Mike in Chi

The current thread on the highest speeds attained in a 993 mentions some of the speeds were attained at night.

Anyone know the effective range of the standard headlights on a 993?

According to R&T, a 996 takes 119 feet to stop from 60 mph, 204 feet to stop from 80 mph.

My calculator says at 120 mph you are covering 350 feet every two seconds.

At some point you obviously can't stop in time, once you see something unlit in your path.

I'm curious as to what speed that would be with a normally illuminated 993?

There is nothing in the manual about effective illumination distances.

Anyone know?

TIA M in C

Bill P.

Mike, great topic and something I have often thought about. I imagine that a lot has to do with reflection, etc. Same thing applies to following the car in front. If they slam on the breaks or move to avoid an object, you MUST have enough room to stop or you are following too close. In that vein, we need to remember how quickly our cars stop and leave room for the car/s behind to avoid US.

I think of these things every time I read of the massive pile-ups that occur in the fog from time to time. Sheesh, what’s wrong with these people? Talk about being victimized!

Regards,

Bill

Randall G.

>At what speed are you outdriving your headlights at night?

3.01e8 m/s, the same if you have your headlights on during the day.

Ray Calvo

With my night vision, about 30 MPH.

Speedraser

Could be wrong about this, but I thought 60 mph is 88 ft/second. No calculator handy, this is just from memory.

H20NOO

Mike,

I believe you outdrive your headlights at about 186,000 miles per second.

MC <img src="graemlins/roflmao.gif" border="0" alt="[hiha]" />

maurice97C2S

On a slightly more serious note, I was very grateful for my HID conversion on Sunday night in the aftermath of the storms we had in the UK.

On my outward journey the main road to the M40 motorway was blocked by fallen trees in several places, so I went 'the back way' on my return journey. I had been stuck in a jam for the last ten miles of the M40, so was 'impatient' to get home. The back road was fine until, about a mile from home, I came round a corner, there was no road any more, a forest had taken over. The tree trunk was much thicker than the 993......... severe ABS moment, and just as well I was down around 50 mph!

Still determined to improve high beam, even bought spare headlights to investigate fitting projectors to high beam, or flipping the low beam cutoff plates out the way, but can't see a good way to do it. Maybe aux lights will have to go on!

Cheers, Maurice

Mike in Chi

Ahh, some very amusing answers.

H2 -- But doesn't time slow down at the speed of light, so wouldn't the light catch up with you?

Bullitt - Ya mean you haven't bought that option yet that allows you to outrun 'em?

Speedraser Yep at 60 mph you're going a mile a minute, so 5280ft / 60 sec = 88, at 120 it's 176 ft/sec and in two seconds it's actually 352 feet. But what do I know, I'm a word guy...

Seriously, I remember reading about some accident, involving a Lambo as I recall, that got in a wreck at night or this reason.

M

Jim Michaels

An excellent question. I appreciate the chuckles, but still would like to know the correct answer. Of course, it depands on just how good the headlights are at illuminating the road. I suspect that most of us are often outdriving our visibility; I'm pretty sure I am. I can see the edge of the road and the center line, I know where the road bends, but I'm still driving on faith that there is nothing big in my lane beyond my headlight's reach. I remember when my father let me drive for the first time at night. I couldn't see squat and was poking along so slowly even my dad ask me to go faster (in the day time he had to tell me to slow down). Now I have developed enough blind faith to overdrive the headlights regularly.

I think most collisions with deer are due to not seeing them in time to slow enough. I assume that deer can see our headlights before we can see them, but headlights apparently mean nothing to deer. Famous last words: Hey; what are those two lights over there?

KC993

Just my 2 cents....
I used to drive to OK. City and to Hot Springs AR. every other weekends and always at night... In pitch black condition 110 to 120 is about as fast as I am willing to go in low beam, tried 130 for awhile in high beam but gotten flashed by oncoming traffic.
If the freeway were lighted well then there is no problem at all( then again I think we all know this <img src="graemlins/c.gif" border="0" alt="[ouch]" /> )
It also depends on how late and sleepy I was... Kenny Loggon's "Danger Zone" from the movie "Top Gun" helped a lot at 3 o'clock in the morning...

cmoss

Randall G
[quote] 3.01e8 m/s <hr></blockquote>

Hmmm... Is that why your car looks so short when it goes by?

There once was a fencer named Fisk,
Whose thrust was exccedingly brisk,
So fast was his action,
The Fitgerald-Lorentz contraction,
Turned his rapier to a disk.

Cheers,
Chris

STLPCA

[quote]Originally posted by cmoss:
<strong>... The Fitgerald-Lorentz contraction ...</strong><hr></blockquote>

One of the great things about Rennlist and it's diverse posters is that I find I learn something new almost every day - usually it's about cars, but today it was Relativity Theory (not that I understand it).

Mike
I haven't been able to locate source material, but years ago there were published car mag & lighting supplier tests of effective headlight range. As I recall, at surprisingly low speeds (70-80mph) you were at the very limits of low light reaction time + braking distance for a non-reflective target (e.g., animal, person, road debris) in the middle of the lane w/low beams. High beams didn't get you up to high speed visibility. Those tests prompted all the sportscar/rally folks to add Lucas/Hella/Marchal/Cibie halogen pencil beam driving lights. Oem lighting has gotten better since then, but a cursory web search came up empty.

It's all academic for me - I'm w/Ray on this. <img src="graemlins/crying.gif" border="0" alt="[crying]" />

Mike in Chi

Hi Dan

[quote] As I recall, at surprisingly low speeds (70-80mph) you were at the very limits of low light reaction time + braking distance for a non-reflective target (e.g., animal, person, road debris) in the middle of the lane w/low beams. <hr></blockquote>

I suspected it might be a lot lower than one would think. I imagine our cars with their superior brakes would allow a higher speed, but...

I too had a near miss. Mine was with a deer when I was playing around on the back roads near Road America. It caused me to rethink what is safe, even for a P-car at night.

I remember reading that the Le Mans cars in the 70s and early 80s (at 225-250 mph), even with all the lights they used, were basically faster than what was illuminated, or what the driver could safely react to.



Mike