Small block Chevy (SBC) and big block Chevy (BBC) engines differentiate between GM V8 pushrod engines. Besides, displacement is not the only thing that sets them apart. These motors are architecturally distinct, and a closer look at the bore and stroke will tell you more about them.
However, it’s not as simple as the bore, stroke, and displacement. As you’ll find out, some small block engines have large displacements, throwing the discussion into a new rhythm.
Let me walk you through the small block vs. big block Chevy engine as we get to the bottom of each aspect that defines each type.
SBC vs. BBC: What Are They?
What Is A Small Block Engine?
The first thing that distinguishes a small block Chevy engine is it’s simply physically smaller than a big block engine. The small size prompted GM to make shorter strokes and pistons with smaller bores. Therefore, the design resulted in a smaller displacement.
Small blocks may not produce that much power, but they are light, making them easier to handle.
In fact, the car can accelerate faster since it has no drag at the front axle. Small engines can produce up to 5,800 RPM.
What Is A Big Block Engine?
The big-block Chevy engine, on the other hand, is physically larger and heavier than the small block. In addition, it has longer strokes, larger bores, bigger valves, and ports for outstanding power production.
Initially, big block engines were for larger cars and trucks. But now, they are being added to passenger cars. Big blocks can withstand higher compression and heat, and they are also more durable since the cylinders are further apart.
The downside is that they are big and bulky, which puts a lot of extra weight on the car, especially for front-mounted engines, affecting handling. Thus, they may sacrifice acceleration for power.
Which Is Better, Big Block or Small Block?
Small Block Engine Pros and Cons
- Small weight distribution for better handling
- More space under the hood
- Readily available speed parts
- Swift acceleration
- Less horsepower due to shorter strokes
- Relatively less durable than big-block engines
Big Block Engine Pros and Cons
- More displacement than small block engines
- Highly efficient because of more torque
- Generally, more durable
- Can tow heavy loads with no problem
- Heavier than small block engines
- Slower acceleration
Which Is Better?
When determining which is better between a big block and a small block, you’ll want to keep in mind their size and the manufacturing year. A small block is smaller in size and weighs less than the big block, making it better at handling and acceleration. On the other hand, big blocks are larger and weigh more, which allows them to produce more torque and power.
Nevertheless, recent small block engines in the LS1 family are just as powerful as some big-block engines. Hence, it’s down to what you want in a particular motor.
Read more: LS1 Vs. LS2 Vs. LS3 (With Comparison Chart)
Is A Big Block or Small Block Better for Drag Racing?
Choosing between the two engines is a battle since a big block has more torque and better head flow. As such, it can overcome the added weight. On the other hand, a small block weighs less, meaning it can run higher RPM where horsepower is made.
In this regard, you could take the small block and give it a looser converter and a steeper rear-end gear ratio. These drivetrain changes could beat the big block in a drag. Hence, what changes you make to your engine matters when bringing it to a drag race.
Small Block Vs. Big Block: Key Differences Explained
Big Block Vs. Small Block Dimensions
Big blocks usually measure 9.8 inches except for the 427, which measures 10.2 inches.
Small block motors, including the 302, 327, 305, and 350, measure 9.025 inches. Aftermarket models come in a tall deck measuring 9.325 inches.
Big Block Vs. Small Block Weight
Big block engines are mainly made from aluminum to cut on the weight, but they still put on a hefty 685 pounds when the engine is completely assembled.
On the other hand, small blocks are made from either cast iron or aluminum, averaging 575 pounds. The weight difference makes a huge difference in these engines’ handling, acceleration, displacement, and torque.
Big Block Vs. Small Block Stroke
Big block engines tend to have longer strokes, while small blocks have shorter ones.
The larger stroke on the big blocks results in a higher displacement, but the revving is not as quick as the small block engines.
Big Block Vs. Small Block Bore
Big block engines have smaller bores than strokes, and this configuration leads to improved breathing resulting in increased power from the engine. However, the small bores in big block engines cause high pressure, creating more torque.
Small block engines have larger bores than strokes. While it results in less displacement, their revving is much quicker than big-block engines.
Big Block Vs. Small Block Torque
Torque affects a vehicle’s drivability, which is the engine’s rotation force. In the case of big-block motors, they tend to have an easy time achieving low-end torque. They can get their highest torque in the rev range of 4000 – 5700 RPM. This rev range allows the vehicle to be more responsive.
Nevertheless, small block engines with lower torque than big block engines can accelerate just as quickly as the big block since they are lighter.
Big Block Vs. Small Block Horsepower
The horsepower affects how fast a car accelerates. Big blocks have higher horsepower than small block engines because they are heavier. Thus, they require high horsepower to allow the vehicle to accelerate. They start at a horsepower of 250 – 350 hp in the 1958, 348 ci engine up to the all-powerful 2022 ZZ632 with a horsepower of 1004.
The compact and lightweight, small block Chevy engines don’t need lots of horsepower. The earliest models could only produce 180 hp. But that changed to 350 hp in the L46 and 370 hp in the 1980 LT1 motor.
Small Block Vs. Big Block Displacement
In most cases, a large displacement indicates the motor can take in more air and fuel, which correlates to more power. Typically, small block engines have a displacement of under 400 cubic inches.
In comparison, big blocks’ displacement is above 400 cubic inches except the 396, which is considered a big block because of its architecture.
Big Block Vs. Small Block Heads
The big block has seen various variations in the heads of the years. The first-gen heads came in aluminum and cast iron in a closed combustion chamber. However, they were so compressed that the second-gen big block featured an open chamber design that allowed 2.250 intake valves and 1.88-inch exhaust valves.
You could pick between oval ports for a base engine and rectangular ports for performance motors. The best oval port, open-chamber heads, had large 2.25-inch intake valves and 1.88-inch exhaust valves.
Small block engines have also evolved from the double hump heads of the mid-1960s with 2.02 intake valves and 1.60-inch exhaust valves. The power pack heads had 1.72-inch intake valves and 1.50-inch exhaust valves.
Besides, the most notable heads were of the L31 Vortec produced in 1996, and they had 1.94-inch intake valves and 1.50-inch exhaust valves.
Big Block Vs. Small Block Fuel Pump
While the small block and big block have similar housing in their fuel pump, you may be wondering if they are interchangeable and what sets them apart. The first thing you’ll notice is that the levers are not the same, and the big block sticks out further.
Even though some big-block fuel pumps have similar physical dimensions as some small block fuel pumps, they operate at different pressures. If you were to install a small block pump in a big block engine, it would be starved off at wide-open throttle.
Small Block Vs. Big Block Sound
There’s little noticeable difference between a small block and a big block’s sound. Both engines have a deep rumble that signifies they are powerhouses out to rule. The two motors are V8s with a cross-plank configuration.
Thus, they have the same firing order, producing two consequent exhaust pulses on the same side. Hence, the irregular firing order produces the rumble. The difference will come from the exhaust and intake and not the engine.
Best Chevy Small Block Engines
The Chevy 350 is the best-known small block Chevy engine. It is a 350 ci (5.7L) engine with a 3.48-inch and 4-inch stroke and bore. GM first produced it in 1967. It has different versions starting with the L46 in 1967 to the L31 in 2005. Depending on the manufacturing year, this engine has horsepower ranges from 145 to 370 and up to 380 lb.-ft of torque.
The 350 small block engine has low fuel economy and may require premium fuel. However, it’s still a good candidate for towing.
It’s considered one of the simplest engines to rebuild. You can easily find lots of aftermarket parts, including high-performance exhaust and intake components.
Nevertheless, you can find new and rebuilt Chevy 350 crate engines with a base horsepower of 195 and an 8:5 compression ratio.
Before the 350 ci engine, GM produced the 327 ci small block motor. The 327 is a 5.4L displacement motor with 4-inch and 3.25-inch bore and stroke. It has a power range between 250 hp and 350 hp depending on the choice of the carburetor, fuel injection, cylinder heads, intake manifold, pistons, and camshaft.
This engine is compact and efficient due to the large cylinder wall castings. The bores use large valve heads and yield a 1.75:1 rod to stroke ratio. Besides, it came in four different power ratings, with the performance model boasting an 11.25:1 compression ratio, and it could produce 340 hp and 344 lb.-ft of torque.
The 305 small block motor was a 305 ci engine that was developed between 1976 and 2003. It was a fuel-efficient engine, made with a similar architecture to the 350. Additionally, this engine had a bore and stroke of 3.736 x 3.48 inches with only a handful of variants. Chevy 305 started with the LG3 with a two-barrel carburetor and an 8.5 compression ratio.
The 305 variants lasted until 2003 with the L30, also known as the Vortec 5000. It features a bore and stroke of 3.74 x 3.48 inches and a 9.1:1 compression. You can find it in the Chevy and GMC Savana Work vans and GMC C/K series trucks.
Best Big Block Chevy Engines
This engine was used as an optional engine in the 1965 Corvette. It is a direct descendant of the 427-racing engine, which debuted in the 1963 Daytona 500. The 396 L78 motor has a significant appeal based on its structural integrity. It has a bore and stroke of 4.094 x 3.76 inches and produces an 11.0:1 compression ratio.
The 396 L78 features a cross-drilled, forged steel crankshaft. It also has robust alloy connecting rods and aircraft-grade rod bolts to bolster the bottom for more durability.
Further, this engine has free-flowing cylinder heads with staggered valves. The design of the valves allows efficient exhaust outflow, which is why it was named the new power plant of the Corvette, boasting 4,000 RPM.
The 427 L88 was born out of Duntov’s (Corvette engineer) desire for an aggressive engine featuring a competitive camshaft, increased compression ratio, and a larger carburetor in the 427 big-block Chevy. Thus, the L88 was developed with a cross-drilled, forged steel crankshaft. It also featured aluminum pistons and had a bore and stroke of 4.25 x 3.76 inches.
While the bore and stroke were similar to the already existing 427 L36 and & L76 engines, the L88 had a higher 12.5:1 compression ratio. Additionally, its aluminum cylinder heads shed 70 pounds of weight over the iron cylinder heads used in 427 engines.
The 427 L88 produced a max of 380 hp, but it’s believed that the GM downplayed the number to discourage casual consumers from purchasing the engine.
The 454 ci engine first appeared in 1970 with similar architecture as the Mark IV. Nonetheless, it had a bigger stroke of 4 inches but still maintained the 4.27-inch bore size of the 427. The LS6 was its second version, available in the El Camino, Chevelle, and Monte Carlo. It could reach a horsepower of 450 in the Chevelle and El Camino vehicles.
LS6 is distinct from its other 454 counterparts since it has an 11.25:1 compression ratio. The engine also comes with cast-iron, rectangular port heads, which feature an intake opening of 2.19 inches and an exhaust opening of 1.88 inches.
Chevy LS6 had a solid lifter camshaft, forged aluminum pistons, and low-rise aluminum intake. Its massive 800-cfm 4bbl Holley carburetor made it a ruler in the streets.
SBC Vs. BBC: FAQs
350 Big Block Vs. 350 Small Block
First, let’s get the 350 big-block out of the way because it was never a big block in GM’s line of BBC engines. To this end, the 350 is a small block engine which was GM’s corporate standard. The engine was discontinued in 2003 and replaced by the LS1 line.
427 Small Block Vs. 427 Big Block
Again, Chevy did not make a small-block 427 ci engine but rather a 427 big block engine. It started production in 1966 with a diverse range of power according to its application. This motor is considered the least expensive to rebuild for more horsepower.
400 Small Block Vs. 400 Big Block
Chevy never made a 400 big block engine, only the 400 small block engine. Nevertheless, Chevy had big blocks which had a 409 cubic inch displacement. The 400 small block engine had a large 4.125 bore and stroke of 3.75 inches to achieve a displacement of 400.9 cubic inches.
350 Small Block Vs. 454 Big Block
The 350 small block is a great engine, but it does not come close to the performance of the 454 big block engine. It is ideal if you’re not spinning or towing. But if you’re hauling, the 454 will stomp on the 350 in terms of horsepower, displacement, and torque.
The 350 small has an impressive torque as it can reach 350 lb.-ft at 2800 RPM. However, the 454 achieves 500 lb.-ft torque at 3600 RPM. Looking at the two engines, you can tell that the 454 is a powerful and fast engine.
The good thing with the 350 ci engine is that it won’t be sending you to the fuel pump as often as the 454 ci engine. Yet, the 454 ci is more reliable for race cars, muscles cars, and classics. In addition, it has lots of available spare parts in case you need to repair it.
454 Small Block Vs. 454 Big Block
Chevrolet only made a 454 big block and not a 454 small block engine. The big block 454 ci motor remains a favorite in classic cars and trucks. It comes with excellent stock power, and you can upgrade it to get more performance out of it.
Since it’s a popular engine, many aftermarket parts support a new engine build. The only issue with a 454 ci motor is adequate cooling since it can run hot. Hence, it’s best to use a good radiator and check the coolant regularly.
396 Small Block Vs. 396 Big Block
The 396 ci is the smallest of the big block engines, which is easy to confuse with a small block. However, it’s as heavy as a big block, and it has the same architecture as a big block, although its displacement is under 400 cubic inches.
This engine did not follow as a continuation of the engines before it, like the 348, 409, and 427. Instead, it had the same 4.84-inch bore spacing as the W motor and a similar flat tappet and two-piece main seal. With an 11:1 compression ratio, it was the hallmark of the times.
396 Big Block Vs. 400 Small Block
These engines exist and are some of the most popular when rebuilding an engine. The 396 has larger cylinder heads that offer better breathing to make up for the weight.
Both motors have an almost similar bore and stroke 4.094 x 3.75 inches in the 396 BBC versus 4 x 3.75 inches in the 400 SBC. Yet, the 396 BBC has longer rods allowing better rod length to stroke ratio and less side loading on its cylinder wall.
The 396 BBC pulls 375 hp over 275 hp on the 400 SBC although the torque is almost similar.
It’s better to go with the 396 BBC for towing. But if you’re looking to rebuild, you’re better with 400 SBC since it’s lighter and cheaper and maintenance is simpler.
The 396 BBC has more pros than cons except for the price and maintenance.
402 Big Block Vs. 350 Small Block
The 350 SBC is perhaps the best small-block Chevy ever made. It’s a durable engine that is fast since it makes 255 hp at 4600 RPM.
Aftermarket cranks, pistons, and rods can make 450 hp. For this reason, it can easily beat the 402 BBC that produces 375 hp at 5600 RPM.
The 350 SBC has a good reputation in terms of reliability. The 402 BBC, on the other hand, is a rare find, and it’s easier to rebuild to get more power. But since its parts are not easy to find, it’s better to go with the 350 SBC.
540 Big Block Vs. 400 Small Block
The 540 is a crate engine, but it’s not an original model by GM. It is built similarly to Chevy big-block engines. To this end, if you’re looking to compare the two motors, you’ll find the 540 BBC in countless configurations. The hp varies between 650 – 950 hp depending on the parts added, so it’s not going to come close to a 400 small block engine.
Because the 540 BBC is considered a mega motor, hot rods love its stock power because it does not require modifications. On the other hand, the 400 SBC outperforms all other small block engines. It has proven itself over the years on the drag strip, and it’s easy to find the engine in a crate design.
Since 400 SBC has an iron construction, it’s incredibly durable; thus, this engine continues to be a good candidate for drag racing.
I hope we are closer to ending the big block vs. small block Chevy engine debate.
The above aspects, including the displacement, torque, stroke, and heads, distinguish between the two engine types.
It’s down to lots of power and torque in the big block engines versus better handling and faster acceleration in the small block engines.
So, I recommend picking the BBC for muscle cars and hot rods while the SBCs are better for drag race cars.
Read more: SBC BBC V6 Chevy Engines Specs and Sizes