The upcoming EPA emissions standards slated for 2027 are set to reshape the landscape of fire apparatus engines. This article discusses what these new guidelines mean for engines, cab and chassis design, and apparatus bodies, drawing on expert insights to help fire service professionals navigate this transition.
Why Are the EPA Standards Changing?
For several decades, engine emissions standards have been steadily tightened to reduce pollutants, particularly nitrogen oxides (NOx). Since 1988, regulations cut NOx emissions by approximately 80%. In 2027, the EPA and California Air Resources Board (CARB) are aligning on a further 80% reduction target within just four years. Such a dramatic drop—from 200 mg to 35 mg of NOx emissions per horsepower-hour—represents a steep technical challenge.
Chris Crowel, Emergency Vehicles Lead at Cummins, explains the magnitude of this change. The first drop in emissions was costly but achievable. Now, pushing that second 80% reduction requires completely new engine designs. Additionally, these standards extend warranty periods for emissions components from five to ten years and impose stricter compliance requirements. Engines must meet emissions across the entire operating range rather than relying on emissions averaging.
One Engine Manufacturer’s Approach
Cummins is responding with a $2 billion investment in research, development, and manufacturing enhancements to deliver a new generation of fire apparatus engines. Existing engines like the B6.7, L9, X12, and X15 will be replaced with all-new platforms, including the AB7.2 (a 7.2-liter displacement engine) and the X10 (a 10-liter engine replacing the L9 and X12).
Several key technological innovations are driving these new engines:
Dual SCR Catalysts in One Module: To meet the low emissions thresholds, the after-treatment system will feature two Selective Catalytic Reduction (SCR) catalysts housed together, sometimes called a “snowman” or “infinity” design, increasing reaction surface area while managing packaging constraints.
Advanced After-Treatment Heaters: New heater elements before the Diesel Particulate Filter (DPF) and SCR catalysts will help engines meet emissions standards earlier after startup, but these require significant electrical power. Therefore, Cummins will add a belt-driven 48-volt alternator dedicated to generating this heat.
Clean-Sheet Engine Design: Leveraging computer-aided design (CAD), engineers have optimized material placement, improving cooling, oil flow, and block stiffness. For example, moving the gear train from the front to the rear reduces potential oil leaks and enhances durability.
Weight Management: Despite adding emissions hardware, the new X15 engine system will be roughly weight-neutral compared with current setups. The X10 engine will be about 300 pounds heavier than the L9 but similar to the current X12, which is itself lighter than most mid-bore engines in the market.
Improved Engine Performance: The X15 will maintain familiar horsepower and torque ratings, including the 605-hp/1,850 ft-lb rating popular in fire service applications. The X10 will cover all previous L9 ratings with a new high-torque family offering up to 1,650 ft-lb, close to the X12’s current capability.
Environmental Improvements: Moving to canister-style oil and fuel filters, replacing steel housing and elements separately, supports environmental sustainability through reduced waste.
Cummins plans to launch the new X15 as early as April 2026, ahead of the 2027 mandate, giving manufacturers time to prepare. However, the last date to build with the current L9 engine frame will be December 31, 2026.
Posted: Aug 8, 2025
Teri Figueroa
The San Diego Union-Tribune
(TNS)
When San Diego’s fire season hits its peak this year, there should be a couple of new tools in the firefighter’s old toolbox. Among them, two new brush rigs, which are trucks designed for fighting wildfires, and a nearly-ready-to-deploy helicopter. The department also boasts a new high-tech mobile command center.
“Wildfires won’t wait, and neither will we,” San Diego Mayor Todd Gloria told reporters at a news conference Thursday morning to highlight local fire prep. “We will be prepared.”
Recent years have seen what is often called “fire season” — a time of high danger for big wildfires — stretch to become year-round. Even so, the region sees more fire activity roughly around September and October, when Santa Ana winds whip hot air through dry and brittle brush.
“These conditions can turn what would normally be a manageable fire into something much greater that threatens homes and communities in minutes,” San Diego Fire-Rescue Chief Robert Logan said at the news conference at the Fire-Rescue Training Facility near San Diego International Airport.
When the two new brush rigs come online this fall, Fire-Rescue will have 13 such specialized wildfire trucks in its fleet. Logan said the new rigs hold 600 gallons of water and “are designed to move quickly and methodically through tough terrain to stop the progress of wildfires.” They run about $750,000 each.
Then there is that new helicopter, a Bell 412 EPX, brought in to replace an already retired 40-year-old chopper in the fleet. The $14 million helicopter is nearly ready to go — it’s getting about $2 million in add-ons — and is expected to be in use by the end of November, according to Battalion Chief Chuck McFarland, who runs Fire-Rescue’s air operations division. McFarland said it features modern avionics, upgraded engines and a larger water tank (it can drop 375 gallons). And like the other two helicopters currently in San Diego’s fleet, it can fly at night.
Gloria and Logan addressed reporters while standing in front of Fire-Rescue’s new $3.2 million mobile command unit, which is essentially a command and communications vehicle sent to large-scale incidents and planned events. Logan called it “a high-tech hub built to support complex incidents, coordinate multi-agency responses and even back up our 911 dispatch system if needed.”
Since putting it into service in April, Fire-Rescue has used the vehicle for the Rock ‘n’ Roll Marathon and Fourth of July operations, and sent it to a wildfire in San Pasqual Valley. It was also brought to the scene of the deadly May 22 plane crash in a Murphy Canyon residential neighborhood, according to Deputy Chief Ted Moran, who oversees Fire-Rescue’s logistics division.
Moran said it provides a central setting for decision-makers on scene; during the plane crash, it gave a place for police and fire leadership to work directly with federal aviation and transportation safety officials. “A lot of different agencies were in the room together, all receiving the same information in real time, allowing us to make collaborative decisions,” Moran said. He said it can also accommodate up to six dispatchers in case a disaster or emergency knocks out the actual dispatch center.
Another slice of fire preparedness, Gloria said, is for San Diego residents to take “simple yet credible steps” — from clearing brush and debris on their property to crafting an emergency plan for their family. It might also help to get digital — downloading the Genasys Protect app, which provides information regarding evacuations, and registering to get emergency messages through Read more
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