Aftermarket Air Intakes? Fact or Fiction

Very little measurable gain using these. The OEM's aren't going to give up several HP by using an air filter that is too small given how HP crazy people are today. At best you =MIGHT= see 2-3HP and at the same time gain a BUNCH of intake noise. Also some designs draw hot air from the engine bay which hurts power..

What people "think" is: this is making a huge difference because of all the noise, just like those "fart can" mufflers make a car sound faster while doing nothing for the actual performance. Anyone who claims more MPG is

-wrong-, the stock air box/filter can easily deal with cruising air flow.

fiction

yes

The stock cold feed duct on most cars is rubbish, they usually have a restrictive S bend in them causing about 1/3 of total inlet pressure drop. Just change the OEM filter 2-3 times more often and add extra cold air duct or ducts into the dirty side of the filter housing fed from high pressure areas in front of the slam panel. Will work as well if not better than a hot air induction kit.

Typically about 3-5% of inlet pressure loss is due to filter when it's new and clean. K&N claim their filter reduces the loss due to filter by 10% so that's just 0.3-0.5% reduction in total intake loss. They also claim about 4% power gain - all due to removal of intake snorkel.

Thanks for thoughtfull response!

Peter, that sounds like the voice of a designer speaking. Mind sharing your background in this subject?

Dave

I work as an Engineer for an engine maker based in Derby, England.