Turbo, Transmission, And Traction Bars

Just to recap, the beginning of this story dates back more than 10 years and it serves as proof that—with the right combination of parts in the mix—a stock bottom end 7.3L Power Stroke can live, indefinitely, at 600 hp. In Part 1, we highlighted the stronger pushrods and valve springs, the heads being re-anchored to the block via ARP head studs, big fuel introduced in the form of Unlimited Diesel Performance 350/200 hybrid injectors and a competition fuel system from Irate Diesel Performance. High-pressure oil needs were met with the late SRP1.1 and Gearhead Sales tied everything together with PCM calibrating, made available by way of a Power Hungry Performance Hydra chip.

By developing an all-in-one T4 turbo mounting kit, Irate Diesel Performance filled a huge void that existed in the 7.3L aftermarket. The company’s system, released more than a decade ago, made it possible to run virtually any T4 BorgWarner or Garrett turbocharger on a 7.3L Power Stroke—which paved the way for all of the 600, 700 and even 800 hp trucks you see today. Irate’s T4 turbo mounting system comes with a new pedestal, exhaust collector with 304 stainless steel up-pipes, 304 stainless intercooler pipes and intake Y, a two-piece downpipe (3-inch on OBS trucks, 4-inch for Super Duty’s), a stainless air intake tube, oil and drain lines (and fittings), and all installation hardware. Kits start at $2,145.
When you convert a 7.3L to Irate’s T4 mounting system, there are literally dozens of turbo options to choose from. In the 7.3L application—and for horsepower goals in the 600hp range—the S467.7 BorgWarner is a popular choice. Opting to do something slightly different, we reached out to Fleece Performance Engineering, a company with a billet S468 that was supporting north of 800 hp in Duramax applications while still offering great drivability. Its T4 S400 sports a billet 68mm (inducer) compressor wheel, makes use of a 81/87mm turbine, and utilizes a relatively tight .90 A/R exhaust housing. Our thinking was that the 87mm turbine would provide solid high rpm exhaust flow and the .90 housing would offer quick spool up despite the large turbine. It works very well.
Because we were campaigning the original engine in our ’97 F-350 and ’94.5-’97 versions didn’t come intercooled, we had to source an intercooler and then get it installed. After scoring a Spearco unit taken out of a 2000 Super Duty for next to nothing, we had it leak and pressure tested at a local radiator shop. Then it was time to tear into the front-end of the OBS Ford.
Depending on your mechanical skill level, installing an intercooler in an OBS Ford can be an extensive undertaking. For one, the radiator core support has to be cut yet not hacked apart. Our lives were made easy thanks to using a plasma cutter. But first we mocked up and measured precisely where the intercooler pipes were going to route around the radiator (measure twice, cut once right?). Our intercooler install also consisted of repurposing some stainless steel bracketry we had at our disposal in order to securely mount it.

But that was only the beginning. The factory turbo—and in fact the entire OEM turbo arrangement—had to be scrapped in pursuit of adequate airflow. We found what we needed in Irate Diesel Performance’s T4 turbo mounting system. The company’s all-inclusive turbo kit facilitated the use of an S400. And because the build involved a ’97 F-350—a truck that left the factory void of an intercooler—installing an intercooler was part of the extensive turbo system upgrades. Then when it came time to both harness the newfound horsepower and torque, we contacted John Wood Automotive for a billet internal E4OD, along with adding a set of high-quality traction bars from One Up Offroad.

Next time, we’ll show you the truck’s dyno sheet, its 8.00-second eighth-mile timeslips, and its odometer—225,000 miles strong, and counting.

Installing Irate Diesel’s T4 turbo mounting kit began with the removal of the factory up-pipes, Garrett turbo and its pedestal. The 1-inch thick pedestal plate supplied by Irate sits on top of the same pedestal mounting pads in the lifter valley, and Irate includes four 8x25mm bolts to fasten it in place. The T4 collector and up-pipe assembly is fastened to the new pedestal via three supplied 8x25mm bolts. In this photo, the included 1/8-inch NPT x 6 JIC fitting and its corresponding braided stainless steel oil feed line has also been connected.
Prior to installing the S468, the factory 2-inch inlet intake plenums were ditched in favor of these 3-inch billet-aluminum units from Irate Diesel. In flow testing, the factory OBS 7.3L plenums move a measly 240 cfm. By comparison, 3-inch inlet plenums flow 540 cfm. Their high-strength aluminum construction also means they won’t crush due to too much boot clamp pressure. Additionally, Irate claims they can withstand higher boost levels than the factory ’99.5-’03 3-inch plenums can.
Rather than wrestle with the S468 during its install, we opted to break the turbo down and install the exhaust housing to the T4 collector first. Then the rest of the turbo assembly was installed (the shaft, complete with the center cartridge, compressor wheel, turbine wheel and compressor housing). From there the oil feed line was connected with the fitting in the S468’s center section.
Downwind of the turbo, we installed a 5-inch aluminized exhaust system from Diamond Eye Performance. Coming off the turbo is a 3-inch, two-piece downpipe. The upper section that connects to the S400’s outlet is fabricated by Irate Diesel while the lower section is the same lower piece included in Diamond Eye’s ’94.5-’97 downpipe kit. The rest of the muffler-less system was cut to fit, with seven inches of total material having to be removed during the install.
To keep the engine from defueling, we installed one of Driven Diesel’s overboost annihilators. That’s right, we had issues with the MAP sensor causing the PCM to pull power away from the engine in an OBS truck. Although it’s not nearly as common for the ’94.5-’97 7.3L’s to defuel like the ’99-’03 engines do, if too much boost is seen too quickly in the rpm range it can happen. Driven Diesel’s boost fooler is built around the use of a high-quality, adjustable pressure regulator that only allows the MAP sensor to see 22-23 psi of boost. It retails for less than $65.
The finished turbo system presents a picture very different from stock—and the performance it provides is night-and-day different. Thanks to the Unlimited 350/200’s, SRP1.1 HPOP, Irate Competition fuel supply system, and Gearhead tuning you read about in Part 1, the S468 can produce as much as 50-psi of boost. And thanks to the ARP head studs, Comp Cams valve springs, and Hamilton Cams pushrods we don’t have to worry about popping a head gasket, experiencing valve float, boost or drive pressure creep, or bending a pushrod.
Knowing the E4OD wouldn’t stand a chance in hell of holding up to 600 hp, it was pulled and sent to our builder of choice: John Wood Automotive. After crafting a transmission pan cradle, cinching the transmission down to a pallet, and turning it over to the shipper, we hopped on a flight to SoCal to watch it be transformed into one of Wood’s Street Performance units. Trust us, watching the latest and greatest billet parts make it into your transmission is a sight to behold—and watching a transmission’s factory shortcomings be addressed, reengineered or reinforced is extremely fascinating as well.
Power transfer begins with a triple-disc torque converter, a piece that’s manufactured by Sun Coast according to John Wood’s specs. The billet-steel front cover eliminates the ballooning that occurs in factory converters when high pressure and excessive heat are present. This converter also conceals a host of upgraded internals designed to promote both efficiency and durability at high horsepower.
Here you can see that furnace brazing and TIG-welding has been employed inside the converter. These techniques are used to ensure the fins don’t lay over in high torque applications, where immense force is on the table. And because it’s responsible for driving the transmission pump, a billet drive hub is welded in place, which offers stronger stator and turbine splines.
Our converter’s OEM quality, converter clutch material was sourced from Raybestos Powertrain, who also handled the process of bonding it to the clutch discs. The two-disc converter clutch features one disc with friction material on each side while the other disc features friction material on one side (effectively making it a triple-disc).
A billet stator is a wise decision for competition use, but it should also be considered in high-horsepower trucks that are still used to tow. Because we drag race the truck occasionally and also tow a 10,000-pound camper with it, we opted for John Wood’s billet stator option. This particular stator gives our converter a 2,100-rpm stall speed (vs. 1,900 rpm stock). The higher stall speed helps bring the S468 to life quicker.
Every transmission builder has a recipe they like. For Wood, a mix of factory-spec BorgWarner and aftermarket Alto clutches are employed. It’s a combination he says provides for both great holding power but also optimum longevity.
Because the E4OD’s transmission pump tends to warp over time, Wood resurfaces every used core (or remanufactured) pump he uses. Affixed to his CNC lathe, 0.040-inches is removed from each side of the pump. After that, the pump gets a new boost valve and sleeve, the component that controls converter lockup.
The OEM reverse hub in the E4OD is notorious for flexing (and even exploding) when exposed to excessive torque loads. To ensure this never occurs in his transmission, Wood TIG welds a reinforcement ring to the top and bottom of the Low/Reverse hub. The reinforcement rings are made of Inconel, a material that’s known to resist distortion due to high stress or heat (think turbine wheels and valves).
Going beyond the strength of traditional 300M billet-steel, we opted for Wood’s Maraging 300 alloy input shaft upgrade. On top of offering more torsional strength than 300M, our Maraging 300 input was also heat-treated. The intermediate shaft was upgraded to 300M and the output shaft remained factory but was cryogenically treated for improved wear resistance.
Wood’s E4OD and 4R100 transmissions are known for their quick yet smooth shifts, and most of the magic that makes that happen takes place in the valve body. Using a custom line pressure modulator valve, exclusive capacity valves (which are machined in-house), and hand-picked accumulator spring sets, Wood can fine-tune the shift points, eliminate shift flare, reduce clutch slippage, decrease clutch wear, and even lower the operating temperature of the transmission.
With big torque known to rip the center section out of the factory flex plate, we threw in a billet version ahead of the transmission install. Sourced from the late Elite Diesel Engineering, the flex plate is made of 4340 billet-steel and meets SFI specification 29.3. While some elect to cryo treat a factory flex plate, we wanted permanent peace of mind here.
For added fluid capacity (approximately 4.5 quarts over stock), we installed a lightweight, cast-aluminum pan from Goerend Transmission. The company’s E4OD/4R100 pan makes use of a magnetic drain plug with a copper sealing ring and that calls for a 1-inch socket to remove, a sloped floor for 100-percent fluid drainage during servicing, and a high-quality, Duraprene gasket that won’t crack when you tighten up the pan bolts.
To keep the built E4OD cool at all times, the undersized factory transmission cooler was ditched in favor of this 37-row, stacked-plate unit from Mishimoto. Originally intended as a bolt-in upgrade for the 31-row heat exchanger that came standard on ’03-’07 Super Duty’s equipped with the 5R110W TorqShift and 6.0L Power Stroke, we had to make room for the Mishimoto cooler in our OBS Ford. We found enough space between the A/C condenser and the radiator and settled on that location. To date, ATF temps haven’t top 140 degrees F—not even when we’re hooked to our 10,000-pound trailer on 95-degree days.
Believe it or not, traction bars were needed when our OBS was knocking on the door of 350 hp, so needless to say these have been under our F-350 a while. The high-quality, short gusset type traction bars came from One Up Offroad and (along with the transmission) they represent one of the most overbuilt items on the truck. On top of quelling axle wrap, they settled down the chassis during transmission upshifts, drastically reduced driveshaft plunge, and have surely helped keep our U-joints alive.
Electing to run bolt-on frame and axle mounts for the traction bars, we had our work cut out for us drilling the mounting holes. But with eight 3/8-inch bolts fastening each mount to the frame rails, they aren’t going anywhere—ever. The traction bars attach to the frame mounts via burly, 7/8-inch bolts, with bushings on each side of the mount.
One Up’s axle tube mounts boast polyurethane bushings, and after more than 11 years of being on the truck they don’t make a sound or show any signs of deterioration. For the traction bar install, we switch to the company’s ’11 style, inverted U-bolt system, which upsized the diameter of the U-bolts to ¾-inches from 5/8-inches. Also take note of the Grade 8 hardware used throughout and the beefy, ¾-inch thick steel plate center gusset on the axle mount.


Driven Diesel

Fleece Performance Engineering

Goerend Transmission

John Wood Automotive

Irate Diesel Performance


One Up Offroad

Raybestos Powertrain

Sun Coast


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