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They most likely will not tell us per customer request. |
I wonder if they will let those LTH go? :)
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street racing and a miss shift i assume, red line 4th shift to 5th and go into 3rd...
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I will say that there was no evidence of detonation: the valves weren't burnt, the pistons weren't melted or pitted. Granted, only the owner of the car knows what happened and we aren't necessarily privy to that information in the first place. Also, you need to remember that not every car owner really knows what is going on under the hood or what they did to cause a catastrophy. I've seen many a "deer in the headlights" looks from people with broken stuff. They just don't know and simply aren't able to understand that by doing X, Y can happen. By them not knowing, they have no way of communicating relevant information. I can't tell you how many times I've heard "I was just driving along normally, and suddenly it just blew up". They usually forget that the night before when they were ripping on it with reckless abandon something subtle happened that they didn't notice and the next day the nature of the true damage reared its ugly head when they were casually taking off from a stoplight and they're like "OMGWTFBBQ just happened!?!?...I didn't even do anything!!!". Ultimately, there is always a level of uncertainty when modifying cars. The bottom line with this particular failure is that we've given you guys all the facts and you must draw your own conclusions as to the cause...not that you'd listen to us anyway as evidenced by some people's posts. Also, there was no Nitrous Oxide involved or signs that it was ever installed. If there had been, don't you think we would have mentioned it? |
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Well...probably as good an excuse as any to build something nice. It's a wreck going into GTM, let's see how it comes out. |
I think everyone here were just curious as to what exactly happened, considering there are quite a few people on here with roughly the same mods. Knowing you guys at GTM are pro's at this, we just thought you would know more about the circumstance leading to the engine grenading.
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sent from my SAMSUNG SINGLE TURBO SGH1717 |
I think there are to many variables to know exactly what happened, and I can easily see GTM not wanting or needing to know what the owner was doing when it happened or if the owner even knew. Guy could have been at the track two days before and when driving to work it blew.
Could have been all the bolt ons, driving it hard and the tune was just bad. |
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It's actually funny, but the guys on the G37 forum seem to get it. But, that's what happens when you've got a physicist who understands harmonics on that board. Quote:
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Oh, for sure... I doubt the likely vibrations from that pulley helped keep things in tact though... We will never know what AFR that engine was getting... obviously... lol |
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--- Meh, better not even think about those LTH. I have bigger and better things in the plans for next year. |
I'm guessing oil pump failure... gee, wonder what caused that...
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Scary stuff in here
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Either way, I wouldn't use any of the old parts and put new gas in the car. |
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Hmm. |
subbed for build progress, more pictures, 700 horsepower, and tons more conjecture on what made the engine turn into a bomb
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Is this thread dead? Was sub'd for updates!
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We are talking about a total engine eradication just like what you saw on the photos that Sam posted. This looks so much like what happened to my friend 9 years ago on his BMW 328 with the E36 motor series ( Inline 6 in this case ). As we all know, the popular method for making power pulleys on E36 engines is by removing the harmonic damper and replacing it with an underdrive lightweight alloy assembly. This is a VERY dangerous product because this stock damper is essential to the longevity of an engine. The substitution of this part often results in severe engine damage. It is also important to understand that while the engine in a BMW is designed by a team of qualified engineers who understood the engine characteristics inside and out, these aftermarket power pulleys are created by the people who do not understand many of the very important principles of physics. To put things simple, it is not the underdrive feature that kills the engine, but rather the lack of dampening the harmonic vibration that the crankshaft generates every time after each cylinder firing sequence. When this sinusoidal harmonic vibration coincide with the phase vector of the engine RPM, resonance frequency will occur. When this occurs, it must be counterbalance immediately and that is the exact job of the harmonic balancer pulley. If not, the power under the sine curve will keep on increasing or accumulate exponentially and that will guarantee to destroy the entire engine and the possible surroundings, such as the starter in this case of this VQ37VHR engine....... Think 5 times BEFORE you put in an underdrive aftermarket pulley. The risk is 1000 times the reward.... Not worth it at all...... |
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Detail of engine complication and destruction without a properly designed and installed harmonic balancer:
1) Elastic Deformation Though it is common belief that large steel parts such as crankshafts are rigid and inflexible, this is not true. When a force acts on a crank it bends, flexes and twists just as a rubber band would. While this movement is often very small, it can have a significant impact on how an engine functions. 2) Natural Frequency ( Resonance frequency ) All objects have a natural frequency that they resonate (vibrate) at when struck with a hammer. An everyday example of this is a tuning fork. The sound that a particular fork makes is directly related to the frequency that it is vibrating at. This is its "natural frequency," that is dictated by the size, shape and material of the instrument. Just like a tuning fork, a crankshaft has a natural frequency that it vibrates at when struck. An important aspect of this principle is that when an object is exposed to a heavily amplified order of its own natural frequency, it will begin to resonate with increasing vigor until it vibrates itself to pieces (fatigue failure). 3) Fatigue Failure Fatigue failure is when a material, metal in this case, breaks from repeated twisting or bending. A paper clip makes a great example. Take a paper clip and flex it back and forth 90° or so. After about 10 oscillations the paper clip will break of fatigue failure. The explanation of the destructive nature of power pulleys begins with the two basic balance and vibration modes in an internal combustion engine. It is of great importance that these modes are understood as being separate and distinct. 1) The vibration of the engine and its rigid components caused by the imbalance of the rotating and reciprocating parts. This is why we have counterweights on the crankshaft to offset the mass of the piston and rod as well as the reason for balancing the components in the engine. 2) The vibration of the engine components due to their individual elastic deformations. These deformations are a result of the periodic combustion impulses that create torsional forces on the crankshaft and camshaft. These torques excite the shafts into sequential orders of vibration, and lateral oscillation. Engine vibration of this sort is counteracted by the harmonic damper and is the primary subject of this paper. Torsional Vibration (Natural Frequency) Every time a cylinder fires, the force twists the crankshaft. When the cylinder stops firing the force ceases to act and the crankshaft starts to return to the untwisted position. However, the crankshaft will overshoot and begin to twist in the opposite direction, and then back again. Though this back-and-forth twisting motion decays over a number of repetitions due to internal friction, the frequency of vibration remains unique to the particular crankshaft. This motion is complicated in the case of a crankshaft because the amplitude of the vibration varies along the shaft. The crankshaft will experience torsional vibrations of the greatest amplitude at the point furthest from the flywheel or load. Harmonic (sine wave) Torque Curves Each time a cylinder fires, force is translated through the piston and the connecting rod to the crankshaft pin. This force is then applied tangentially to, and causes the rotation of the crankshaft. The sequence of forces that the crankshaft is subjected to is commonly organized into variable tangential torque curves that in turn can be resolved into either a constant mean torque curve or an infinite number of sine wave torque curves. These curves, known as harmonics, follow orders that depend on the number of complete vibrations (cylinder pulses) per revolution. Accordingly, the tangential crankshaft torque is comprised of many harmonics of varying amplitudes and frequencies. This is where the name "harmonic damper" originates. Critical RPM's When the crankshaft is revolving at an RPM such that the torque frequency, or one of the harmonic sine wave frequencies coincides with the natural frequency of the shaft, resonance occurs. Thus, the crankshaft RPM at which this resonance occurs is known a critical speed. A modern automobile engine will commonly pass through multiple critical speeds over the range of its possible RPM's. These speeds are categorized into either major or minor critical RPM's . Major and Minor Critical RPM’s Major and minor critical RPM's are different due to the fact that some harmonics assist one another in producing large vibrations, whereas other harmonics cancel each other out. Hence, the important critical RPM’s have harmonics that build on one another to amplify the torsional motion of the crankshaft. These critical RPM’s are know as the "major criticals". Conversely, the "minor criticals" exist at RPM's that tend to cancel and damp the oscillations of the crankshaft. If the RPM remains at or near one of the major criticals for any length of time, fatigue failure of the crankshaft is probable. Major critical RPM’s are dangerous, and either must be avoided or properly damped. Additionally, smaller but still serious problems can result from an undamped crankshaft. The oscillation of the crankshaft at a major critical speed will commonly sheer the front crank pulley and the flywheel from the crankshaft. I have witnessed front pulley hub keys being sheered, flywheels coming loose, and clutch covers coming apart. These failures have often required crankshaft and/or gearbox replacement. Harmonic Dampers Crankshaft failure can be prevented by mounting some form of vibration damper at the front end of the crankshaft that is capable of absorbing and dissipating the majority of the vibratory energy. Once absorbed by the damper the energy is released in the form of heat, making adequate cooling a necessity. This heat should be dissipated in order to keep the damper at optimal operating temperatures. While there are various types of torsional vibration dampers, most Japanese and BMW engines are primarily designed with "tuned rubber" dampers. http://www.atiracing.com/products/da...n/pully_wp.jpg It is also important to note that while the large springs of a dual mass flywheel absorb some of the torsional impulses conveyed to the crankshaft, they are not harmonic dampers, and are only responsible for a very small reduction in vibration. That's why there is zero problem when you replace the 370Z dual mass flywheel with a lighter quality flywheel, such as Jim Wolf Technology one. |
Way over my head. I read this in Psychology class, and had more fun reading about this rather than listening to my professor ramble on lol.
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Nothing better than a true harmonic balancer. I personally use the Fluidampr for my 2006Sti. I feel its even more important if you have other lighten components like a flywheel. These hollow "lightweight pullies" just seem like a poor idea.
Thanks, Alex Goodwin AlexG@motionlabtuning.com |
Damn that's a lot of damage. Whether the harmonic balancer effect is real or not, pulleys are not worth this kind of risk. I guess I got lucky because I used to have the same thing on my car.
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It's been four months; any progress / updates?
Thanks, Jeremie |
I still don't think an aftermarket pulley did this. The stock crank pulley is not a harmonic balancer or damper. It doesn't look like one, it looks like a pulley to me. Seriously, it only has a small rubber gasket and that is it. The pictures, story and diagram are great... but we aren't removing a harmonic balancer and putting on a crank pulley, we are removing a crank pulley and putting on a lighter crank pulley. The crank and pulley fusing together doesn't cause motor failure either. Now a lightweight crank failing, I have seen on this motor.
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For engine that have internal balance shaft, you do not need a harmonic balancer. But for most motors out there without internal balance shafts, everyone of them come with crank harmonic balancers. |
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Edit: More food for thought. How do you spin a motor up to 7500 RPM and not balance it internally? How do you spin a motor at 7500 RPM and have a heavy A$$ dampener hanging off of it? The Nissan Engineers answered this question for you. I'm not saying your whole copy and pasted explanation is incorrect, what I am saying is that I do not believe an aftermarket crank pulley caused this failure by allowing resonance to occur in the engine. |
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As for why the motor exploded, it probably has a combination of issues, such as running full boltons with no tune, probably being driven into the ground, and the fact that the pulley was replaced. |
So what happened to the build?
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I'm sure he's still trying to get his wallet back together at the moment... |
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