The 2010 Cadillac Escalade engine is the 6.2L V8 engine code L94 (except for the Escalade Hybrid which uses the LZ1 6L). It is the most powerful normally aspirated engine available in a Cadillac. What makes this engine special?
The Vortec 6.2L is a fourth-generation descendant of one of the most important and successful engines in automotive history – the original Chevrolet small-block, which debuted in 1955. Key features for 2010:
- Variable valve timing: cam phasing allows a flatter torque curve, higher peak horsepower, and an extremely smooth idle.
- Active fuel management: during light load conditions, the L94 can operate as a V-4 engine in order to save fuel.
- Enhanced Noise, Vibration, and Harshness measures to ensure smooth, Cadillac – quality operation
- The 6.2.L is the most powerful of GM’s Gen IV Vortec V-8s; indeed, it is the most powerful small-block truck engine ever, with the most torque.
- Flexfuel: The L94 can operate on E85 (85% renewable ethanol fuel)
Engine Dyno: 403 hp @ 5700 rpm (301 kW), 417 lb-ft @ 4300 rpm (565 Nm)
Yes, the LS3 engine makes more peak hp (436 hp in the Corvette Grand Sport with optional exhaust vs the 403 hp L94 in the Escalade), but it does not have the low-end torque and flat torque curve that the L94 has.
|2010 Vortec 6.2L V-8 VVT ( L94 )||06/05/2009|
|Type:||6.2L Gen IV V-8 Small Block|
|Displacement:||6162cc (376 ci)|
|Engine Orientation: L=Longitudinal, T=Transverse||L|
|Valve configuration:||Overhead valves|
|Valves per cylinder||2|
|Assembly site:||Romulus, MI|
|Valve lifters:||Hydraulic roller|
|Firing order:||1 – 8 – 7 – 2 – 6 – 5 – 4 – 3|
|Bore x stroke:||103.25 x 92mm|
|Bore Center (mm)||111.76|
|Bore Area: ( cm2 ) ( total engine bore area )||669.82|
|Fuel system:||Sequential fuel injection|
|Premium fuel recommeded and E85 Flex Fuel||All listed models|
|Maximum Engine Speed:||6000 RPM|
|Engine Mass: ( kg / lbs )||TBD|
|Emissions controls:||Catalytic converter|
|Positive crankcase ventilation|
|Applications:||Horsepower: hp ( kw )|
|Cadillac Escalade||403 hp ( 301 kW ) @ 5700 rpm SAE CERTIFIED|
|Cadillac Escalade ESV||403 hp ( 301 kW ) @ 5700 rpm SAE CERTIFIED|
|Cadillac Escalade EXT||403 hp ( 301 kW ) @ 5700 rpm SAE CERTIFIED|
|GMC Yukon Denali||403 hp ( 301 kW ) @ 5700 rpm SAE CERTIFIED|
|GMC Yukon XL Denali||403 hp ( 301 kW ) @ 5700 rpm SAE CERTIFIED|
|Applications:||Torque: lb-ft ( Nm )|
|Cadillac Escalade||417 lb-ft ( 565 Nm ) @ 4300 rpm SAE CERTIFIED|
|Cadillac Escalade ESV||417 lb-ft ( 565 Nm ) @ 4300 rpm SAE CERTIFIED|
|Cadillac Escalade EXT||417 lb-ft ( 565 Nm ) @ 4300 rpm SAE CERTIFIED|
|GMC Yukon Denali||417 lb-ft ( 565 Nm ) @ 4300 rpm SAE CERTIFIED|
|GMC Yukon XL Denali||417 lb-ft ( 565 Nm ) @ 4300 rpm SAE CERTIFIED|
|Cylinder head:||Cast aluminum|
|Exhaust manifold:||Cast nodular iron|
|Main bearing caps:||Powder metal|
|Crankshaft:||Cast nodular iron with undercut and rolled fillets|
|Connecting rods:||Powder metal|
|Additional features:||E85 Flex Fuel|
|Active Fuel Management ( AFM )|
|Electronic throttle control|
|Extended life accessory drive belt|
|Extended life coolant|
|Extended life spark plugs|
|Oil Life Monitor System|
|Variable Valve Timing ( VVT )|
Cadillac Escalade 6-speed Automatic Transmission: The Hydra-Matic 6L80 is a heavy-duty six-speed automatic transmission for rear-drive vehicles, designed with modular flexibility and compatibility with advanced electronic controls. It was introduced for the 2006 Model Year Cadillac STS-V high-performance rear-drive sedan, and the XLR-V and Chevrolet Corvette two-seat sport coupes and convertibles. Since 2007, the Hydra-Matic 6L80 has been the transmission for the Cadillac and GMC full-size SUVs and GMC Sierra Denali Pickup.
All the Details:
2010 Vortec 6.2L V-8 VVT (L94)
VORTEC 6.2L Gen IV V-8 (L94) TRUCK ENGINE
2010 Model Year Summary
New engine RPO content and benefits for 2010 model year:
- New Active Fuel Management
- E85 FlexFuel-capable
- Gen IV Cylinder Block
- Variable Valve Timing
- Returnless Fuel Injection with Stainless Steel Fuel Rail
- Advanced Electronic Throttle Control
- Advanced Engine Control Module
- Extended life accessory drive belt
- Premium fuel recommended
- 58X Ignition System
- Enhanced Noise, Vibration and Harshness Control
- Advanced Ignition Coils
- Iridium Tip Spark Plugs
- Low modulus A/C compressor belt
The new engine RPO code reflects addition of Active Fuel Management (AFM) on 2010 models of GMC Yukon Denali and Yukon XL Denali, as well as Cadillac Escalade, Escalade ESV and Escalade EXT. RPO L94 replaces the previous, non-AFM L9H engine code. It is also E85 FlexFuel-capable.
In all applications, the L94 engine is teamed with GM Powertrain’s Hydra-Matic 6L80 (MYC) six-speed automatic transmission.
The Vortec 6.2L is a fourth-generation descendent of one of the most important and successful engines in automotive history – the original Chevrolet small-block, which debuted in 1955. The Gen IV Vortecs feature technology creators of the first small block could not have imagined, yet they share one fundamental trait with the original: a market-leading balance of performance, sophistication, economy and durability.
The 6.2.L is the most powerful of GM’s Gen IV Vortec V-8s; indeed, it is the most powerful small-block truck engine ever, with the most torque. It delivers new levels of refinement to go with brute strength, and industry exclusive technologies such as cam-in-block variable valve timing.
When vehicle development teams demanded class-leading performance for full-size luxury utility vehicles, GM Powertrain delivered the all-new Vortec 6.2L V-8. The 6.2L applies high-performance features developed for the LS2 and LS7 Corvette engines, with advanced technologies like cam-in-block variable valve timing.
In short, the Vortec 6.2L is the most powerful small-block truck V-8 in history, yet it delivers the smooth, quiet operation, balanced performance and drivability befitting premium brands. It’s also one in the most efficient lines of truck V-8 engines in GM’s history
The latest Vortec V-8 engines were developed to improve fuel economy and reduce emissions. Compared to the typical truck engine a decade ago—much less the original small block in 1955 – the new Vortec V-8s generate 90 percent fewer exhaust and evaporative emissions. And they should last longer than any of their predecessors, with nothing more than routine maintenance (which is limited to oil changes for the first 100,000 miles). The new Vortecs have undergone the toughest, most comprehensive validation in five decades of small-block development, in laboratories and through road-testing in extreme climates. The Vortec 6.2L has been dyno-tested to the equivalent of 150,000 miles.
Gen IV Cylinder Block
The Gen IV cylinder block shares two key design elements with GM’s original small block V-8: a 90-degree cylinder angle with 4.400-inch bore centers. Beyond that, the latest small block applies design, casting and machining technologies that were unfathomable in the 1950s.
The Gen IV block debuted in 2005 as the foundation for the 400-hp LS2 V-8 in the Chevrolet Corvette, and Pontiac GTO, and in 2006 for the Cadillac CTS-v . The Vortec truck block applies all the improvements in the LS2, tailored for the demands of truck application.
Developed with the latest math-based tools and data acquired in GM’s racing programs, the block provides an exceptionally light, rigid foundation for an impressively smooth engine. Its deep-skirt design helps maximize strength and minimize vibration. The bulkheads accommodate six-bolt, cross-bolted main-bearing caps that limit crank flex and stiffen the engine’s structure. A structural oil pan further stiffens the powertrain.
The new-generation small block is cast with oil ports in its V, or valley, to accommodate advanced technologies available in the new Vortec V-8s, and others yet to be introduced. As a result, knock sensors located in the valley on the Gen III V-8 have been moved to the outside of the engine block, while the cam sensor has been moved from the rear of the block to the front cover.
Like the LS2, the Vortec 6.2L engine block features crankcase “windows,” or vents that help improve bay-to-bay breathing. These improve efficiency in high-output applications by reducing pumping losses. It’s also manufactured of aluminum, allowing vehicle engineers more latitude in tailoring weight distribution in the all-new Cadillac Escalade. The Gen IV aluminum block is cast from A356-T6 alloy. With cast-in iron cylinder liners, it weighs roughly 100 lbs. less than a comparable cast-iron engine block.
Variable Valve Timing
The Vortec 6.2L brings GM Powertrain’s industry first cam-in-block variable valve timing (VVT), or cam phasing, to the small block V-8. VVT eliminates the compromise inherent in conventional fixed valve timing and allows a previously unattainable mix of low-rpm torque, even torque delivery over a broad range of engines speeds, and free-breathing high-rev horsepower.
The cam-phasing system in the Vortec 6.2L is similar in concept to that introduced in GM’s 3.9L and 3.5L V6 car engines for 2006. The 6.2L’s dual-equal cam phaser adjusts camshaft timing at the same rate for both intake and exhaust valves. A vane-type phaser is installed on the cam sprocket to turn the camshaft relative to the sprocket, thereby adjusting the timing of valve operation.
The vane phaser is actuated by hydraulic pressure from engine oil, and managed by a solenoid that controls oil pressure on the phaser. The phaser uses a wheel or rotor with four vanes (like a propeller) to turn the camshaft relative to the cam sprocket, which turns at a fixed rate via chain from the crankshaft. The solenoid directs oil to pressure points on either side of the four phaser vanes; the vanes, and camshaft, turn in the direction of the oil flow. The more pressure, the more the phaser and camshaft turn. The Vortec 6.2L’s new E38 engine control module (below) directs the phaser to advance or retard cam timing, depending on driving demands. The dual-equal phaser system has the authority to retard the cam timing by up to 52 crankshaft degrees.
The benefits are considerable. The cam phaser changes valve timing on the fly, maximizing engine performance for given demands and conditions. At idle, for example, the cam is at the full advanced position, allowing exceptionally smooth idling. Under other operating demands, the phaser adjusts to deliver optimal valve timing for performance, drivability and fuel economy. At high rpm it might retard timing to maximize airflow through the engine and increase horsepower. At low rpm it can advance timing to increase torque. Under a light load (say, casual everyday driving), it can retard timing at all engine speeds to improve fuel economy. Without cam phasing, a cam design must be biased toward one strength or another—high-end horsepower or low-end torque, for example—or profiled at some compromise level that maximizes neither.
Variable valve timing allows linear delivery of torque, with near-peak levels over a broad rpm range, and high specific output (horsepower per liter of displacement) without sacrificing overall engine response, or drivability. It also provides another effective tool for controlling exhaust emissions. Because it manages valve overlap at optimum levels, it eliminates the need for an Exhaust Gas Recirculation (EGR) system.
Active Fuel Management
The L94 engine features GM’s Active Fuel Management technology. AFM temporarily de-activates four of the 6.2L engine’s cylinders under light to moderate load conditions to help enhance fuel economy by approximately 6 percent under the federal government’s required testing procedure and potentially more in certain real-world driving conditions.
Active Fuel Management stems from a simple premise: most V-8 engines offer more power than owners demand in all conditions. With AFM, drivers save fuel by using only half of the 6.2L’s cylinders during some driving conditions and reactivates them on demand when necessary.
Managed by the sophisticated E38 engine control module (ECM), AFM automatically shuts down every second cylinder, according to firing order, during light-load operation. In engineering terms, this allows the working cylinders to achieve better thermal, volumetric and mechanical efficiency by reducing heat loss, combustion loss and friction, and lowering cyclical combustion variation from cylinder to cylinder. As a result, AFM delivers better fuel economy and lower operating costs. Perhaps the most sensible aspect about AFM is that it harnesses the engine’s existing capabilities, starting with the potential designed into the E38 ECM. The only mechanical components required are special valve lifters for cylinders that are deactivated, and their control system. The incremental cost for the customer is nominal per engine. Active Fuel Management relies on three primary components: De-ac (for deactivation) or collapsible valve lifters, a Lifter Oil Manifold Assembly (LOMA), and the ECM.
One of the most sophisticated engine controllers in the industry, the E38 ECM measures load conditions based on inputs from vehicle sensors and interprets that information to mange more than 100 engine operations, from fuel injection to spark control to electronic throttle control. AFM adds an algorithm to the engine control software to manage cylinder deactivation and reactivation. When loads are light, the E38 automatically closes both intake and exhaust valves for half of the cylinders and cuts fuel delivery to those four. The valves re-open to activate all cylinders when the driver demands brisk acceleration or full torque to move a load. The engine’s electronic throttle control (ETC) is used to balance torque following cylinder deactivation or reactivation. The transition takes less than 20 milliseconds.
Valve lifters are operated by the engine’s camshaft, and lift a pushrod that operates the valves in the cylinder head. In the Gen IV 6.0L (L76), the De-Ac lifters are installed in cylinders 1, 4, 6 and 7, while the remaining cylinders use conventional lifters. The hydraulically operated De-Ac lifters have a spring-loaded locking pin actuated by oil pressure. For deactivation, hydraulic pressure dislodges the locking pin, collapsing the top portion of the lifter into the bottom and removing contact with the pushrod. The bottom of each De-Ac lifter rides up and down on the cam lobe but the top does not move the push rod. The valves do not operate and combustion in that cylinder stops. During reactivation, the oil pressure is removed, and the lifter locks at full length. The pushrods, and therefore the valves, operate normally.
The final AFM component is the LOMA. This cast-aluminum assembly is installed in the valley of the 6.2L (L94) in place of a conventional engine block cover. The LOMA holds four solenoids, control wiring and cast-in oil passages. The solenoids are managed by the ECM, and each one controls oil flow to a De-Ac Lifter, activating and de-activating the valves at one cylinder as required for Active Fuel Management.
The fuel injectors in the 6.2L (L94) are identical for all cylinders; those feeding the de-activated cylinders are simply shut down electrically by the ECM during de-activation. When the cylinders are deactivated, the engine effectively operates as a V-4. AFM operation is load based, as measured by the ECM using dozens of inputs, overlain with the driver’s demand for power as measured by throttle application. AFM’s response time varies with oil temperature, but in all cases is measured in milliseconds. Operation is always transparent to the driver. The engine returns to V-8 mode the instant the controller determines that acceleration or load requires additional power.
The benefits are substantial. Active Fuel Management does not affect exhaust emissions, and it will reduce overall emissions significantly, including greenhouse gases such as carbon-dioxide, to the extent that less fuel is used. Further, the savings reflected in EPA numbers may not account for AFM’s full impact. Owners who primarily travel long distances at steady speeds will see substantially greater fuel-economy improvements. Because of the mass differences the GMC Yukon and Cadillac Escalde models have compared to trucks and cars, the calibrations for switching to V-4 are specific and tailored to optimize efficiency.
High-Flow Cylinder Heads
The Vortec 6.2L is equipped with high-flow cylinder heads based on those developed for the high-performance LS2 and LS6 car V-8s. These heads have offset rockers, like those in the LS7. They also have larger valves than other Vortec V-8 heads, and increase airflow in and out of the engine for higher horsepower. The cylinder heads feature special valve seat inserts to accommodate the engine’s use of for E85 fuel. A special high-lift cam, with 12.7-mm maximum lift, was further refined to take full advantage of the improved flow characteristics and optimize idle quality. In conjunction with unique pistons, the high-flow heads give the Vortec 6.2L a 10.5:1 compression ratio. They are the single biggest contributor to the 6.2Ls increased horsepower, compared to other Vortec V-8s.
In 2009, a new low modulus A/C compressor belt was employed. It eliminated the need for a separate belt tensioner, further simplifying the design and reducing mass.
Returnless Fuel Injection with Stainless Steel Fuel Rail
The Vortec 6.2L is equipped with a “returnless’’ fuel injection system, also known as a demand system. The E85-compatible injectors also incorporate USCAR-standard electrical connectors. This standard was developed to promote common, reliable connections across the auto industry and streamline regulatory oversight. The connectors are more compact than previous connectors, and designed for improved sealing.
Returnless fuel injection enables greater performance with decreased evaporative emissions. Earlier Vortec V-8 engines used a return line between the engine and the fuel tank to manage fuel pressure by bleeding off excess fuel at the fuel rail and returning the excess to the tank. The returnless system eliminates the return lines and moves the fuel pressure regulator from the fuel rail on the engine to the fuel tank. Because it delivers only the amount of fuel needed by the injectors, and returns no fuel to the gas tank, the returnless system essentially eliminates heat transfer from the engine to tank. This reduces the amount of vapor generated in the tank and captured by the vehicle’s Onboard Refueling Vapor Recovery (ORVR) system.
With the returnless system, the 6.2L uses a fuel rail manufactured of stainless steel. The stainless steel rail allows installation of baffles that manage fuel pulses in the returnless system and reduce noise.
Advanced Electronic Throttle Control
GM has led the industry in applying electronic throttle control (ETC). With ETC, there is no mechanical link between the accelerator pedal and the throttle body. A sensor at the pedal measures pedal angle and sends a signal to the engine control module (ECM), which in turn directs an electric motor to open the throttle at the appropriate rate and angle. ETC delivers a number of benefits to the customer. Besides throttle pedal angle, the ECM measures other data, including the transmission’s shift patterns and traction at the drive wheels, in determining how far to open the throttle. ETC delivers outstanding throttle response and greater reliability than a mechanical connection, which typically uses a cable that requires adjustment—and sometimes breaks. Cruise control electronics are integrated into the system, further improving reliability and simplifying engine assembly.
The Vortec 6.2L takes ETC to the next level by taking advantage of capability built into its advanced E38 ECM (below) and further streamlining the system. Its up-integrated ETC system eliminates a Throttle Actuator Control (TAC) module. The TAC takes commands from the ECM and then operates the electric motor that opens and closes the throttle. The E38 manages the throttle directly, without a TAC. Eliminating the TAC reduces cost and improves reliability. The direct link between the ECM and the throttle motor improves throttle response time (albeit in millisecond increments that are not apparent to the driver) and improves system security by removing a device (the TAC) that must be monitored for malfunction
E38 Engine Control Module
An advanced controller manages the multitude of operations that occur within the Vortec 6.2L every split second. The E38 is the mid-line controller in GM’s family of engine control modules (ECM), which will direct nearly all the engines in GM’s lineup. In combination with advanced sensor technology, the E38 includes the ability to control and synchronize advanced technologies such as cam-in-block variable valve timing. It features 32-bit processing, compared to the conventional 16-bit processing in previous Vortec engines. The E38 operates at 59 MHz, with 32 megabytes of flash memory, 128 kilobytes of RAM and a high-speed CAN bus, and it synchronizes more than 100 functions, from spark timing to cruise control operation to traction control calculations. The E38 works roughly 50 times faster than the first computers used on internal combustion engines in the late 1970s, which managed five or six functions.
The family strategy behind GM’s new ECMs allows engineers to apply standard manufacturing and service procedures to all powertrains, and quickly upgrade certain engine technologies while leaving others alone. It creates both assembly and procurement efficiencies, as well as volume sourcing. In short, it creates a solid, flexible, efficient engine-control foundation, allowing engineers to focus on innovations and get them to market more quickly. The family of controllers means the ECM and corresponding connectors can be packaged and mounted identically in virtually every GM vehicle. GM creates all the software for the three ECMs, which share a common language and hardware interface that’s tailored to each vehicle.
The E38 also applies a new, rate-based monitoring protocol sometimes known as run-at-rate diagnostics. Rate-based diagnostics improve the robustness of the Onboard Diagnostics System (OBD II) and ensure optimal performance of emissions control systems. The new software increases the frequency at which the ECM checks various Vortec 6.2L systems, and particularly emissions-control systems such as the catalytic converter and oxygen sensors. Rate-based diagnostics more reliably monitor real-word operation of these systems, and allow regulatory agencies to more easily measure and certify emissions compliance.
Enhanced Noise, Vibration and Harshness Control
Like other Gen IV Vortec V-8s, the 6.2L was developed for quieter operation, with virtually every system or component reviewed in an effort to reduce noise, vibration and harshness. Quiet features built into the engine are complemented by an improved engine cradle and mounting system. These help reduce vibrations transmitted through the chassis and into the passenger compartment. The net effect is smooth, quiet operation befitting the premium Cadillac and GMC Denali brands.
The enhancements include floating-pin pistons that reduce noise and increase durability. These pistons have wrist pins that “float” inside lead-free rod bushings and the piston pin bores. Compared to a conventional fixed pin assembly, in which the connecting rod is fixed to the piston’s wrist pin and the pin rotates in the pin bore, the floating pins reduce stress on the pin. It allows tighter pin-to-pin bore tolerances and reduces noise generated as the piston moves through the cylinder. To further reduce wear, the pistons are coated with a polymer material that limits bore scuffing, or abrasion of the cylinder wall over time from the piston’s up-down motion. The polymer coating also dampens noise generated by the piston’s movement. The result for the customer is less engine wear, improved durability and quieter operation.
The Vortec 6.2L features a heavy-duty timing chain developed expressly for quiet operation. The chain, which connects the cam and crankshaft, is validated for 200,000 miles of operation and fitted with a leaf-spring dampener. Even the most durable chains stretch with time. In many engines they must be adjusted or replaced at scheduled intervals. The 6.2L’s chain dampener maintains optimal chain tension for the life of the engine and eliminates any flapping motion that might develop as the chain stretches with mileage. It ensures that the timing chain operates as smoothly and quietly as new, even as the engine accumulates high mileage.
Exhaust manifolds were developed to improve durability and sealing and reduce operational noise. Cast nodular iron was the material of choice for its basic durability and excellent heat management properties. The manifolds feature saw cuts along their cylinder head mounting flange. Originally developed for the big-block Vortec 8.1L, these cuts split the flange into three separate sections, allowing each section to move under extreme hot-cold temperature fluctuations without interacting with, or creating stress on, another section. The cuts virtually eliminate friction on –and movement of—the exhaust manifold gaskets. This helps ensure proper sealing for the life of the engine and reduces the chance of gasket failure.
The exhaust manifolds are fitted with new triple-layer heat shields fabricated from stainless steel and insulating material. The shields limit heat transfer from the engine to the engine bay, allowing the Vortec 6.2L to reach optimal operating temperature more quickly, yet reducing heat in the engine compartment once that temperature is achieved. They also dampen the sound of exhaust gas rushing through the manifolds and further reduce the amount of engine operational noise that finds its way into the vehicle interior.
58X Ignition System
The Vortec 6.2L has an advanced 58X crankshaft position encoder to ensure that ignition timing is accurate throughout its operating range. The new 58X crankshaft ring and sensor provide more immediate, accurate information on the crankshaft’s position during rotation. This allows the E38 ECM to adjust ignition timing with greater precision, which optimizes performance and economy. Engine starting is also more consistent in all operating conditions.
In conjunction with 58X crankshaft timing, the Vortec 6.2L applies the latest digital cam-timing technology. The cam sensor is now located in the front engine cover, and it reads a 4X sensor target on the cam sprocket. The target ring has four equally spaced segments that communicate the camshaft’s position more quickly and accurately than previous systems with a single segment. It provides precise control required for variable valve timing.
The dual 58X/4X measurement ensures extremely accurate timing for the life of the engine. Moreover, it provides an effective back-up system in the event one sensor fails.
Advanced Ignition Coils
The Vortec 6.2L’s individual coil-near-plug ignition features advanced coils developed for the LS2 and LS7 Corvette V-8s. The new coils are smaller and lighter than those used on previous Vortec V-8s, and while they are still mounted on the rocker covers, they attach with a new mounting bracket that simplifies engine assembly. An individual coil for each spark plug delivers maximum voltage and consistent spark density, with no variation between cylinders.
Iridium Tip Spark Plugs
The Vortec 6.2L’s spark plugs have an iridium electrode tip and an iridium core in the conductor. The iridium plug has a recommended life of 100,000 miles, but it offers a number of advantages over the platinum-tip plugs previously used in Vortec V-8 engines.
The iridium spark plug has higher internal resistance, maintaining optimal spark density over its useful life. Its “self-cleaning” properties are improved, decreasing potential for plug fouling and further reducing the likelihood of maintenance over the 100,000-mile plug life. The electrode design improves combustion efficiency for maximum fuel economy and minimum emissions. Finally, iridium is more plentiful than platinum, reducing the plug’s material cost and preserving scarce noble metals.