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No more VR4!
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Discussion Starter · #1 ·
Originally, I'd asked about how long people have had their 3SX pulleys here:

http://www.3si.org/forum/f35/how-lo...g-your-3sx-aluminum-pulley-543009/index2.html

I ordered the aluminum pulley, and it's been a year and around 10k miles. I've had no problems with it, and my engine hasn't spun a bearing (yet). If it does, though, I'm not going to blame the pulley. I'll likely blame the 170k miles on it, fact that it didn't get a 120k until 150k, was driving around with a dented oil pan for a long time, etc...

It definitely improved the engine's ability to rev, although it was a minor improvement. I think the flywheel will help more when I do that. I notice at idle it got a minor vibration that will come and go. However once I put poly motor mounts on, that increased the idle vibration enough to make it irrelevant.

Anyway, I'm a satisfied customer. If anyone is considering doing this, I'd say go for it. It saves money, hasn't caused me any problems (I only run around 450 HP, though), and the engine does get a minor improvement in revving, which it needs. The only reason I'd say to not do it is if you're looking to keep the car completely stock or hate any sort of vibration at idle, which was the only place I saw any extra vibration.
 

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3/S owner since 2003.
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I am running one as well and so far so good, but every now and then I think about the possibility of braking stuff because of it and that gives me a uneasy feeling. I hope nothing happens though... Good luck to you too! :)
 

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The only problem I found is that the timing mark on mine was way off. If you have a first gen with adjustable timing keep your stock pulley around to set the timing.
 

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Wheee! 2 wheels is fun!
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...or you could just scribe a line in the correct place!

It saves money?? :) Sorry I'm on the science side of the fence and I'll be waiting for your subsequent report of crankshaft failure.

-SP
 

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No more VR4!
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Discussion Starter · #10 ·
It saves money?? :) Sorry I'm on the science side of the fence and I'll be waiting for your subsequent report of crankshaft failure.
My point was that it's cheaper to buy.

One of the things I notice on here is that many forget that not everyone is looking for "serious" power and drive it like you stole it. With my relatively meager setup that almost never sees more than 4k RPM and is only running 15 psi with 15Gs, I'm not making much power and not stressing my engine much for what is a daily driver that gets 20-22 mpg on my city/highway commuting cycle.

If I were interested in doing something special, I'd go for one of the nice and expensive balancers. I'm not, so I'll go for this. Worst case, my 3.8L build happens sooner. But I'm not convinced that my engine will see any loss of longevity compared to everything else that's been wrong with it.

I'll report back at 200k (which will be 40k miles with it) or when my crankshaft breaks. :D
 

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No more VR4!
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Discussion Starter · #11 ·
I got asked about this - I'm now at 178k (so 18k miles) and still a happy customer. I also replaced the main and rod bearings for fun at 175k, and they actually looked pretty good. So, 15k with the 3SX pulley didn't seem to do any damage.

Speedy will just have to keep waiting for my crankshaft failure. :)
 

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Good report!, although I do believe harmonic vibrations can do damage, for some reason I am not to worried, I have all 4 solid motor mounts, aluminum light weight fly wheel and 3sx crank pulley, with cams, between all of those things I get some pretty wicked vibrations going through my entire car, not to mention its gutted which doesn't help. so far its been about 5000 miles and I still bring her around to 7200 rpms whenever I feel the need to get gas lol
 

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Smooth and Fast
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Redfoo
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Mine was on my car when I bought it almost 5 years ago. Had a fresh rebuild at the time it was put on. My bearings are all fine after 30-40k on it.
 

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Lord of Boost
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Well... the vibrations that the harmonic damper damps out are the Torsional ones in the crankshaft.

Those will cause cracking and such, especially if the input excitation force is high. That's nerd talk for high torque (combustion event) at the damped/natural torsional frequency of the crankshaft.

So... high HP cars with larger turbos won't physically be able to pound the crankshaft because they make their peak torque at RPM ranges much higher than the damped/natural torsional frequency of the crankshaft.

A stock car would probably break a crank sooner than a modded turbo car.

If I remember correctly, back in my Crank Dampers days, most V shaped 6 cylinder crankshafts had damped/natural torsional frequencies of the 2000-2400 RPM range, some in the 2600 RPM range.

Of course, these torsional vibrations were much harder on cast iron crankshafts because of their brittleness when compared to the stainless and carbon steel forgings that were much more ductile.

So... unless you get a crankshaft magnafluxed or otherwise radiographed, you probably won't notice an issue until one broke. Even then, the forged crank cars might hardly ever run into issues because of the number of fatigue cycles required at that one particular RPM range.


With that said, I run an OEM one. HAHA
 

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One fix at a time
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I had one on my car when I bought it. I knew the topic was controversial and I didn't want to run one but didn't think it was enough of a threat to change immediately. It eventually backed out my tensioner pulley bolt nearly causing me to bend valves and it also accelerated the wear on my main bearings. My car isn't lightly modded either so that didn't help. Here's what Ray recommends:

more than just taking out vibration, the stock damper uses it weight as a "flywheel" for the front half of the crank. what that does is it keeps the nose of the crank from accelerating and decelerating rapidly each revolution as each cylinder fires.

when the weight is not there, that motion yanks on the slack side of the belt pulling the tensioner loose. it can also loosen the cam gear adjuster bolts (if you have them)

Ray
My main bearings confirmed the crank was moving around on the timing side as more copper was showing there. This was probably over 20-30k miles.
 

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Lord of Boost
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Yep, this also is an effect of putting a lighter weight pulley on.

If the crank is stock... I'd keep its OE damper on it.
 

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SOHC you in the FACE
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Well... the vibrations that the harmonic damper damps out are the Torsional ones in the crankshaft.

Those will cause cracking and such, especially if the input excitation force is high. That's nerd talk for high torque (combustion event) at the damped/natural torsional frequency of the crankshaft.

So... high HP cars with larger turbos won't physically be able to pound the crankshaft because they make their peak torque at RPM ranges much higher than the damped/natural torsional frequency of the crankshaft.

A stock car would probably break a crank sooner than a modded turbo car.

If I remember correctly, back in my Crank Dampers days, most V shaped 6 cylinder crankshafts had damped/natural torsional frequencies of the 2000-2400 RPM range, some in the 2600 RPM range.

Of course, these torsional vibrations were much harder on cast iron crankshafts because of their brittleness when compared to the stainless and carbon steel forgings that were much more ductile.

So... unless you get a crankshaft magnafluxed or otherwise radiographed, you probably won't notice an issue until one broke. Even then, the forged crank cars might hardly ever run into issues because of the number of fatigue cycles required at that one particular RPM range.


With that said, I run an OEM one. HAHA
Well crankshaft failures and cracking was very well documented in the 6g72 racing years and the evidence does not support any of your classwork when it comes to the 6g72. The high HP cars still make huge torque and whether or not they are at the perfect rpm, knock at already high cylinder pressures is the real killer of the cranks. Heavy dampers and heavy flywheels have been shown to prevent the cracks that people were finding while magnafluxing. Ray was already doing it and 3sx had to swap to stock (without telling anyone) to prevent their crankshafts from cracking in T4.

They were pushing those motors very hard and 3sx's motor combo in particular was NOT optimal so I would say it was very prone to knocking.
 
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