How to Turn up the Wick on Your 7.3L Power Stroke
Much like legends, good engines never die. Be it for reliability, performance potential or a loyal following of enthusiasts that just won’t let them fade away, this seems to be the case for the 7.3L Power Stroke. Despite the last mill rolling off the Indianapolis assembly line nearly 15 years ago, truck lovers continue to use them to tow, haul and even commute. Thanks to a host of injection system, turbocharger and tuning advancements coming to market over the last decade, the 7.3L has proven to be an affordable, reliable and viable performance candidate—even amongst the latest and greatest being offered from the Big Three.
With items such as hybrid injectors, high-flowing turbochargers and custom-tailored powertrain control module (PCM) tuning available, engines can be modified on a budget and remain reliable even while producing three times the power they made in stock form! Having tinkered with our own 7.3L Power Stroke over the course of the last 10 years, we’ve lived through the 7.3L performance resurgence and can personally vouch for the setups recommended in this article.
Take it from us—if you want the best overall package for performance, drivability and reliability, check out the power recipes at the bottom of this article.
HEUI Injector (Oil-Fired)
It’s important to remember that the 7.3L Power Stroke utilizes a hydraulically activated electronically controlled unit injector (HEUI) injection system. This means the fuel side of the injector relies on the oil above it in order to fire. The injectors are supplied engine oil (via the high-pressure oil pump) that has been pressurized to as much as 3,200 psi.
As far as making big horsepower is concerned with 7.3L’s, hybrid injectors are the ticket, because this style injector doesn’t require additional oil volume in order for it to fire. A hybrid unit can carry you into the 550hp range before a higher volume (aftermarket) high-pressure oil pump is required.
Custom Tuning and Injector Builders
Premier injector builders in the 7.3L world include: Full Force Diesel, Unlimited Diesel Performance, Rosewood Diesel, and Swamps Diesel Performance. Complete, rebuilt injector sets, where all major wear components are replaced, start at roughly $1,200 for an injector that can get you into the 350hp range and top out around $3,000 for a competition-ready, high flowing injector capable of supporting more than 650hp.
High-Pressure Oil Pump
While a stock high-pressure oil pump (HPOP) will suffice for most power levels below 500hp (provided the pump is in good health), at a certain point, a stock displacement HPOP won’t keep up with the injector’s oil demands. When a pump can’t keep up, injection control pressure (ICP) won’t be maintained at the 3,000 psi (or more) that’s needed to get maximum performance out of the injectors.
As a general rule of thumb, going beyond 250cc hybrid injectors usually warrants a higher volume, high-pressure oil pump, or the use of dual HPOP’s. To feed any size 7.3L injector, Swamps Diesel Performance offers a Gen3 unit, and Full Force Diesel sells arguably the best dual HPOP system on the market.
Electric Fuel Supply Systems
Aside from keeping the oil side of the HEUI equation happy, the fuel supply system is one area that must be upgraded. This is especially true for ’94.5-’97 trucks, as the fuel system employs a cam-driven mechanical fuel pump in the lifter valley. In stock form, this pump is known to supply 40 to 45 psi worth of fuel pressure to the injectors, even though 7.3L injectors need to see roughly 65 psi for optimum performance and longevity
If you’re upgrading the injectors on a ’94.5-’97 Power Stroke, you’ll definitely need to scrap the mechanical lift pump in favor of an electric fuel supply system. Complete, bolt-on kits are offered by Irate Diesel Performance (shown), Beans Diesel Performance, and Marty’s Diesel Performance for $1,000 or less. These kits include a lift pump, filters, mounting bracket(s), all fittings, hose and hardware.
A regulated return system is a must-have item with Super Duty engines, which eliminates the factory design that allows fuel to dead-head in the fuel rails by tying each end of the fuel rail together using a bypass style pressure regulator. Driven Diesel offers arguably the most popular regulated return systems on the market.
The Little Pump That Could
As for Super Duty trucks (’99-‘03), the factory fuel supply system is electric, and provided that the stock lift pump is in good working order, can support a small set of injectors (160cc’s). For moderately large injectors (180cc to 238cc), the Walbro GSL392 pump shown works wonders. A direct, bolt-in replacement for the factory lift pump, it can support up to 500hp (and up to 600hp in conjunction with an aftermarket fuel system utilizing larger fuel lines, fittings, etc.). Other highlights for the Walbro pump include the fact that it’s been proven to be just as reliable as the factory pump and can be found online for $100 or less.
Drop-In Turbo Options
Due to their unique mounting circumstances, neither the ’94.5-’97 F-series trucks or ’99-’03 Super Duty’s have a lot of direct replacement turbo options. Because of the compact size of the factory Garrett TP38 on the early 7.3L engines (in which the compressor housing nearly sits on the driver side valve cover), factory-based aftermarket turbo options are the only real way to go for those in search of a direct, bolt-in replacement.
The Dominator 66 from Beans Diesel Performance fits a 66mm inducer compressor wheel, custom compressor housing back plate, and 360-degree thrust bearing assembly into the factory TP38 charger, which flows 300 cfm more than stock (1,050 cfm vs. 750 cfm) and can safely support 450hp.
On the Super Duty side of things, Garrett’s GTP38R unit is a direct, bolt-in replacement for the unique V-band, dual volute exhaust exit used on Super Duty engines. The GTP38R (shown) features a 66mm compressor wheel, a ball bearing center cartridge for quick spool up, can support 500 to 550 horsepower. This was extremely popular prior to the T4 turbo mounting options coming to market (for more information on T4 setups, keep scrolling).
T4 Turbo Systems
For years, 7.3L owners were stuck with drop-in turbo options (unless someone wanted to fabricate their own up-pipes, exhaust collector and pedestal). But when all the performance enhancements began to pick up steam in the aftermarket (namely hybrid injectors and better tuning), the demand for more serious turbo options gave birth to a supplier.
Roughly six years ago, Irate Diesel Performance entered the fray and began building T4 turbo mounting kits for the 7.3L crowd. These systems scrap the factory turbo mounting hardware and intercooler piping and replace all of it with a setup that can accommodate virtually any T4 flanged turbocharger. This means the popular BorgWarner and Garrett chargers many Cummins and Duramax owners have benefitted from for years can now be used on a 7.3L. Thanks to Irate’s commercialization of its T4 mount kits, custom-built BorgWarner turbos based off of the S400 chassis and out-of-the-box S400’s have become the norm, as well as 500, 600 and even 700 horsepower being easier to achieve.
On-the-Fly Performance
Anytime larger injectors are added to a 7.3L, custom PCM tuning is required to not only get the truck to run correctly, but to reap the biggest performance gains from them. Companies like Gearhead Automotive Performance, DP Tuner, Power Hungry Performance, Tyrant Diesel, Swamps Diesel Performance and Dyno Proven are among a long list of popular tuners for the 7.3L Power Stroke.
Without a doubt, the six-position chip from TS Performance revolutionized the 7.3L Power Stroke tuning market back in the day. It offered six tuning options, all of which could be navigated on the fly (i.e. you didn’t have to pull over and plug in your programmer in order to change files), and—due to it piggybacking directly to the 7.3L PCM’s circuit board—provided considerably more performance gains than the comparable programmers of the day could. Some years ago, TS Performance released the rights of its tuning software. When this happened, aftermarket calibrators soon began to offer even better tuning (referred to as custom tuning or custom tunes) for 7.3L owners. Key aspects of custom PCM tuning are that high-mile, stock bottom end engines can be made to live while making upward of 500hp.
Another notable benefit of custom tuning is that big injectors can be detuned in order to keep the engine safe when working the truck (hauling and towing). For example: the sixth position on your chip can be reserved for an all-out, race file that makes 600hp, but your number one position entails a tow tune that keeps exhaust gas temperature in check, optimizes the transmission’s shift points for towing a 20,000-pound trailer and makes a tow-friendly 350-to-400hp.
Hydra Chip
While the TS Performance six-position chip previously mentioned kick started the custom tuning craze in the 7.3L segment, in recent years, this little gismo has taken over. Called the Hyrda Chip, it’s made by Power Hungry Performance and allows you to update/change tunes by simply plugging directly into your laptop. From a “no downtime” perspective, this improvement alone puts it light-years ahead of the TS chip in terms of technology (the TS chip has to be removed from the PCM, mailed to your tuner, reburned, shipped back and then reinstalled). The Hydra can hold up to 17 tuning files at a time, and like the TS chip, tunes can be adjusted on the fly.
Rock-Solid Automatics
It’s unclear when an E4OD or 4R100 automatic will bite the dust, but a lot of enthusiasts have kept their transmissions alive at the 300 to 400hp level with nothing more than an upgraded valve body and a reputable triple disc torque converter. Throw those two latter items at a fresh reman version, and you could have a solid reliable transmission for years to come. However, there is no guarantee the clutches will hold, the Overdrive snap-ring will stay in place, the center support bolts won’t back out, the Reverse hub won’t blow apart or any of the other problems the E4OD/4R100 is notorious for won’t occur.
For a bulletproof version of the four-speed automatic, the most reputable names in the industry are John Wood Automotive and Brian’s Truck Shop. Either company can build a transmission to handle any horsepower level or survive any working condition. Note: if you have a ZF-5 or ZF-6 manual transmission, look into the upgraded clutch options offered by South Bend Clutch.
HP Recipes
300-350HP
- 160cc injectors with stock nozzles
- Custom tuning via TS Performance six-position chip or Hydra chip
- Electric fuel system (required on ’94.5-’97 trucks)
- Valve body and triple disc torque converter
400-450HP
- 180cc to 205cc injectors with 80 percent or 100 percent larger nozzles
- Custom tuning via TS Performance six-position chip or Hydra chip
- Drop in turbo (Dominator 66 on ’94.5-‘97, GTP38R on ’99-‘03) or T4 mount
- Electric fuel system (required on ’94.5-’97 trucks, Walbro drop-in pump on ’99-’03 trucks)
- Regulated return fuel system
- Valve body and triple disc torque converter
500-550HP
- 238cc to 275cc injectors with 80 percent or 100 percent larger nozzles
- Custom tuning via TS Performance six-position chip or Hydra chip
- S400-based BorgWarner turbo
- ARP head studs
- Stiffer valve springs and stronger pushrods
- Electric fuel system
- Regulated return fuel system
- Built transmission (if auto)
*Engine serial numbers 1425747 to 1440712 and 1498319 to completion were built using powdered metal connecting rods (vs. the preferred/stronger forged rods), which become a major weak link between 450 to 500 hp. Find out which rods your engine has before pushing any stock bottom end this far.
600-800 HP
- 300cc to 400cc injectors with 200 or 400 percent larger nozzles
- Custom tuning via TS Performance six-position chip or Hydra chip
- 75mm or larger S400-based BorgWarner or Garrett turbo
- Electric fuel system
- Regulated return fuel system
- Ported heads with matching cam (preferred but not a necessity)
- Built engine with aftermarket rods, piston work, etc... is a good idea
- Built transmission (if auto)
