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Old 02-13-2017, 04:35 AM   #43
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Captain Snooze: regarding (2) i recall seeing posts from few shop workers about crank bearings having short live for EJ & FA engines they had rebuilt or repair for cases where both lightweight CP & FW were installed. Rather soon at it. Something along the lines that only one of them should be installed, not both.
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Old 02-13-2017, 08:49 AM   #44
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Fluidamper also claims 2lbs of rotating mass does not behave as rotating mass...

I know nothing of harmonics in an engine, but I see only that harmonics exist on all 3 pulleys, with similar magnitude, but in different orders and rpm. And the OEM pulley seems worst of the bunch on that 2nd order line... But what's actually destructive? No idea. I tried researching but haven't found any materials...

It could be NVH is the only reason for a damper pulley.

Of course, the OP's wobbly install would definitely be bad.

C
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Old 02-13-2017, 09:46 AM   #45
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Originally Posted by churchx View Post
Rather soon at it. Something along the lines that only one of them should be installed, not both.
My ej has lightweight crank pulley and flywheel, I always thought those were just rumors. Been 20k miles so far at around 300 whp, on an engine with 80k since rebuild
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Old 02-13-2017, 09:53 AM   #46
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One of those posts of different experiences. Another. Later cites info from other shop doing even more rebuilds and with "similar experiences". It's my only car, and one i like & want to use for long time .. preferring to play on safe side.

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Old 02-13-2017, 12:18 PM   #47
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Hey @why? ...... where did you run off to ...... ??

I wasn't done with you yet.




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Old 02-13-2017, 04:32 PM   #48
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Originally Posted by Captain Snooze View Post
Two other points:
1/ There has been no controlled testing of the effect of fitting a solid cp on the FA20 as far as I know and it would not be economically viable to do so.
2/ There doesn't seem to be a high correlation of engine failure with having fitted a lwcp.
Now we're cooking with gas. I referred to the cost of the damper versus a solid CP because it was the most general argument I could think of to support my position.

1. The OEM commits considerable resources into understanding how each component responds to the environment in which it operates. The customer is not privy to the mounds of information collected but it exists.

2. I agree with you on this point but that does not mean I think it's a good idea.
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Old 02-13-2017, 05:05 PM   #49
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Captain Snooze: regarding (2) i recall seeing posts from few shop workers about crank bearings having short live for EJ & FA engines they had rebuilt or repair for cases where both lightweight CP & FW were installed. Rather soon at it. Something along the lines that only one of them should be installed, not both.
Yeah, I recall those/that post. It was a respected builder (MAP? Element? I can't be bothered searching ) but the issue was the combination of the two when the flywheel was reduced below a certain mass. That is, one could have a lwcp and a lighter flywheel. One could not have a lwcp and light weight flywheel. There seemed to be a critical mass at which the engine fell apart when the flywheel mass was reduced too much.

Speaking of which.
There seems to be a lot of discussion about the pros/cons of a light weight crank shaft pulley but I don't seem to read much about the impact of a light weight flywheel on the harmonics of a crankshaft. I am hypothesising given the much greater mass of the flywheel it would play a greater role in crankshaft damping/harmonics.
I am totally out of my depth here.
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Old 02-13-2017, 07:09 PM   #50
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As someone considering getting a lighter flywheel at a later date, I too would like to know how a lighter flywheel affects damping on stock cp.
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Old 02-13-2017, 08:51 PM   #51
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I hear the mass of a flywheel allows it to absorb some vibration.

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Old 02-13-2017, 08:59 PM   #52
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Quote:
Originally Posted by Captain Snooze View Post
Yeah, I recall those/that post. It was a respected builder (MAP? Element? I can't be bothered searching ) but the issue was the combination of the two when the flywheel was reduced below a certain mass. That is, one could have a lwcp and a lighter flywheel. One could not have a lwcp and light weight flywheel. There seemed to be a critical mass at which the engine fell apart when the flywheel mass was reduced too much.

Speaking of which.
There seems to be a lot of discussion about the pros/cons of a light weight crank shaft pulley but I don't seem to read much about the impact of a light weight flywheel on the harmonics of a crankshaft. I am hypothesising given the much greater mass of the flywheel it would play a greater role in crankshaft damping/harmonics.
I am totally out of my depth here.
Note that they were talking about turbo's. FA20dit and EJ turbos. Also note there are so many issues with ej's and the fa20dit's seem to also be having all sorts of problems. I see no reason to mess with the crank pulley on a turbo. More complexity changes things, however that article I posted trying to sell that so called damper proves everything has vibrations, and even the fancy expensive aftermarket damper sold as smoothing everything out actually just changes the vibrations and has more vibrations than the stock ones.

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Hey @why? ...... where did you run off to ...... ??

I wasn't done with you yet.




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I went to sleep, it was way past my bedtime. I only responded because I was drunk. I really truly don't care what people think about this stuff, it has been hashed, rehashed ad naseum and people are trying to shove info about old school big block engines into tiny 4 cylinders and try and make everyone believe it is the exact same thing when it simply isn't.

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Originally Posted by Hawk77FT View Post
Man, do you even graph? LIke seriously. I take it you looked at the second chart, which actually shows the extent of the actual vibrations, hence they recommend to look at the smoothness of the damping capabilities.
"Second order comparison between the OEM tuned elastomer damper and Fluidampr performance damper. The dominant second order represents the firing order in four-cylinder, four stroke engines. Clear start and stop damping range spikes of the tuned elastomer damper are present at 3900 and 5250 rpm, or 130Hz to 175Hz, for a narrow operating range of only 45Hz. Note the smoothness of the Fluidampr damping capability through the same rpm range."
Also, the third and fourth graph actually shows "The Fluidampr performance damper was able to cut amplitude of the excited 3rd order vibration generated by the 260Hz crankshaft resonance in half, down to below .1 degrees peak." I dare ask, do you even know what that means? You know, different frequencies and grades of vibrations, etc. I am not by any means an engineer but i have a somewhat clue about the complexity of it.
If you really want it simplified, the fifth chart shows the extent of vibrations at different rpm.
Attachment 149447

Next time, when you challenge the findings of a professional test, please make sure you really know what you are talking about.
Also, please stop spreading wrong info. "What this article tells you is harmonics don't exist at all for our cars." Yeah it so does hey! Totally! Please read my previous post for educational purposes!

Did you look at the entire article? Oh wait, no no you didn't. There are a bunch of graphs that show a bunch of different vibrations and the fluidampr supposedly specially made dampr has more vibrations in a bunch of different places over the stock one. They cherry pick above 5500 rpms on that graph you posted. Funny thing though most people dding there car are never ever going to get anywhere near there. Hell I shift at 2500 rpms or less. Also note even they admit it might add only 3 times more stress at most. Not exactly exploding engine type of levels there. Funny how nowhere in that article did they every say they actually stressed anything until it broke. Gee, I wonder why? Could it be that all three do the job just fine and there is no actual case where any of them could cause a condition that would actually cause damage? That is my educated guess.

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Originally Posted by humfrz View Post
....... how DARE you correct ME ....... I've already made up my mind and "don't give a crap what anyone says"! ......., to quote a recently self declared expert in the field of pulley things........

Seriously, I'm simple minded and just remembered this from what that guy Wiki had to say:

"A harmonic balancer (also called crank pulley damper, crankshaft damper, torsional damper, or vibration damper) is a device connected to the crankshaft of an engine to reduce torsional vibration and serves as a pulley for drive belts.[1]"

Is there a difference or are you just slapping around an old man for giggles ...??




humfrz
don't need to be an expert to see no one will ever change their opinions. Also don't need to be an expert to see big block old school v8's are not tiny boxer engines. People can take the time to do their own research, all the info is on the web. Subaru's internally balanced engines mean it really doesn't matter.

Quote:
Originally Posted by humfrz View Post
WOW!

For now, @why? , I'll just challenge the statement which is bolded above.

Are you saying that a boxer engine is more "balanced" than an in-line six ....??




humfrz
No, that's silly. Almost as balanced though.

Quote:
Originally Posted by cjd View Post
No giggles, I learned to respect my elders...

On some engines the pulley plays a crucial role in balancing the whole thing.

On this engine it really is internally balanced, and the pulley itself is balanced (OK, I haven't verified this one, but the engineers say the engine is balanced internally, so I'm pretty sure it's like my previous car, which I did test... that pulley had the same rubber insert and people ran lightweight undamped underdrive pulleys hundreds of thousands of miles no problem...) So the only thing it can do is change how the crankshaft etc. sees harmonic resonance... Which it dampens. No balancing involved.

Pedantic, but if you're arguing its importance when we haven't seen clear failures as a result of pulleys,... I have no clue if it's good or bad. But I do know it's not balancing anything. I also haven't installed a lightweight pulley, though I have one somewhere...

C
I've learned to hate pretty much all of humanity.
But you've struck a good point, there are engines that are way out of balance and need all sorts of things to make it not blow up. Some people decided that since some engines need this that must mean all of them do, which is of course nonsense.

There can be no clear failure of pulley's as it is not something people would do and never modify anything else. People do claim they have seen ej's and fa20dit's with failures in cars that happen to have lightweight pulley's among a bunch of other mods as well. Of course the problem is we are seeing failures in both engines in completely stock cars as well.

Quote:
Originally Posted by Ultramaroon View Post
If the damper wasn't deemed necessary the OEM wouldn't have specified it. A stamped steel pulley is much cheaper to manufacture.
That's silly. It could be done because "it is how it has been done for decades and there is no reason to rethink it." Like the reason for how so much is done. The research put into thinking a new way to do it would probably cost far more than any benefit that could be seen. It could also be used in many different engines and vehicles as it is now, instead of making a unique design for every engine which would add unneeded cost and complexity. If it works right and doesn't fail, why should they try and change it? There are a ton of reasons for a company to use a part that has never failed and always worked instead of trying for something new and different in this one area. Also note aftermarket pulleys are really expensive, that fluidampr thing is $370. This really is not an area of a car where revolutionizing things would bring much press or praise, while screwing things up would really ruin reputations. I have no problem with Subaru being conservative, hell I am sure a lot of people wish they would be more conservative when it comes to ej25 engines. But to say every little piece and part is why it is because of some mythical reason that has nothing to do with cost savings or part sharing is silly.

Quote:
Originally Posted by Captain Snooze View Post
I refute that statement as a valid argument. Are you suggesting that everything on this car is "necessary". If I remove the radio is the car going to blow up? It would have been cheaper to omit the radio.
nothing is necessary. We know they went the cheap route when it came to engine oiling, which is why the engine just can't rev much past 8300 rpm's without major modifications for the oil system. Hell we know they settled for the crickets, I assume fixing them would cost an absurd amount of money. The manual gearbox is one hell of a compromise, and it seems they compromised quality and usefulness for making it less expensive. I wish they had found other areas to cut costs like the interior, the wheels and tires, etc. I don't know why they made the wheelbase or the car as long as they did, would have been nice to make both shorter and lighter, but that doesn't mean they designed it that way, it probably means they borrowed parts from other vehicles to keep the costs down. I could go on, in general the car is the way it is because that was the least expensive way for them to do it, with few exceptions, and they still missed their original stated price goals by a ton.

I hate when people say the stock way is the best way, instead of the way they compromised for everything because they have so many other goals and qualifications other than making the car as sporty and fun to drive as possible. While the aftermarket has that one goal and can easily cost a heck of a lot more than the stock part it replaces without issue.
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Old 02-13-2017, 11:53 PM   #53
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" More complexity changes things, however that article I posted trying to sell that so called damper proves everything has vibrations, and even the fancy expensive aftermarket damper sold as smoothing everything out actually just changes the vibrations and has more vibrations than the stock ones. "

Man, are you reading the same article? Because it actually says the opposite. Or is it again based on your extensive experience? Alternative facts?

Look I get it, it might be a marketing spin, but considering Fluidampr has been around for years, had stellar results on trucks and cars, and been tested independently by quite a few places, i tend to believe them instead of your personal uneducated opinion. No disrespect, just a choice.

Here is another one that might interest you.
http://www.motoiq.com/MagazineArticl...dent-Test.aspx
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Old 02-13-2017, 11:56 PM   #54
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Here is an educated answer from an engineer:
The crankshaft damper has nothing to do with engine balance and vibrations. Motion and oscillation of the powertrain, as an assembly, is addressed by your engine mounts, transmission mounts, and potentially roll restrictors.

The purpose of a crankshaft damper is to reduce the angular twist / deflection of the crankshaft. Combustion creates pressure. Pressure becomes load into the connecting rod which creates torque on the crankshaft. That torque creates deflection of the shaft as it's not infinitely stiff. Depending on the material, journal offset, length of the shaft, and loads created in the cylinders you can see several degrees of angular deflection in the crankshaft. I've seen an OEM crankshaft which displayed 7° of deflection without a damper. With the damper it was under 2°.

The mass of the crank damper and the stiffness of the spring element (the rubber part) are vital to the effectiveness of the damper. They control the resonant frequency of the damper and impact the effective damping. If you change the mass or change the spring stiffness you change the frequency at which it operates. If you don't have enough mass, even at the correct frequency, you don't provide sufficient damping. An incorrectly tuned damper could actually make things worse."
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Old 02-14-2017, 12:15 AM   #55
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" More complexity changes things, however that article I posted trying to sell that so called damper proves everything has vibrations, and even the fancy expensive aftermarket damper sold as smoothing everything out actually just changes the vibrations and has more vibrations than the stock ones. "

Man, are you reading the same article? Because it actually says the opposite.
According to their graph at certain rpm there is more twist with the Fluidampr than with oem. I have no idea if any of this is significant.

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Old 02-14-2017, 12:27 AM   #56
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I've seen an OEM crankshaft which displayed 7° of deflection without a damper. With the damper it was under 2°.
This is a generalised explanation that may or may not have ramifications for the FA20 engine. Does the the FA20 crank twist 7 degrees with a lwcp? No, it does not. I am suggesting that broad sweeping statements cannot be attributed to every particular example. The most twist I could see with a lwcp from that Fluidampr article was 0.37 of a degree. I have no idea if this is significant.
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