Individual Throttle Bodies V’s Single Throttle Body
In this article, we will explain the benefits and limitations of the different types of inlet systems.
Single Throttle Bodies
A single throttle body is the most common setup found on production engines. The whole engine is feed air through the one throttle body mounted to an air chamber or plenum at is common to all the engine cylinders. Each cylinder draws air from the plenum during its induction cycle. This system is simple and reliable as there is only one moving part. An Idle valve or bypass valve can be used to allow a small amount of air to bypass the throttle body and feed air into the plenum so that engine will continue to run when the throttle plate is closed.
Individual throttle bodies
The use of individual throttle bodies is commonly found on motorsport engines and high-performance road vehicles. Adding throttle bodies is a popular modification for performance car enthusiasts on their road cars due to its improvements in engine performance & throttle response.
Unlike a single throttle body arrangement an individual throttle body setup has a throttle body for each cylinder of the engine, therefore a 6 cylinder engine would have 6 throttles.
The advantages of having a throttle body per cylinder are that it improves throttle response and allows for a larger inlet diameter. The improvement in throttle response is achieved by the shorter distance and reduced volume between the throttle plate and inlet valve, meaning less air is required to fill the space and get to the cylinder.
The increase in inlet diameter allows more air to flow into the cylinder. The size of inlet diameter does have an effect on the performance as explained in this article throttle bore and length
Direct to Head Individual throttle bodies
Originally many throttle body installations were based on DCOE carburetors arrangements but instead of using a pair of carburetors, a pair of throttle bodies would be used which have a fuel injector as the method of delivering fuel. This method worked well and allowed the fueling to be mapped to provide the ideal amount of fuel over the whole rev range.
Direct to head throttle bodies are individual throttle bodies that have been designed for a particular engine. This method of installation removes the need for an intermediate manifold and therefore allows the throttle plates to be moved closer to the head to further increase the throttle response as well as allowing the larger diameter inlet tract to be closer to the head reducing frictional loses and therefore providing more potential for power improvements.
True direct to head throttle setups have a detachable mounting plate that allows the head flange to be mounted to the head without the throttle bodies attached so that it can be ported to perfectly match the cylinder head inlet ports.
Individual throttle bodies are a common upgrade on normally aspirated engines as they increase the amount of air to the engine, which in turn allows more fuel to be injected and therefore more power. With a normally aspirated system, there does not need to be any plenum chamber or other restriction.
In some applications due to the location of the engine or noise limits, a plenum chamber can be used to feed cooler air to the throttle bodies and stifle the noise. The plenum and associated pipework feeding it would be normally be over sized so that it does not restrict the air flow.
Individual throttle bodies work with turbo charged and supercharged applications and provide the same benefits to the engine and driver as normally aspirated.
A forced induction engine will still require a plenum chamber to feed the pressured air from the turbo to the cylinder with the throttle bodies sittin between the plenum and the head.
To monitor boost pressures to the engine a take off is required after the throttle plate, this is
It is possible to run Anti-lag with individual throttle bodies by using an air bypass valve which feeds air into the
However there are some points that need to be addressed when installing individual throttle bodies to a forced-induction engine. Due to the limited space and pressure cycles bet