Diesel engines are the preferred power source for much of the equipment on a concrete construction jobsite, and with good reason. But the new Tier 4 emissions requirements being imposed on diesel engines are going to add a big premium to the price. “Tier 4 requirements will add expense to all equipment,” says Bobcat marketing manager Greg Rostberg. “But the percentage increase for compact equipment will be much greater than for larger earth-moving machines.” That also applies to equipment with smaller engines.
Older equipment, in some cases, may not be usable—machines with pre-Tier 3 engines, especially. Or, you may be forced to change out the engine for a new one with the Tier 4 (or Tier 4 interim) emission controls. But that’s easier said than done.
“First, new Tier 4 engines are nearly impossible to get,” says Hank de Carbonel, director of the California Concrete Pumpers Alliance. “The true Tier 4s are mostly going to the equipment manufacturers. And, second, replacement engines will have a completely different footprint than the older engines. All of the new pollution control equipment makes them bigger and also makes them run hotter. They won’t just be a drop-in, that’s for sure. So you would have to not only pay for a new engine but also would have to modify the equipment to accommodate the bigger size.”
Switch to gas
Some equipment manufacturers are reacting to the new diesel requirements by abandoning diesel engines altogether. For example, Whiteman, a division of Multiquip, has converted one of its ride-on power trowels to gasoline. In this conversion, most of the initial concerns Whiteman had about noise, heat, and balance of the machine were resolved.
“From a horsepower and torque standpoint,” says Dan Roche at Briggs & Stratton. “Our Big Block Vanguard engines match up to the lower end of Tier 4-affected diesel engines. Those diesels are required to meet tighter emissions goals than in the past and the cost and complexity of compliance is making it difficult for OEMs to stick with diesels. That’s why a growing number of OEMs are considering air-cooled gas engines to maintain selling prices while delivering comparable performance.”
Roche notes that while diesel fuel has some advantages at the jobsite (storage, flexibility), converting to gas raises some concerns that have been overcome with modern gas engines, such as:
- Sound: Diesel engines are typically liquid-cooled, with the water jacket serving to dampen the sound of combustion. But air-cooled gasoline engines with their lower compression ratio and ignition pressures can actually be quieter.
- Torque: Gas engines develop maximum torque at higher RPMs than diesel, but at over 2500 RPM the torque values produced from both engines get much closer.
- Heat: Air-cooled gasoline engines have phase-modulated fan blades and highly-engineered blower housings that work together to manage engine cooling. The only drawback is that air-cooled engines can’t be enclosed.
- Weight: If a heavier engine is desired, diesels, with their cast-iron blocks, have an advantage over aluminum block air-cooled engines. But for equipment that will be lifted into place, lighter weight and lower center of gravity favors air-cooled engines, which can weigh as little as 125 pounds.
- Vibration: Diesel engines typically have all cylinders aligned in the same axis (straight); air-cooled gas engines are typically in a V configuration, which might suggest more vibration. But modern V-twin engines balance the vibration so well they can actually be smoother running.
- Durability: Diesel engines are legendary for long life. While aluminum blocks can see slightly more deformation through heat cycles, their metallurgy and internal components are designed for long life. “The Vanguard engines carry a three-year warranty,” says Roche, “which helps prove the engine manufacturer stands by the product. Warranty length, however, should not be the only consideration. I encourage equipment owners to investigate the engine manufacturer’s number of dealers, speed of parts delivery, warranty flexibility, and reputation for honoring warranty claims.”
The California Air Resources Board (CARB) rules over the emissions regulations in California with an iron fist. Although there are 35 air districts in the state that can set different rules than CARB’s, most follow the state’s lead pretty closely. CARB rules only apply in California, although CARB and the EPA have coordinated the final Tier 4 regulations pretty closely and many other states or air control districts have used CARB as a model.
De Carbonel monitors the CARB rules closely. “There are three categories for engines in California, both diesel and gasoline: trucks & buses, portable equipment, and off-road equipment,” he says. “Portable includes anything that isn’t self-propelled, so generators, trailer pumps, compressors, anything with an engine over 50 brake-horsepower. Off-road equipment includes crawlers, excavators, and so on.” And in California, these rules apply to all equipment—there’s no grandfathering exception, although there can be some averaging among all the engines a contractor owns.
The biggest danger for contractors, de Carbonel explains, is in their contracts for work in California. “When a general contractor signs a contract he is stating that all of his equipment is in compliance and that all equipment used by any of the subcontractors is also in compliance. Even equipment that comes from a rental house—both the rental company and the contractor are liable if anything is not in compliance.”
Contractors must review their fleets, whether in California or elsewhere, since Tier 4 requirements come into effect this year. Bob Weatherton, The Concrete Pump Store, says that there is lots of equipment in California that can no longer be sold because it doesn’t meet the new requirements. All engines have to be registered with CARB and given a certificate of compliance.
What California really wants is for everyone to go to electric or natural gas engines. “But natural gas is difficult to refuel on a jobsite,” de Carbonel says. “You would need a certified pressure vessel and refueling can be very slow.”
“By June 2014 everyone needs to be compliant and registered with CARB or the local air district,” de Carbonel warns. While that is specifically for California, similar rules apply nearly everywhere in the U.S. Perhaps the only good news is that this should be the final rule changes until at least 2020.
Tier 4 and your Heavy Equipment Fleet
The U.S. has come a long way on its 17-year trek to cleaner air and has less than two years to go. The 1996 implementation of EPA’s Tier 1 standards launched a schedule of progressively lower targets that ends with near-zero nitrous oxides (NOx) and particulate matter (PM) emissions for 2015 off-road diesel engines. This category, called nonroad mobile equipment engines, includes excavators and other construction equipment and utility equipment like generators, pumps, and compressors. In other words, most of your equipment.
The final set of emissions targets is split into two parts:
- Tier 4A (Tier 4 Interim, Interim Tier 4, and iT4): Requires 90% less PM and 50% less NOx than 2006 Tier 3 levels; applies to 2013 and 2014 model-year engines.
- Tier 4B (Final Tier 4): Requires 90% less NOx than Tier 3; applies to 2015-and after model years
Manufacturers have developed a host of technologies—direct-flow air cleaners, cooled-exhaust gas recirculation (CEGR), variable geometry turbochargers (VGT), diesel oxidation catalysts (DOC), and diesel particulate filters (DPF)—to meet these goals. But all that innovation has a price. Interim Tier 4 engines are 5% to 15% more fuel-efficient but 10% to 40% more expensive than Tier 3 models; final Tier 4 engines are 10% to 20% more expensive than iT4.
Upgrade, replace, or wait it out?
Federal law allows owners of equipment with Tier 3 engines to use the equipment until the end of its expected service life. Therefore, it’s not necessary to upgrade pre-iT4 engines unless your state requires it (for example, in California). EPA’s Engine Flexibility Program allows equipment manufacturers to transition into producing iT4-compliant products but restricts the number of each “flex engine” backhoe, skid-steer loader, and excavator model they can manufacture annually. Construction owners buying used equipment should be aware that future projects and bids might consider the ages and emission levels of their mixed fleet. So, prospective buyers should consider emissions performance of both new and existing equipment in trade and resale options.
A critical difference between Tier 3 and interim Tier 4 engines is that the latter require ultra-low sulfur diesel (ULSD) fuel and American Petroleum Institute CJ 4-certified, low-ash-content engine oil. Non-ULSD fuel can immediately damage an iT4 engine.
Beyond that, changes vary from one engine category to another. Some iT4 engines that are less than 173 hp don’t have DPFs. Instead, the soot is continuously burned in the after-treatment system. Engines with DPF have additional indicators and a switch in the dashboard to alert operators to the regeneration cycle. To learn if a piece of equipment is equipped with an iT4 engine, look for a ULSD fuel only decal in the fuel filling area. This is mandated on all iT4 machines regardless of power category.
Technicians are challenged to make sure they use the appropriate maintenance procedures, fluids as directed by the engine and equipment manufacturers. Fleet superintendents and managers play a key role in training operators and maintenance crews on iT4 changes. New technologies may require formal classroom and on-the-job training.