table of contents
When these 1994-1997 OBS Ford trucks were new, the 7.3L Power Stroke was not intercooled and could put down around 180-200hp. With a 2020 Power Stroke capable of twice that in stock form, a 7.3L will need quite a bit of attention to make 400+ horsepower. Don’t worry though, it’s capable of doing it and this F350 is going to be an excellent build with a great combination of parts to show you how to get it there.
We’ve already tackled fuel pressure problems with an electric fuel system conversion that will maintain a set 65-psi and now it’s time to make a turbo upgrade. At Complete Performance we pride ourselves with offering only the best upgrades for your old Ford truck, and when it comes to turbochargers for the 7.3L Power Stroke, KC Turbos of Arizona will always be our go-to. When picking a turbocharger there are a couple questions you have to ask yourself. What kind of power would you like to make? What are your drivability and smoke concerns? And of course what’s your budget? Lucky for all of us, KC Turbos specializes in 7.3L applications and have multiple options to fit just about any build. For this build looking to make 450hp, their latest rendition of their stock replacement KC300x turbocharger with a 63m compressor wheel, 73mm turbine and choice of either a .84 or 1.0 turbine housing will be perfect.
The journal bearing turbo uses a few pieces unique to KC that their team has spent countless hours developing and perfecting specific to optimizing performance of the older 7.3L Power Stroke platform. The 7.3L uses a reverse rotation turbocharger not common on other diesel platforms, so making compressor and turbine changes isn’t as easy as there aren’t other wheel sizes and profiles readily available. Determined to bring something new and exciting to the market, the KC team looked at the technology in the Borg Warner S300 SX-E turbochargers and tried to adapt a lot of that science into reverse rotation version that could create a direct fit, stock replacement turbocharger for the 1994-1997 Ford trucks. What they’ve brought to the market is a 100% drop-in unit with the best in turbo tech for better drivability, great low end spool-up and off idle response, with the airflow and EGT control you need in a modified application.
For our particular build, their 63mm compressor wheel would move enough air to support our 205cc injectors and our low 400-horsepower goals. The 63mm wheel offers great spool-up and a broad power curve thanks to its 7x7 extended tip blade design and profile. On the backside of the turbocharger you’ll find a much different turbine wheel design compared to a factory 7.3L turbine wheel. Again, based off the Borg Warner S300 platform, KC developed a reverse rotation version in a 73mm size that would not only increase turbine flow substantially, the blade design would allow it to do so without sacrificing low end grunt and spool-up. Since we aren’t going for an all-out power house here, and the truck spends most of its time at higher elevations where the air is a bit thinner and hard to come by, we opted to run the tighter .84 a/r housing. The .84 will offer great drivability under 3000-rpms where this truck spends most of its time. We know we’ll sacrifice some top end and EGT control compared to that of a looser 1.0 a/r, but for our specific application the .84 was the better choice.
To get the maximum potential out of this new turbocharger, we also opted to install a few other supporting products from KC Turbos like their Non-EBPV turbo pedestal and high flow turbine outlet. Since our factory pedestal has been leaking oil from the Warm Up Valve rod, this was the perfect time to eliminate that problematic system from the truck all together. This offers two benefits. First, we’ll eliminate that pesky oil leak. Second, we can remove the restrictive warm up butterfly valve from the exhaust outlet and free up the exhaust to help bring exhaust temps down some more.
While we’re on the subject of exhaust, we need to also replace our factory up-pipes that connect our exhaust manifolds to the turbine inlet of the turbocharger. The factory Ford design leaves a lot to be desired and uses a simple crush donut to seal the pipes to the turbine collector. These crush donuts have been known as a bit of a problem area for the 7.3L and leak substantially in most trucks, especially high mileage trucks like ours. We knew ours were leaking when we purchased the truck, so swapping them out while doing the turbocharger upgrade was a no brainer.
These bellowed up-pipe kits for the 7.3L were designed to replace the donut gasket with a better performing design that fits like OEM pieces would. They are built aircraft grade 321 Stainless Steel, ensuring they’ll never rust or crack. By incorporating a bellow into the pipe, you’ll still get the flex and expansion needed in the up-pipe with continuous heat cycles, while keeping a leak free seal.
While the end results have been proven to be worth every bit of work that had to go in to this installation, we feel it needs to be expressed just how hard a turbo swap can be on this 1994-1997 7.3L platform. Whether it be the lack of accessibility to some of the bolts or 200+ thousands miles of driving on it all, removing the factory turbo and up-pipes is not a job for the faint of heart. On a scale of 1-5 wrenches, this is most definitely a 5, and the toughest job we’ve done on this truck to date. It will take some specialty sockets to get to the turbine inlet hardware and an extreme amount of patience. If you have hesitations, don’t shy away from asking a local shop with previous experience making this swap for you. Again, with all that said, after driving and towing with the truck, we are very glad we went through with it.
With only a few more parts to install, we’re extremely happy and impressed with how this build has turned out and it honestly gets compliments and looks everywhere we take it. Anyone that loves diesel trucks has some kind of a connection to an OBS Ford and it’s a truck that will just always be a classic. Next we’ll look at an intercooler upgrade and finally adding those big injectors!
1 – When adding power to your Ford diesel truck, a turbocharger upgrade is almost a necessity. The factory turbo is sufficient for factory power levels, but for much more than 250hp increasing airflow will be mandatory. A great solution for a daily driver and towing application is the drop-in replacement turbochargers from KC Turbos. The labor required to swap turbos also makes this a great time to upgrade to bellowed up-pipes.
2 – With larger injectors planned for this truck, increasing airflow is going to have to happen first. For the 450hp range we’d like to see, it was decided the 63mm compressor size would be the ideal match for both towing and good street manners. KC Turbos uses their very own compressor wheel design that offers great low-end spool-up without sacrificing top end power.
3 – On the exhaust side of the turbocharger from KC Turbos, their proprietary 73mm turbine wheel is used for better drivability and lower drive pressure. AS a replica to the better performing Borg Warner SXE style turbine wheel, it uses the latest flow technology working much better than the factory 7.3L turbocharger would.
4 – The exhaust up-pipe design in the 7.3L Power Stroke uses a crush donut for exhaust expansion and sealing pre-turbo but has been known to premature failure and leaking. To resolve any exhaust leak problems and maximize turbocharger performance these bellowed up-pipe kits are far superior.
5 – As you can see by the red paint on our factory turbocharger, it’s apparent this one has been out and replaced once before, but it’s still all factory parts right down to the big 1.15 a/r turbine housing. Changing turbocharges on the 1994-1997 OBS trucks is not an easy job and will take a lot of time and patience but will be worth it in the long run.
6 – Getting access to the four bolts that hold the turbine housing to the exhaust collector is challenging to say the least. Penetrating oil, time, and patience will be your saving grace here. With those four bolts removed, the four turbo pedestal bolts are next, and the complete assembly can be removed from the engine bay.
7 – We had to remove the T4i style collector so the factory up-pipes could be removed, but as you can see from the black soot around the pipes these have been leaking for a while. The seal was so poor, we didn’t even have to remove the bolts attaching the crush donut collar to the collector to remove it all. Be prepared to get creative to remove the driver side up-pipe, like lowering your t-case down or removing cab mounts so it can be raised up a bit.
8 – On the bench you can see just how pretty that KC unit is compared to the stock piece. Obviously looks isn’t everything, as how it performs is key in this application. The new 63mm turbo will still be very drivable and help control EGT’s while towing.
9 – A simple change and upgrade right now is to also remove the exhaust warm-up valve which helps free up our exhaust path for lower drive pressure and eliminate the leaking EBPV pieces in the factory pedestal.
10 – Oh, the billet shiny goodness! More airflow, better efficiency, and improved surge control. Plenty of reasons to upgrade that old worn out Garret turbocharger.
11 – This helps explain some of the laggy turbo performance we’ve had from the truck recently. Not only were those leaking exhaust up-pipes giving up some turbine efficiency, but some excessive wear on the turbine wheel and that 1.15 a/r turbine housing were losing some ability to make boost as well.
12 – This is that leaking EBPV turbo pedestal we had mentioned. This warm-up valve is only used under very specific situations and is not needed in most applications. The rod assembly leaks oil from the pedestal and that butterfly valve in the turbine outlet path is less than ideal. So we’ll eliminate it all with this upgrade.
13 – Factory up-pipe design next to the new bellowed up-pipe design. The bellow allows for expansion and contraction with heat cycles, while that steel gasket keeps a constant seal that will keep you exhaust leak free for basically ever if the installation is done correctly.
14 – The up-pipe kit will include the required gaskets and new hardware to make this in easy reassembly process. Due to a broken bolt in our turbo collector, we opted to replace it with a new cast unit rather than fight with drilling the old one and commencing with labor intensive bolt extraction.
15 – The new polished turbo looks so good back in the Power Stroke’s engine bay. Being a stock replacement turbocharger, it all goes back together the same way it came apart. It reuses the factory style exhaust downpipe and compressor discharge pipe. Depending on your intake system, the turbo will come supplied with the proper intake boot to connect to the new 4” ported inlet.
