Underpulley gains
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With all of this talk about modding an exhaust and intake that are pretty good to begin with, has anyone put an underpulley on their Z, and to what effect? It looks like Stillen is selling one from their website, and I can't see how the ECU would negate the gains produced by a lighter pulley. Seems like this is also one of the cheaper and easier mods to do. Any experiences?
Craig
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Its called Underdrive pulley... that is if its smaller in diameter than the stock one. Read about the gains on the 3.5 Altima here:
http://www.nissanperformancemag.com/...r02/altima_ur/
http://www.nissanperformancemag.com/...r02/altima_ur/
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Freesup rotational engergy that was used to turn a heavier and bigger pulley. good for NA cars, revs up alot faster. subsequent adverse affects on powersteering are slightly noticable but they're thats the thing its noticable.
i had it on my 5spd max before i did the S/C. good cheap mod. less than 200 with the belts and all.
i would think a lightweight smaller pulley on the Z would probably benefit nicely.
Unorthodox Racing is a great company, and thats where i got my UDP from last time...hopefull they'll make one for us.
--cheston
i had it on my 5spd max before i did the S/C. good cheap mod. less than 200 with the belts and all.
i would think a lightweight smaller pulley on the Z would probably benefit nicely.
Unorthodox Racing is a great company, and thats where i got my UDP from last time...hopefull they'll make one for us.
--cheston
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Anyone have any U/D Pulley experience with an aftermarket stereo?
Back when I had my 300ZX I was considering getting one. I actually had placed an order with Unorthodox and then a few hours later, my alternator took a dive. Too much draw with accessories plus a 600W Xtant sub amp. Cancelled the order that day just because I needed the money to get the damn alternator fixed!
Let me know if any stereo folks have done this mod, simply because I want to develop more power, but I don't want to risk overworking the factory pieces once the stereo upgrade begins...
Also, does anyone know if the Z33 can import alternators from any other VQ model? Anything more powerful in the Murano or G35 possibly? Maybe the FX45 with its big-ole V8?
Thanks
Back when I had my 300ZX I was considering getting one. I actually had placed an order with Unorthodox and then a few hours later, my alternator took a dive. Too much draw with accessories plus a 600W Xtant sub amp. Cancelled the order that day just because I needed the money to get the damn alternator fixed!
Let me know if any stereo folks have done this mod, simply because I want to develop more power, but I don't want to risk overworking the factory pieces once the stereo upgrade begins...
Also, does anyone know if the Z33 can import alternators from any other VQ model? Anything more powerful in the Murano or G35 possibly? Maybe the FX45 with its big-ole V8?
Thanks
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I know that underdrive pulleys are supposed to have no ill effects and since it is less rotational weight, it should free up "parasitic drag" but I think there is more to it-I mean what is the point? For Nissan to detune the car by putting on a heavier pulley? Doesn't seem likely.
Besides, I think that a underdrive crank pulley isn't just a pulley, its a harmonic balancer. This piece actually absorbs crankshaft vibration and helps to minimize abuse to the thrust, main, and rod bearings. I know that counter balance shafts are made so that the vibration cannot be felt, but the balancer is for a different purpose all together.
Anyway, I don't see that there would be a disadvantage to changing the water pump and accessory pulleys. I just think that the crank pulley/harmonic balancer is better left alone.
Besides, I think that a underdrive crank pulley isn't just a pulley, its a harmonic balancer. This piece actually absorbs crankshaft vibration and helps to minimize abuse to the thrust, main, and rod bearings. I know that counter balance shafts are made so that the vibration cannot be felt, but the balancer is for a different purpose all together.
Anyway, I don't see that there would be a disadvantage to changing the water pump and accessory pulleys. I just think that the crank pulley/harmonic balancer is better left alone.
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Originally posted by catzo350z
I know that underdrive pulleys are supposed to have no ill effects and since it is less rotational weight, it should free up "parasitic drag" but I think there is more to it-I mean what is the point? For Nissan to detune the car by putting on a heavier pulley? Doesn't seem likely.
I know that underdrive pulleys are supposed to have no ill effects and since it is less rotational weight, it should free up "parasitic drag" but I think there is more to it-I mean what is the point? For Nissan to detune the car by putting on a heavier pulley? Doesn't seem likely.
Look at the grounding wires that people are putting on. I don't know if they are truly causing better performance, but if they are, then Nissan could have spent less than $50 more to get a smoother engine on the Z.
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Remember the VQ35 is a mass produced engine used in many Nissan/Infinitis. Only so much funding can go into research/development of particular engine components. Now if Nissan was building a race only engine then they would put the lightest and most efficient pulley on the engine.
And also the VQ is internally balanced so the crank pulley is NOT a harmonic balancer.
I've never been one to have a booming system, but I've heard of people with 600w amps and full pulley sets not having any problems.
And also the VQ is internally balanced so the crank pulley is NOT a harmonic balancer.
I've never been one to have a booming system, but I've heard of people with 600w amps and full pulley sets not having any problems.
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Years ago I had underdrive pulleys on my mustang. That worked out great, if you call great having someone push the car to start it every time. If you have a high power stereo, be careful with these underdrive pulleys. I had a very high output alternator and still couldn't charge the damn battery. Finally bought an overdrive pulley for the alternator and everything was fine again.
Rob
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I don't believe this is something that Nissan would not have done if it were better in every way. The cost of a lighter pulley instead of a heavier one is negligible. And they definitely could have made the pulley a smaller diameter without a change in cost; they make it the size it is because that's the speed the accessories are designed to run at. Of course you can go messing with things like the speed you run the alternator, A/C and water pump at, but is that really wise? Do these little companies making pulleys know more about the engineering of our cars than the engineers who designed them? I think it's nuts to go screwing with stuff like this to get gains so small that even the promotional web site claims can't be felt with the "seat of the pants dyno".
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You could make basically that same argument about any tons of mods. CAIs, exhausts, grounding cables, retunned ECUs, etc.
Several things combined make a difference.
I'm not saying pulleys are the end all, but the logic that if it would improve performance, Nissan would have done it aren't logical.
Several things combined make a difference.
I'm not saying pulleys are the end all, but the logic that if it would improve performance, Nissan would have done it aren't logical.
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Only one person touched on the harmonic balancer. I would stress not to change out the crank pulley. I mean hell screw with accessory pullies all you want for the extra 2 hp you might get. I'd just say to leave the crank pulley alone, unless you like the idea of premature wear to engine. This is the main reason a good bit of people that will do all/almost all bolt-ons on newer cars shy from changing the crank pulley. Anyways just my .02
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I was under the impression that most of the gains came about as a result of reduced rotational mass, not the reduced diameter (I realize that to some degree these two go hand in hand). If that is the case, would it make sense to build a reduced mass pulley, using lighter materials, that was identical in size to the original? It would seem that way you could get most of the gain without having to worry about reduced power going to your accessory systems.
Regards,
Craig
Regards,
Craig
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Just to respond to the guy who said that since it is an internally balanced engine, therefore the pulley isn't a harmonic balancer is just dead wrong. There are many engines that are "internally balanced", in fact I think all engines produced are "internally balanced." Balancing rotational components (crank, rods, pistons) have a degree of error. I mean not each one of these engines are made from flawless forging processes, hand machined, and balanced to perfection. Don't get me wrong, they are close-but not perfect. That is one reason, another is that it doesn't rob enough hp to make a measurable difference-so what is the reason to do it? I am sure if there was a debate (which there probably are plenty when it comes to this), the accountants would want whatever they can get to lower any chances for need to warranty anything-I would bet that this probably is in the list of engineering specs. Overbuilding and durablitiy in any worse case scenarios concerning slight manufacturing defects. How much do you think that Nissan would spend on, say 100 cars, requiring major labor/parts costs like a problem that could arise from excessive vibration? A relatively low number but call it a measly $2500 (low-low-low) per. What do you think is cheaper, a quarter million or a heavier harmonic balancer?
Anyway, do you think that the extra 3bhp that could come from this is going to put the engine at its peak output? NOT-the engine can be higher tuned for one main reason, it is overengineered anyway. Otherwise it would fall apart when someone tried to squeeze some sauce (NOS as F&F would call it) into it or stapped a supercharger to the intake. Point-The guy who stated that the costing differences between a heavier pulley and a lighter one is negligable is 100% correct. My point is that they don't tune the engine in the 90% capacity rate-that is for the factory built race spec cars (i.e. Ferrari's comp 348TB).
With the quantity that Nissan does in pulleys and pulleys for replacement parts, do you think that they are going to have a slightly higher price thrown at them for a different spec on a lighter pulley? I'm sure Nissan could negiotate a good price on them-would you know the difference if you spent another $30 on a different crank pulley. C'mon....surely a factory having a contract like this would not bat an eye at Nissan-that is if Nissan even outsources it. Think about it, if it were lighter-it may even be cheaper to produce...
What I mean is that is why Mitsubishi did an "internally balancing", a harmonic balancer, and counter rotating balance shafts. Redundancy and every chance to avoid a need for warranty. A harmonic balancer is what absorbs the slightest of vibration and helps to dicipate it or kill it altogether. Its not enough to absorb vibration from a non balanced engine. Do you really think that harmonic balancers are only put on engines that are not balanced? The name doesn't mean that it is the only component that does this-and it really doesn't balance anything, it just kills a possibility in those 4-6% of cars that may suffer from some type of internal vibrations that could cause bearing failure at 40,000 miles. And don't think that you would feel it, between the engine mounts and the rest of the smooth engine, one would likely never tell until failure of one or all bearings that vibration was even occuring. ****, most likely only happens in a very small number to begin with.
Sorry to ramble, just wanted to make sure the correct info was getting posted. I am not meaning to be offensive, I know plenty of people are reading so I just want to represent the most accurate information that I am aware of. If anyone wants to do this, I would highly suggest it AFTER the engine is ripped down, hand balanced by a professional machinist and built for race (taken apart after every few races, inspected, and freshened up with new bearings and honing.) Otherwise, forget about the 3bhp that you might pick up and put it toward getting an exhaust that might bump you to like 15-20bhp.
Hey if you don't believe me, call one of these companies that sell the pulleys and tell them you have a stock 350z and ask them if they will cover the warranty on the engine if something fails and Nissan determines that it was from the subtraction of the heavier stock crank pulley. If they say sure, get it in writing and get your metric wrenches out. Unless you think that the money could be better spent for larger gains
Anyway, do you think that the extra 3bhp that could come from this is going to put the engine at its peak output? NOT-the engine can be higher tuned for one main reason, it is overengineered anyway. Otherwise it would fall apart when someone tried to squeeze some sauce (NOS as F&F would call it) into it or stapped a supercharger to the intake. Point-The guy who stated that the costing differences between a heavier pulley and a lighter one is negligable is 100% correct. My point is that they don't tune the engine in the 90% capacity rate-that is for the factory built race spec cars (i.e. Ferrari's comp 348TB).
With the quantity that Nissan does in pulleys and pulleys for replacement parts, do you think that they are going to have a slightly higher price thrown at them for a different spec on a lighter pulley? I'm sure Nissan could negiotate a good price on them-would you know the difference if you spent another $30 on a different crank pulley. C'mon....surely a factory having a contract like this would not bat an eye at Nissan-that is if Nissan even outsources it. Think about it, if it were lighter-it may even be cheaper to produce...
What I mean is that is why Mitsubishi did an "internally balancing", a harmonic balancer, and counter rotating balance shafts. Redundancy and every chance to avoid a need for warranty. A harmonic balancer is what absorbs the slightest of vibration and helps to dicipate it or kill it altogether. Its not enough to absorb vibration from a non balanced engine. Do you really think that harmonic balancers are only put on engines that are not balanced? The name doesn't mean that it is the only component that does this-and it really doesn't balance anything, it just kills a possibility in those 4-6% of cars that may suffer from some type of internal vibrations that could cause bearing failure at 40,000 miles. And don't think that you would feel it, between the engine mounts and the rest of the smooth engine, one would likely never tell until failure of one or all bearings that vibration was even occuring. ****, most likely only happens in a very small number to begin with.
Sorry to ramble, just wanted to make sure the correct info was getting posted. I am not meaning to be offensive, I know plenty of people are reading so I just want to represent the most accurate information that I am aware of. If anyone wants to do this, I would highly suggest it AFTER the engine is ripped down, hand balanced by a professional machinist and built for race (taken apart after every few races, inspected, and freshened up with new bearings and honing.) Otherwise, forget about the 3bhp that you might pick up and put it toward getting an exhaust that might bump you to like 15-20bhp.
Hey if you don't believe me, call one of these companies that sell the pulleys and tell them you have a stock 350z and ask them if they will cover the warranty on the engine if something fails and Nissan determines that it was from the subtraction of the heavier stock crank pulley. If they say sure, get it in writing and get your metric wrenches out. Unless you think that the money could be better spent for larger gains
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Good reply Catzo
Wow, I'm glad I started such a good thread, but I'm sorta embarrassed about calling it an Underpulley, and not an Underdrive Pulley, especially with all the rocket scientists who know waaaay more about engines than I ever will. Every time I get an e-mail telling me to look at a new reply in this thread I look at the thread title and can't help but think "Whata dork I am!"
Craig
Wow, I'm glad I started such a good thread, but I'm sorta embarrassed about calling it an Underpulley, and not an Underdrive Pulley, especially with all the rocket scientists who know waaaay more about engines than I ever will. Every time I get an e-mail telling me to look at a new reply in this thread I look at the thread title and can't help but think "Whata dork I am!"
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Craig