Does Chevy Make A 6.6 Gas Engine? | Truck V8 Facts

Yes, Chevrolet sells a 6.6-liter gasoline V8 in Silverado HD trucks and Express vans, with 401 horsepower and 464 lb-ft of torque.

Chevy does make a 6.6 gas engine. It is General Motors’ L8T 6.6-liter gasoline V8, built for heavy-duty work, not for light-duty half-ton pickups. You’ll find it in Silverado HD trucks and in the Express van line, where buyers want strong low-rpm pull without stepping into a diesel.

The easy way to think about it: Chevy has two different 6.6-liter stories. One is the Duramax turbo-diesel V8, known for huge torque. The other is the gas V8, a simpler gasoline workhorse rated at 401 horsepower and 464 lb-ft of torque in factory listings. Shoppers mix them up because both wear the same displacement badge.

Chevy 6.6 Gas Engine In Current Trucks

The 6.6-liter gas V8 is the gasoline engine choice in Silverado HD. Chevrolet’s current Silverado HD engine lineup lists the 6.6L V8 gas engine at 401 horsepower, 464 lb-ft of torque, paired with a 10-speed Allison automatic transmission, and rated for up to 19,080 pounds of gas-engine towing.

That makes it a real HD engine, not a small truck motor with a bigger badge. It is meant for 2500 HD and 3500 HD buyers who tow, haul, plow, carry tools, or run a work truck all week. It won’t match the Duramax diesel’s 975 lb-ft torque figure, but it also skips diesel exhaust fluid, diesel fuel pricing swings, and many diesel-specific service costs.

What The L8T Name Means

L8T is the factory engine code for GM’s 6.6-liter gasoline V8. GM’s L8T engine specifications list 6,564 cc displacement, a 10.8:1 compression ratio, overhead valves, direct injection, regular 87-octane fuel, a cast-iron block, aluminum heads, and a 5,600-rpm maximum engine speed.

Those specs tell you what Chevy was chasing. This engine is built for load, heat, and steady work. The iron block adds weight, but it is a good match for heavy-duty use. The aluminum heads cut some mass up top. Direct injection and variable valve timing help the engine make cleaner power across a wide rpm range.

Where Chevrolet Uses The 6.6-Liter Gas V8

Chevrolet uses the gas 6.6 in more than one work vehicle. The main retail name is Silverado HD, but the Express van lineup also offers it. The 2026 Express Vans engine options page lists the 6.6L V8 as available on Express 2500 and 3500, with 401 horsepower, 464 lb-ft of torque, direct injection, variable valve timing, and an 8-speed automatic.

That matters for buyers who tow with a van, carry heavy cargo, or run upfitted trade vehicles. In an Express, the same basic power figure sits in a different package: more cargo space, van seating choices, and a lower step-in load bay than a pickup bed.

• Silverado 2500 HD and 3500 HD: Best fit for towing, bed cargo, plows, trailers, and daily work duty.
• Express 2500 and 3500: Best fit for enclosed cargo, passenger shuttle work, and trade upfits.
• Not a Silverado 1500 engine: Chevy’s half-ton lineup uses different gas and diesel choices.

Gas V8 Or Duramax Diesel: Which One Fits?

The 6.6 gas engine is the better match when the truck works hard, but not at the highest trailer weights every day. It starts cleanly, runs on regular gas, and can cost less to buy than a diesel-equipped truck. For fleets, that can free money for racks, boxes, tires, trailer brakes, or other work gear.

The Duramax is still the better tool for the heaviest trailers. Its 975 lb-ft of torque changes the feel under load, mainly on grades, highway merges, and long hauls. If the truck spends its life pulling large fifth-wheel, gooseneck, livestock, or equipment trailers, diesel still earns a hard look.

When The Gas Engine Makes Sense

The 6.6 gas V8 fits drivers who want HD frame strength and payload rating more than diesel torque. It also fits people who make shorter trips, idle less, tow on weekends, or keep trucks for work where repair costs matter more than peak towing bragging rights.

• You tow medium-heavy trailers, not max-rated trailers, most of the time.
• You want a lower purchase price than a diesel truck.
• You prefer regular gasoline and simpler fueling stops.
• You use the truck for mixed work: hauling, errands, towing, and job sites.

For factory numbers, start with Chevrolet’s Silverado HD engine lineup, then match the engine code against GM’s L8T engine specifications. For vans, Chevrolet’s Express Vans engine options show the same 401-horsepower rating in a different body style.

Item	6.6L Gas V8 Detail	Why It Matters
Factory code	L8T	Helps identify the gas engine, not the Duramax diesel.
Displacement	6,564 cc / 6.6 liters	Large V8 size gives strong work-truck pull.
Output	401 hp and 464 lb-ft	Enough for HD gas towing and heavy payload use.
Fuel	Regular 87-octane gasoline	No diesel fuel or DEF needed.
Engine design	OHV V8, direct injection, variable valve timing	Traditional truck layout with modern fuel control.
Block and heads	Cast-iron block, aluminum heads	Built for heat, load, and steady work cycles.
Silverado HD transmission	10-speed Allison automatic	Keeps the gas engine in a better pull range.
Express transmission	8-speed automatic	Matches the van’s cargo and passenger role.
Max gas towing in Silverado HD	Up to 19,080 lbs.	Plenty for many equipment, camper, and utility trailers.

How The 6.6 Gas Engine Feels In Real Use

Drivers coming from the older 6.0-liter GM gas V8 will notice the difference most under load. GM says the L8T’s 464 lb-ft peak torque arrives 200 rpm sooner than the prior 6.0-liter HD gas V8 and is 22 percent higher. That helps the truck feel less strained when a trailer is attached.

It is still a gas engine, so it likes rpm more than the Duramax does. That is normal. A gas Silverado HD may downshift and rev on hills where the diesel stays lower and quieter. Some owners dislike that sound. Others prefer the simpler gas setup and accept the higher revs as part of the deal.

What It Is Not

The 6.6 gas V8 is not a Duramax. It is not the older 8.1-liter big-block. It is not the same engine as the 6.2-liter V8 used in some lighter GM trucks and SUVs. It is a heavy-duty gasoline V8 with its own parts, tune, torque curve, and job.

It also is not the automatic winner for every buyer. Diesel buyers get bigger towing numbers and stronger low-rpm pull. Gas buyers get a simpler fuel choice, strong factory power, and a lower-cost path into a Chevy HD truck.

Your Use	Better Match	Plain Reason
Daily HD work with moderate trailers	6.6 gas V8	Strong output without diesel extras.
Heavy gooseneck or fifth-wheel towing	Duramax diesel	Far more torque under heavy load.
Short trips and mixed local use	6.6 gas V8	Gas power is easier for many stop-start routines.
Long highway towing	Duramax diesel	Diesel torque feels calmer at speed with weight behind it.
Lower entry cost	6.6 gas V8	Gas HD trucks often cost less before options.
Maximum rated towing	Duramax diesel	Chevy’s top towing number belongs to the diesel.

Buying Notes Before You Pick One

Before choosing the 6.6 gas engine, match the truck to the trailer, not just the badge on the fender. Payload, axle ratio, cab style, bed length, hitch type, and four-wheel drive can change ratings. A diesel badge alone does not fix a low payload number, and a gas badge does not mean the truck is weak.

Check These Before Signing

• Read the door-jamb payload sticker on the exact truck.
• Compare your loaded trailer weight with the truck’s tow rating.
• Check tongue weight or pin weight against payload.
• Price insurance, fuel, service, and tires for gas and diesel builds.
• Test drive both engines with your normal use in mind.

So, yes, Chevy makes a 6.6 gas engine, and it is still active in current work vehicles. For many HD buyers, the L8T is the sensible middle ground: more muscle than older gas HD engines, less cost and fuss than diesel, and enough factory rating for a wide range of trailers and work loads.