Stumbled on a stat that cold air intakes barely do anything on modern cars

I was reading through some airflow tests on a forum last night and found out most stock airboxes flow better than aftermarket intakes under 5000 RPM, has anyone else seen actual dyno sheets backing this up?

2 comments

2 Comments

theaw651mo ago

...and it reminded me of a buddy back in the 90s who swore his K&N filter added 15 horsepower to his Mustang. He could feel it, he said, the whole car just pulled harder. We never did get it on a dyno though. Turns out he'd also put a bigger throttle body and some headers on at the same time, so who knows what was doing what. I remember another guy at a car meet who had a big cold air intake on his Honda and it just sounded like it was sucking in gravel every time he revved it. Still, he was real proud of that noise.

dakota_fox1mo agoTop Commenter

@theaw65 you're right that the butt dyno is basically useless, but K&N filters do give a real gain on certain engines that are choked from the factory. The old 5.0 Mustangs came with a super restrictive airbox and snorkel setup. Swapping just the filter element and removing that intake silencer can actually free up 5-8 hp on a stock one if you also cut the airbox. 15 hp is still a stretch though, that's probably mostly the headers talking.