Stay Away From Throttle Body Spacers

The engine in your Tundra is essentially a giant air pump – the more air that you can get into your motor, the more fuel that can be mixed with it and then combusted in order to generate more horsepower. There are a lot of different methods out there designed to help an engine “breathe” and maximize its power potential. Truck owners install performance air filters, cold air intakes, and even superchargers in order to get the most airflow possible, all in a chase for that extra horsepower edge.

There are some products out there that claim to be able to improve on the already significant engineering that has gone into your motor. Some of these products, like performance air filters and cold air intakes, work as advertised. These accessories improve performance because they trade an increase in performance for an increase in something else. In the case of air flow, it’s usually a trade between increased engine noise and an increase in power (not to mention expense).

Unfortunately, these usually simple enhancements sometimes claim excessive increases in horsepower and fuel mileage. We’ve tested a few cold air intakes and none of them matched the results printed on the box. Having said that, none of them disappointed us. However, one device that we have a hard time endorsing is known as a throttle body spacer.

We don’t recommend AirRaid’s throttle body spacer, or any other brand of throttle body spacer, for the Toyota Tundra (or any other modern fuel injected vehicle).

Designed to be installed between your truck’s throttle body and its intake, these devices, such as the PowerAid made by Airaid, claim to be able to create an intense “vortex” of air which will help better atomize fuel when the two are mixed together. According to the manufacturers, this is accomplished by a series of grooves which are carved inside the device itself.

Unfortunately, there are some flaws behind the engineering in this device. From a common sense perspective, if it were really that easy to add significant amounts of horsepower or fuel mileage gains, then these spacers would be stock equipment from the factory. Automakers need every competitive edge they can get in today’s market (especially when it comes to fuel economy) and none of them are leaving anything on the table in that area. The idea that a “vortex” could help the air and fuel mix together is not a bad one, but in the modern fuel injected engine air and fuel are not mixed together until they both find themselves in the cylinder [correction] air and fuel are mixed together inside the intake manifold, relatively far away from the throttle body prior to combustion.

In primitive forms of fuel injection (such as throttle body injection or old-fashioned carburetor models), where fuel was sprayed directly at the throttle body and then mixed with the air immediately before being routed to the cylinders, then perhaps a spacer would be of some benefit. However, the technology used in the Tundra’s multi-point fuel injection system precludes any useful effect from such a device. The chances that the air would still be feeling the effects of a vortex by the time it got through the intake to the cylinder are very low.

UPDATE: The Tundra 5.7 and 4.6L V8’s have something called ACIS, which stands for Acoustically Controlled Induction System. This system varies the airflow inside the intake manifold depending upon engine RPM in an attempt to generate a vortex and improve fuel mixing. While this is the same technique a throttle body spacer is supposed to employ, most Tundras already have this feature. If you own a 5.7 or 4.6 Tundra, do not but a throttle body spacer. You’ve already got ACIS.

If you drive anything other than a Tundra, we still don’t recommend a throttle body spacer. They rarely add more than 1 or 2 hp, and that’s just not cost effective. Your money can add more horsepower elsewhere.

Bottom Line: We do not endorse the use of a throttle body spacer on any modern fuel injected engine. Save your money and put it towards something else. A K&N performance air filter, for instance, costs half as much and it will definitely improve your engine’s performance and fuel economy.

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