Can You Put A 6.7 Turbo On A 5.9 Cummins?
If you're an owner of a 5.9-liter Cummins, you might've wondered how to close the gap between your engine and the more modern 6.7-liter Cummins. Naturally, this question leads directly to the turbocharger. The 6.7-liter comes factory-equipped with a Variable Geometry Turbo (VGT), while the 5.9 uses a much simpler Fixed Geometry Turbo (FGT). It might sound wild, but it's worth asking: Can you install a 6.7-liter turbo on your 5.9 Cummins? Unbelievably, the answer is yes — and it's actually not all that wild, either.
Today's aftermarket options make it possible to install a VGT onto the 5.9-liter engine instead of a 6.7-liter. Companies like BD Diesel Performance have even developed kits so you can do it yourself, like the Howler VGT series, designed specifically for 2003-2007 Dodge trucks with the 5.9 Cummins. These kits include everything you need for turbocharging the engine – plus a controller system that allows the VGT to work properly with your truck's systems, no factory tuning or extensive modification needed.
Why upgrade from a fixed geometry turbo to a variable geometry unit?
The main advantage of swapping in a VGT is how it transforms the driving experience of a 5.9-liter Cummins. Traditional fixed geometry turbos, like the one on this 5.9 engine, are known well enough for their durability, but they come with a trade-off: turbo lag. That delay in power can be frustrating, especially when towing or accelerating from a stop.
VGTs solve this by adjusting the vanes inside the turbo, effectively mimicking both a small and large turbo at different RPMs. At low speeds, the turbo vanes close down, creating quicker spool-up and better throttle response. At higher speeds, the vanes open up to reduce drive pressure and maintain high-end power.
In simple terms, a VGT makes your truck feel like it's always in that sweet spot. Kits, like BD Diesel Performance's BD Howler VGT kit, take this a step further with integrated exhaust brake functionality – another feature native to the 6.7 that isn't found in the 5.9. By controlling the vanes to create exhaust backpressure, the exhaust brake cuts down on wear to your service brakes and adds more control when hauling heavy loads down steep grades.
What you'll need and what to expect
If you're planning to upgrade, you've got some options. In addition to the multiple Howler kits available from BD Diesel Performance, you can also source your own turbo. The install kit should supply everything else, including oil lines, exhaust manifold, and wiring harness.
Of course, any major modification raises valid concerns about durability and compatibility. The smaller, earlier Cummins is known for its reliability and resistance to common issues like head gasket failure. Of course, the 5.9-liter Cummins has problems of its own, but these specific issues are more common on the 6.7-liter.
It's all thanks to the increased cylinder pressure from its longer stroke. Thankfully, because VGT kits are designed specifically for the 5.9-liter and don't include emissions components like an EGR or a DPF, you'll be able to avoid many of the downsides with the 6.7's emissions.
All in all, if you're looking to breathe new life into the 5.9 engine, adding the horsepower and torque of a 6.7-liter might be the most worthwhile upgrade you can make. With better power, greater towing, and a plug-and-play installation, the 6.7 VGT is totally possible ... and a lot less headache-inducing than you'd think.