The main bearings were placed into the saddles in our block and the bearing surfaces covered in fresh oil.
JE Pro Seal rings were also selected. They're significantly thinner than the OEM ring set. This design results in less radial tension, therefore less friction and more power. The thinner profile also means that the rings are lighter and less prone to inertial flutter from the base of the ring groove. Plus, they won't lose their seal at high revs. The chrome-faced top and oil rings are perfect for our iron bores.
JE makes the 185915 pistons for 85mm bore sizes. This is approximately 0.007-inch larger than the standard Zetec bore. The design incorporates a piston-to-wall clearance of 0.004-inch. Honing our bores 0.007-inch oversize to exactly 85mm is all that is necessary to prepare them properly. We handed our block to Cosworth Engineering in Torrance, California, to make use of its world-class machining facility.
To hang the pistons, we needed to find a stronger connecting rod. We chose Eagle for its ESP rods, forged from a high nickel and chromium 4340 steel alloy. The nickel and chromium give the steel a high tensile strength and a much improved fatigue resistance over regular high carbon, and even chromoly steels. A good feature is that the rod is forged in two pieces, with the cap forged separately. This allows it to have the metal's grain flow in a circle around the big end bore. With this forging method, there is greater strength and less distortion of the rod's big end under load. Typically, rods are machined from a one-piece forging, where the grain flow is along the length of the rod. When the big end of the rod is machined, the grain is interrupted by the hole.
The rod's beams are machined in an H profile. This profile is stiffer, putting more material where it is needed for strength and none elsewhere. With this sort of construction, an Eagle rod is typically about 100 grams lighter that most stock rods. In the machined valley of the H is a small rib at the base. This enhances the beam's strength.
Before the connecting rods and pistons were installed, we installed the piston coolers. These are jets that spray oil on the undercrown of the piston at high revs to help it stay cool. Although standard in the SVT engine, piston coolers are helpful for any turbo or high compression engine.
Piston pin oiling holes are drilled upwards at an angle towards the pin. This is unlike the standard practice, where pin oiling comes from a single hole drilled at the top of the rod. This hole significantly weakens the small end of the rod. By putting two smaller holes at the bottom, at the less stressed portion of the pin boss, Eagle has a much stronger part.
The rod's entire surface is machine finished. This ensures consistency in both dimension and weight. After machining, the rod is subjected to shotpeening, a process where it is bombarded by hard steel shot at high velocities.
Shotpeening helps refine the metal's grain over the surface of the rod, creating a finely grained compressed layer of steel where cracks have a hard time propagating. Shotpeening improves fatigue resistance in most steel parts by over 100 percent.
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. Eagle uses genuine ARP 8740 7/16-inch rod bolts for all its sport compact series. These have a tensile strength of over 230,000psi, many times stronger than the factory bolts. Altogether, each new piston, pin and rod assembly weighs 1.9 pounds. The far weaker stock components weigh 2.35 pounds.
The main caps were installed with the stock bolts and torqued down in several steps to the factory Ford specs.
Once the block machining was complete and the parts lined up, FocusSport assembled our motor's bottom end, making doubly sure it would hold up if Holstein ever found his way behind the wheel of Project Focus SVT again. All critical clearances were double-checked and the bearings replaced with genuine Ford parts. As the stock SVT crankshaft is a beefy fully counterweighted forged part, FocusSport retained it.
With our bulletproof bottom end cinched up, next time we'll be ready to bolt on our Cosworth cylinder head, Quaife-equipped transmission and stuff it all back into the chassis. That is, just as soon as we kill all the black widow spiders that have claimed our Focus as their home for the past two years.
A ring compressor was used to help prevent breaking a ring while being installed into the block's bore. A soft plastic mallet handle tapped the piston into place without marring it. | 
The assembled bottom end just needs the oil pan installed. | 
Our freshly assembled bottom end awaits the installation of our Cosworth cylinder head and turbo system. |