NTS2KOC Road TestMajorHavoc Headrest Wind Blockers A wind-breaking analysis.
MajorHavoc Headrest Wind Blocker? • A pair of clear lexan sheets • Cut to fit behind the “cheese graters” in your headrests. • A snap to install • Low cost ($20) • Nearly invisible
One Minute Installation Literally a snap: • Slip fingers under plastic headrest backing, tug firmly. Backing snaps off. • Rest Wind Blocker against cheesegrater. • Snap backing back in place. • Ready to go! 1. Remove headrest backing with a firm tug. 2. Wind Blocker in place. Note four holes for backing snaps. Note: Blockers are clear lexan, but since we were using “demo” units, we left on the peel-off protective wrap, which looks blue… 3. Backing has four snaps. A firm tap or squeeze reinstalls. 4. Backing back in place, done!
Questions to be Answered • Do the Wind Blockers reduce wind in the cockpit? • Do they reduce noise in the cockpit? • Do they reduce the wind chill effect in the cockpit? • Are the Wind Blockers worth it? But how can we find out?
Test Methodology • Measure wind speed and ambient noise directly in front of the passenger head rest • Test various configurations • Windows up or down with… • Wind Blockers installed or removed at… • 25 mph, 40, 55, 70 and 85 mph (i.e., speeds equivalent to funeral, school zone, Dallas street, Plano street, freeway) • Compare the results • Wind, noise and wind chill improvements? • We provide the data, you be the judge!
Equipment Radio Shack Digital Sound Level Meter 33-2055 Honda S2000, MY2000 Stock, 41k Miles Top Down No Boot Cover Skywatch Meteos SW-3 Elite Hand-held wind meter
Set Up Wind speed meter, 4” from headrest grate*, level with bottom 1/3 of opening * Approx. equal to distance from grate to back of spouse’s neck. Data logging sheets Sound level meter, pointed at headrest opening
Run #1 Run #2 Procedure For each configuration, two runs were made, one in each direction, to minimize the effects of the prevailing wind. • Set windows and Wind Blockers • Start Run #1 • Set cruise control at proper speed • For 2 miles take sound and wind readings • Pull over, record readings • Turn around, do Run #2 • Change windows, Wind Blockers or speed to next test configuration • Repeat for 19 more round trips… Test Conditions Ambient temp: 78 Prevailing winds: NNE Windspeed: 2-18 mph RPM: 3500 - 4800 Sample of data logging sheet
Location Breckenridge Blvd. 25 mph and 40 mph runs. 1 mile each way. Prevailing Wind 2-18 mph GB Highway between Hwy 78 and Renner (Breckenridge) 50 mph, 70 mph and 85 mph runs. 6.25 miles each way.
And now, finally… The Results!
% Change in Wind Noise • With the windows up, the Blockers reduced wind noise at the passenger headrest by an average of 0.4% decibel (dB). Since dBs are logarithmic (each 10 dB is 2x as loud as the last), this reduction, though not large, is bigger than it appears. At 85mph, however, the Blockers increased wind noise. • With the windows down, the Blockers usually raised noise levels. Best guess: when the windows are down, more road noise is reflected into the cockpit by the Blockers.
% Change in Wind Speed • With the windows up, the Blockers reduced wind speed at the passenger headrest by an average of 45%, which is significant. At 85 mph, the reduction was a huge 84%. At 40mph, though, the Blockers increased wind speed slightly. • With the windows down, the Blockers generally raised wind levels somewhat. Best guess: windows down, the vacuum behind the car normally pulls wind over the doors and through the headrests. Windows up, there is more swirling behind the headrests, which the Blocker effectively stops from coming back into the cockpit through the headrests.
Change in Wind Chill • Assuming an ambient temperature of 50 degrees F, rolling up the windows reduces wind chill by 3.5 degrees. • With the windows rolled up, the Blockers further reduce wind chill by 1.82 degrees. • With the windows down, the Blocker increases wind chill very slightly (0.2 degrees). • Compared to windows down and no Blockers, rolling up the windows and installing the Blockers reduces wind chill by 4.45 degrees.
Conclusions • If you like to drive with the top down and windows up (as does your humble author), the Blockers significantly reduce wind and noise in front of the headrests, and reduce the “cold neck” wind chill factor. • If you prefer to drive “top down, windows down”, the Blockers are actually slightly counterproductive. • Being low cost and quick to install and remove, the Blockers can easily be an effective part of your S2000’s cool-weather “windows up” configuration.
Subjective Observations • We noticed the reduction in draftiness right away after installing the Blockers, before we ran any tests. We almost always drive with the windows up. • Any additional quietness due to the Blockers was not readily noticeable. But ambient noise is hugely and rapidly variable. The dB meter doesn’t lie, but ears are apparently more easily fooled. • Given the effect of cold drafts on the back of the neck and ears, the perceived “warmness” effect of the Blockers probably increases as the ambient temperature gets colder. • My usual passenger likes knowing her driver has taken all reasonable steps to ensure her comfort during cool weather drives at unreasonable speeds.
Other Observations • At any speed, rolling up the windows reduces cockpit wind and noise significantly. Since dB are logarithmic, a 9% reduction (i.e from 82dB to 75 dB) is ~7dB, or ~40% reduction in noise level.
Other Noise Observations • A passing luxury car increases cockpit noise by 3 – 4 dB, the same as a Harley at 100 yards. • A passing SUV with street tires increases noise by 4 – 6 dB. • Full throttle acceleration at any speed registers 87dB, the same as steady-state driving at 85 mph with the windows down • At all speeds including 85 mph, running with the top and windows closed (up) increases cockpit noise by 3 – 4 dB. Wind and external noise is apparently more than replaced by trapped mechanical and road noise.
Other Cockpit Wind Observations 0.5 mph – S2000 @ 40 mph, windows up 1.1 mph – S2000 @ 70 mph, windows up 1.2 mph – S2000 @ 25 mph, windows up 1.4 mph – S2000 @ 85 mph, windows up 1.7 mph – S2000 @ 40 mph, windows down 3.2 mph – S2000 @ 55 mph, windows up (strong ambient gusts); 70 mph windows down 4.3 mph – S2000 @ 85 mph, windows down 6.8 mph – S2000 @ 25 mph, windows down (strong gusts) 10.3 mph – S2000 @ 55 mph, windows down (strong gusts)
Other General Observations • Cruising at 55 mph in the slow lane on a mostly empty, new freeway, cars will line up behind you nose to tail, contentedly chewing their cuds and following along. • As indications that Honda really did put a lot of work into the aerodynamics around the headrests and roll bars: • During two runs when strong wind gusts were present (the 25mph and 55mph runs), having the windows up provided excellent protection from noise and wind increases in the cockpit. • The Blockers generally produce adverse results when the windows were rolled down. • As long as he gets paid, the toll booth attendant appears not to notice that the same guy in a black roadster with wacky cockpit gear has passed through 12 times in the space of 2½ hours…or maybe it happens all the time.
Never Asked Questions • Did you connect the meters to a laptop to record the data? • No, these were not meter-to-PC downloads, just “eyeball” readings off the meters’ displays. • Didn’t cars and trucks pass you during the test runs? • Yes, extraneous winds and noises frequently intruded, but we made efforts to “delete” them from our readings • Is this a scientifically valid test? • No, due to the above, the use of “hobby” meters, and the amateur statistical analysis. Unfortunately, I lent my wind tunnel and anechoic chamber to NASA last year and never got them back. • Do you have any background or training that would qualify you to perform this test? • None whatsoever. • So these results are invalid, scientifically and statistically speaking? • Completely. • So, then, you won’t be buying the Wind Blockers. • Wrong, SUV-breath! They work well when I want them most – on long drives through the cool fall and spring air with my honey beside me…