Throttle body spacers. Who'd have known so much controversy could surround such a small part? Most auto novices hear about throttle body spacers from a TV commercials, or from a friend who's been lucky with one installed for a few weeks. Ads claim noticeable gains in horsepower, acceleration, gas mileage and more. Some people who buy one get all of those things. Others don't.



For some, a throttle body spacer becomes a $150 paperweight, doorstop or garage wall decoration. The horsepower and throttle response are nowhere to be found, and their gas mileage has dipped while trying to find those elusive HP boosts. What's even worse, cheap throttle body spacers can be ineffective and excruciatingly noisy to boot. Specifically, drivers notice a high-pitched whistling coming from their new spacer. A lack of impressive results and an abundance of screeching usually lead to pulling the spacer as fast as it was put in.

How is it supposed to work? A throttle body spacer is designed to straighten the airflow snaking through the crooked plumbing of a vehicle's factory air box and intake tubing. The idea is that the straightened flow is much more prone to efficient atomization, pairing better with fuel molecules and burning more completely than before. Some spacers even offer another twist: a machined vortex pattern in the surface that swirls the incoming air, much like the integrated parts in GM's Vortec engines (you've probably also seen this in products like the Tornado).

Truth be told, throttle body spacers work quite well for some people who give them a shot. Some, like the Airaid PowerAid Throttle Body Spacer, boasts a bevy of online testimonials about the extra performance the purchaser feels in the seat of their pants after installation. Some even report a 1-2mpg boost in fuel economy. Other combinations of spacers and vehicles leave the driver with nothing to show for their cash?reviews like these litter message boards across the auto community.

Should you play this expensive game of roulette with a machined aluminum block which has no backup use if it fails to thrill? Absolutely not?which is why research is critical before making a purchase. First, read a trusted message board for enthusiasts who own your vehicle. Chances are, somebody has tried a throttle body spacer and posted a detailed account of their experiences for all to read. Look for a driver with your specific engine who tried the same spacer brand you're considering buying. Next, don't be persuaded by overwhelming opinions for or against the spacer. Look only for people who have actually tried the part out. Weigh the actual accounts, and you'll know whether or not to buy. Also, remember that everybody's driving style is different, which will make the experience different too.

To close it all up nicely, throttle body spacers work well in certain circumstances, and they're a complete waste in others. Do your homework before deciding to buy, focusing on real-world accounts from drivers with the same make, model and engine. That way, you'll be more likely to get the advertised horsepower and acceleration gains instead of dead weight.