Subject	Shorter crank only means the resonant frequency is higher
Posted by	AshsZ (FABio) on February 25, 2003 at 12:33 PM
	This message has been viewed 85 times.
In Reply To	You forgot the key words, was it a tested on a VG or posted by Spongerider (Now PFC) on February 25, 2003 at 12:17 PM
Message	Even at 22" long, applying 3000+ lbs of pressure to a crank journal at cylinder #1 is going to make that entire crank twist several degrees. 400ft/lbs @1.6" (1.6" is the radius from the conrod journal to the crank centerline). 12/1.6 = 7.5:1 7.5 * 400ft/lbs = 3000lbs of pressure at the conrod journal. The deflection of the crankshaft when this cylinder fires over a 20" of irregularly shaped steel (crankshaft conrod journal #1 to flywheel) is going to be an appreciable amount that one should consider. The effects of twisting the crank up this much and rebounding should be cause for concern. This rebounding of the crankshaft is absorbed by the tortional dampener in a stock pulley. Imagine making 500ft/lbs at the FW. That's 3750lbs at the conrod journal which is roughly the weight of your car hanging from a journal 3/4" wide and 2" in diameter. [ ashleypowers.com ] [ agpowers@bellsouth.net ] [ Zemulator Information Sheet ] Enthusiasts soon understand each other. --W. Irving. Are you an enthusiast?
Follow Ups	I Have Heard Some Bad Rumors about Lightened crank pulleys.. - 5liter-eater 11:16:38 02/25/03 Absolutely, 100% YES, they are the worst thing EVER!!! (n/m) - my91z 11:19:41 02/25/03 Every last person who has used one has hda their engine blow (n/m) - my91z 11:20:14 02/25/03 They are SO bad oil will shoot out of your engine the > - my91z 11:20:38 02/25/03 thats enough girly man (n/m) - TARGETZ 12:34:23 02/25/03 Uh-huh.... a bit late on that comeback, eh? (n/m) - my91z 12:37:23 02/25/03 My 91 Z - seoulski 10:45:13 02/26/03 I was going to lay into you, but I'll take the high road> - my91z 16:11:49 02/26/03 Please use SEARCH for "underdrive pully" (n/m) - YugoBernie (NoVA) 11:22:29 02/25/03 yes/no (n/m) - genic 11:25:53 02/25/03 maybe (n/m) - Spee 13:03:58 02/25/03 so? (n/m) - -Ever- 13:13:14 02/25/03 I have over 20,000 miles and no problems. :) (n/m) - Spongerider (Now PFC) 11:27:55 02/25/03 There is a huge debate on this >>> - Mal1ce 11:28:32 02/25/03 Do Not Get one, IMO - WhiteOutZ 11:40:37 02/25/03 according to ASHs logic, Detonation is OK. Ask AK[zip] (n/m) - niXit 11:43:26 02/25/03 Where did you get that from? - AshsZ (FABio) 11:50:48 02/25/03 umm...haters? I don't think so - aliaZ 12:03:23 02/25/03 I wasn't pointing fingers. (n/m) - AshsZ (FABio) 12:52:20 02/25/03 Ok (n/m) - aliaZ 12:54:09 02/25/03 Aren't you going to soak people for the same price? - Turbodog (CT) 12:37:51 02/25/03 Nope. My ECU upgrade that is the same kind of upgrade as JWT - AshsZ (FABio) 12:46:07 02/25/03 what about dual MAFS? - aliaZ 12:57:28 02/25/03 I will have a dual-intake setup which will not require - AshsZ (FABio) 13:25:41 02/25/03 I'm more interested in the benefit of running... - aliaZ 13:39:16 02/25/03 Dual-intake splits the air between two filters so you - AshsZ (FABio) 13:42:00 02/25/03 ok I misunderstood (n/m) - aliaZ 14:35:17 02/25/03 Why not do a MAP sensor...much better for high Hp... (n/m) - Kyle(Houston) 13:39:32 02/25/03 The ECU uses a VE calculation to determine engine load - AshsZ (FABio) 13:44:33 02/25/03 Everything I have read, has said MAP is very innaccurate. - niXit 14:13:23 02/25/03 Hmmm - Marshall 14:24:14 02/25/03 Any race car I have ever seen has had a Map sensor---> - Kyle(Houston) 07:40:48 02/26/03 Yeah, having one for 85K w/ 205K on motor is WAY unreliable. (n/m) - my91z 11:49:27 02/25/03 You also have an NA. (n/m) - AshsZ (FABio) 11:52:03 02/25/03 Which sees redline everyday it is driven...your point is? (n/m) - my91z 11:53:53 02/25/03 Its not specific to RPM - its specific to torque. - AshsZ (FABio) 11:57:25 02/25/03 I agree with this (n/m) - aliaZ 12:04:39 02/25/03 I don't buy it. I think it's an NVH issue >> - my91z 12:18:37 02/25/03 Ok. (n/m) - AshsZ (FABio) 12:21:29 02/25/03 So this is Ash's opinion, not yours then? (n/m) - Woody75 (Denver) 11:56:12 02/25/03 Oh boy.. Thanks for the support, but you're gonna get it.. - AshsZ (FABio) 11:58:24 02/25/03 nice blanket statement :-/ (n/m) - aliaZ 12:05:35 02/25/03 Yup. (n/m) - AshsZ (FABio) 12:22:02 02/25/03 I see your pattern, "yup, ok", I like that new you =) (n/m) - ZEngineer 12:27:26 02/25/03 Hmmmm... My engine has a little shimmy between 2200-3500>>> - Bobby12many 12:05:06 02/25/03 I know what you're talking about... - ZEngineer 12:07:50 02/25/03 Damn does it bother me... (n/m) - Bobby12many 12:14:19 02/25/03 Mine does too - Marshall 12:21:50 02/25/03 yes, but mine's a separate issue - ZEngineer 12:30:30 02/25/03 I know what you are talking about>>> - Bobby12many 12:36:33 02/25/03 yes, make it stop Bobby, MAKE IT STOP!! =( (n/m) - ZEngineer 12:42:37 02/25/03 Oh, I will. :) New DS, Diff Bushings, Trans Isol Mount go on - Bobby12many 13:51:50 02/25/03 I have a great diff bushing writeup here if you need it (n/m) - ZEngineer 14:05:09 02/25/03 If youre referring to the one Mike(my91z) wrote, I got it :) - Bobby12many 14:16:38 02/25/03 yup, that's the 1. You're all set I guess, good luck (n/m) - ZEngineer 14:25:50 02/25/03 Sounds exactly like my car... Exactly (n/m) - Bobby12many 12:32:43 02/25/03 Check your U-joints, my Jeep does that when they R going out - my91z 12:50:57 02/25/03 that is possible. - Marshall 13:29:39 02/25/03 dont be surprised if as you're checking it, - ZEngineer 14:10:01 02/25/03 You're probably right. - Marshall 14:26:07 02/25/03 You forgot the key words, was it a tested on a VG or - Spongerider (Now PFC) 12:17:38 02/25/03 Shorter crank only means the resonant frequency is higher - AshsZ (FABio) 12:33:21 02/25/03 Nope... - Spongerider (Now PFC) 12:48:15 02/25/03 Ok. (n/m) - AshsZ (FABio) 12:50:43 02/25/03 that's overly simplied - Marshall 13:10:15 02/25/03 It is possible to move the resonant frequency out of range? - Marshall 12:55:07 02/25/03 In a good design, yes but > - kuah@splparts.com 13:05:30 02/25/03 Nope. Harmonics allow lower frequencies to amplify higher - AshsZ (FABio) 13:06:13 02/25/03 Re: Shorter crank only means the resonant frequency is higher - SactoTodd 12:55:35 02/25/03 An ant can carry many more times its own weight. (n/m) - AshsZ (FABio) 13:39:40 02/25/03 I got this information from Jim at Sunbelt in GA >>> - Mal1ce 17:52:00 02/25/03 no problems here. (n/m) - wickdGSXR 11:47:22 02/25/03 I think its dependent on the HP the car is producing. - AshsZ (FABio) 11:55:25 02/25/03 Agreed, NAs will last long, but a high HP TT will not enjoy - George(boostsolutionsinc.net) 12:03:14 02/25/03 Yep. - Dallas DamonZ 12:15:33 02/25/03 I ran an underdrive pulley from late 97-late 00 and *NEVER*> - Kyle(Houston) 12:21:50 02/25/03 *shrug* - AshsZ (FABio) 12:24:21 02/25/03 LOL.....True..I just have never seen any *actual* proof---> - Kyle(Houston) 12:30:21 02/25/03 I will agree with that. A friend here had an odd plug - AshsZ (FABio) 12:41:01 02/25/03 And what do you suppose a lightweight flywheel does to the > - my91z 12:44:53 02/25/03 harmonic dampers are filled with rubber - Marshall 13:03:19 02/25/03 ?? I don't see your point? The "damper" is still tuned> - my91z 13:14:31 02/25/03 I'll reply with Kuah's answer- it doesn't need to be tuned. - Marshall 13:24:38 02/25/03 Just like shocks on a car don't need to be tuned 2 the mass? - my91z 13:28:37 02/25/03 The shocks on a car should just dampen anything - Marshall 13:36:44 02/25/03 Actually, the damper compression and rebound, but >> - my91z 13:51:00 02/25/03 it's possible... - Marshall 14:13:46 02/25/03 flywheels do nothing to dampen harmonic vibrations - aliaZ 13:08:40 02/25/03 And I said any of this where? >> - my91z 13:17:39 02/25/03 It would actually lower the tortional flexion because - AshsZ (FABio) 13:09:19 02/25/03 Did anyone actually read my post? - my91z 13:31:18 02/25/03 Yup. I answered. (n/m) - AshsZ (FABio) 13:38:30 02/25/03 I did. - Marshall 13:46:21 02/25/03 That is how it operates. It dissipates the vibration - AshsZ (FABio) 13:55:34 02/25/03 You need to look at it in the relative oreders of magnitude> - my91z 14:01:36 02/25/03 Yes I understand that. - Marshall 14:19:55 02/25/03 Such dampeners do not need to be "tuned" for a frequency - kuah@splparts.com 13:10:22 02/25/03 You are re-iterating what I said. I said that by changing > - my91z 13:27:28 02/25/03 Re: You are re-iterating what I said. I said that by changing > - kuah@splparts.com 13:45:50 02/25/03 I agree about the fixed end point, I hadn't thought > - my91z 13:57:29 02/25/03 I guess I was overzealous, it would reduce the effcetivness> - my91z 13:33:52 02/25/03 I have the ASP UDP on my NA, - shawn300zTT 12:23:44 02/25/03 I have installed well over 150 UR Pullies...... - Specialty-Z 13:11:50 02/25/03 Greg do you have the picture of the whole stack of about 40 - YugoBernie (NoVA) 13:59:02 02/25/03 I have it somewhere at home...it's great! (n/m) - SeedyROM 14:18:29 02/25/03 Find that sh!t for me please. (n/m) - YugoBernie (NoVA) 14:55:27 02/25/03
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