If you're thinking about a 6.4 to 6.7 powerstroke swap, you're probably tired of looking at your truck sitting in the driveway with a dead engine. Let's be honest: the 6.4-liter Powerstroke is a bit of a heartbreak. When it's running right, it's a monster with incredible torque and power potential, but when things go south, they go south fast. Cracked pistons, lifter failures, and fuel system meltdowns have turned many a Ford enthusiast toward the idea of putting the much more reliable 6.7-liter "Scorpion" engine into their 2008–2010 Super Duty.
It sounds like the perfect solution on paper. You keep the interior and the body style of the 6.4 trucks—which many people still prefer over the newer ones—but you get the modern reliability and efficiency of Ford's in-house 6.7 diesel. However, before you start ripping out bolts, there's a lot you need to know about what this project actually entails. It's not just a weekend job with a few buddies and a crate engine.
Why Even Bother with This Swap?
The motivation is pretty simple: the 6.4 is a ticking time bomb for many owners. It was the last engine Ford built with Navistar, and while it's capable of massive horsepower, it lacks the longevity most diesel owners expect. Once you've spent $15,000 on a rebuild only to have it fail again 40,000 miles later, you start looking for a way out.
The 6.7 Powerstroke, introduced in 2011, changed everything. It's a completely different animal. It uses a "flow-through" design where the exhaust exits into the "V" of the engine, which helps with turbo efficiency and heat management. It's proven itself to be a 300,000-mile engine with basic maintenance. Naturally, truck owners want that peace of mind without having to sign a 72-month loan for a brand-new $80,000 truck.
The Mechanical Hurdles are Real
If you think a 6.4 to 6.7 powerstroke swap is a "bolt-in" affair, I've got some bad news. These two engines share almost nothing in terms of physical architecture. The 6.4 is a traditional design, while the 6.7 is a "flipped" design. This means your entire cooling system, your exhaust routing, and your intercooler piping have to be completely custom or sourced from a donor 6.7 truck and heavily modified.
Then there's the transmission. The 6.4 usually sits in front of the 5R110 TorqShift. While it's a stout transmission, getting it to talk to a 6.7 engine is a nightmare. Most people doing this swap end up moving the 6R140 transmission over from the 6.7 donor truck as well. This means you're looking at different driveshaft lengths, different transmission mounts, and potentially moving the transfer case if you've got a 4x4. It's a domino effect—you change one thing, and five other things have to change to accommodate it.
The Electrical Nightmare
This is where most people give up. If the mechanical side is a headache, the electrical side is a full-blown migraine. The 2008–2010 trucks use an entirely different communication protocol (CAN bus system) than the 2011 and newer trucks. You can't just plug the 6.7 engine harness into the 6.4 truck's firewall and expect the gauges to work.
To make a 6.4 to 6.7 powerstroke swap actually functional for a daily driver, you usually have to swap the entire interior wiring harness, the dash, and the body control modules. I've seen guys try to use aftermarket stand-alone controllers for the engine, but then you lose your factory air conditioning, your cruise control, and your instrument cluster. If you want the truck to feel like a factory build, you basically have to gut the 6.4 truck and put the "brains" of a 6.7 truck inside it. It's a massive undertaking that requires a deep understanding of Ford's wiring diagrams.
Fuel and Plumbing Issues
Don't forget about the fuel system. The 6.7 uses a different lift pump setup and different fuel lines. You'll need to modify the fuel tank or the sending unit to ensure the 6.7's CP4 pump (or a CP3 conversion) is getting the right pressure and flow.
Then there's the cooling stack. The 6.7 has a very complex cooling system with two separate radiators and two separate coolant loops—one for the engine and one for the intercooler and EGR cooler. Fitting that massive cooling assembly into the nose of a 2008–2010 truck requires some serious "massaging" of the core support. It's not impossible, but it's definitely not a "drop-in" situation.
Is It Worth the Cost?
Let's talk money. Unless you have a wrecked 6.7 donor truck sitting in your yard that you bought for pennies on the dollar, this is going to be expensive. By the time you buy a low-mileage 6.7 engine and transmission, all the wiring, the cooling components, and the custom fabrication work, you could easily be $20,000 deep into the project.
If you're paying a shop to do it? Double that number. Most shops won't even touch a 6.4 to 6.7 powerstroke swap because of the liability and the sheer number of billable hours it takes to iron out the bugs. You're looking at hundreds of hours of labor to get it perfect. At that point, you have to ask yourself: wouldn't it be easier to just sell the 6.4 truck as a "roller" and use that $20,000 as a down payment on a factory 6.7 truck?
Better Alternatives to Consider
I know, I know—you love your truck. But if the goal is reliability, there are other paths that might be less painful.
1. The Cummins Swap (Fummins)
This is actually much more common than a 6.4 to 6.7 powerstroke swap. Companies like Diesel Conversion Specialists have made this almost a science. They sell the adapter plates, the engine mounts, and the wiring jumpers to put a 5.9L or 6.7L Cummins into your Ford. Because the Cummins is a simpler engine (especially the 12-valve or early 24-valve versions), the swap is much more straightforward.
2. A Fully Built 6.4
If you love the power of the 6.4, you can spend that same $15,000 to $20,000 on a "bulletproof" long block. If you get a block with de-lipped pistons, better lifters, and a Stage 1 cam, and then you delete the problematic emissions gear (where legal), the 6.4 can actually be quite reliable. It'll never be a 6.7, but it'll bolt right back into your truck without a wiring nightmare.
Final Thoughts for the Bold
If you're still dead-set on doing a 6.4 to 6.7 powerstroke swap, more power to you. It's a cool project, and a finished, well-sorted truck is a total unicorn. You'll have the best-looking Super Duty body style with the best engine Ford ever put in a pickup. Just go into it with your eyes wide open.
This isn't a project for someone who needs their truck to get to work on Monday morning. This is a project for someone with a secondary vehicle, a massive tool chest, and a lot of patience. You're going to be a pioneer in a lot of ways because there isn't a "kit" for this. You'll be doing a lot of your own troubleshooting.
But hey, that's the fun of being a gearhead, right? Just make sure you've got a good relationship with your local parts department—you're going to be seeing them a lot. If you manage to pull it off, you'll have one of the most unique and capable Fords on the road. Good luck, you're gonna need it!