone. I doubt that the billet alum crank pulley would reduce enough weight to make much of a difference. As the adv. says they would look very nice. But I think the performance gains in a (<1lb?) weight reduction would be minimal on our small displacement engines that already have dinky crank pulleys. I am not saying that one should not buy one, but just don't expect big power gains.

I installed a light weight billet steel flywheel on my Camaro and dropped about 8lbs of weight. There was a distinct power improvement and the engine rev'd much quicker.
 
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Hey Fellow Rav4 Owners,

I'm part of R4E Singapore and here are my opinions after installing the light-weight-crank-pully (LWCP).

Agreeing with Rav4Don the pros of having a LWCP installed enables your engine to rev faster and also more freely. DO NOT as mentioned expect large gains from doing this mod. It actually need more complimenting parts then just the main pully.

I have held the 2 pully in hand and the weight difference is quiet great. Overall FC improves but this is subject to individual driving patterns and habits.

My engine which is only a 1.8 2WD revs more freely and previous and if you (like me) like to rev above the 3K - 4K RPM, then you would notice that the pick would be slightly more significiant.

This is quiet a good mod for a modest price. The 2.0 and 2.4 should be sharing the same LWCP as the aftermarket Lexus RX300 aka Harrier.

Well have fun with this modification!

Cheers

fatshark!
 

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Re: HAS ANYBODY INSTALLED A LIGHT WEIGHT CRANK PULLEY?

Hi,

Having once owned 2 Dodge Neons, one with an aftermarket aluminum "underdrive pulley" one without, I can add a little bit here.

Everything said here has been true. A little better revving ability, a very little gain, but it is there. I'd say at MOST, two to three horsepower, no more. The question is, with ~160 horsepower, is your gludius maximus sensitive enough to really "feel" three more horses? (less than 2% gain if I'm doing my math right).

One thing the article didn't touch on was whether it was talking about a true underdrive pulley (smaller diameter than the original) or simply replacing the steel pulley with an equal diameter pulley made of aluminum?

If you're talking equal size, and this is your first step towards adding lots of mods (CAI, exhaust, etcetera) to truly stretch for that magic 200hp mark, then cool.

That being said, if it's a smaller diameter pulley, it's also going to require new belts (usually custom, only available through the pulley maker) or at least a new tensioner for the smaller belt. Also, when you go with a smaller pulley, certain devices -- the very ones he mentioned in the article -- tend to suffer a bit, as the smaller pulley doesn't sufficiently spin enough to power things like the A/C, the alternator, etcetera.

I went through three batteries the approximately 9 months I owned that Neon with only standard usage. To be fair, I didn't install the pulley, Neither I, nor the dealer caught it when he sold it to me used, and it was only reported to me when the Dodge dealership wouldn't fix the cracked head under warranty because "the engine had been modified".

My basis for comparison is the fact that my ex-wife also had a same generation Neon at the time. Mine felt a bit more spritely, but I had always attributed that to the fact that mine was the sport model whereas hers was the "loaded" model. Both Neons are the very reason I would not care to ever own another American car again, but that's a whole different story.

If you want corroborating feedback, you might google for a similar forum for Dodge Neons. While I'd be crazy to compare a Chrysler 2.4 to Toyota's 2.4 in reliability, it would be a similar comparison since they're both about the same size/power and mpg.

Wayne
 

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With any light weight pulley, you always have to consider balancing. If the stock crank shaft pulley is designed to be a harmonic balancer as many are ( I am not sure about the Rav4's ) then adding a lightweight and/or underdrive pulley, while adding a little bit of power will ultimately cause a decrease in engine life.

If you decide to do this mod, bear in mind that you may be shortening the life span of your engine. Personally, I would never change the crankshaft pulley on any car for that reason.

I think that there are many other and better ways to properly add horsepower to any engine.

*edited to correct a couple errors
 

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I agree with Wayne and Adamdirt's comments above.

But back to the orignial post. Has anyone installed one of these on a RAV? I would be interested to see how it was designed and engineered, as that might determine if it would add some minor HP and TQ improvement without the headaches mentioned above.
 

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Discussion Starter #7
On one of the Scion Tc forums, i think they do install this mode and since the later Rav4's have the same engines as the TC I am just wondering if someone has installed this in their RAV.

I am also guessing that sooner or later someone here would even try installing the supercharger for the Scion TC.....slightly modified though....

So, everybody is waiting for somebody who would do the first move on this MOD's..... :lol:
 
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Lightweight crank pulleys (most of the aftermarket ones) do not have any form of vibration dampening. This has led, on some Celicas (similar engines, kinda) the vibrations causing the water and/or oil pump to fail prematurely, causing a rather unpleasant death of the entire engine.

So you may get a small power gain, but at the risk of engine longevity :)

:edit: As Adam already pointed out! :oops:
 
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I hate to beat a dead horse....but...*smack*!

The truth about this mod just like any other mod is that there is a trade off. When a UDP (which i am assuming this is because i can't see much, if any benefit to just adding lighter pulley) a is installed it forces the alternator and other belt driven parts to work harder thank they normally do. This mod can rip through belt driven engine parts.

The reason I am so against this mod is because having been into the mustang scene for soo long, I have heard from people time, and time again say that when they use UDPs that they blow alternaters, need new batteries, and that their lights will dim when they rev their engine or at start up. And all this for minimal HP gains

And if you do decide to go this route, forget about a huge system with an Amp and Sub because that is a death wish for your car. Their are many other ways that HP can be achieved. And more importantly done without negative effects on the car.
 

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bonemachine said:
I hate to beat a dead horse....but...*smack*!
While I agree with your conclusions, there are a few points I would like to make. UDP do not cause your alt, wp, ps or any other parts to "work harder". In fact they generally cause them to work less. The key word is underdrive. The ps, wp, alt, a/c pulley is turning slower with UDPs and working less. Assuming the UDP system is well designed (and there are some that are not), then the main downside to UDPs is the possible drain on the battery at lower RPMS. I have never had a problem with any UDP system that I have installed. I may be lucky but I also don't have a sound system that needs the amps, either.

BTW, my first Mustang was a '66. I bought it in 1968. You could say I was part of the Mustang scene a long time ago. :D
 

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lol so nobody has tried it? i have sitting beside me an Agency Power lightweight crank pulley, which i will get the toyota techs to put on my brand new engine while they are doin the swap :)

AP says it adds 10HP dyno proven.
 

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I have changed to light weight pulley since last year and ran for 20k km, so far no scary story to tell.

I brought one with original diameter and comes with harmonic dampener, a bit overprice at ~USD200. Asked my local mechanic to fixed it for USD8, as it's a easy task. Simply remove right tyre to access pulley, loosen belt tensioner, change pulley by just unscrewing one bolt.

I noticed acceleration improves after new pulley changed. Never did Dyno test yet but I believe there is not much changes in power. Still it will move your engine power curve to the front, in a way saying your power comes earlier, but peak power remains almost the same. Idling RPM has dropped as well. Yup my RAV4 more revving... :twisted:

With little acceleration gain I don't believe it will "decrease engine life" or "damaged water pump". Only wearing to worry about is too much revving will wear off transmission..
 

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This crank pulley is 3.5lbs lighter than the stock. But because I haven't driven my Rav in over a month and it'll have a new engine, I won't be able to tell you if theres a difference (unless I drive 700KM to the nearest AWD dyno).

Heres a pic of the pulley sitting on my center console with carbon fiber trim:

 
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