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Hybrid 6.0/6.4L Power Stroke Short Block Build

Best ’Stroke

Chris Tobin
Sep 16, 2019

In most racing circles, hearing the phrase "there is no replacement for displacement" at some point is fairly common. And, in most cases, the adage rings true. Increasing cubic inches is a great way to add power and performance to a race engine. When properly built, Ford's 6.0L Power Stroke is actually a good platform for a competition powerplant. But it's the smallest of the Power Stroke V-8s.

When Cass Choate of Choate Engineering Performance and Matt Fetty of Fetty's Automotive teamed up to build a new race engine for Matt's Punisher 2.0 drag truck, they wanted to show the diesel-performance world what could be done with the veritable 6.0L. Of course, their demonstration included increasing the engine's displacement as well, but how far could they safely go?

The 6.0L Ford Power Stroke has many known shortcomings that both Cass and Matt have repaired and overcome through their years of experience. They also know the block itself as well as the crankshaft and even the stock rods are very strong when used in race conditions. The main weaknesses lay in reliably sealing the cylinder heads to the block and improving airflow within the heads. By using ARP head studs and further increasing clamping strength with C-ring grooves machined into the heads, Matt knew combustion pressure could be contained within the cylinder. And for airflow, Choate Engineering Performance had developed aggressive CNC-porting profiles for ProMAXX aluminum 6.0L heads that even include dimples machined into the port walls to further enhance airflow.

Photo 2/60   |   As hard as it is to believe, this gaggle of parts will be brought together by skilled builders to create a 6.0L-based, hybrid 6.4L Ford Power Stroke engine that is estimated to make more than 1,000 hp.

For insights on machining enhancements that could be performed on the block and crank, Cass worked with United Engine & Machine pistons to develop a hybrid slug for the project, which, when combined with custom large-bore cylinder sleeves by L.A. Sleeve and longer River City Diesel Performance connecting rods, would yield a 6.4L displacement and help achieve the 1,500 hp they were after.

Knowing the stock crank is very strong, Cass and his team simply balanced and blueprinted the arm, then polished the journals to optimize performance. The UEM hybrid pistons are stronger, shorter, and lighter than stock 6.0L slugs.

You have probably heard that proper preparation is the key to success in virtually any endeavor. This applies to building high-performance diesel engines as well. The team at Choate Engineering Performance has the necessary skills, tools, and equipment to handle everything from engine removal and reinstallation to cleaning and machining, blueprinting and balancing, and, of course, final engine assembly. CEP employs skilled technicians and owns a host of Rottler CNC multi-axis machines as well as engine-specific machine-shop equipment.

Photo 3/60   |   Compared to the stock piston on the left, the UEM Pistons custom hybrid slug is shorter, lighter, and stronger. The piston uses proprietary coatings to ensure it will meet the serious demands of diesel racing.

Before any machining is done to one of the 6.0L blocks Cass uses as the foundation for a performance build, a used engine is completely stripped, with all its components cataloged and measured for fitness (to be reused on other builds). High-end race engines receive all-new parts, with very few exceptions, like piston squirters and other non-load-bearing items. New fasteners (rod bolts, head studs, and such) from ARP are used to ensure the engine stays. Total Seal file-fit piston rings are installed on the specially coated UEM pistons to make sure the combustion charge stays in the chamber.

While we are not able to show you each and every one of the thousands of individual steps involved in machining and assembling a diesel race engine, this article provides an overview of the process and showcases this unique high-performance Power Stroke short-block prepared by Choate Engineering Performance. Stay tuned for more on this big-bore monster, including completion of the top end (dry-sump oil system, cylinder heads, fuel system and boosted air), as well as a feature on Matt's "Punisher" Ford F100 drag truck. It's all coming as soon as Matt and his team get it back out on the track again.

Whether you are building an all-out race engine or simply giving your diesel a refresh after hundreds of thousands of miles on the road, follow the examples and suggestions presented here to get the most performance and longevity out of your build. If you entrust pros like Cass and his team or your local diesel performance shop to create your rig's powerplant, be sure to tell them that Diesel Power magazine suggested you seek their expertise and assistance.

Photo 4/60   |   To ensure the engine stays properly timed even under high loads at high rpm, Justin Noble TIG welds the timing gear to the River City Diesel Performance camshaft.
Photo 5/60   |   Niels Gade handles quality control for every Choate Engineering Performance engine build in addition to measuring and balancing the rotating assembly, among other duties at the shop. Here, he weighs an RCD rod as well as the piston, rings, wristpin, and retainers.
Photo 6/60   |   With the rotating components weighed and documented, Niels installs simulation weights on the crankshaft before balancing it.
Photo 7/60   |   A CWT Industries balancer allows Niels to balance the rotating assembly to a much tighter tolerance than stock.
Photo 8/60   |   After an engine is stripped down for a rebuild, Jeremy Burnes runs the block through a bake cycle in CEP's industrial oven. The process burns off built-up grime and scale and bakes oils out of the block.
Photo 9/60   |   The shot-peen tumbler further cleans and works the surfaces of the block.
Photo 10/60   |   After removing the residual shot from the block, Jeremy loads it into the high-temperature washer and runs it through a complete cycle to make sure the block is completely free of any contaminants or impurities that could harm the rotating parts inside the engine after it's assembled.
Photo 11/60   |   With the bedplate installed and torqued on the block, Cass Choate measures each main bore in multiple directions to make sure they are perfectly round and symmetrical.
Photo 12/60   |   Jack Miller runs the line hone through the main bores to clean up any slight misalignments that show when the block is measured.
Photo 13/60   |   A close visual inspection reveals a common problem Cass and his team encounter with used blocks. A slight offset in the deckplate shows the main bore is not completely round, as the hone did not make contact with the shaded area (as highlighted by the arrow).
Photo 14/60   |   After a few additional passes with the hone, the main bores are now completely round, with no visible shadow in the surface.
Photo 15/60   |   Engine blocks are measured and machined inside this Rottler CNC boring machine. Precise measurements ensure the cylinders are properly aligned and located in the block as well as the desired diameter.
Photo 16/60   |   To make room for the big bore of this 6.4L build, the CEP crew machines the block to accept a set of L.A. Sleeve Molly 2000 ductile-iron cylinder sleeves. The bore on the left is ready for the sleeve, while the cylinder on the right already has the sleeve pressed into place.
Photo 17/60   |   The sleeve looks simple enough, but the precision machining, high-quality metal, and unique construction methods allow a sleeved block to support a larger bore and handle more power.
Photo 18/60   |   The Rottler CNC also handles machining the deck surfaces to make sure everything is completely flat and within desired build specifications.
Photo 19/60   |   This machine can deliver whichever specific cylinder-hone pattern the builder desires. It also measures the bore while honing to make sure the cylinder walls maintain parallel and symmetrical surfaces.
Photo 20/60   |   Cass verifies the cylinder bore diameters after the honing process.
Photo 21/60   |   He then measures the surface finish to make sure the microscopic peaks and valleys are just right and will allow the oil to lubricate the pistons and rings without being so smooth that combustion gases will blow by the rings into the crankcase.
Photo 22/60   |   In this pair of cutaway 6.0L cylinder-head crosssections, we see the original restrictive port (left) compared to Choate Engineering Performance CNC porting . Ports in the Choate-treated head are much larger and have smoother transitions, for far greater airflow than the factory castings.
Photo 23/60   |   Another Rottler multi-axis CNC machine goes to work on a cylinder head.
Photo 24/60   |   On Matt Fetty's race heads, the team programmed the CNC to dimple the port walls to further enhance the aerodynamic flow inside the head, much like a dimpled golf ball that flies farther than a smooth golf ball.
Photo 25/60   |   The dimples are machined into the full length of the port walls.
Photo 26/60   |   025 Hybrid 6 0 6 4l Power Stroke Short Block Build Dimples
Photo 27/60   |   CEP has the necessary machines to cut and install new seats and valve guides in cylinder heads in-house so they have 100 percent quality control over every aspect of its engine builds.
Photo 28/60   |   027 Hybrid 6 0 6 4l Power Stroke Short Block Build Valves
Photo 29/60   |   Once the heads are assembled, Cass draws a vacuum against the valves to make sure everything is properly seated and sealed.
Photo 30/60   |   He also uses a SuperFlow flow bench to test and verify changes and upgrades on cylinder heads.
Photo 31/60   |   Using a Cam Pro Plus, Cass measures the exact profile of the camshaft including lift, duration, lobe separation, and valve timing to determine how it will perform with the modified heads.
Photo 32/60   |   Part of the precision that goes into a race-engine build like this one is using file-fit piston rings like these from Total Seal. They are precisely custom-fit to each cylinder before the engine is assembled.
Photo 33/60   |   032 Hybrid 6 0 6 4l Power Stroke Short Block Build Filefit
Photo 34/60   |   Before he actually starts to assemble the short-block, Jack Miller taps threads into the five oil-galley plugs in the block rather than using the push-in plugs that could pop out and ruin an engine at an inopportune time.
Photo 35/60   |   After tapping then cleaning the passages, Jack applies thread sealant to the galley plugs then installs them in each of the holes (three on the rear and two on the front of the block).
Photo 36/60   |   035 Hybrid 6 0 6 4l Power Stroke Short Block Build Oil Gallies
Photo 37/60   |   From the bottom side of the block, Jack marks the location of each of the oil passages for cam oiling then aligns the hole in the bearing with his marks (see arrow) before driving the cam bearings into the block.
Photo 38/60   |   One at a time, Jack installs each of the cam bearings with green Permatex high-temperature sleeve retainer, applied on the outer surface to keep the bearings from rotating and cutting off the oil supply to the cam.
Photo 39/60   |   Other critical oiling components are the piston squirters. Forgetting to install them will lead to a very large internal oil leak that will cause a low-oil-pressure condition that could damage the engine. Jack uses red thread locker on the bolts.
Photo 40/60   |   Jack uses Lubriplate Motor Assembly Grease on both halves of the main bearings, the block, and the bedplate; then he lowers the plate onto the block. Notice the coating on the bearings: CEP applies a Dry Film Lubricant by Techline Coatings that provides additional protection and lubrication.
Photo 41/60   |   040 Hybrid 6 0 6 4l Power Stroke Short Block Build Mains
Photo 42/60   |   Then he installs and torques the ARP main studs using Ultra-Torque assembly lube on the threads to yield accurate torque readings and prevent galling the threads.
Photo 43/60   |   Next, Jack measures each main bearing with a bore gauge and compares those measurements to the main journals on the crankshaft.
Photo 44/60   |   Cass and Jack carefully lower the precision-balanced crankshaft into the block.
Photo 45/60   |   Jack uses the stock seals along with a thin bead of Motorcraft RTV silicone to ensure there are no oil leaks from the bedplate.
Photo 46/60   |   For the final time, Jack torques the ARP 12-point nuts on the main studs to lock the crankshaft into the powdercoated engine block.
Photo 47/60   |   Just like the main bores and journals, Jack assembles the rods and measures their bores and journals to make sure everything is within specification.
Photo 48/60   |   Then he can install the Total Seal piston rings on each slug, making sure to install them in the correct order and orientation.
Photo 49/60   |   The pistons are hung on each specific rod (Niels numbers them when he weighs them to balance the crank) using the wristpin and retainers to keep the assembly together.
Photo 50/60   |   Using a ring compressor and the butt end of a dead-blow hammer, Jack drops each piston and rod assembly into the block and attaches the rod to the crank before moving on to the next cylinder.
Photo 51/60   |   Once the rods are connected to the crankshaft, Jack torques them all at once to ensure none are missed or improperly tightened.
Photo 52/60   |   To install the cam and properly align the timing gear, the hub must be removed from the crank.
Photo 53/60   |   Then the camshaft is lubricated and slid into the engine block.
Photo 54/60   |   The dots on the cam gear and crank gear are properly aligned (see arrow). Failure to do this results in an engine that is not properly timed and could cause damage to the pistons and valves.
Photo 55/60   |   Installing and torquing the retaining bolts for the camshaft requires using red thread-locking compound on the fasteners to prevent them from loosening.
Photo 56/60   |   Cass has the crank barred at the front while Jack torques the flexplate bolts.
Photo 57/60   |   Piston protrusion (or recession, in this case) is measured to make sure the engine will have the proper clearances once the heads are bolted on.
Photo 58/60   |   Using a Dakota Ultrasonics sonic tester, Cass shows us that with the L.A. Sleeve inserts in place and machining finished, the cylinder walls have 0.262-inch thickness.
Photo 59/60   |   The completed short-block is ready to be packed and shipped out to Colorado.
Photo 60/60   |   As a teaser, here is what the completed engine looks like before Matt installs it in the truck.


ARP (Automotive Racing Products)
Ventura , CA
ATI Performance Products
Baltimore, MD
(800) 822-6005
Total Seal
Phoenix, AZ
(800) 874-2753
(800) 648-7970