Piston Slap: Buffeting Past the Helicopter Effect?

Sajeev Mehta
by Sajeev Mehta

Scott writes:

Hi Sajeev!

I have a 2015 Civic, but my question applies to lots of cars.

I live in Maine, which has lots of nice weather for driving around with the windows down. The buffeting, or “helicopter effect”, with the windows down is driving me batty! Also the “white noise” of the rushing wind is quite loud when the windows are open. I can adjust the windows to limit both issues somewhat, but is there anything else I can do?

Seems like they used to sell rectangular plexiglass air deflectors that mounted on a car’s A pillar. Is anything like that still available? Would stick-on side window deflectors help? I’m not keen on them because all of them I see are tinted, and visibility is already limited enough by the car’s thick A pillars. (True dat. – SM)

Sajeev answers:

Aeroelasticity is one of those fascinating sciences that scared me far, far away from a Mechanical Engineering degree. There’s even a software company hawking a solution toolbox to minimizing wind throb. I’m sure it’s only a million or so to get an R&D lab to work it out perfectly!

Cars have ways of reducing the air pressure concerns that lead to buffeting, wind throb, the helicopter effect or whatever you wanna call it. There are flapper ducts in the trunk that make it easier to close doors, circulate fresh air and maybe even to ensure the airbags inflate properly. Sunroofs have pop-up visors. Side view mirrors, headlights and fenders are sculpted to move air more efficiently/quietly around the body side. Everything is can be designed for good reason.

My first car, a 1965 Ford Galaxie 500 LTD, had a flow-through ventilation system; drawing in air from the kick panels (both sides), sucking it out behind the rear window. It rocked on those rare occasions when Houston had Maine-like weather. I never cracked open the windows unless I wanted the wind in my hair or to peep that sweet pillarless hardtop design. Ahhh, memories!

So can you improve the factory’s built-in tech? Probably. I’ve had good luck reducing buffeting by tilting my moonroof after finding no correct combination of cracking open my windows. If your Civic has one. If not? Well, I’d have it installed nearby: what a great way to enjoy Maine summers and/or global warming!

If a moonroof is not helping, too expensive to retrofit, not your cup of tea…well you could…

Yeeeeesh, those are surprisingly unsightly! The tilting moonroof is the right answer.

What say you, Best and Brightest?

[Image: Shutterstock user OmniGrace]

Send your queries to sajeev@thetruthaboutcars.com. Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice.


Sajeev Mehta
Sajeev Mehta

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  • Lorenzo Lorenzo on Sep 12, 2015

    When I was in high school, my older sister would roll down all the windows in her '57 Pontiac Chief and crank up the radio. Compared to Elvis and the 4bbl V8, the wind noise was a minor irritant. It was fun waving back to all the pedestrians waving at us, though.

  • JakeC JakeC on Feb 24, 2017

    You are absolutely right, there’s nothing more annoying than the ‘helicopter effect’ on a roadster while trying to relish a top down cruise. I had to endure this bogey for some time until I decided to go for an external wind deflector. Thanks to the Windblox windblocker now I need not shout my jugular out to get myself heard.

    • JaneWill JaneWill on Oct 01, 2017

      Windblox windblocker is definitely one of the best draught-stops in the market. I too have one affixed on my ride and now my cabin is devoid of all gust gremlins.

  • Joe This is called a man in the middle attack and has been around for years. You can fall for this in a Starbucks as easily as when you’re charging your car. Nothing new here…
  • AZFelix Hilux technical, preferably with a swivel mount.
  • ToolGuy This is the kind of thing you get when you give people faster internet.
  • ToolGuy North America is already the greatest country on the planet, and I have learned to be careful about what I wish for in terms of making changes. I mean, if Greenland wants to buy JDM vehicles, isn't that for the Danes to decide?
  • ToolGuy Once again my home did not catch on fire and my fire extinguisher(s) stayed in the closet, unused. I guess I threw my money away on fire extinguishers.(And by fire extinguishers I mean nuclear missiles.)
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