many guys don,t realize that the rod bolt material and cross sectional area are critical to durrability , especially in a high rpm range combo,while the rods themselfs ocassionally fail, its much more likely that the rod bolts lost thier clamping strength, stretched a bit first and that was a major contributing factor in the bearing failure or the rod failure process.
interesting info from ARP
Other Stresses
It must be realized that the direct reciprocating load is not the only source of stresses in bolts. A secondary effect arises because of the flexibility of the journal end of the connecting rod. The reciprocating load causes bending deformation of the bolted joint (yes, even steel deforms under load). This deformation causes bending stresses in the bolt as well as in the rod itself. These bending stresses fluctuate from zero to their maximum level during each revolution of the crankshaft.
Fastener Load
The first step in the process of designing a connecting rod bolt is to determine the load that it must carry. This is accomplished by calculating the dynamic force caused by the oscillating piston and connecting rod. This force is determined from the classical concept that force equals mass times acceleration. The mass includes the mass of the piston plus a portion of the mass of the rod. This mass undergoes oscillating motion as the crankshaft rotates. The resulting acceleration, which is at its maximum value when the piston is at top dead center and bottom dead center, is proportional to the stroke and the square of the engine speed. The oscillating force is sometimes called the reciprocating weight. Its numerical value is proportional to:
It is seen that the design load, the reciprocating weight, depends on the square of the RPM speed. This means that if the speed is doubled, for example, the design load is increased by a factor of 4. This relationship is shown graphically below for one particular rod and piston
http://www.arp-bolts.com/Tech/TechWhy.html
"are all rod stretch gauges created equal "
obviously no more than all girls are equally good looking
but most of the gauges are functional, some just have more features or more precise calibrations, some are adjustable in length ,over a wider range, some have digital read outs, ETC.
http://store.summitracing.com/partdetail.asp?autofilter=1&part=SUM-900015&N=700+4294854225+115&autoview=sku
http://www.carcraft.com/techarticles/116_0609_using_rod_bolt_stretch_tool/index.html
http://www.chevyhiperformance.com/techarticles/0710ch_proper_engine_fasteners/index.html
crank shaft mods info
read these links also https://garage.grumpysperformance.com/index.php?threads/bearings-and-oil-flow.150/#post-99327 http://garage.grumpysperformance.com/index.php?threads/whats-a-windage-tray-do.64/...
garage.grumpysperformance.com
interesting info from ARP
Other Stresses
It must be realized that the direct reciprocating load is not the only source of stresses in bolts. A secondary effect arises because of the flexibility of the journal end of the connecting rod. The reciprocating load causes bending deformation of the bolted joint (yes, even steel deforms under load). This deformation causes bending stresses in the bolt as well as in the rod itself. These bending stresses fluctuate from zero to their maximum level during each revolution of the crankshaft.
Fastener Load
The first step in the process of designing a connecting rod bolt is to determine the load that it must carry. This is accomplished by calculating the dynamic force caused by the oscillating piston and connecting rod. This force is determined from the classical concept that force equals mass times acceleration. The mass includes the mass of the piston plus a portion of the mass of the rod. This mass undergoes oscillating motion as the crankshaft rotates. The resulting acceleration, which is at its maximum value when the piston is at top dead center and bottom dead center, is proportional to the stroke and the square of the engine speed. The oscillating force is sometimes called the reciprocating weight. Its numerical value is proportional to:
It is seen that the design load, the reciprocating weight, depends on the square of the RPM speed. This means that if the speed is doubled, for example, the design load is increased by a factor of 4. This relationship is shown graphically below for one particular rod and piston
http://www.arp-bolts.com/Tech/TechWhy.html
"are all rod stretch gauges created equal "
obviously no more than all girls are equally good looking
but most of the gauges are functional, some just have more features or more precise calibrations, some are adjustable in length ,over a wider range, some have digital read outs, ETC.
http://store.summitracing.com/partdetail.asp?autofilter=1&part=SUM-900015&N=700+4294854225+115&autoview=sku
http://www.carcraft.com/techarticles/116_0609_using_rod_bolt_stretch_tool/index.html
http://www.chevyhiperformance.com/techarticles/0710ch_proper_engine_fasteners/index.html
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