Sometimes profiling a builder is as simple and natural for us as turning the ignition key on one of our vehicles. Hesco has been building engines for more than 34 years. Why does this interest us? Hesco builds Jeep engines. How good are they? We figured it was a good indication when Jeep asked Hesco to help create Jeep's engine manuals. Hesco is also credited with supplying engines for 13 Daytona and NASCAR wins, and preparing engines for Chrysler Motor Sports' desert racing.
The straight-six 4.0L H.O. engine for Jeep has been one of the workhorses for the company since its release. In factory form, the engine cranks out approximately 190 hp and 224 lb-ft of torque. The engine responds exceptionally well to performance modifications. Hesco's rebuilds have consistently turned out powerplants with massive amounts of additional power. The company's stroker engines with CNC cast-iron heads put out approximately 270 hp and 333 lb-ft of torque. Stroker engines fit with Hesco's aluminum heads crank out 300 hp and 365 lb-ft of torque.
Because of Hesco's reputation and quality product, and because we only like to tell you about products that actually work, we gave our contact at Hesco, Bennie Fulps, a ring and had him walk us through an engine build. This information should help you in selecting a new engine for your Jeep or give you some pointers on your next home build.
Engines reborn at Hesco are hand-selected cores from select suppliers. Each block, head, connecting rod, and crankshaft is heavily scrutinized after cleaning. We were told that only the best cores are selected to become a Hesco rebuilt engine.
All components are hot-tanked twice and then dipped in an anti-rusting solution before inspection. Each block is bored to whatever specifications a customer has requested for their new engine. Torque plates are installed for the block deck and water pump to ensure a bore. After the block has been bored and honed, it is hot-tanked again to remove the honing oil and any debris from boring the cylinders. Once this process is complete, the block is hand-washed and blown-dry. It now begins its journey to a final inspection before being selected for a new life.
The block is then placed on a stand in a temperature-controlled build room. It will be mocked up with the crankshaft, piston, and rod. The deck height is checked and the block disassembled. It is removed from the engine stand and placed in the decking machine, where a predetermined amount of material is removed to obtain a set compression ratio. At this time, a Hesco machinist works a little magic with a die grinder in strategic places in the block. The block again goes through a cleaning and hand-washing process. The block is now ready for a final trip to the build room, where it is placed back on an engine stand. Next the cam bearings and freeze plugs are installed. Assembly lube is applied to the cam lobes, and the camshaft is installed in the block after having been through a cleaning process. All internal engine parts go through a cleaning and inspection period. Nothing is taken out of its package and installed without having been hand-washed and inspected.
The crankshafts used in Hesco's engines are hand-selected, inspected, and magnafluxed. They are checked for straightness and any visible flaws. If necessary, they will be turned. They are turned to very precise tolerances, as dictated by the machine shop manager. The crankshafts are then deburred, balanced, and shot-peened. Once these steps are complete, they are cleaned and blown-dry, and inspected by a machinist.
The connecting rods used in Hesco's engines are one of the most scrutinized pieces in the engine. They are hand-picked for weight, length, and straightness. They are then placed into matched sets. Each connecting rod is deburred, the beams polished and shot-peened. If the rod is destined for a stroked engine, it will go to the CNC machine, where the pin end counter weight is precisely machined off for clearance to fit the forged stroker pistons. Once these steps are complete, the connecting rods are fitted with ARP rod bolts and each end machined to strict tolerances for the particular engine they are to be used in. The rods are then balanced and washed before final inspection and assembly onto the pistons.
All pistons go through the same routine, whether they're forged pistons destined for a race engine or a stock cast piston used as an everyday driver. They are checked for uniformity in weight and size. The quality of the casting or forging is checked and the pistons deburred. All forged pistons and any cast pistons a customer requests are sent to a ceramic coating room. Once there, the piston rings' lands are taped, and the piston domes and skirts are media-blasted in preparation for coating. The pistons are washed in a solution and dried. They are preheated to a minimum of 90 degrees F before any coatings are applied. Once they are at the appropriate temperature, a ceramic coating is sprayed on the domes. A DFL moly coating is sprayed on the piston skirts. The tape is removed from the ring lands and the pistons baked at a minimum temperature of 300 degrees F for one hour.
Back in the machine shop, the piston pins are fitted to their respective tolerances using a Sunnen connecting rod machine. Then the pistons are balanced, cleaned, and given a final inspection. The pistons are then pressed on their respective connecting rods using Sunnen piston pin lubricant. The piston rings are removed from their packaging and each fitted to their cylinder. Piston rings are placed in the cylinder they best fit. The end gap is precisely measured on each ring to insure a perfect fit. The results are recorded on the build sheet. The rings are then installed on the pistons.