Rick's Free Auto Repair Advice

Do Cold Air Intakes work?

cold air intake

Cold air intake myths and legends

If you’re reading this, you’re already wondering if an aftermarket cold air intake is better than the factory intake. Here’s a tip to sorting out all the conflicting information you’ll be watching and reading. Every source that says they add a lot of power to your vehicle is a source that has a horse in the race. They usually sell racing parts, so of course, they’re going to want to sell you an aftermarket cold air intake.

I don’t sell parts so I have nothing to gain.  I’m coming at this strictly from a technician’s point of view with the knowledge I’ve gained from engine designers.

Cold air intake manufacturers make lots of promises. But they also make a lot of “slight-of-hand” comparisons. For example, they often compare the results of their aftermarket cold air intake to a factory intake thats’ drawing air from under the hood. That’s not a fair comparison because just about every fuel-injected vehicle made in the last 20 years comes from the factory with a tuned cold air intake.

If you make no other changes to your stock factory vehicle, a cold air intake will NOT deliver better gas mileage or more power.

Aftermarket cold air intake manufacturers want you to believe that the factory intake is substandard because it restricts airflow into your engine. What they fail to tell you is that the throttle body and valves are the biggest restrictions in the engine. You can’t overcome those restrictions by using a larger intake pipe or larger exhaust pipe. You’re still limited by the size of the throttle body and the size of the valves.

Aftermarket cold air intakes actually reduce performance

Factory intake systems are already cold air intakedesigned to give maximum performance. First, they already take in cold air from outside the engine compartment.

Second, the air filter box and ductwork is factory tuned to minimize air turbulence going into the MAF sensor and the throttle body. If you change the ductwork,  you screw up the factory tuning. Don’t believe me? Read this piece from the July 13, 2013 article of Brake & Front End magazine. This is a trade publication written for professional mechanics.

“Turbulence in the intake air stream can also affect MAF sensor calibration.” – Brake & Front End, July, 2013

Still don’t believe me? Watch this complete diagnosis on a Ford F-150 5.4 fitted with a CAI. It’s an 18-min. video and all the owner’s problems come down to the CAI with poor laminar flow across the MAF from the crummy design on the aftermarket air intake.

cold air intake

Here’s the important point to remember; the original equipment air filter and intake air box are specifically designed to reduce turbulence of air flowing into the MAF sensor. Replacing the original equipment air intake system with various customized intake systems can increase air turbulence and, thereby cause a calibration error resulting in an engine performance complaint.

Still don’t believe me? Read this from one of the major mass airflow sensor manufacturers:

“Mass airflow sensors require laminar airflow, which occurs when the air flows in parallel layers, with no disruption between the layers. The MAF element only samples a small part of the incoming air stream, so if the laminar flow is not present, the air measurement and fuel delivery will be incorrect. Some older vehicles have a diffuser installed, but most rely on the air filter design to provide laminar airflow.

It’s crucial to have an OE-design air filter. Some oiled filters can get over-oiled, which ends up contaminating the MAF sensor and causing worse performance.  Some cheaper replacement filters have a different design that alters the airflow direction, thus skewing the reading of the MAF.

Make sure there are no “performance” airflow devices installed in the air intake. These devices will disrupt the planar airflow that is crucial to accurate MAF readings.”

So aside from the fact that aftermarket cold air intake systems don’t provide any better power or gas mileage over the factory intake systems, they can actually decrease performance.

To understand why aftermarket cold air intake kits don’t do what they claim, see this post.

Save your money and pass on the cold air intake.


© 2012 Rick Muscoplat



Posted on by Rick Muscoplat

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