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11-19-2012, 10:59 PM | #61 |
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Re: Is a lightened flywheel overrated? (I think so)
One of the better discussions on the forum that I have read in quite a while. Lots of reasoned opinions and no name calling.
Well done and thank you. |
11-20-2012, 04:02 AM | #62 |
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Re: Is a lightened flywheel overrated? (I think so)
Brent, excellent topic... Here's my quick 2cents worth. I've driven and used both in my persnal engines and quite frankly I can't tell much difference, except that a stock flywheel definately enables the car to idle much more smoothly than one that is lightened. I think that was the intent of Ford to help give the engine it's smoothness, motion, and torque ( maybe I'm relating this wrong but then maybe not).
All things created equal in rebuilding engines it is no surprise that all engines do not run exactly the same. I always tell my customers these are like kids... as much as you want them to be the same they are not. As far as breaking crankshafts I don't think that's much of an issue with Model A Cranks.... after messing around with these for 35 years I've not personally heard of anyone I know or otherwise who "broke" a crank. There's lots of factors of that including metallurgy, abuse...etc As I said... personally I can't tell a difference but I do think that the smoother running Model A, idler and otherwise will have the stock flywheel. Again, just my 2 cents worth. Isn't this a great hobby! so many great cars, so many great people! Thx. Larry S. |
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11-20-2012, 07:13 AM | #63 |
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Re: Is a lightened flywheel overrated? (I think so)
Hey Mike K; I LOVE it! Nice work.
Vic: You are an astute thinker! Chris: I agree with you. Great thread.
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11-20-2012, 09:12 AM | #64 | |
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Re: Is a lightened flywheel overrated? (I think so)
Quote:
This is getting pretty funny. Eigen functions, huh? That Ouija board is looking pretty good right now. Again, if we were to perform a Fourier Analysis on the rotating assembly, we could come up with an ideal weight for the flywheel/pressure plate assembly. My guess, based entirely on Ouija board consultations would be somewhere between 30 and 36 lbs as an ideal weight for an I-4 of 200 cubic inches and three mainbearings. My own flywheel is 40lbs stand-alone, but the next time I have the engine apart I think I'll try to get it to 36 w/ pressure plate. I have a single channel Fast Fourier Analyser, but you really need a two channel unit to do the necessary calculations... By the way, is your Ouija board single or dual channel? Happy Thanksgiving to all cranks everywhere - balanced and unbalanced! |
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11-20-2012, 09:23 AM | #65 |
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Re: Is a lightened flywheel overrated? (I think so)
Now another thought. If a person chooses to lighten a flywheel some will depend on where the weight is removed the most, outboard or inboard next to the crank flange. Just some thoughts about inertia in this whole debate. Rod
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11-20-2012, 09:32 AM | #66 | |
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Re: Is a lightened flywheel overrated? (I think so)
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Jim Cannon Former MAFCA Technical Director "Have a Model A day!" |
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11-20-2012, 11:52 AM | #67 | |
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Re: Is a lightened flywheel overrated? (I think so)
Quote:
Dual channel: If you have a single channel fast fourrier transform (FFT) device you could still do independent acceleration analysis at different axis points and get a very good data set for good 'ol pencil and paper 3-axis graphing. It would take a while (forget 'fast'). Of course, there will always be 968 1/2 variables unaccounted for in any specific engine build, so perhaps Brent's "Come one, come all.." statement is valid. A multi channel Ouija may be the way to go. |
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11-20-2012, 12:06 PM | #68 |
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Re: Is a lightened flywheel overrated? (I think so)
I have more layman's questions concerning the energy the flywheel must store and release. At firing impulse on a stock A, the crankshaft flexes torsionally from the energy imparted at the journal and must then "snap back" (and vibrate somewhat torsionally). When it snaps back (primary return pulse), it tries to impart more spin to the flywheel and it also tries to push the rod and piston backwards. Am I right so far? This un-even rotation of the rotating mass (it was already uneven because of uneven rod angularity during each rotation, pressure cycling, etc.) results in another character in the vibration signature. What is the duration of the primary pulse/return pulse? The point in crankshaft angularity when the return pulse will occur increases as rpm rises and will not only change the vibration signature, but will also change the magnitude and timing of the pulses in relationship to the crank's natural frequency. (Harmonics implied.) One of many new thoughts to me, as already stated in this thread, is that the counterweight's mass performs another important function in addition to "counterweighting". (You can't completely counterweight a mass that is part unevenly-reciprocating and part rotating with a purely rotating mass.) That other important function is to reduce crank flex.
It seems to me that the vibration signature would be different for any point it could be measured along the length of the crankshaft. This thread has moved my "theoretical wall" either past my present view or I am against the wall. |
11-20-2012, 01:38 PM | #69 | |
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Re: Is a lightened flywheel overrated? (I think so)
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11-20-2012, 02:01 PM | #70 |
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Re: Is a lightened flywheel overrated? (I think so)
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11-20-2012, 02:57 PM | #71 | |
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Re: Is a lightened flywheel overrated? (I think so)
Quote:
See technical video here: https://www.youtube.com/watch?v=oIS5n9Oyzsc It all makes perfect sense (classical mechanics).
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Jim Cannon Former MAFCA Technical Director "Have a Model A day!" Last edited by Jim/TX; 11-20-2012 at 04:48 PM. |
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11-20-2012, 03:58 PM | #72 | |
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Re: Is a lightened flywheel overrated? (I think so)
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I first saw it in 1946. http://www.adl.com/uploads/tx_extprism/1995_q1_29.pdf |
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11-20-2012, 04:38 PM | #73 |
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Re: Is a lightened flywheel overrated? (I think so)
Well Pete, you got me. I googled Chlomondelly's grillage and got more good info. 'Next time you're in my neighborhood we can go to Chlomon's Delli and Grille. My CCPU may sound smoother after that.
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02-24-2018, 09:37 AM | #74 |
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Re: Is a lightened flywheel overrated? (I think so)
I have read this before and I do not who first said it but here it is.
If you are in a hurry you are driving the wrong car. |
02-24-2018, 11:52 AM | #75 | |
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Re: Is a lightened flywheel overrated? (I think so)
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02-24-2018, 05:36 PM | #76 |
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Re: Is a lightened flywheel overrated? (I think so)
A lightened flywheel does affect the idle condition. A stock model a with a heavy flywheel will idle down to 3 - 400 RPM.
The same engine with a lightened flywheel will idle quite slow but not as smooth. Important to some folks / not so much to others Dave |
02-25-2018, 02:20 PM | #77 |
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Re: Is a lightened flywheel overrated? (I think so)
Very good thread here, lots of correct information.
The one thing, and I may have just breezed by it, is the intended use of the motor combination. The lightened flywheel will be most noticed in the acceleration of the car. Usually this is in conjunction with multiple modifications to increase performance of vehicle. I have been told many things about flywheels, including that a Model A will not run without one. Keep up the good work, all of this is to be considered in the world of the Model A/B. Also, if the original Turbo Encabulator article surfaces, I would like to send to some youngsters at work, just to see their reactions......... John
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02-25-2018, 02:56 PM | #78 | |
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Re: Is a lightened flywheel overrated? (I think so)
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02-25-2018, 04:21 PM | #79 | |
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Re: Is a lightened flywheel overrated? (I think so)
Quote:
You feel the vibration at resonance or harmonics of resonance but the vibration is there at all other rpm's, just to a lessor degree. Even if you only did parade driving at idle, an engine would benefit from balancing and last longer. I have a pic of a 12 lb. big block Chev damper installed on a B race engine but can't post it. Probably because the website certificate has not been renewed. |
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02-25-2018, 04:59 PM | #80 | |
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Re: Is a lightened flywheel overrated? (I think so)
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