View Poll Results: When you put down your headlights does your car speed up?
Yes
14
46.67%
No
11
36.67%
Not sure
5
16.67%
Voters: 30. You may not vote on this poll
When you put your headlights down does your car speed up?
06-10-10, 09:01 PM
#1
When you put your headlights down does your car speed up?
Like it says, when you put your lights down does your car speed up? Yes, no or not sure.
Mine does. I was wondering about this because there always seemed to be a subtle thrust when I put them down. So I tried a scientific experiment. On a flat road at cruising speed (70 mph on the interstate) I put the lights up, then down, carefully measuring the small thrust change with my internal thrustometer. Sure enough, two out of three times I got a good reading (the other might have been a problem with a crosswind).
So I was wondering if any of you guys were seeing the same thing?
Mine does. I was wondering about this because there always seemed to be a subtle thrust when I put them down. So I tried a scientific experiment. On a flat road at cruising speed (70 mph on the interstate) I put the lights up, then down, carefully measuring the small thrust change with my internal thrustometer. Sure enough, two out of three times I got a good reading (the other might have been a problem with a crosswind).
So I was wondering if any of you guys were seeing the same thing?
06-10-10, 11:21 PM
#4
Wrkn Toyota, Rootn Wankel
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Internal Thrustometer? Hmm... Ray are you making up old school tools again? LoL
Maybe those headlights really slow you down in terms of wind resistance, I find it hard to believe that its that noticeable, but I've heard of weirder stuff with our cars.
Maybe those headlights really slow you down in terms of wind resistance, I find it hard to believe that its that noticeable, but I've heard of weirder stuff with our cars.
06-10-10, 11:46 PM
#6
Jolly Green Giant
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I remember reading somewhere for the first gens the headlights up increase wind resistance from .36 to .38 so it could be attributed to that, I do know when I put my headlights down whilst cruising on the highway I can feel it ever so slightly.
Stevan, I love that bumper in your Avvie...would make for some nice night time driving so you wouldn't have to put the headlights up in the first place.
Stevan, I love that bumper in your Avvie...would make for some nice night time driving so you wouldn't have to put the headlights up in the first place.
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06-11-10, 06:16 AM
#8
Waffles - hmmm good
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Putting the headlights up does add wind resistance as stated but I would
serisously suspect your ignition Ray. Let me know if you want to build one
like mine. Ford and Chevy ignition parts FTW!
serisously suspect your ignition Ray. Let me know if you want to build one
like mine. Ford and Chevy ignition parts FTW!
06-11-10, 08:49 AM
#9
I agree with many above....
It's obvious that the car is more aerodynamic with the headlights down, but you'd have to have a very sensitive "thrust-o-meter" in order to actually feel a difference.
I'm not buying the added drag from the alternator either.
It's obvious that the car is more aerodynamic with the headlights down, but you'd have to have a very sensitive "thrust-o-meter" in order to actually feel a difference.
I'm not buying the added drag from the alternator either.
06-11-10, 09:10 AM
#10
I should have mentioned, this test must be done on a perfectly tuned car with no mechanical issues such as a weak alternator or an ignition issue, neither of which my DD the Silver One has, of course.
Tim you know my ignition is always in perfect condition! GM parts in a 1st gen, in a mint SA, no less? Sacrilege I say!
Also, for useful results, the driver must be completely free of mind altering medications.
It helps if you really know your car really well, drive it daily for many miles so you are sensitive to it's most subtle changes. That's the case with the Silver One and I've discovered that she prefers her headlights down.
Tim you know my ignition is always in perfect condition! GM parts in a 1st gen, in a mint SA, no less? Sacrilege I say!
Also, for useful results, the driver must be completely free of mind altering medications.
It helps if you really know your car really well, drive it daily for many miles so you are sensitive to it's most subtle changes. That's the case with the Silver One and I've discovered that she prefers her headlights down.
06-11-10, 09:43 AM
#11
Lives on the Forum
Maybe my "thrustometer" (which is external, btw since I am male) is faulty, but I'm not sensing it at all. I would think this might be caused by a slightly weak battery, forcing the alternator to carry the full load while the lights are on. Maybe a weak ground could do the same thing. 
.
.
06-11-10, 10:27 AM
#13
Well, physics dictates that any energy emitted from a free object must exert an equal and opposite reaction, and the headlights are emitting 110 watts worth of photons out the front of the car...
That equates to a 0.15 HP rearward thrust.
That equates to a 0.15 HP rearward thrust.
06-11-10, 10:32 AM
#14
Waffles - hmmm good
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We can rule out the whole electrical issue by putting them up manually with the
little toggle switch in the console and leave the lights off.
You should get one of those portable performance thingies with the built in GPS
and force sensors so we can measure this. Sounds like a great experiment for
the track at ZoomFest!
Ray, your ignition is weak, you just don't know it
When my hoods closed you can't tell there's anything unusual under there,
so its ok in my book.
I voted yes in the poll just so you know.
little toggle switch in the console and leave the lights off.
You should get one of those portable performance thingies with the built in GPS
and force sensors so we can measure this. Sounds like a great experiment for
the track at ZoomFest!
Ray, your ignition is weak, you just don't know it
When my hoods closed you can't tell there's anything unusual under there,
so its ok in my book.
I voted yes in the poll just so you know.
06-11-10, 11:04 AM
#15
FB=OS Giken LSD
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I used to notice it in my GXL. However, since I had removed my ac, I was driving around NM with the windows down (hot) and there would be a lot of wind buffering inside the cabin. However, with the headlights up, the buffering was much lower as the headlights would deflect the air around the car and not billowing through the cabin, so I know it does make a difference on low powered cars around 80mph.
Please reference my highly tenical drawings below:
Headlights down: |II|
Headlights up: /II\
(*Note: The above drawings do not acurately portray anything and are not to scale)
I would be interested in a MPG test as I think that is more accurate than an internal or external thrustometer. On a side note, try placing the thrustometer out the window at 80mph and see what happens.
Please reference my highly tenical drawings below:
Headlights down: |II|
Headlights up: /II\
(*Note: The above drawings do not acurately portray anything and are not to scale)
I would be interested in a MPG test as I think that is more accurate than an internal or external thrustometer. On a side note, try placing the thrustometer out the window at 80mph and see what happens.
06-11-10, 11:20 AM
#16
There's your problem right there Ray!! 
Sorry, I couldn't resist. I used to notice this in the first 1985 GS that I owned. It was really noticeable when I was on the interstate. I think it is probably just attributed to wind resistance. I never noticed the problem unless I was on the interstate. Cruising around town at night with the lights on at lower speeds had no effect. It was only high speed operation on the interstate, that I noticed change. That car had quite a few performance upgrades too, so I don't think it was ignition related in my case.
Sorry, I couldn't resist. I used to notice this in the first 1985 GS that I owned. It was really noticeable when I was on the interstate. I think it is probably just attributed to wind resistance. I never noticed the problem unless I was on the interstate. Cruising around town at night with the lights on at lower speeds had no effect. It was only high speed operation on the interstate, that I noticed change. That car had quite a few performance upgrades too, so I don't think it was ignition related in my case.
06-11-10, 01:20 PM
#17
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a couple of my friends have 89 civics, and since those only generate .2hp stock, the .15hp the headlights use is significant!
oh and the power is so low on those things you actually do need an internal thrustometer to measure it
the Rx7 is different of course...
06-11-10, 04:10 PM
#18
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It makes perfect sense! I can't argue with those maths.
06-11-10, 04:42 PM
#20
Environmentally-Hostile
06-11-10, 05:58 PM
#21
Michael, I was on my way home from work, fully eligible to conduct the test.
I think that DD has found the explanation, the speed up is mostly caused by the Forward Photon Force (FPF). Here's what he claims:
"Well, physics dictates that any energy emitted from a free object must exert an equal and opposite reaction, and the headlights are emitting 110 watts worth of photons out the front of the car...
That equates to a 0.15 HP rearward thrust."
DD's FPF, combined with the Streamline Efficiency Index (SEI - exquisitely refined by the Mazda engineers in the 1st gen design) probably accounts for the increased Forward Thrustometer Force (FTF) that I'm seeing.
FTF = [3(FPF + SEI)] x URC
where URC = Universal Rotary Constant
Nice work DD!
You guys who say there's no effect probably haven't done the test, can't get your headlights down or have the sensitivity of a Neanderthal with a dysfunctional thrustometer.
__________________
I think that DD has found the explanation, the speed up is mostly caused by the Forward Photon Force (FPF). Here's what he claims:
"Well, physics dictates that any energy emitted from a free object must exert an equal and opposite reaction, and the headlights are emitting 110 watts worth of photons out the front of the car...
That equates to a 0.15 HP rearward thrust."
DD's FPF, combined with the Streamline Efficiency Index (SEI - exquisitely refined by the Mazda engineers in the 1st gen design) probably accounts for the increased Forward Thrustometer Force (FTF) that I'm seeing.
FTF = [3(FPF + SEI)] x URC
where URC = Universal Rotary Constant
Nice work DD!
You guys who say there's no effect probably haven't done the test, can't get your headlights down or have the sensitivity of a Neanderthal with a dysfunctional thrustometer.
__________________
06-11-10, 06:27 PM
#22
Caramelldansen
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Saw someone post a diagram from a brochure showing the pressure zones of an FC once, was pretty interesting but didn't really understand it.
06-13-10, 12:31 PM
#24
Could be useful DD, kind of like that pass button they're using in Formula 1 these days.
So the poll results are in and they confirm that putting your headlights down causes your FB to speed up noticeably (11 yes, 9 no, 4 don't know). Thanks guys, time to send this thread to the archives.
So the poll results are in and they confirm that putting your headlights down causes your FB to speed up noticeably (11 yes, 9 no, 4 don't know). Thanks guys, time to send this thread to the archives.
06-13-10, 06:09 PM
#25
I used to notice it in my GXL. However, since I had removed my ac, I was driving around NM with the windows down (hot) and there would be a lot of wind buffering inside the cabin. However, with the headlights up, the buffering was much lower as the headlights would deflect the air around the car and not billowing through the cabin, so I know it does make a difference on low powered cars around 80mph.
Incidentally, since this is a first gen question, I refrained from voting lest I corrupt the important scientific data collection.