Does the 6.7L Cummins continue the legacy of the tried and true 5.9L Cummins? The 5.9L gained a near cult following during its reign, from the good ole 12 valve to the common rail ISB. How does the 6.7L Cummins, which replaced the 5.9L in 2007, stack up against old faithful?

Performance

The last 5.9L was offered with 325 hp and 610 lb-ft of torque. In its first year, the 6.7L Cummins produced 350 hp and 650 lb-ft. The latest 6.7L offers 350 hp and a frame twisting 800 lb-ft. Both engines produce power over roughly the same rpm intervals – brutally strong on the low end, a strong mid-range, and dropping off in upper rpm range. In terms of stock performance, the 6.7L gets the nod.

Reliability

The 5.9L had very few reliability concerns, whether it was a mechanically injected or a common rail model. The 6.7L has had a few problems that stem from the emissions system. Reliability has been compared to that of the early 6.0L Power Strokes. Clogged DPFs, failing EGR valves, blown turbos, and malfunctioning CCV systems are amongst the troubles that some owners experience. There has also been an outcry of mysterious “low performance” or “no power” conditions that Ram mechanics can’t explain. Furthermore, Cummins has yet to address many of, what owners consider, issues with the engine. The 5.9L wins hand down in the reliability contest.

Fuel Economy

Under the right driving conditions, the 5.9L Cummins is a 20+ mpg motor on the highway. Unfortunately, the 6.7L is equipped with that pesky diesel particulate filter. The DPF and accompanying active regeneration are fuel economy killers, and if you’re getting 15-17 mpg in a 6.7L Cummins you should be very pleased. When the engine goes into active regeneration to clean the DPF, additional fuel is consumed that is not used for actually moving your truck. This wasted fuel leads to poor fuel economy, especially when your loaded down. For fuel economy, its all about the 5.9L.

Aftermarket Support/Product Availability

The 5.9L Cummins remains more popular in terms of aftermarket performance and accessories. While the 6.7L is also very capable, the emissions equipment create an expensive hurdle for those looking to modify their turbo diesel for additional power. If you’re planning a performance build, the 5.9L will suit your needs better. It’s truly the “Chevy 350″ of the diesel marketplace with extensive support and product availability for any build, mild to wild.

Even a diehard diesel man can appreciate Ford’s 3.5L EcoBoost V-6, offered in the Ford F-150 among other applications. Direct injection technology allows the 10.0:1 compression, twin turbocharged thoroughbred to run on pump gas while generating a maximum 365 hp and 420 lb-ft of torque; 40 lb-ft more than the standard 5.0L V-8. While the concept of owning a V-6 doesn’t have much sex appeal to a truck guy, the performance of the engine is remarkable. And the EcoBoost is making a huge splash in the market – it’s quite popular, maybe even too popular?

If you’ve been following the industry, you know that 1/2 ton diesels by each of the Big 3 were under development, and in some cases under testing, when they were all scrapped due to economic woes. Since Ford’s financial position was the best of the worst, prospective buyers were hopeful that Ford would follow through with their plans to outfit the Ford F-150 with a 4.4L V-8 diesel. Unfortunately, Ford shifted directions and launched the EcoBoost, and have been devoting a significant amount of their resources to marketing the V-6 to F-150 buyers.

Did the EcoBoost kill the possibility of a diesel F-150? It seems safe to assume that, for the short term at least, Ford is gearing their focus on efficient gasoline engines. While there’s no shortage of innovation within the walls of the EcoBoost V-6, it’s disappointing that Ford didn’t break the ice and take advantage of the unique opportunity to dominate the 1/2 ton DIESEL market.

So is a diesel F-150 dead? Of course not, it’s just on the back burner. We’ve got to come to the realization that diesel is less popular outside of the heavy duty crowd. Consumers want fuel economy – how the MPGs are delivered is less important. And then there’s those pesky, increasingly stringent emissions regulations that have made the cost of diesels skyrocket. The moral of this story is that Ford made a smart move, as disappointed as we all may be. The EcoBoost powered F-150s are selling like hotcakes, getting great 3rd party reviews, the 2012 F-150 was Motor Trend’s truck of the Year. Not to mention, the EcoBoost can be used in a variety of platforms, not just trucks.

So for those of us that had our fingers crossed for the diesel F-150…what did we want, and what did we get instead?

1. Increased performance – we got 365 hp and 420 lb-ft of torque compared with the 325 hp and 515 lb-ft expected from the 4.4L Lion V-8.
2. Torque Output at low RPM – The V-6 EcoBoost makes peak torque at 2,500 rpm. The 4.4L V-8 was estimated to make peak torque at 1,900 rpm.
3. Longevity – In testing, Ford has pushed the EcoBoost as hard as they have pushed their Power Stroke (relatively speaking), and the engine didn’t skip a beat; though we all expect that a diesel would outlast the gasser 2 fold.
4. Fuel economy – The EcoBoost is rated to achieve an estimated 16 city/22 hwy unloaded. We’d hope to see 25 mpg out of the 4.4L V-8, as well as improved fuel economy while loaded.
5. Tow capacity – It’s unlikely that a diesel powered F-150 would be given a higher tow capacity than the gasoline powered versions since the platforms are identical. The EcoBoost is rated to handle the F-150 maximum towing/hauling capacity.

Ford. The EcoBoost is truly impressive, but we still want the diesel engine option in the F-150.