Extra Airflow and Efficiency with Silverado Throttle Bodies & Spacers

In today’s day and age, throttle bodies are bolted under the hood to control airflow in the engine of GM trucks. The throttle body is a device with a butterfly valve that is controlled by the throttle pedal. The further the pedal is depressed, the wider the valve will open.

The operation of a throttle body is very similar to a carburetor but there is no fuel squirted in with the air. Fuel is not introduced into the engine through the throttle body on these engines, but through fuel injectors that squirt the fuel directly into each cylinder. The amount of fuel delivered is determined by the MAF sensor and ECU.

Throughout the years the technology used with throttle bodies has changed tremendously. One major change is the jump from cable drive throttle bodies to fly-by-wire setups on the Silverado. A cable drive setup links the throttle body directly to the throttle pedal with a cable. The further you push the pedal to the floor, the further the cable will be pulled. As the cable is pulled, the valve on the throttle body will gradually open.

This is a mechanical connection while fly-by-wire is completely electronic. Sensors are used to determine how far the pedal has been depressed to determine how far the throttle body needs to open up.

Fly-by-wire throttle systems sound like a late-model truck feature, but Silverados have been using these types of throttle bodies for a surprisingly long time. Fly-by-wire throttle systems were an optional feature for Silverados since the very first generation. 

Fly-by-wire throttle systems weren’t widely accepted out of the gate so they wouldn’t come as standard equipment until later generations. However, it is possible to find the first generation Silverados with fly-by-wire throttle body systems under the hood.

The factory throttle body on a Silverado can only deliver so much air. The maximum amount of air they can deliver is meant to help an engine with factory equipment hit peak performance. As modifications pile up to produce more power, the engine can begin to outrun the throttle body and may even fall flat on its face when the RPMs run high enough. 

An aftermarket throttle body is designed to help more air to be drawn into an engine. Upgrading the throttle body should be approached as a compliment to these sort of mods as opposed to a lone upgrade. 

The kind of mods that will push the engine to draw in more air or will warrant more air being drawn in are camshafts, custom tunes, bigger injectors, aftermarket cylinder heads and so forth. The idea is to allow the engine to draw in all the air it needs with no restrictions. A beefed up engine trying to draw air through a factory throttle body is like trying to breathe through a straw; pushing the engine to the red line is then like trying to breathe through a straw while running.

While shopping around, you will find that throttle bodies arrive in a variety of sizes. This will beg the question of whether or not there’s such thing as too much; can a throttle body be too big?

Stay Within Your Realm: In the good old days, throwing a massive carburetor on a small engine was a bad idea. This is because a carburetor is a mechanical device; no matter how well tuned a carburetor is it’s still set to send a set amount of fuel and air into the engine solely based on the position of the throttle pedal. The problems presented were running an engine rich and never being able to get it run smoothly.

Throttle bodies on Silverados are linked to a series of sensors that manage to tune for you and theoretically, it should be able to compensate for the larger throttle body. However, massive throttle bodies are designed to work with massively powered engines. 

The ECU judges how much fuel will need to be sent to each cylinder based on the air that’s present in the manifold. Too much air may leave the ECU scrambling to compensate resulting in a poor tune. It's best to stay within the realm of your engine and pick a throttle body that’s just the right size.