Briggs & Stratton Vanguard Big Block

Briggs & Stratton Vanguard Big Block

If you’ve been in the market for a big piece of outdoor equipment, and in particular a new mower, you’ve probably come across Briggs & Stratton’s Vanguard Big Block. While the name sounds like a throwback to classic muscle cars, this state-of-the-art engine has become a major player in the top end of the market. What sets it apart?

What is the Big Block?

This is a series of industrial V-twin engines producing anywhere from 28-37 hp. They’re designed specifically for use in lawn mowers but have found their way into other high power demand equipment.

What’s “big” for an engine used in outdoor equipment? In this case, it’s 896-993 cc. This puts these engines in a class at the very top of the gas market, often offered alongside small diesel engines. These sizes were chosen by Vanguard specifically for the torque demands of large ZTR mowers and lawn tractors.

Vanguard vs Briggs & Stratton

The Big Block is a Briggs & Stratton motor, but it’s also a Vanguard. What’s the difference? Realizing that they needed to have marketing, development and dealer training in place to support commercial customers, Briggs & Stratton created the Commercial Power division in the early 2000s. From there, they partnered with Daihatsu and Mitsubishi Heavy Industries to bring state-of-the-art manufacturing technologies to small engines while using the residential division’s development labs to improve usability. That includes access to the Engine Application Center (EAC) which works with equipment manufacturers to integrate the engine into the design process instead of simply designing the equipment and attaching the engine. This saves a lot of time and troubleshooting for the manufacturer and ensures the engine will work perfectly wherever it’s used.

The Vanguard Big Block is a collaborative effort between Briggs & Stratton and Daihatsu: Vanguard designed the engine and a lot of the parts are made in the U.S. Final assembly takes place at a Daihatsu plant in Japan using the same tooling and machining the company has developed for their commercial vehicles. The end result is a motor designed from the ground up for the needs of lawn care professionals with the build quality of an automobile engine.

Engine Construction

The inside of these engines looks a lot more like something that would power a car than a lawnmower: cast iron cylinders are paired with lightweight pistons and rings to ensure durability and reduce noise and vibration. These spin a crankshaft that is dynamically balanced at the factory to reduce vibration, lowering internal stresses and making the mower more comfortable to operate.

Cooling and Lubrication

While most engines in this class are liquid-cooled, the Big Block is air and oil-cooled. This makes maintenance less complicated and helps reduce weight. The oiling system is fully pressurized, drawing oil from a sump and pumping it through galleries around the entire engine from the heads to the crankshaft. The pickup point is mounted low in the center of the sump to get the system pressurized quickly after the start and prevent starvation at severe angles of operation. This oil is kept clean by an automotive-style spin-on filter.

These engines also have what Vanguard calls “Advanced Debris Management.” Everything from the grille over the flywheel to the metal plates surrounding the cylinders has been designed and tested to allow cooling while reducing dust contact. This helps keep engine temperatures down and efficiency up while reducing the need for cleaning. These components have also been tuned to reduce resonance to make the engine quieter.


Vanguard has been rolling out electronic fuel injection versions of the Big Block in the past couple years with outputs ranging from 33 to 37 hp. This is a closed loop system developed by Delphi with an oxygen sensor in the exhaust, letting the ECU track how fuel is burning and adjust the mixture accordingly. Not only is this good for the environment, it can cut operating costs significantly by increasing fuel efficiency by up to 25% over a carburetor-equipped engine. This makes these motors a compelling alternative to more expensive types of diesel.

Fuel injection systems are also far less temperamental when it comes to fuel freshness and content: straight gas with or without ethanol can be used in most situations, while the fuel can be treated when the engine is stored instead of draining the entire fuel system.

Parts and Service

Shank’s Lawn Equipment is a Vanguard dealer, and we sell a wide range of mowers and other equipment that use the Big Block. To see if this engine is a good fit for your needs or you need to have your motor serviced, visit our shop at 4900 Molly Pitcher Highway in Chambersburg, PA. That’s one mile East of I-81 via Exit 10.

Not in the area? We ship OEM parts across the U.S. and Canada. To order, visit us online at

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2 Responses to Briggs & Stratton Vanguard Big Block

  1. wayne pearson says:

    I have a 2021 grasshopper 729 big block front mount 61 inch cut,I check the oil every time I fill with gas ,about every 2 to 3 tanks the oil is low,can’t find any leaks,and engine doesn’t smoke,does anyone have any suggestions to the problem?I use 10 w 30 oil and change it every 50 hours.

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