The diesel truck gossip mill is perpetually active. Whether it’s rumors about a newcomer manufacturer entering the market or exaggerated tales of emissions modifications becoming legal, enthusiasts love to chat. One of the most recurrent rumors I’ve encountered suggests that we’re on the brink of seeing a bigger Cummins, Duramax, or Power Stroke engine in the upcoming versions of Ram, GM, and Ford pickups. To assess the validity of these assertions, I consulted the engineers behind these powertrains: Does that even make sense?
Some people are convinced that increased displacement is the solution to boosting power while controlling tailpipe emissions. The premise is that larger engines working under lower stress can generate more output without depending on diesel particulate filters to capture excessive soot or diesel exhaust fluid to minimize nitrogen oxide. Interestingly, there’s some truth to this notion, but it’s definitely not a universal fix.
The Big Three automakers in Detroit haven’t modified the size of their diesel engines in quite some time. Ford has utilized 6.7 liters of displacement since the 2011 model year; Ram transitioned from 5.9 liters to 6.7 liters in 2007.5; and GM has maintained a steady 6.6 liters since the Duramax’s debut in 2001. Nevertheless, they’ve dramatically stepped up their power outputs. The initial 6.7-liter Power Stroke from Ford Super Duty produced 400 horsepower and 800 lb-ft of torque, while the current high-output version generates 500 hp and 1,200 lb-ft of torque. That’s impressive!
What’s even more noteworthy is that all three makers have dramatically ramped up power while adhering to stricter emissions regulations. Love it or loathe it, this feat is achievable due to higher-performing systems employing selective catalyst reduction. That would be the DEF if you weren’t paying attention.
GM’s Duramax Assistant Chief Engineer Rob Moran elucidated:
“If you compare our emissions levels now to a decade ago, it’s clear that we’re not only generating more power, but we’re also certified at lower emissions levels. The only way to achieve this is through a highly efficient aftertreatment system. In the early days, without a diesel particulate filter on the engine or SCR, what exited the engine was what came out of the tailpipe.”
I inquired with Moran about the potential advantages of larger engine displacement, and he appeared rather unenthusiastic. “There will always be compromises,” he remarked. “Whenever you have lower emissions from the engine, the aftertreatment has less work to do. However, to be truthful, today’s aftertreatment systems are exceedingly efficient.” According to Moran, they can capture around 90% to 95% of NOx emissions.
An essential factor in ensuring emissions systems function optimally is temperature. For maximum performance, these systems must operate within a “sweet spot” that enables optimal NOx conversion without damaging any components. In this context, larger displacement engines may actually be less advantageous for emissions, as Ford Research and Advanced Engineering Specialist Daniel Styles pointed out.
“Increased displacement can actually operate somewhat cooler, which can complicate meeting emissions,” Styles stated.
Ford has made significant strides in this area by relocating the SCR system closer to the engine for enhanced heat. Increasing displacement could be counterproductive regarding this issue. Styles further noted that a larger engine’s adverse effect on operating temperature could be intensified by driver behavior.
“We picture the Super Duty 6.7-liter pickup truck pulling a 40,000-pound trailer up Eisenhower Pass [in Colorado], yet many people use them for grocery runs as well,” Styles explained. “Some of the regulatory cycles focus more on typical urban driving.”
Styles went on, “Diesels prefer to be worked hard, right? Luckily, most individuals who buy a diesel do so for that reason. They’re towing or hauling heavy loads. Many are utilized in businesses for commercial tasks, but yes, the best thing for a diesel is to hit the freeway and really push it.”
However, even if you operated a larger diesel at full throttle 90% of the time, you would still face the tough challenge of cooling it. This was a central point addressed by Kerk McKeon, Cummins lead engineer for the Ram pickup platform, during our discussion. In a way, that represents the primary hurdle to introducing larger engines to this truck category.
“People frequently query why the front end of a Ram heavy-duty needs to be so large. It’s all about the thermal aspect,” McKeon explained. “There’s only so much radiator space available. If you attach a 36,000-pound trailer to a truck in 100-degree heat, drive it up a hill with the air conditioning fully on, there’s a limit to how much liquid you can fit in that vehicle.”
McKeon refers to the SAE J2807 certification, which is how manufacturers evaluate their vehicles’ maximum towing capacity. To assert that a truck can tow a specific weight, they must demonstrate it by pulling up Nevada’s Davis Dam grade in scorching temperatures with the air conditioning at full blast, all without going below 40 miles per hour (or 35 mph for dually pickups). McKeon recalls working as a cooling engineer on the 6.7-liter Cummins when it first launched, and he noted that the challenge was “creating a sufficiently large radiator and a suitably large charge air cooler.”
Typically, automotive PR representatives and engineers become uneasy when inquiries about future products arise. Alternatively, they might immediately dismiss them. My discussion with McKeon and others at Ram was intriguing because they directly addressed the speculation regarding Cummins’ 7.2-liter engine being intended for pickups.
“It simply will not fit unless we redesign for a Class 8 front end,” Ram spokesperson Nick Cappa remarked.
On the topic of boosting power, McKeon elaborated, “If you can meet the rating with the same displacement, there are numerous advantages to that. From the perspective of product size, product weight, and honestly questioning, ‘Do you really need to design a brand new engine?’ versus upgrading the existing engine. So, maintaining it within today’s spatial constraints offers many benefits.”
McKeon asserted that significant demands would need to arise for a larger engine to be justified:
“At some point, one might say, ‘Alright, you want 8,000 horsepower, and the only way to achieve that is to melt the exhaust manifold and turbo off the side of the engine. Or, you increase displacement.’ And eventually, you would have to consider increasing displacement.”
“You’ll eventually reach a physical limitation, but it’s only once you approach that point that you’d say, ‘Alright. Now, we have to opt for higher displacement.’ It’s not an aspiration you actively seek,” McKeon added.
Having conversed with authorities from the three principal diesel pickup engine makers, I doubt we’ll witness larger powertrains in the near future—if ever. The expenses and intricacies of upsizing appear to outweigh the advantages, especially as emissions systems operate at increasingly improved levels. And as each expert I consulted articulated, displacement isn’t nearly as much of a restricting factor in diesel engine performance as it is in gasoline engines.
So, the next time you come across some chatter about an 8.3-liter Duramax, an 8.0-liter Power Stroke, or a 7.2-liter Cummins destined for tomorrow’s dually, take a moment and ponder: “Could that be plausible?” Everything here suggests, “Probably not.”
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**The Evolution of Diesel Truck Engines: Professional Insights on Potential Size Growth**
As the transportation sector progresses, diesel truck engines are central to discussions about efficiency, emissions, and performance. With technological advancements and evolving regulations, experts are investigating the feasibility of increasing diesel engine sizes and what implications this could have for the future of trucking.
**Current Developments in Diesel Engine Engineering**
Diesel engines have historically been preferred in the trucking field due to their resilience and fuel efficiency. However, the drive for greener technologies and stringent emissions standards has prompted manufacturers to innovate. Present-day trends concentrate on reducing engine sizes while sustaining power output through turbocharging and complex fuel injection systems. This has led to inquiries about the practicality and implications of expanding engine sizes in the future.
**Possible Advantages of Larger Diesel Engines**
1. **Boosted Power and Torque**: Larger diesel engines can deliver increased horsepower and torque, which is vital for heavy-duty tasks. This can improve performance when transporting heavier loads and overcoming difficult landscapes.
2. **Greater Durability**: Bigger engines frequently feature larger components that endure higher stress levels. This could lead to improved engine longevity and decreased maintenance expenses over time.
3. **Better Fuel Efficiency**: Although it might appear counterintuitive, larger engines can operate more effectively under certain conditions. By tailoring engine size to meet load demands, manufacturers can realize enhanced fuel economy.
4. **Adaptation for Alternative Fuels**: As the industry investigates alternative fuels, larger diesel engines may be more adaptable. They can be engineered to accept biofuels or synthetic fuels, aligning with sustainability objectives.
**Obstacles to Increasing Engine Size**
1. **Regulatory Adherence**: Stricter emissions guidelines represent a substantial challenge. Larger engines may generate more emissions, necessitating advanced after-treatment solutions to fulfill compliance standards.
2. **Weight Implications**: Enlarging engine size generally leads to increased weight, which can influence the overall payload capacity of trucks. Manufacturers must find a balance between engine size and efficient load management.
3. **Market Demand**: The shift towards electric and hybrid vehicles is altering market conditions. Manufacturers need to assess whether there is adequate demand for larger diesel engines in a landscape increasingly focused on sustainability.
4. **Technological Integration**: With ongoing technological progress, melding larger engines with existing systems can be challenging. Manufacturers must invest in research and development to ensure compatibility with modern trucking technologies.
**Expert Forecasts for Upcoming Trends**
Industry specialists foresee that, although there may be a niche market for larger diesel engines, the overarching trend will favor efficiency and sustainability. Innovations such as hybrid systems and improved aerodynamics will likely take precedence over size expansions. Nevertheless, for specific uses, such as construction and heavy hauling, larger engines may continue to hold significant importance.
**Final Thoughts**
The future of diesel truck engines is set for significant changes as the industry addresses the challenges of emissions regulations, market demands, and technological advancements. While there is a possibility for larger engines, the focus will likely stay on enhancing engine performance and efficiency. As manufacturers evolve with these changes, the equilibrium between power, sustainability, and compliance will shape the next wave of diesel engines in the trucking sector.