How to Build a Briggs Racing Engine

9 mins read

In 1991, Briggs & Stratton launched a division called Briggs Racing. This division produces high-performance engines used in snowmobiling and karting. Their long-standing partner asked Starkmedia to create a new website for the company. They needed to provide information about their engines, as well as appeal to the loyal fan community. This site fulfills both of those goals.

Intake manifolds

A Briggs Racing engine’s intake manifolds need to be custom-made for the specific model. This engine’s class rules call for a single four-barrel intake manifold. A two-piece casting begins as a base for the intake manifold and goes through extensive welding and machining to create its final shape. Its parts include an Accufab 8500 throttle body, Jesel shaft mount rocker arms, and 60mm bearings.

107ss cam

The 107ss cam is a mild low lift mod that works as well as a hot stock cam in a 5 HP Briggs, yet is gentle on the valve train. This cam works very well in a Briggs without relieving the head. The 107ss cam is usually installed in a Tool Steel Billet core, allowing for a wide range of valve timing. Because the 107ss is a plug-and-play cam, it is relatively easy on the valve train and needs little clearance work.

The cylinder bores need to be welded up, and the lifter bores may need welding to make them fit properly. Then, you can install the new springs and assemble the engine. You can use the Dynocams 97ss cam or 94ss cam. You will also need new valve springs and split retainers. The higher lift cams require heavier springs, and they will suck out a lot of power.

Spring pressure

In building a racing engine, one of the most critical components is spring pressure. Without proper spring pressure, a racing engine will run into valve float, wasting horsepower. This loss increases as engine speed increases, and the higher the spring pressure, the more power will be lost. A good way to avoid this problem is to carefully measure spring pressure yourself. In this article, we will show you how to measure spring pressure accurately.

In modifying an existing engine, spring force must be increased to compensate for the added speed. To do so, adjust the spring rate to match the desired performance. You may need to change the spring rate to achieve the proper over the nose pressure, or to achieve a high-lift, low-rpm performance. Using the manufacturer’s recommended spring rates is a good way to start. When measuring spring force, remember to include the spring force of your valve train.

The stock Briggs engines are available in two different models. The Flathead is the most common, but this model has been discontinued. However, aftermarket sources still carry it. The new OHV Animal engine is replacing the Flathead. Stock form of the OHV engine produces about 5-6 hp. With modifications, you can increase this power to three or four times what the stock engine can do.

The springs in the valve train are essential for high-rpm operation. The springs in these components are used to push the valve train components against the cam. A spring’s inertia increases with the square of the speed, so doubling the speed requires four times the force. Because of this, spring pressure should be adjusted accordingly. You can also use valve springs that have higher tension to increase valve lift.

Engine blueprinting

While machining the stock parts of a Briggs racing engine may be tempting, it’s not really an option unless you have a special purpose. Engine blueprinting refers to machining the stock parts to improve their performance or tolerance. This process is not recommended as it may lead to miscommunication and disappointment. Instead, you should consult a professional racing engine shop to complete the job correctly.

The process for modifying a Briggs racing engine begins with a stock 5hp Briggs. This engine runs for three hours on a dyno at 5800 rpm under temperature monitoring. The engine is then used as a training engine and is run with a small load to familiarize it with the moving parts. During this run, the pistons, crankshaft, valves, and timing chains will be adjusted to achieve the desired results.

After the blueprinting process, the next step in the process is engine balancing. Both balancing and engine squareness are important for racing engines. Blueprinted engines should have exact tolerances. If you’re building a Briggs racing engine, balancing and squareness will be important factors. If the engine’s components aren’t aligned, they won’t work properly.

While the Briggs brand name may not sound like a racing engine to most people, it carries great power and respect for kart drivers. Regardless of the kart class, Briggs engines will be required to undergo engine blueprinting sooner or later. The Animal class gives you the opportunity to get into the kart engine market early. It is possible to make a Briggs racing engine out of the stock.

Engine dyno pull

When building a Briggs racing engine, you’ll want to perform an engine dyno pull to ensure that the final outcome is what you expect. Normally, this means a 5hp Briggs stock that has been seasoned. In this case, you’ll want to run the engine for three hours at approximately 5800 rpm with a small load on the dyno. This run is used to season the block and familiarize the parts of the engine with the process.

The first step in determining the engine’s power is to find out the minimum and maximum horsepower requirements for the flywheel. The dyno operator must show that their pulls are repeatable before making any modifications. Unless you are comfortable with the process and have a good idea of what the desired power output is, you should not perform the engine dyno pull yourself.

Another important step in the dyno testing process is to take note of weather conditions. The lower the barometric pressure, the higher the air temperature, and the more humid the atmosphere, the lower the engine’s power output. Unless you know exactly what the conditions are, it will be difficult to compare engine performance under different conditions. However, most dynamometers come with atmospheric correction tables, which multiply the torque data by different factors. This way, the resulting power output is closer to what a vehicle would be expected to produce when racing in a “standard” atmosphere.

Another key step in the engine dyno pull process is determining the ideal amount of hop-up modifications. These modifications are important because they help with high-rpm power, but will sap power from the low-rpm range. Those modifications can be difficult to achieve without the right amount of testing, and your track-based experience may be limited to days, not years. You don’t want to make a mistake by overestimating a 1-percent gain that you might have experienced in a few races. This is how pros win races and trophies, and you need to know how to use the information you gain from the engine dyno.

About The Author

Mindy Vu is a part time shoe model and professional mum. She loves to cook and has been proclaimed the best cook in the world by her friends and family. She adores her pet dog Twinkie, and is happily married to her books.