powder metal rods by definition are formed from a compressed mix of
granulated metallic slurry obviously the exact content of that metallic slurry and how its compressed matter,how it's heated and compressed/forged to form a component,matters a great deal. it can be as strong as a
solid forging of top grade steel (4340 etc.) but the metallic mix and the forging process vary a great deal between different connecting rods, if your thinking of using them in a performance application its rarely going to be the best choice for a true performance application,they do make a decent rod for a stock engine but under high stress theres usually better options, they are stronger than the old stock sbc rods or old style (PINK) RODS in the BETTER designs like HOWARDS CAMS SELLS but thats not always true of the O.E.M. powder metal rods the caps are fractured not machined ,making resizing very difficult, as after machining the large end needs extensive reworking.
keep in mind when someone states that a powdered metal rod is (JUST AS STRONG) as a forged rod,you need to consider the thickness of any component, either forged or powdered metal, a more massive component may weigh more but its also likely to be stiffer and stronger, its been my experience that the O.E.M. powdered metal rods are noticeably thinner in cross section, so even if they WERE of similar strength materials.....powdered metal rods are strong enough for the application they are designed for but they do not have the strength of the better aftermarket forged 4340 rods with 7/16" ARP bolts and the cost of those aftermarket rods makes reusing the powdered metal rods in a performance application a bad value
IM OFTEN ASKED WHY I DON,T REBUILD CHEVY CONNECTING RODS, WELL MAYBE A PICTURE WILL HELP,

a good set of SCAT FORGED 4340 forged connecting rods costs less than $400 and they are 150%-200% stronger than MOST OEM chevy SBC rods
it will cost you almost that much to replace the bolts with ARP wave lock bolts, balance and polish and resize stock rods and you have far weaker rods when your done
example
GOODhttp://www.adperformance.com/index.php? ... cts_id=516BETTER for not much more cashhttp://www.adperformance.com/index.php? ... cts_id=241 http://www.mpif.org/designcenter/powder ... ?linkid=43As in conventional PM, powder forging begins with custom-blended metal powders being fed into a die, then being compacted into a “green” shape, which is then ejected from the die. This compact, called a “preform,” is different from the shape the final part will acquire after being forged. Again as in the conventional PM process, the green compact is sintered (solid-state diffused) at a temperature below the melting point of the base metal in a controlled atmosphere furnace, creating metallurgical bonds between the powder particles and imparting mechanical strength to the preform.
The heated preform is withdrawn from the furnace, coated with a high-temperature lubricant, and transferred to a forging press where it is close-die forged (hot worked). Forging causes plastic flow, thus reshaping the preform to its final configuration and densifying it, reducing its porosity to nearly zero.
Powder forging produces parts that possess mechanical properties equal to wrought materials. Since they’re made using a net-shape technology, PF parts require only minor secondary machining and offer greater dimensional precision and less flash than conventional precision forgings.
Parts fabricated through the PF process are subject to certain limitations. Tooling and the maximum press tonnage capabilities impose size and shape constraints on parts, just as in impression die hot forging. Annual production quantities in excess of 25,000 pieces are typically required to amortize the development costs of tool set-ups and maintenance. Finally, material systems are somewhat limited (all commercial PF products are steel).


read thesehttp://www.forging.org/FIERF/pdf/FatigueBehavior.pdfhttp://www.circletrack.com/enginetech/c ... _4260.html http://www.superchevy.com/technical/eng ... index.htmlPowder-Forged Connecting Rod - The Power Of Powder
Powder Forging Enters The Short-Track World
From the July, 2004 issue of Circle Track
By Larry Jewett
Photography by Courtesy Of Howards Racing Components, GKN Sinter Metals
Powder Forged Connecting Rods Available Connecting Rods
Precision powder-forged connecting...
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Powder Forged Connecting Rods Available Connecting Rods
Precision powder-forged connecting rods have become available for racing applications. Powder-forged components have been used in high-performance applications like Formula 1 racing and have been part of the domestic original equipment automotive products since the mid-'80s.
Technology has proven to be the key to unlock better performance. As methods are tested and found to be beneficial, the supporters line up to take their programs to the next level. Advantage is the universal element sought by all racers.
Sometimes, the advantage can lie deep within the engine. Expensive exotic metals are one way to go about it, but there is a far more cost-effective way to get reliability and performance in some key engine parts.
Howards Racing Components has joined with GKN Sinter Metals to unveil a line of connecting rods for racers. These rods are manufactured in the precision powder-forged process. This allows the rods to be extremely durable for high-horsepower applications. In addition, the cost of the rods is going to be within the range of an average racer's budget.
The name "precision powder-forged connecting rod" has been shortened to "PPF con rod," which is the way it will be referred to from this point forward.
Powder Forged Connecting Rods Con Rod
The design for Howards Racing...
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Powder Forged Connecting Rods Con Rod
The design for Howards Racing Components' PPF Con Rod utilized state-of-the-art computer programs for modern efficiency.
The goals of the PPF con rod were simple. The companies wanted to design a part that was stronger and lighter while keeping cost affordable. The combination of strength and light weight is a definite boost to the production of horsepower.
The technology is new to short-track racers. It has been used for high-performance applications for more than two decades. Auto-motive original equipment manufacturers have also used components using powder metal for nearly 15 years. There's a good chance your street vehicle contains some powdered metal components.
The Process
Just like most operations, the process begins with a need and then a plan to fulfill the need. Once there is an established plan, the part must be designed. In the case of the connecting rod, the designing phase utilized the concept of solid modeling. The solid modeling phase used a CAD (Computer Aided Design) system that insures design integrity. It allows for the accurate prediction of overall weight and center of gravity of the part. Once the manufacturer is satisfied, the file is transferred to FEM (Finite Element Modeling) analysis and used by a CAM system for prototype production.
Powder Forged Connecting Rods Metal Forged
The goals of the powder metal...
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Powder Forged Connecting Rods Metal Forged
The goals of the powder metal forged rod included strength and light weight. The economics became an added bonus.
In the case of this connecting rod, Howards and GKN worked together to determine the best piece. The companies reviewed current billet and conventional forge designs available to the racer. The finished design was machined from billet stock to serve as a proof for the concept. During the analysis of the Finite Element Modeling, the weight was further reduced, and stress areas were identified.
With a definite model in place, the process of determining material composition (a proprietary secret) is underway. A base powder is combined with selected alloying elements, and in some cases, lubrication materials or graphite is added. The newly formed combination is placed into a mixing apparatus for blending the components. This blending process points out one advantage of the powder metal. Custom blends can be accommodated, though GKN has standardized thousands of combinations for components. Physical characteristics can be enhanced with a slight change in the blended material. The process of mixing also allows for closer elemental interaction. Metal-forming alternatives like die-casting molten metals face limitations in alloy choices because of the behavior of the raw material when melted and processed.
After mixing, the material is fed into a compaction machine. The material is placed into a die cavity with two punches. A press squeezes the powder into the shape of the component. The compounds in the existing powder serve as an adhesive to form the part.
Powder-Forged Connecting Rod - The Power Of Powder
Powder Forged Connecting Rods Fracture Split
The fracture-split technology...
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Powder Forged Connecting Rods Fracture Split
The fracture-split technology will provide better alignment for rod bolts.
The next step is sintering. This is the process of forming a cohesive mass by the use of heat without melting the part. During the sin-tering process, parameters such as temperature, atmosphere, belt speed, and environmental factors are monitored and registered. Lubricants and binding agents are driven from the part. The heat of the sintering process forces the alloying agents to diffuse throughout the part. After the sintering operation, parts are maintained in a controlled atmosphere to prevent decarburization. At this stage, the rods are known as pre-forms. The pre-form is quickly heated to above 1,500 degrees, and a mechanical screw press is used for final forging. Force, speed, timing, tool temperature uniformity, and tool lubrication are controlled. The rods are now complete to near net shape and are forged to full density.
The rods also involve a practice known as fracture notching, which falls into the classification of "secondary operation." There are advantages to the fracture split technology that serve the part better than the standard saw cut. Superior alignment is assured with the processing. The fracture split surface will also eliminate fretting, thus there's no need for guide bushings with this procedure.
Powder Forged Connecting Rods Aggressive Testing
GKN's aggressive testing program...
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Powder Forged Connecting Rods Aggressive Testing
GKN's aggressive testing program was a key selling point in its relationship with Howards Racing Components. Static and dynamic testing is used to determine ultimate tensile strength (breaking point) as well as endurance and fatigue.
The parts require other secondary operations. These could include honing, boring, grinding, and drilling. If a chamfered or beveled face is needed for a product, this can also be implemented at this step.
The finished product is thoroughly tested to determine its ability to withstand the demands of the application. After satisfactory completion of the testing phase, mass production of the pieces can be ordered.
Precision powder forging has several advantages over the conventional forging process:
1. Greater material flexibility
2. Fewer burrs that require additional work to remove
3. Minimal weight fluctuation between pieces-allowing easy replacement of a single rod
4. No material textures
In terms of weight fluctuation, the tolerances are tightly maintained. The whole part is weighed and must fall within a total tolerance area. In the case of the connecting rods, by the nature of the part's design, the pin end has a 6 percent tolerance while the crank end has a 2 percent tolerance.
Powder Forged Connecting Rods Rods
The rods are the product of...
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Powder Forged Connecting Rods Rods
The rods are the product of an evolution. They start in the briquette form (left), go through the forging to reach the middle stage, and then become heat-treated and finish-machined before shipment to the customer.
GKN has the capability of making 130,000 rods daily. The material used in the rods is ASTM 4260, which, in many ways, is superior to 4340 steel. The metal standard was established by ASTM International, formerly known as the American Society of Testing and Materials.
The rods will be made in America and can be easily reworked by using oversized bearings available from three different manufacturers. Initially, the rod has become available for the small-block Chevrolet applications. The cost savings was expected to reduce the racers' budget by as much as 40 percent in comparison to units of similar quality. Top quality rod sets, equally matched, are expected to cost $600 at the retail level. The target weight of the small-block Chevy rods is between 500 and 600 grams, and the approximate horsepower range is between 700 and 800.
The search for better technology has found the powder metal application starting at this point, but the drive to find more use is clearly underway. The methodology and materials have been proven in lab tests, product tests, and real life applications. Racers looking for competitive alternatives have to consider the advantages found in powder metal. If they don't, their competition will.
Editor's Note: Special thanks to Al Barra for research and material provided.
Powder-Forged Connecting Rod - The Power Of Powder
In the blending process, the important elements are mixed. GKN has the ability to create custom blends for certain applications.
Sintering is a process that involves heat without melting. As these diagrams and microscopic pictures show, the bonding takes hold as the key components fuse, while the lubricants and binding agents are expelled.
Powder Forged Connecting Rods Blending Process
Powder Forged Connecting Rods Sintering
Powder Forged Connecting Rods Powder Forging
Powder Forged Connecting Rods Taking Shape
An explanation of the complete powder forging process. The first four steps are handled by GKN, while Howards Racing Components will take care of secondary operations as needed.
The powder begins to take shape in the compaction process. The rod will take the briquette form, essentially very brittle, before moving to the sintering cycle.
4340 vs. ASTM 4260 Metallurgy
4340 Round ASTM 4260
* Nickel 1.65-2.00 * Nickel 0.40-0.50
* Molybdenum 0.20-0.30 * Molybdenum 0.55-0.65
* Manganese 0.65-0.85 * Manganese 0.20-0.35
* Chromium 0.70-0.90 * Copper, Max 0.15
* Sulfur, Max 0.025 * Sulfur, Max 0.03
* Silicon 0.15-0.35 * Silicon, Max 0.03
* Phosphorus, Max 0.025 * Phosphorus, Max 0.03
* Carbon 0.38-0.43 * Carbon determined by purchaser
* Iron balance * Oxygen determined by purchaser
* Iron balance
IF your considering rebuilding any first or second generation SBC connecting rods, and especially the powdered steel connecting rods?
honestly why bother, a good forged aftermarket rod with far stronger 7/16" rod bolts, far fewer stress cycles on it, are available for between $270-$360 a set that's rated at 600-1000hp
theres NOTHING you can do to a O.E.M. powder rod that will make it nearly as strong,or will remove the past stress,in a used connecting rod and the last time I priced both adding ARP 2000 rod bolts and resizing and polishing the O.E.M rods and polishing out surface imperfections, the cost for a finished set of those INFERIOR STRENGTH O.E.M. connecting rods would have been similar or HIGHER.
rods normally fail in TENSION, when the rod bolt stretches distorting the big end an pinching bearings or allowing the piston to contact the heads theres no way that a O.E.M. 3/8" rod bolt can match the strength of a 7/16" ARP rod bolt
theres at least a 100% -150% higher margin in the larger diam. ARP bolts and 4340 forged rods