High-HP,  Budget-Built  7.3L - Diesel World

A Reliable 650 HP Without Breaking The Bank

Thanks to their overbuilt nature, diesels afford us the ability to double, and sometimes even triple, their factory horsepower rating without having to dig very far into the engine. The 7.3L Power Stroke is one such power plant. Due to its relatively low horsepower potential right off the showroom floor (a ’94.5-’97 Ford typically dyno’s 160 to 170-rwhp, while a Super Duty usually lays down 190 to 210-rwhp), huge gains can be made with the right injector, turbo, and tuning combination. In fact, versions of the 7.3L graced with forged-steel connecting rods can be pushed to 500-rwhp, 550-rwhp and even 600-rwhp with relative ease.

However, there is no telling how long the stock rotating assembly or valvetrain will tolerate its newfound stress of supporting the added cylinder pressure, boost, and drive pressure that comes along with it. Some original short blocks last 100,000 miles. Others window the block in a matter of days. For those not willing to roll the dice on a stock bottom end, we’ve pieced together a comprehensive parts list in the following pages. The best part? While not cheap, it won’t bankrupt you. What it will do is cover all the bases, from the oil pan to the turbo, and allow you to enjoy a 600 to 650-rwhp recipe for the long-term.

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Ford’s master rebuild kit was one of the best and most affordable things to ever hit the 7.3L market. This baby comes with everything you’ll need, from new pistons and rings (standard bore, 0.010-inch, 0.020-inch, or 0.030-inch), rod bearings, wrist pins, main bearings and a fresh main bearing seal, to head gaskets, glow plugs, and even an oil cooler. You can find a complete OEM kit for a little over $1,200 (Riff Raff Diesel stocks them for $1,247). Irate Diesel also offers overhaul kits with additional options like de-lipped piston bowls, valve pockets, 3-stage piston coating, and coated main and rod bearings.

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It all starts with a good machine shop. The cylinders in our ’00 block had to be bored 0.030-inch over for this particular build, but much more was involved than that. All main bearing surfaces were taken through an align-hone process before the block was decked and bored on the same square fixture. In many high-horsepower builds, the final cylinder hone work is done using a torque plate, secured in place using the same head fasteners you plan to employ in the build.

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Factory cast-aluminum pistons are proven performers in the 7.3L world, but they can definitely be improved upon with a little bit of machining and coating. At the very least, removing the sharp edge from the piston bowl (known as de-lipping) and ceramic coating (thermal barrier) the tops should be done to help them stand up to elevated EGT. Dry-film lubricant coatings are also commonly used on piston skirts to reduce friction. Here, a factory piston has been de-lipped, cut for valve reliefs for added valve-to-piston clearance, and treated to both ceramic coating up top and dry-film coating on the skirt.

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If we were entertaining the prospect of making a lot more horsepower than 650, we might fork over the cash for an internally balanced crankshaft, but for our purposes sticking with a factory (externally balanced) crank fit our needs. With new connecting rods and altered factory pistons (in terms of weight) in the mix, the entire rotating assembly was balanced. The OEM main bearings that came in the Ford overhaul kit were shipped off for dry-film coating, too.

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In addition to coating the main bearings, the camshaft and connecting rod bearings were treated to self-lubricating, dry-film coating. Beyond that, the wrist pins were sent to Ionbond, where the company’s Tribobond 40 DLC coating was employed. It will give the OEM wrist pins supplied in the Ford master overhaul kit lower friction yet superior wear resistance.

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To secure the crankshaft as best as possible, four ARP main studs per cap will provide very affordable insurance. To be sure, crankcase girdles and bedplates are available for the 7.3L, but can tend to blow budgets wide open. Plus, for our 650-rwhp goal (and somewhat conservative tuning) we don’t expect to see significant cap walk.

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Prior to any machine work being performed on the block, there is a fairly affordable way to increase cylinder bore rigidity. Half-filling the block in 7.3L applications has long been commonplace. By filling 50-percent or a little more of the water jackets with concrete (usually Hard-Blok), you can cut down on cylinder wall distortion without sacrificing any streetability (i.e. no overheating to worry about).

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Not that the 7.3L is notorious for dropping piston oil jets, but it happens enough that anyone building an engine and that has access to a MIG welder welds the tube in place. For those that aren’t handy with a welder, Riff Raff Diesel offers welded piston oil jets. For $61, added insurance doesn’t get much cheaper.

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Even though Ford’s master overhaul kit includes a new low-pressure oil pump, with dual HPOP’s in the mix (what we’re doing) you want all the volume you can get. A Melling LPOP has long been a budget-oriented way of adding an improved pump to a 7.3L, but this is the cat’s meow. DieselSite’s high volume low-pressure oil pump employs custom cut gears, which increases flow and pressure over stock from idle to wide-open.

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Now for the primary reason behind the build: installing stronger connecting rods. For their affordability, the company name, and the fact that we’ve seen them in multiple trucks making way more horsepower than we plan to make, Manley’s Pro I-beam rods got the nod. Made from 4340 forgings, Manley treats them to shot-peening after machining and also individually magnafluxes them. They utilize 7/16-inch ARP2000 rod bolts and retail for less than $2,400—making them one of the best budget rods in the 7.3L aftermarket.

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This is often the result when owners of ’01-’03 Super Duty’s increase their 7.3L’s horsepower, the engine lives trouble-free for a few thousand miles, but then they grow bored and decide to push things even further. Whereas the forged-steel rods found in ’94.5-’00 (and select ‘01) engines typically bend when they fail, the powdered metal rods usually break off completely, potentially trashing the block.

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An aftermarket damper works wonders for controlling torsional vibrations on a diesel engine. This unit from ATI is specifically designed for the 7.3L Power Stroke and, once fine-tuned for our application, will end up bolted to the snout of our crankshaft.

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It can’t be understated how important a billet flex plate is on a higher horsepower 7.3L. With 1,200 or 1,300 lb-ft of torque on tap, the center section of the factory piece can be torn apart in short order. Turning to DieselSite, a company that builds its own line of E4OD and 4R100 transmissions, we’ve elected to run its billet flex plate. It’s made from high speed alloy steel, and at $495 is one of the most affordable 7.3L flex plates in the aftermarket.

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The factory 7.3L camshaft leaves much to be desired, and over the years cam manufacturers such as Colt Cams have developed versions that are much more efficient. For its ability to improve exhaust flow, thereby lowering EGT, driving the turbo harder and providing quicker spool up, we went with the company’s Stage 2 unit. And although we did have slight valve pockets machined into our pistons, it wasn’t necessary to run this cam. It is designed to be a direct drop-in replacement for the factory camshaft.

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A major peace of mind item for any 7.3L engine is welding the cam gear in place. From the factory, the cam gear is press-fit onto the camshaft. At high horsepower levels, the cam gear can be forced off of the camshaft. To keep this from happening, we TIG-welded the cam gear to the camshaft in three different places.

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After the truck’s original heads checked out warpage and crack-free, they were resurfaced. Note: According to Ford, if warpage exceeds 0.001-inch within any 2-inch radius, it warrants a new cylinder head. Then the heads were equipped with all new valves, valve seats, and treated to a performance valve job.

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While Comp Cams’ popular 910 valve springs are a solid upgrade in the 7.3L world, even a shimmed version of the big-block-intended spring has issues when 7.3L engines are producing big boost and more than 600-rwhp. Knowing this, we sprang for Irate Diesel Performance’s competition valve spring kit. The beehive springs provide a closed seat pressure of 150-lbs and come with the required retainers and locks needed to install them.

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To ensure pushrod flex will never be an issue, a set of Stage 2, stock-length pushrods from Smith Brothers Pushrods is going in this engine. They boast a 0.120-inch wall thickness (vs. .065-inch on the Stage 1’s), and 3/8-inch 4340 chromoly tubes with 3/8-inch ball ends. They are actuated via new, factory spec Mahle hydraulic lifters.

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Surprise surprise, ARP head studs will fasten our refreshed and upgraded heads to the block. With plans for the 7.3L to see approximately 55 to 60-psi of boost, OEM replacement head gaskets and ARP studs will more than suffice. When boost gets into the 70 to 75-psi realm, the need for additional combustion sealing (i.e. fire-rings) becomes a concern.

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It’s no secret that the factory, stamped-steel rockers aren’t the stoutest valvetrain components in the 7.3L. But rather than reinvent the wheel or balloon the budget, we had a set of rocker arms cryogenically treated—a process that is estimated to make them 25 to 30-percent stronger.

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The last thing you want to have happen with a new engine build is reuse components that can leave you stranded. This is precisely why we purchased new UVCH gaskets and harnesses. We don’t need a bad connection in an old UVCH wiring harness producing a dead cylinder once we’ve buttoned everything up. The same goes for the glow plugs. They’re relatively inexpensive to purchase and easy to install when you’re already under the valve covers.

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Now that the foundational work has been laid, it’s time to go over the parts that will both add and support the 650-rwhp number we’re after. Instead of relying on a single high-pressure oil pump to provide enough oil volume to the injectors, we’re going to run two factory displacement, 17-degree Super Duty pumps. The twin pump arrangement will be made possible thanks to Full Force Diesel’s dual HPOP pump kit.

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If you want to make big power with a 7.3L you have to go straight for the jugular. In 7.3L speak, that means starting with a sizeable hybrid injector. For us, it was a set of Unlimited Diesel Performance’s 350/200 hybrids—injectors that can easily support north of 700-rwhp with the right combination of parts. With adequate ICP (high-pressure oil) and low-pressure fuel supply, this injector can flow a maximum of 350cc’s through a 200-percent over nozzle. Better yet, the 200-percent nozzle can be tuned to yield tremendous street and drivability manners.

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You won’t find the factory fuel bowl in the valley of our engine. Instead, our fuel filter and water separator will be located along the driver side frame rail in the form of Driven Diesel’s race fuel supply system. Packaged along with it will be a brushless Fuelab Prodigy 41401-1 lift pump, which will pull fuel from a sump in the tank. Fuel returning to the tank will be regulated as well, with the adjustable regulator being set somewhere around 65-68 psi.

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For its build quality, fit and finish, and obvious ability to accommodate a large frame T4 turbo, Irate Diesel’s T4 turbo mounting system helps take any 7.3L to the next level. Its comprehensive kit entails a pedestal, T4 exhaust collector with stainless steel up-pipes, two-piece downpipe, 3-inch intercooler piping, a cold air intake, oil supply and drain lines, fittings, and all installation necessary hardware. We also ordered Irate’s 3-inch inlet intake plenums, which thanks to their aluminum construction won’t crush from excessive boot clamp pressure.

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The biggest thing Irate’s T4 turbo mounting kit provides is the ability to run a BorgWarner S400 such as this. Because it’s been thoroughly proven to support 625 to 650-rwhp, our decision to run an S467.7 was easy. The turbo features BorgWarner’s forged milled 67.7mm compressor wheel (inducer), makes use of an 83mm (exducer) turbine wheel, and sports a 360-degree thrust bearing assembly for utmost durability. Given the extent of our injection system upgrades, this turbo will spool quickly yet allow for solid high rpm power thanks to its loose 1.10 A/R exhaust housing.

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If you’re working with an old body style 7.3L (’94.5-‘97), running an intercooler isn’t a recommendation but rather a requirement. And if you’re living with a Super Duty that came with a plastic end tank intercooler, upgrading to one with aluminum end tanks is highly advised, especially for one that will see 60-psi of boost. For the budget-minded, CSF manufactures an proven intercooler with welded metal end tanks for just $241 through Summit Racing.

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Tying everything together boils down to custom PCM tuning, and there is no shortage of outstanding calibrators in the 7.3L aftermarket. Our tuning platform of choice will be the most popular one in the 7.3L world: the Hydra chip from Power Hungry Performance. It allows for up to 15 files to be stored and available on-the-fly at any given time. And if you spring for the $25 USB extension cable, you’ll never have to pull the PCM to tune your truck again.

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One final thought: any time you’re overhauling a 7.3L Power Stroke it greatly behooves you to buy a new oil pan. Especially on Super Duty versions of the 7.3L, the oil pans are notorious for rusting through—and the only way to install a new one is to pull the engine from the truck. Whether it’s an OEM oil pan (F7TZ- 6675-BBB) or an aftermarket variant such as a Moroso, they can be found for $200 to $280.

SOURCES

ARP
800.826.3045 / ARP-BOLTS.COM

COLT CAMS
604.856.3571 / COLTCAMS.COM

DIESELSITE
888.414.3457 / DIESELSITE.COM

FULL FORCE DIESEL
615.962.8291 / SHOP.FULLFORCEDIESEL.COM

IRATE DIESEL
503.435.9599 / IRATEDIESEL.COM

MANLEY PERFORMANCE PRODUCTS
800.526.1362 / MANLEYPERFORMANCE.COM

POWER HUNGRY PERFORMANCE
687.890.1110 / POWERHUNGRYPERFORMANCE.COM

RIFF RAFF DIESEL
541.879.1052 / RIFFRAFFDIESEL.COM

STRICTLY DIESEL

623.582.4404 / STRICTLYDIESEL.COM

SUMMIT RACING
800.230.3030 / SUMMITRACING.COM

 

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