Subject	typically, fasteners are preloaded to 75% of yield strength
Posted by	LitlElvis on April 06, 2010 at 7:16 AM
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In Reply To	Exactly, it's not about breaking bolts posted by Brett@AwesomeZ on April 06, 2010 at 12:44 AM
Message	"If" the fasteners were loaded to the point of permanent deformation, this means they have yielded (stretched) and are now permanent junk. The "snap back" that you refer to will only occur if the yield point has not been exceeded. Keep in mind, it's not the cylinder pressure that's going to cause this.
Follow Ups	Stock head bolt tensile tests >>> - LitlElvis 17:19:23 04/05/10 have you tested the replace ARP studs for reference? - Carlos Ramirez 17:37:15 04/05/10 ARP lists their standard 8740 studs to be 200ksi - LitlElvis 17:47:04 04/05/10 Interesting... - Gold300zx 17:38:36 04/05/10 I'm curious, was the breakpoint at the nut, or does it have - zellamay 17:53:55 04/05/10 it's more to do with the start of the threads - LitlElvis 21:37:58 04/05/10 To clarify, if the threaded portion was longer, and the - zellamay 21:59:16 04/05/10 it will break where the threads start to form on the shank - LitlElvis 22:05:54 04/05/10 Thanks, you have been very informative. (n/m) - zellamay 23:14:59 04/05/10 So the bolts dont really stretch? Just break.... (n/m) - ZXoltan 18:37:31 04/05/10 Yes they stretch - Brad(RI) 18:53:41 04/05/10 The threads are rolled. Like you, I hoped this would - LitlElvis 07:54:18 04/06/10 Out of curiosity... - Obeeone 19:13:36 04/05/10 Re: Out of curiosity... - Brett@AwesomeZ 19:31:20 04/05/10 Re: Re: Out of curiosity... - Brett@AwesomeZ 19:32:30 04/05/10 The graphs and some math tell the tale that you want to see - LitlElvis 22:03:39 04/05/10 This is not about outright failure of head bolts - LitlElvis 21:50:30 04/05/10 Never seen one issue with the factory head bolts yet (n/m) - Seb@Specialty-Z 22:36:43 04/05/10 Seb, what's the highest HP you have run with stock bolts? (n/m) - ZXoltan 07:45:11 04/06/10 a little over 1000 BHP (n/m) - Seb@Specialty-Z 10:12:31 04/06/10 Do you guys recommend the stock head gaskets or MLS styles? - KongZTT GT28RS MD 01:48:13 04/07/10 Exactly, it's not about breaking bolts - Brett@AwesomeZ 00:44:29 04/06/10 typically, fasteners are preloaded to 75% of yield strength - LitlElvis 07:16:53 04/06/10 I thought stock head bolts fell into this stretch category. (n/m) - Antihero 08:36:50 04/06/10 All fasteners stretch when preloaded, the key is to not - LitlElvis 11:56:01 04/06/10 the new ARP L19 hardware... - KongZTT GT28RS MD 01:54:07 04/07/10 You have an instron in your shop? Impressive! (n/m) - Scotts94z32 11:44:26 04/06/10 It's not mine, I just get access to it :-) (n/m) - LitlElvis 12:07:25 04/06/10 What adjustment factor do you apply to the steel>> - ZUL8TR 14:37:31 04/06/10 This is perfect.. I have been thinking of pulling - KongZTT GT28RS MD 01:41:27 04/07/10 err.. L19 (n/m) - KongZTT GT28RS MD 01:46:06 04/07/10
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