The 2020 Chevrolet Silverado 2500HD and 3500HD represent a significant leap forward in heavy-duty truck engineering, combining raw power with advanced technology. Whether you’re hauling equipment to a job site or towing a fifth-wheel camper across the country, these trucks deliver exceptional capability. Understanding the available performance upgrades can help you maximize your investment and tailor your truck to your specific needs.
Understanding the 2020 Chevy 6.6L Gas Engine
The GM L8T engine is a 6.6-liter V8 gasoline powerplant with an overhead valve layout that debuted in the 2020 Chevrolet Silverado HD and GMC Sierra HD. This engine replaced the previous 6.0L V8 and brought substantial improvements to the heavy-duty truck segment.
Engine Specifications and Performance
The L8T produces 401 horsepower and 464 pound-feet of torque in the 2020 Silverado HD and Sierra HD, with strong performance at low rpm where it’s needed when pulling away with a loaded cargo box or trailer. The engine features aluminum heads and direct injection, delivering more precise fuel control resulting in a higher compression ratio of 10.8:1.
At 401 horsepower and 464 lb-ft of torque, the 6.6L offers significantly greater performance than the 360 horsepower, 380 lb-ft 6.0L V-8. The new L8T engine delivers 41 horsepower and 84 pound-feet of torque more than the L96, which translates to gains of 11.4 percent and 22.1 percent, respectively.
Towing and Hauling Capabilities
With the 6.6L gas engine, the Silverado 2500 has a towing capacity of 14,400 pounds with the Double Cab Long Box 2WD configuration. The 6.6 gas engine shines in towing, with a top capacity of 22,500 pounds when set up right. The engine runs on regular 87 octane unleaded gasoline despite its relatively high compression ratio, making it economical to operate.
Gas vs. Diesel: Making the Right Choice
The 2020 Silverado HD offers both the 6.6L L8T gas engine and the 6.6L Duramax L5P diesel engine. Understanding the differences helps you choose the right powerplant for your needs.
Power and Torque Comparison
The gas V8 engine puts out 401 horsepower at 5,200 RPM, but the diesel puts out 445 horsepower at a lower 2,800 RPM, and the 6.6L Duramax diesel engine produces 910 lb-ft of torque, nearly twice as much as the gas engine’s 464 lb-ft.
Cost and Maintenance Considerations
Over a 12 year span the gasser will cost you less in maintenance, and once the diesel emissions junk is out of warranty, it gets spendy. The Duramax starts at $58,110, which is $10,615 more than the base model 2500HD WT with the gas engine.
While the diesel is more fuel efficient and hauls a lot more with a lower RPM, broader torque band, the gas V8 is certainly more cost-effective in terms of maintenance. For drivers who don’t regularly tow heavy loads or travel long distances while towing, the gas engine provides excellent value.
Top Performance Upgrades for the 6.6L Gas Engine
While the L8T delivers impressive stock performance, several aftermarket upgrades can enhance horsepower, torque, fuel efficiency, and overall reliability. Here are the most effective modifications for the 2020 Chevy 6.6 gas engine.
1. Performance Tuners and Programmers
Tuners represent one of the most cost-effective performance upgrades available for the L8T engine. Once unlocked, you gain access to preloaded, emissions-friendly calibrations tailored for daily driving, towing, fuel economy, and performance—giving you noticeable horsepower and torque improvements where you need them most.
The provided preloaded/preset tunes have shown gains of 28 RWHP and 50 RWTQ over stock, on good 93 octane gas. Popular options include the Edge Evolution CTS3, which offers advanced transmission tuning support and customizable gauge layouts.
Performance tuners can improve throttle response, optimize shift points, and unlock hidden power in your engine. Many modern tuners also provide diagnostic capabilities, allowing you to read and clear trouble codes. When selecting a tuner, look for emissions-compliant options that won’t void your warranty or cause legal issues.
2. Cold Air Intake Systems
Upgrading to a high-quality cold air intake system improves airflow to the engine, resulting in better performance and potentially improved fuel economy. Cold air intakes are engineered to minimize air restriction and flow better than stock, with fully enclosed airboxes that protect the filter from dirt and keep out engine heat.
Intakes feature two air inlet points—a large opening at the fender and a large scoop opening at the bottom. Premium brands like S&B Filters offer snap-in lid designs that require no screws, making installation and filter inspection quick and easy.
Quality cold air intakes use silicone components that handle temperatures up to 400°F without cracking or deteriorating. Many systems include washable filters that eliminate the need for frequent replacements, reducing long-term maintenance costs.
3. Performance Exhaust Systems
While the L8T doesn’t support full turbo-back exhaust systems due to emissions regulations, cat-back and axle-back exhaust upgrades still provide benefits. These systems reduce backpressure, improve exhaust flow, and enhance the truck’s sound.
Performance exhaust systems typically feature larger-diameter piping, high-flow mufflers, and mandrel-bent tubing that maintains consistent diameter throughout bends. This design minimizes turbulence and allows exhaust gases to exit more efficiently.
When combined with other modifications like cold air intakes and tuners, exhaust upgrades contribute to noticeable performance gains. They also give your truck a more aggressive exhaust note without being excessively loud.
4. Supercharger Kits
For enthusiasts seeking dramatic power increases, supercharger kits represent the ultimate upgrade. Complete supercharging systems for Chevy and GMC 2500/3500 HD with 6.6L gas engines can increase horsepower from 401 stock to 600+, producing 50%+ more HP with boost.
ProCharger offers several intercooled systems with different boost levels and configurations. These kits include all necessary components for installation, including intercoolers, drive belts, and mounting hardware. While superchargers require significant investment and professional installation, they deliver unmatched performance gains.
Upgraded blocks and internals can handle 2,000 horsepower, so you can pretty much build this engine to make whatever you want, provided you have the funds. The L8T’s forged steel crankshaft and strong connecting rods provide a solid foundation for forced induction.
5. Upgraded Fuel Systems
Aftermarket fuel tanks offer practical benefits beyond performance. While they don’t add horsepower, larger fuel tanks extend your driving range and allow you to be selective about fuel quality.
Most 2500HD and 3500HD trucks come with 36-gallon fuel tanks. Upgrading to a 56-gallon aftermarket tank extends your range by 200-300 miles—particularly valuable when towing or traveling through areas with limited fuel stations. These tanks are designed to fit in the same space as OEM tanks and can be recalibrated by GM dealerships to work with your truck’s fuel gauge.
Advanced Towing Technology
The 2020 Silverado HD includes innovative towing features that make hauling heavy loads safer and easier.
Camera Systems
The cameras offer up to 15 different views, including a helpful lane minder, lane change view, and turning view that help keep the trailer on course. Chevrolet was the first truckmaker to offer a unique “transparent-trailer” mode that uses an accessory camera mounted to the back of a trailer to provide a full, unobstructed view of traffic to the rear.
Advanced Trailering System
The segment-first Advanced Trailering System allows drivers to create unique profiles for each trailer through the myChevrolet mobile app or the Chevrolet Infotainment 3 system. Features include pre-departure checklists, trailer tire pressure monitoring, and electrical/lighting diagnostics.
Maximizing Fuel Economy
While heavy-duty trucks aren’t known for exceptional fuel economy, several strategies can help you get the most from every gallon.
Driving Habits
Smooth acceleration, maintaining steady speeds, and anticipating stops all contribute to better fuel economy. Using cruise control on highways helps maintain consistent speeds and reduces fuel consumption.
Proper Maintenance
Regular maintenance keeps your engine running efficiently. This includes timely oil changes, air filter replacements, and ensuring proper tire pressure. Underinflated tires increase rolling resistance and reduce fuel economy.
Performance Tuning
Quality tuners often include fuel economy modes that optimize engine parameters for efficiency. These modes adjust throttle response, transmission shift points, and fuel delivery to maximize miles per gallon during highway cruising.
Choosing the Right Upgrades for Your Needs
Before investing in performance parts, consider how you use your truck. Different applications benefit from different modifications.
Daily Driving and Light Towing
For drivers who primarily use their trucks for daily transportation and occasional light towing, a cold air intake and performance tuner provide noticeable improvements without breaking the bank. These modifications enhance throttle response and can improve fuel economy during highway driving.
Regular Heavy Towing
If you regularly tow heavy trailers, focus on upgrades that improve low-end torque and transmission performance. A quality tuner with towing-specific calibrations optimizes shift points and throttle response for hauling heavy loads. Consider adding a larger fuel tank to extend your range when towing.
Maximum Performance
Enthusiasts seeking maximum performance should consider comprehensive upgrades including superchargers, upgraded exhaust systems, and custom tuning. These modifications work synergistically to deliver dramatic power gains. However, be prepared for higher costs and potential impacts on reliability and warranty coverage.
Installation Considerations
Most bolt-on performance parts can be installed by mechanically inclined owners with basic hand tools. Cold air intakes typically take 60-90 minutes to install, while exhaust systems may require 2-4 hours depending on configuration.
Tuners require ECM unlocking, which can be complex on 2020+ GM trucks due to enhanced security measures. Some tuners include unlock kits, while others require separate purchases and professional installation.
For major modifications like superchargers, professional installation is strongly recommended. These systems require precise calibration and proper installation to ensure reliability and performance.
Warranty and Legal Considerations
Before modifying your truck, understand how aftermarket parts affect your warranty. The Magnuson-Moss Warranty Act prevents manufacturers from voiding warranties simply because aftermarket parts are installed. However, if a modification causes damage, the manufacturer may deny warranty coverage for related repairs.
Emissions-compliant modifications are essential for vehicles registered in states with emissions testing. Many reputable manufacturers design their products to meet emissions standards while still providing performance gains.
Comparing the L8T to Other Engines
Understanding how the 6.6L gas engine compares to alternatives helps you appreciate its strengths.
L8T vs. Previous 6.0L V8
The L8T represents a substantial upgrade over the previous 6.0L engine in every measurable way. With 41 more horsepower and 84 additional pound-feet of torque, the L8T delivers significantly better performance while maintaining similar fuel economy.
L8T vs. L5P Duramax
While the Duramax diesel offers more torque and better towing capacity, the L8T gas engine provides excellent value for drivers who don’t need maximum towing capability. Lower purchase price, reduced maintenance costs, and simpler emissions systems make the gas engine attractive for many buyers.
Real-World Performance
Owner experiences provide valuable insights into how these trucks perform in daily use. Many owners report averaging 16-18 mpg during mixed driving, with highway mileage reaching 14-16 mpg when towing moderate loads.
The L8T’s low-end torque impresses owners who regularly tow trailers. The engine pulls strongly from low RPMs, making it easy to merge onto highways or climb grades with heavy loads attached.
Future-Proofing Your Investment
The L8T’s robust construction and strong aftermarket support ensure long-term viability. The cast-iron block, forged steel crankshaft, and powder-metal connecting rods provide durability for high-mileage use.
As the aftermarket continues developing products for the L8T, more performance options will become available. Early adopters benefit from proven upgrades while future buyers will have access to even more sophisticated modifications.
Conclusion
The 2020 Chevy 6.6L gas engine delivers impressive performance straight from the factory, but aftermarket upgrades can take it to the next level. Whether you’re seeking modest improvements through cold air intakes and tuners or dramatic power gains from superchargers, the L8T platform offers excellent modification potential.
Consider your specific needs, budget, and intended use when selecting performance parts. Start with proven bolt-on modifications that deliver reliable gains without compromising reliability. As you become more familiar with your truck’s capabilities, you can explore more aggressive upgrades.
The combination of modern technology, robust construction, and strong aftermarket support makes the 2020 Silverado HD with the 6.6L gas engine an excellent choice for work and recreation. With the right performance upgrades, you can create a truck perfectly tailored to your requirements while maintaining the reliability and capability that make these trucks legendary.