Pauter Connecting Rods
Pauter Connecting Rods for Aircooled and Watercooled Porsche Engines
Since the 1960s, Pauter Machine Company has been supplying high performance engine components to the automotive aftermarket, all proudly made in the United States. Pauter's 4340 chrome-moly steel and Titanium connecting rods have been used by Porsche engine builders around the world and favored for the windage reducing x-beam design unique to Pauter connecting rods that delivery a balance of strength and weight savings. Pauter billet connecting rods are available for most aircooled and watercooled Porsche models including 356, 904, 911, 912, 914, 924, 944, 928, and Boxster, Cayman, and 996/997 including Turbo, GT2, and GT3 models.
Pauter Connecting Rods feature:
Minimizing Localized Stress Concentrations
The most obvious feature of Pauter’s connecting rod design for Porsche engines is the uniform shape and cross-section of the connecting rod. The X-beam is specifically designed to spread and minimize stress loads over large uniformly shaped areas. In operation, stresses are generated and radiate from one or more sources on an element as it functions. Stress concentrations arise when these forces change direction or multiple forces converge. Translated into Pauter’s x-beam rod design, much effort has gone into maintaining a relatively full length beam shape, into smooth beam transition between the small and big end of the connecting rod, at the bolt seating areas, and also to provide the widest feasible footprint at the cap parting line.
Large Cross Sectional Mass
Given the amount of stretch, flex, and vibratory stresses produced in a Porsche engine, the cross-sectional mass of the connecting rod is critical. Pauter connecting rods for aircooled and watercooled Porsche engines provide an excellent combination of beam rigidity and crank resistance, while maintaining a comparatively light weight compared to OE connecting rods. Average major blade thickness of the beam is 0.220” and minor blade (center rib) is 0.180”, however custom lightweight Pauter connecting rods will be less.
Increased Minimum Thickness on Cap Cross-Section
Ample center mass and elongated ribbing provide Pauter’s Porsche connecting rods superior cross-sectional strength. This ribbing reduces cap flex while reducing connecting rod weight.
The streamlined beam design of Pauter’s x-beam connecting rod reduces crankcase windage in your Porsche engine caused by oil slinging and air displacement as the rod/crank assembly spins. A rotating crankshaft and connecting rod assembly generates a turbulent mix of oil and air thrown outward much like a rotating sprinkler. This effect is amplified by H-beam connecting rods which pocket air and oil. If this same crank assembly were to spin in an unrestrictive environment unlike the tightly confined space inside your engine, this turbulence would have little effect on rotational drag. The inside of an engine however is a confined space what constricts movement and airflow with oscillating hydrostatic pressures on either side displacing the air and oil mix against these rotating parts. This reduces horsepower, increases static case pressure, and hinders normal oil return. Pauter connecting rods unique X-beam design address this by streamlining the leading edge of the rod beam.
Additional Mass at Bolt Interruption Points
Connecting rod and rod bolt failures are common on Porsche engines, with many failing at the bolt/nut seat and big end bore areas. These are areas where substantial material removal during the manufacturing process can result in inadequate cross section mass, increasing the potential points for failure. Pauter pays particular attention to these critically stressed areas in the initial design stage where additional material is engineered into the connecting rod and also during the manufacturing process. Blemish-free surface finishes in these areas is critical to connecting rod longevity. Consequently, all machining and inspection procedures are designed to guarantee superior surfaces on all Pauter connecting rods.
Full Coverage Shot-Peening
All Pauter Connecting Rods for Porsche engines are shot-peened for extra stress resistance and prevention of surface crack formation. Shot-peening is a process by which the lifespan of high performance automotive parts can be prolonged substantially and is commonly incorporated into the manufacturing process in numerous applications, especially in the aerospace industry. Tests have shown that shot-peening can double the cycle lifespan of a highly stressed component.
High Nickel Alloy Premium Chrome-Moly Steel
The steel Pauter specifies in the manufacture of the forgings used in their billet connecting rods, 4340 chromoly, is alloyed with small percentages of nickel. This greatly improves the steel’s resistance to stress crack formation. Another advantage of this alloy is apparent after head treatment: the added nickel gives a tough, deep hardening heat treat condition (36HRCM as measured on the Rockwell C scale), providing a product with superior metallurgy without the brittleness common to lower grades of chrome-moly steel alloys.
Optional connecting rod groove oiling channels machined into the big end cheeks trust surfaces accomplish a number of important functions. They provide an easy exit for spent bearing lubrication, direct a spray of oil to the pin and underside of the piston, and permit the engine builder to maintain tighter rod to crank side clearances. They are available for any Pauter steel connecting rods at no charge at time of purchase.
Another option is EDM (electrical discharge machining) direct pin oiling, in
which oil is pressure fed from crank rod journal, through the rod beam, to the
piston. This is an extra-cost option and it is available on all Pauter 4340
chromoly steel and titanium rods.
Frequently Asked Questions about Pauter Connecting Rods
What is the difference between the ARP 2000 and ARP Custom Age 625 rod bolts
used by Pauter?
The tried, true, and very popular ARP 2000 material is a quench and tempered heavily alloyed martensitic steel with a typical 44-47 C- scale Rockwell hardness and rated at 220,000 psi tensile strength. The ARP Custom age 625 + counterparts are comprised of a higher tensile strength super-alloy corrosion resistant material, also quench and temper heat treated, to a robust 260,000psi. These higher rated bolts are offered as an optional upgrade from Pauter’s standard ARP 2000 Series rod bolts used in all Pauter connecting rods.
Can I order a single replacement rod from Pauter?
Single rods are available from Pauter. The information necessary to match the reciprocating and overall weights of your existing Pauter connecting rod set is included with every set and printed on a yellow card that should be kept for your records. If the information is not available, one of your existing rods will need to be weighed as we will need the pin end, big end, and overall weight for one of your rods to be able to supply a replacement.
What is the difference between a forged and billet steel connecting rod?
A forging is a preformed, closely shaped, individual part, whereas a billet is typically formed from a flat rolled bar stock. Forging is designed to take full advantage of manipulation of grain structure throughout the shape of the finished part. Billet processing in rod manufacturing, on the other hand, is the complete machining of a rectangular block of material resulting in a finished part. Pauter’s manufacturing methods for its x-beam connecting rods combine the strength of forging and the consistency of billet steel.
What bearing operating clearances do I run with Pauter connecting rods?
Bearing clearances depend greatly on the application, however if factory specifications are not available, .0010″/.0015″ per inch of diameter in the big end housing bore is a commonly considered operating clearance standard. Stacked tolerance—the combined tolerances of crankshaft journal, bearing, and rod—of all corresponding parts plays a big role in determining the final clearance. Published dimensions from specification manuals should not be used determine actual physical running clearance. We recommend actual rod and main bearing clearances be verified using precision measurement equipment.
What side clearances do I run with Pauter connecting rods?
Favorable side clearance values for crank guided applications are .010”-.012” with a minimum recommendation of .008” per rod. This value should be doubled in shared journal engines (as in most “V” configurations). In assemblies where minimum clearance is to be maintained, groove thrusts should be considered.
How much do Pauter connecting rods stretch?
What is often referred to as rod stretch is actually a result of flex of corresponding parts combined with movement allowed by necessary operating clearances involved within the assembly as well as thermal expansion inherent in the internal combustion engine. Truth is any true physical rod stretch would likely be from deformation of the big and/or small end bores which could in turn lead to serious engine damage. In short, actual steel rod stretch itself should be near zero with exception of thermal expansion but all aspects mentioned above need to be considered during engine planning / assembly stages with regard to rotating and deck clearance minimum requirements.
Can Pauter connecting rods be rebuilt?
Pauter, like most aftermarket rods, are manufactured in a way that lends itself to rebuilt, provided any damage is within accepted repairable means. Like with most original Porsche connecting rods, worn wrist pin bushing can be replaced and honed. The cap can also be ground allowing the big end to be honed and resized back to standard if the housing bore is out of specification.
How do separate the cap from the rest of the connecting rod?
For Pauter rods with onventional rod bolt layout, unscrew the bolts about a quarter of an inch. Then, holding the cap, tap lightly on the screw heads with a non-marring hammer (aluminum, brass or plastic) until the alignment sleeve is clear of opposite face. You can then remove the connecting rod bolts. On rods with Porsche/VW bolt layout, unscrew the bolts about a quarter of an inch. Then, while holding the beam, tap lightly on the screw heads with a non-marring hammer (aluminum, brass or plastic) until the alignment sleeve is clear of opposite face. You can then remove the connecting rod bolts.
When replacing cap on rod always install rod bolts prior to attempting to position / place surfaces over alignment sleeves, this will prevent damage to critical locating surfaces by guiding the two parts together while allowing easier fitment of both pieces.
How do you properly torque the rod bolts on Pauter Connecting Rods?
Warning! ALWAYS lube the threads and underside of bolt head thoroughly before installation! Never assemble rods without thread lubrication. Incorrect torque figures and/or seized threads will result. These torque specifications are accurate for ARP Ultra-Torque assembly lube. After drawing beam and cap together to seat both pieces evenly, torque should be reached in incremental steps of about 10-15 ft/lbs alternating from one bolt to the other. Stretch method is the preferred method for connecting rod bolt installation. NEVER torque one side completely while the other is loose. If your connecting rods are fitted with ARP Custom Age 625 connecting rod bolts, please contact us for more information on torque specifications.
ARP 2000 Connecting Rod Bolt Torque Specifications
5/16″-24 thread bolts = 32 ft/lbs or .0055” stretch
3/8″-24 thread bolts = 50 ft/lbs or .0055” stretch
7/16″-20 thread bolts = 70 ft/lbs or .0055” stretch