Got the pulleys on today. First impressions:

-The car revs slightly faster, however MUCH smoother
-Shifting into second gear has become alot eaiser, as the car now naturally keeps revs up for a little bit longer
-Downshifting is alot differnt now, as just a little gas will put you at 3.5 K if your not careful (I downshift between 3-4K normally)
-Clutch and gas feel more sensitive, but I think this is due to the engine not loosing revs as fast
-I allowed the synchros to take a 2800 rpm downshift (from 1200 in the previous gear) all by themselves. (IE I slowly released the clutch) Yes, this is bad, I know, but I did it once to see how it would take to the pulleys. The car downshifts like its being revv matched now. Kinda took me by surprise.

The weight difference between the stock and the new pulleys are unbelievable. The crank alone saves a good 2-3 pounds, if not more. The other two werent as drastic (water pump and ac) but still quite noticeable. The one thing that impressed me the most was how smooth my 1-2 shift is now. The notchyness in my shifter seems to have vanished....maybe because the car wasnt driven at all for a day, but it feels quite different. Next up: Plenum. Ill let you guys know when its on.


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what kind of pullys did u get? and how many?

 

I thought those tore up the engine?

 

Nope, they dont "tear" up the engine or anythign like that. On some other cars witht heir engines their are balancing problems or something like that causing power shortages to the ac and water pump's. In the VQ engine, there arent any problems really and this is a great mod!! In the auto you get alot of that low end torque you couldnt get with stock pulleys by just stomping the gas from a stop, now it gets you going quick. Martin


Martin
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Nice mod. Forgive my ignorance but the UR pulleys consist of what pulleys exactly? I might be missing the boat completely but I always thought that lightening up the crank pulley will have more the less the same afftect as a lightened flywheel, that is it will give faster rev up, but because of the loss of weight the revs will fall much faster or in other words not stay up longer than stock. Right??? I don't know how much a lighter crank pulley will really affect rev performance as I have never driven one. Please explain =)

Besides this the main purpose is to just free up the hp required to spin up the heavy stock pulleys in comparison to aftermarket balanced ones. Right???

 

The stock pulley is damped, the UR pulley is not. It's a great mod if you're willing to live with the risk for the 5 HP it delivers. The risk is prematurely worn bearing.

There may be no harm, there may be. To know for sure better do regular oil analysis and check for lead to indicate more than normal bearing wear.

2004.5 Coupe/5AT/Ivory/Everything but front spoiler/Nismo CAI/Crawford V5/Crawford Cats

 

Just a little correction, but the lighter pulleys would make the engine lose revs quicker, not delay. Also, they would not affect your notchiness in the shifter, a tranny oil change would. You might be feeling the same effect of a very loud exhaust making your car seem faster than it is, which is what I am suffering from. I thought my car was a ton faster after my injen/race pipes, and all it took was a couple runs at the track vs. some other coupes to realize that I gained maybe a tenth in the quarter.

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Well, I may be wrong, but from my driving impressions it doesnt loose revs quicker, it has less mass to rotate now, therefore keeping the revs up. The first thing I noticed was how much longer it takes for the car to slow itself down while downshifting. There is less resistance on the rotation of the crank now, therefore it keeps its revs longer. It revs faster up and slower down. For those who had asked the pulley set consists of the Crank, Water pump and AC pulleys. The oil pump is left alone. 3rd gear is alot stronger now post 5000 rpms, and for the first time, I broke 90 in third (no I didn't redline, the car just has the umph now for those extra 2-3 mph, I shifted at 6500 rpms) First and second really don't feel the full effect of the pulleys to be honest. It's third gear that blew me away. I would love to see what 4th can do but I'll have to save that for the ride to work on monday. Gotta love the parkway. As far as the notchiness in my tranny, I'm at 15K and 5 K from my second tranny fluid / rear diff change. I changed at 10 K and even though it smoothed out the gear box, second gear still required a little arm strength to pull into gear. I've heard many people talk about the problem, as it does really require some muscle to pull the shifter down sometimes. The problem is gone now, and 1-2 feels as effortless as every other shift now.

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"it has less mass to rotate now, therefore keeping the revs up."

Which is easier to stop, a 10,000 pound rolling boulder or a basketball? The basket ball will stop more quickly and with less force.

Imagine your stock pulley is a boulder, your new pulley is a basketball, and your foot (which you're going to use to stop the basketball when it comes rolling towards you) is drag and rolling resistance. Which can you stop more quickly with your foot? And which can you propel more easily, with your foot? The basketball or the boulder?

It should rev faster up and rev faster down, assuming you're letting off on the pedal and in neutral.

2004.5 Coupe/5AT/Ivory/Everything but front spoiler/Nismo CAI/Crawford V5/Crawford Cats

 

Damnit, my foot's killing me. I never should have tried to stop that darn boulder. The basketball was easy, but the 10,000 pound boulder really hurt... Just trust him (picture me holding my foot and wincing in pain), I wished I would have. [img]/w3timages/icons/wink.gif[/img]

<font color=blue>The above statements are only my take on the issue. If you disagree with anything I typed then you are 100% right!</font color=blue>

 

Well, if this is the case, then why does it take so much longer for me to slow down only downshifting now? I'm not saying your wrong or anything, but the car does not slow down anywhere near as fast as it did with the stock pullies. Your example....there is no force, or foot, acting upon the pulleys. They are in motion and slow down because of resistance, which is the point of putting them on in the first place, to get rid of resistance. The way I look at it is like when I used to play hockey. My skates started with standard abec-3 bearings. They spun up decently fast and gave you a nice coast afterwards. Once they were gasoline soaked (IE all the lube in the bearing was removed, removing the resistance that keeps the bearings from spinning) they spun up ALOT faster, were capable of spinning alot faster and stayed spinning, on average 2 minutes, compared to the 30 seconds they would stay when they were non-gas soaked. I think the same theory applies here because if there is no force acting on the pulleys besides the motor slowing down, well, the motor is less resisted now, so it should technically be the same way, and slow down alot slower. If I'm wrong whatever, but considering 4 people all said the car doesnt feel like it slows down at all on a downshift now, I tend to think that the skate example is a little better than the foot one,

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When using your gears (downshifting) to slow down, the braking force comes from the energy required to compress the air in the cylinder on the compression stroke. The pulley will have no effect on this 'compression braking' once the lower gear is fully engaged.

What you are noticing is probably the fact that you will notice less of a 'lurch' for lack of a better term when you engage the lower gear. Because there is less rotational weight, the lower gear will be rev matched more easily. If you downshifted and rev matched perfectly, you wouldn't notice a difference between the stock and UR pulley.

I'm sure I used some terms incorrectly but the underlying message is correct.

 

You guys are all bringing some decent knowledge to the topic, but as catatafish (I hope I got that right) said, it is all about rotating mass. It is EXACTLY the same principle as getting a lighter flywheel. Engine braking comes mostly from the weight of the internal and in this case external moving parts. Lighter pulleys, flywheel, clutch, rods, pistons, crank; all these things can effect the engine braking, whether they are heavy and give poor engine braking or light and give the opposite effect.

As far as your explanation of the wheel bearings in your skates, that would more be the difference between the crank and main bearings not being lubed, and then moving more freely when they are lubed. Since the pulleys are directly connected to the crank and do not move relative to the crank, only rotating mass would come into play.


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For your skate analogy, the thing to compare would be the wheels. Get big heavy 4 inch wheels with all the mass farther out. Compare that to small light 2 inch wheels with the mass close to the axle.

Which one is harder to get spinning?

Which one will stay spinning longer?

The effect of the pulley has more to do with having less work to do necause you are underdriving the auxiliaries, not due to less rotational mass. I thought anyway....

2004 G35C 6MT Black. Killer.

 

EX,
You're confusing the principle of inertia with the principle of drag and friction. It's not theory, it's physics. Object in motion...stays in motion.....F=MA.

Your skate example is not analagous to the pulley. Your skate example deals with friction, mine deals with inertia. And I wouldn't rely so much on feel, rather rely on physics and scientific measurement. You have to tease out the independent variable correctly. You're confounding your experiment with your transmission and your pistons. If you want to hone in on the effect of the pulley, time the RPM drop with the pulley after pushing in your clutch, then time it again with the different pulley after pushing in your clutch. "Feel" is the worst measurement you can take. What al said is my guess on why you think it's slowing down faster.

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