apsilon

I don't believe the ECU negates anything. I installed my Amuse, ran it for a week (inlcuding a track day) then dynoed. Gained 10rwkw. About 6 months later I dynoed again on the same dyno with no changes other than more km and gained another 6rwkw. If the ECU was negating changes I should have lost something.

vfr350

I put the UR pulley and at the same time I installed kinetix cats, This car is a whole new animal between 3-4000. Now I had high flow cats before with a y-pipe, it made some power but not like this. Also the load from putting on the a/c is waaaay less now, still works fine. I have not noticed new noise with the pulley, and on this weekends road trip I was getting just over 27 mpg with the cruise set just over 80, can't complain.

PhoenixINX

riiiiiiiiiiiiiiiiiiiight

___DJK___

iTrader: (2)

I dont know about you guys, but the throttle definitely feels more responsive to me with the UR pulley. My butt dyno isnt sure if its making more power though (Although when I first put it on it felt faster).

What is this noise you guys are talking about? I know mine makes a wierd noise every now and then when I shift at about 4500rpms, almost like a high pitched whine for a split second.

VQ35Kompressor

I think pulley's make a major difference if you're building a race motor and not running A/C, no power steering, etc, etc. Speaking from experience with race cars. Otherwise, simple pulley's won't do much (albeit a little). Next other thing would be pulley's are for cosmetic appeal. And it's a bunch of work to replace all of them pulley's. For the guys that are making power, that's great!

vfr350

if you didn't have p.s. or a/c why would you need an underdrive pulley? the main pulley was really easy to swap....

Apexi350z

iTrader: (3)

like someone said, this thread is a madness..

I feel 100% safe with the pulley and also it DOES gain power, not by dyno, but by me personally driving it. You CAN tell the difference before and after the pulley install.. If you don't feel the difference, then something is wrong... this is my opinion of course!

PoWeRtRiP

was it a tailpipe a/f sensor? when was the last time it was calibrated, or cleaned? how long did you wait after installing to dyno? and most importantly were your results showing the dyno lines to be extremely jagged? you were likely getting timing retard so thats why you lost power

John@Victory

iTrader: (36)

i thought it was really senseless to completely rely on chassis dynos anyway..even if the same dyno is being used there are too many veribles like ambient temp..barometric pressure and other factors

wouldnt this contribute to his numbers being almost the same as before the pully install?

you will never be able to duplicate the exact conditions as the last pull so the numbers are going to be differant right?

lotus

DJK I have the same noise I thought I was going crazy. I have only noticed it since installing the pulley.

zzzya

iTrader: (2)

Could it be that there are differences in the ECUs out there across the world, I think this could be the case? I Do believe the ECU plays a part, just how big, I don't know. I would also agree that the changes in temp, humidity, and so on will play a part. Also, did you make any changes to your suspension or wheels?? That can make a difference on the Dyno as well.

Alberto

iTrader: (14)

I know every day on a dyno is different which is why I try not to change anything but the mod in question, and I try to dyno in similar weather conditions. I didnt change my suspension set-up or my wheels, always recharge the filter, and I always change my oil. Apexi350Z-I'm glad you feel 100% safe with your pulley, I'm not out to scare anyone, just wanted to let people know that on MY car the pulley did nothing for me-and for my piece of mind I will be taking it off. I too, felt the difference after the pulley install, but my a$$ dyno is not the same as a real dyno. The pulley in my track and dyno testing has changed nothing, same power, same trap speeds on average....take it for what it's worth guys.

apsilon

Of course there could be different ECU but I haven't seen any proof of this negation. I've seen a few people say they installed mod xxxx and didn't gain anything so the ECU must be negating it. Sounds like an excuse to me rather than facing the fact that that particular mod may have simply not made any gains. As I said above, no changes other than more km.

Anyway this is OT.

On the subject of pulleys remember that every car is slightly different. It may make some gain on one car and nothing on another. It's not as though you'll see a massive gain from it anyway. It's a pulley, not a turbo.

phoenixZ33

Explain how the ECU depends on a "load". This thread is madness.

The DynoJet O2 sensors aren't the most reliable things in the world. It might work perfectly when you dyno on a Monday, but if Billy-Bob dynos his Mustang with leaded race fuel on Tuesday, it can damage the sensor. There is also a filter in the O2 sensor box that can clog up and greatly affect readings. Not to mention they're just like normal sensors in that they wear out.

2ft*lb difference between the two dyno tests is within a margin of error. And weather conditions don't matter for dyno results (provided it's a modern dyno) as there are correction factors that compensate for weather conditions.. they work quite well actually. When they don't work is if the car is knocking, the dyno can't adjust for that. The ECU shouldn't have to learn anything either, the pulley has nothing to do with the ECU and it's controlling. Put an exhaust, headers, cams etc on your engine and the difference, if any, will be immediate.

Overall it's less than 1% different, call it a wash.. the pulley didn't help.

___DJK___

iTrader: (2)

Not every benefit of a mod shows up on the dyno sheet. Am I the only one who thinks the throttle response is much better with the UR pulley? To me, this makes the car easier and more fun to drive.

Apexi350z

iTrader: (3)

DJK, it must be your head... j/k!

I feel the difference as well, even if it really doesn't show any gain on dyno, but the thottle respond, and easy pickup is well worth it.

phoenixZ33

I've never personally tested a pulley on my car, but I imagine it's along the same lines as a light flywheel.. doesn't show on a dyno, but helps greatly with throttle response and helps make the engine feel lighter.

Alberto

iTrader: (14)

If you think the throttle response is so much better with the pulley, I'd like to see your reaction if you ever put a light-weight FW in your car, you'd go nuts. I felt very little difference in response and power...

hfm

iTrader: (1)

I've understand that pulley and lightweight flywheel reduce parasitic loss between the engine and the crank and that the power "gained" or rather, no longer lost due to the weight of these components can not be seen under dyno testing.

On the other hand, you go to NissanPerformanceMag.com and they start taking about 5 to 7 hp dyno gains. I seem to remember an article written by one of the writers at NPM who stated my understanding above. And, speaking with some experts, they agree with this as well.

I felt the difference right after installation. My question is, do you still feel the difference, particularily regarding throttle response?

Alberto

iTrader: (14)

No I dont still feel the difference, the longer Ive had it, the more "normal" it feels. Dont say its the ECU negating it, Im just one of those guys that gets tired of mods and is always wanting more....thats why Ive decided to stop modding the car, with the exception of the clutch and FW I'm about to order, going for the Greddy kit, and I guarantee you, 2 months after getting it, Ill think my car is slow again Anybody looking for a blue crank pulley??