Reviving the 7.3L Powerstroke: Performance Upgrades

7.3L Powerstroke Common Repair

We started this build in hopes of making some great content on some of the ins and outs of these old 7.3L Powerstroke trucks. To show off some of their strengths, point out some of the weaknesses, but most of all, just have the ability to enjoy working on something in the garage. There is a sense of pride earned when you can take something old and forgotten and make it useful, and something that turns heads at the diesel pump. Sure, it’s outdated, it’s loud, it doesn’t ride that great, but there is no doubt this old body style Ford still has a strong following, and if you’re looking, you’ll see one that might be worth your time to fix up and enjoy too.

4-inch Exhaust

One of the most common first mods a diesel owner will make to his truck is an upgraded exhaust system, and for good reason. While an aftermarket system will help give off the throaty sound we all love, on the 1994-1997 Powerstroke trucks, the right 4-inch system, like the stainless MBRP kit, is a legitimate performance upgrade too.

On the 1994-1997 Powerstroke application, the largest gain from an aftermarket exhaust comes from the down pipe section. The factory Ford piece was sandwiched flat to clear the firewall, but really affects exhaust flow and generates unwanted back pressure and heat. MBRP’s mandrel bent 3-inch two-piece design offers huge improvements in performance and EGT control.
New trucks are a pretty simple unbolt, remove, install, snug up, and fire up kind of exhaust swap. The Old Body Style Ford Powerstroke,  however, is notorious for being one of the most challenging exhaust installations out there, thanks to that factory downpipe. With round ends, a flat sandwich piece in the middle, and no room to work with, cutting it in two is your only option… unless removing a cab sounds like less work. (Spoiler alert: it’s not.)

For a reason we’ll never fully understand, the Ford engineers used a nearly flat and pinched-off factory down pipe piece to get exhaust from the turbocharger outlet, down past the engine and firewall to the underside of the truck, where their exhaust system starts. With not much room to work with, MBRP offers a true 3-inch mandrel bent downpipe that outflows the stock piece by over 20%, reducing turbo back pressure for better engine efficiency and cooler exhaust temperatures.

Modifying diesel trucks has been around just about as long as diesel trucks themselves, and one of the most popular first modifications for these older Ford trucks, or any diesel for that matter, is free flowing exhaust. MBRP has been around for years and still offers one of the best fitting easiest to install kits available. As a complete bolt/clamp-in install, it’s a task most dare to conquer in the home garage.
Which one do you think flows better? Kind of a no brainer, right? Obviously, to fit that larger pipe some massaging of the firewall is required, and every truck will be a little bit different. In most cases, however, we’ve found it easiest to make two small slits in the firewall’s pinch weld, then just fold it over with a pry bar and hammer. In most trucks, just flattening out that pinch weld where the downpipe passes is enough to get all the clearance you need.

For those of you in smog counties, this MBRP exhaust system will retain the factory catalytic converter (yes, the government requires you to keep this). It then flows on to a muffler offering a rich sounding exhaust note from the tailpipe. These kits are constructed of stainless steel thick wall full 4-inch mandrel bent tubing and will most likely outlast the truck you’re bolting it on to. When we move on to tuning the truck in the next step, EGT control can become a challenge, so the new downpipe and 4-inch system will be of great benefit when it comes time to try and tow and use the soon to be installed horsepower in a switch.

Surprisingly enough, this new-to-us 25 year old F250 was still running the original exhaust, right down to the restrictive muffler and catalytic converter (which we’re keeping to meet smog and CA regulations). We almost felt a little bad hacking it up with a Sawzall, but the efforts will be well worth the reward.
For our downpipe removal, we opted to unbolt it from the catalytic converter below and the turbocharger above so we could slide the pipe down as far as we could to make our cut as far up on the downpipe as possible. Be careful here, as there are some transmission lines and wiring you’ll need to avoid.

Edge Revolver

When this truck was brand new, there weren’t many ‘chip’ upgrades available, but with time the aftermarket came out with some pretty neat stuff. In the early 2000’s, the multi-position chip was all the rage. For years, companies like Edge Products have devoted thousands and thousands of hours into the 7.3L market and their Evolution handheld tuner was one of the best-selling 7.3L devices ever.

While flash tuning is a big part of diesel tuning these days, Edge still offers that simple plug-in adjustable chip, dubbed the Revolver. It plugs directly into the PCM through the factory J3 port found on the computer board and will control every aspect of the engine and even the transmission for better power and drivability.

One of the biggest reasons we opted to go with the MBRP kit is its ability to retain the factory catalytic converter, keeping our truck smog legal, but two other big reasons to go this route are overall fitment and the statement that big shiny 5-inch polished tip makes.
Since these trucks are offered in different cab configurations and bed lengths, rather than build one kit for every truck, MBRP sets their kits up to be one-size-fits-all, so you will have to measure and cut one section of pipe, which it lays out clearly in the instructions. Cutoff wheel on the grinder, chop saw, Sawzall, pick your poison here. But remember the old adage: measure twice, cut once.

For this build, still running the stock transmission and injectors, the Revolver is a great choice as it’s also smog legal with a CARB EO making it legal for sale in California. The chip came pre-programmed with 6 levels we can flip through while driving: a stock file, hi-idle, light and heavy tow tunes, economy, and performance. The tow tunes offer great shift patterns to keep a heavy load moving, while the daily driver economy tune has great throttle response and pep for stop-and-go style driving. Installation takes about an hour on these older Ford trucks, but the instruction manual makes this a simple step-by-step process you can do at home without much trouble.

On the garage floor side by side, you can see how much different the stock pipe and the new MBRP 3-inch downpipe is. That sweeping mandrel bend will do wonders for exhaust flow and help reduce EGTs as that exhaust exits the turbocharger.

Once you’ve made sure that old truck is sound and all the mechanical parts and powertrain are in tip top shape, bolt-ons can be a worthwhile investment. The 7.3L Powerstroke has never once been accused of being a powerhouse. In fact, it’s often been quite the opposite. OBS trucks in stock form, with their large 1.15 a/r exhaust housing, lack of an intercooler and sub 200-horsepower can be quite lethargic to drive, and tow with. It’s reliable as anything on the road, but it won’t ever be the first one over the mountain.

The Powertrain Control Module (PCM) is the brains of the older 7.3L Power Stroke and handles all the electronic systems under the hood, from taking inputs from various signals, to sending signals to the Injector Drive Module and High Pressure Oil Pump or Injection Control Pressure sensor so they know when to fire. It also controls transmission shift strategies for factory E4OD transmission.
With the port cleaned off, now we just need to plug the chip into the PCM (it only fits one way), reinstall it into the truck, then plug in the Revolver’s multi-position switch and mount it somewhere on the dash. While Edge markets these for gains as much as 140hp in the 7.3L applications, that’s normally for the Super Duty truck, as the OBS doesn’t quite have the injector size (fuel) or turbocharger (air) to support gains like that. This truck should see a solid 80hp/175ft-lb of torque on the Extreme tune, which is a significant gain considering it only made 185hp/371ft-lb stock.

The larger 4-inch exhaust and tuning from Edge Products made a massive improvement in drivability, taking us from an uninteresting 187hp/ 371ft-lbs of torque to a whopping 272hp/ 540ft-lbs. You’ll notice a difference behind the wheel, no doubt. Soon, we’ll take performance to the next level by installing a modified intake system, rebuilt turbocharger, and doing the one modification that every early Powerstroke must have on its list, an intercooler kit.


SOURCES

MBRP Exhaust
mbrpexhaust.com

Edge Products
edgeproducts.com


 

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