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The stock SR20DE rods are very strong and are safe for extended use at up to 8000 rpm and for a low buck motor, they are perfectly adequate. However, for our goal of a very bulletproof inexpensive build we chose some rods from Eagle. Eagle ESP rods are forged from 4340 steel alloy with a high nickel and chromium content. The Nickel and chromium give the steel a high tensile strength, high toughness and a much improved fatigue life over high carbon and chrome molly steels. A good feature of the eagle rods is that the rod is forged in two pieces with the cap forged separately. This allows the rod to have the metals grain flow in a circle around the big end bore. With this forging method, there is less distortion of the rods big end under load and superior strength of the part, especially fatigue strength.
The rod’s have “H” profile beams. The “H” profile puts the rods stiffness axis in line with the bending stresses it sees under use, making the rod strong for its weight. At 100 grams per rod lighter than the stock rods. If you look in the machined valley of the “H” you will notice a rib at the base of the valley, this rib increases the fatigue strength of the rod’s beam. The oiling holes for the piston pin are drilled upwards at an angle towards the pin. Putting two smaller holes at the bottom makes a much stronger part.
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| Eagle Rods are an outstanding rod at an exceptional price |
The entire surface of the rod is machine finished. This ensures consistency in dimensions and weight. It also creates a smooth finish with no irregularities where a crack inducing stress riser can form. After machining, the rod is subjected to shotpeening. This is where the rod is bombarded by hard steel shot at high velocities. Shotpeening helps refine the grain over the surface of the rod, creating a finely grained compressed layer of steel where cracks have a hard time propagating. Shotpeening causes the fatigue strength of most steel parts to rise by over 100%.
The piston pin bushing is tough silicon bronze, one of the most wear resistant bushing materials available. As the rod bolts are the most critical part on the connecting rod, no expense was spared here. Eagle uses genuine ARP 8740 7/16″ rod bolts on all of their sport compact series of rods. These rod bolts have a tensile strength of over 230,000 psi, many times stronger than the factory bots.
For our next installment of the low buck SR20DE we will get more into what we are doing with the engines bottom end, and discuss what can be done and what is optional for a really low dollar build.
Sources
Technosquare Inc.
Engine assembly, machine work and fabrication
http://www.technosquareinc.com
310 787-0847
Eagle Rods
ESP Connecting rods
http://www.eaglerod.com
662 796-7373
Swain Technology
High tech coatings
http://www.swaintech.com
585 889-2786
G-Spec Performance
Nissan performance parts, JDM parts
http://www.gspec.com
760 535-2259
WPC Metal Treatment
JDM wonder stuff
http://www.wpctreatment.com
310 782-7624
