In a TL-S discussion someone asked how fast the thing could go. The discussion has progressed to the point where a TL-S owner says those of us TL-P drivers who reported speeds approaching 150 were misled:

"You got to remember that the spedometers are 'off' at that kind of speed. 152 on the spedometer is probably more 1ike 145 mph."

Well, I offered the following response:

"If they're off, then how can you assume that they're over-reporting vehicle speed? How do you even know that they are off?
I can come up with an explaination showing that the opposite is true, that at high speeds the speedo actually shows lower than true speed.

Consider centrifugal force - when something spins, it wants to spread out. In fact, the earth actually bulges at the equator due to this effect. If your car was going 140mph+, then wouldn't the tires bulge a little, too? And when they do, they'll have a larger circumference, and therefore rotate fewer times for each unit of distance covered. Hence, speed shown on the speedometer would be lower than actual speed."

Comments/suggestions?


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'01 White Diamond Pearl 3.2TL
-Wing, tint, wood and Whistler

 

True, the centrifugal force would cause a slight buldge of the tires, increasing diameter and thus providing a longer time period to complete a rotation. This longer rotation period, however, would be proportionally influenced by the decreased friction seen at the tire/road interface, which would actually allow the car to register higher speeds than it is actually performing. The decreased friction is assumed by the decreased surface area of tire contacting the road, which results when the tire buldges. I think (and I am by no means a physicist) that an increased diameter will result in an increased angular velocity at the center of the wheel, which will account for the higher velocity (mph) on the speedometer. I could be way off, though...

 

Hmm, interesting point doc, but let's re-evaluate that friction thing:

Sure, if the tires bulge out you'll have less friction, but do you really think the tires will be peeling out? At 150mph?!? We're not talking about high-G acceleration at 150mph (although I wish my TL would accelerate hard enough at 150 to peel out), we're just doing indicated speed vs actual.

Something else that just occured to me is that at high speed, the tires will be hotter, and so will the air inside. Said air will expand with heat, causing further bulging and subsequently reducing indicated speed.

Either way, I doubt that the speedometer is really that accuate to begin with, but suffice to say that the TL hauls butt...

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'01 White Diamond Pearl 3.2TL
-Wing, tint, wood and Whistler

<FONT COLOR="#800080" SIZE="1" FACE="Verdana, Arial">[This message has been edited by Gomez on April 01, 2001 @ ]</font>

 

That is totally metamusiel. The propagation of the marginal - excuse me, vaginal - smegma increase in expoliation would never lead to the circumcision of the rectoral simulacrum.

 

lol

 

I would have to agree with the statement that anyone without fiarly signifigant modifications could not be travelling over 150 in their regular TL... It is my understanding that the TL was limited to 140mph electronically. But even if that is not the case, the book says it will only do 140. If Acura is right, and 140 for a 3400 pound car with only 225 hp is about right. So if you are registering 155, something is wrong, the TL isnt that fast. I owned a 500 hp mustang before my TL. At speeds over 120 or so, the wind resistance is so incredible. It takes a LOT of HP to increase a very little bit of top end speed, so please dont reply with well, a stock TL can go 140, so with my home maid CAI and my 2 red type R badges, my TL can easily do 197 mph... I know BMW intentionally set the speedo of the z3 to be off by about 5 mph at 60-70 mph so that people would have fun thinking they were going fast. This was confirmed with a call to the BMW service deparment. So if the Acura is off by say 5mph at 70, so it would be registering 75. At 140 it would register 150. And conversily at 35, you would actually be doing 32.5... So whatever, it is a mute point. If someone tells me that they can do 155 in their stock TL or even slightly modified TL, I would tend to think 1 of 2 things... Either that car has a slight speedo error of about 5%, or that person is a liar.

 

Since the original discussion was about the TL-S and TL-P top speeds, wouldn't an error on the TL-P speedo also exist onthe TL-S? In fact, if I designed the cars, I would keep the "error" consistant so that if a TL-P driver were to move up into a TL-S, the top speeds read on the speedo would go up. Otherwise, if the TL-P speedo were off, but the TL-S was not, the driver who upgrades would/could be disapointed when it seems the S was topping out at the same speed reading.
As for actual top speeds...I think I'll never personally experience it, not in the TL anyways.

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1999 Satin Silver TL Dunlop SP9000 215-45/17-mounted on CL-S 17" Rims
H&R Springs-Axiss MetalMasterPads-Crossdrilled Rotors
-Inspire Tailights-20/30/40 tint

MY2000 S2000 Honda Roadster
- Mingster Aeroscreen, Smokin Front mesh Grill, Clear Sidemarkers...

 

You guys are too much, lol.

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2001 Acura 3.2TL w/ Navi Black ext. Ebony int., Sunroof Visor,
35% Smoke Metallic Tint, Burlwood Shiftknob, Alpine CHM-S620 6-disc cd-changer

In da works...
Video in my Navi Kit. & Playstation 2(Almost Done)
New Paint Job(Should be done this weekend)
JL Audio 12w6 Sub. & Audiobahn A1800E Amp.

 

How about this... measure your tire circumference when the tires are fairly warm. Write down what the RPM's are when you are doing your top speed run, and as long as you know the gearing for your 4th gear and final gear drive, you can calculate how fast your car was actually traveling. I don't know all the exact math, but if you know the RPM's your engine is turning, the gear ratio of the transmission, and the circumference of your tires then it should be a relatively simple plug it in and solve equation.

 

That caused an In Living Color flashback. Damn, that show was FUNNY!

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Jason
<A HREF="http://www.adamoski.com/acura.html" TARGET=_blank>

</A>
2000 Acura 3.2 TL w/ Navigation
Satin Silver / Ebony Interior
Comptech Headers & Exhaust
Comptech Springs & Sways
Comptech Air Filter
Factory Spoiler & CD Changer
Burlwood Shift Knob
30%? Tint, Tinted Rear Plate Cover
Removed Acura & 3.2TL Badging From Trunk
Removed Front Plate Holder

 

Well, I don't know for sure how fast I was going. My speedometer was showing 147 mph. This was done at SR 80. After about 130. It took the car about 2-+ minutes to reach 147 mph. I was clock by the state tropers at 104 the other day on I-95 in west palm beach FL. My radar showed laser, but it was too late. My speedometer was showing 115, before I apply the breakes. With all my driving experinece I will assume I lower my speed to about 110, but not 104 before I was clock. By this been said. I belive the speedometer is off By a little bit. If you are wondering. I was not taken to jail. The ticket was $269.00 dollars. It was two tropers in two cars. I had to wait 2 about a minute on the side of the road, before they came. Case close. Oh I pleged not guilty.

 

LOL... I was gonna post something similar but after I finished reading all the posts... I'm lost... what are we talking about here... I seem to remember vaginal circumcision....

 

My car is a lease, if my car is registering 75 miles per hour on the spedo, but I am actually doing 70 mph, then I am gettting screwed for mileage. I pay to get 12,000 miles per year.

Anyone hear of arguements toward mileage credit or lawsuits?

Thanks.

 

I have seen studies done on this problem. Conclusion was odometer is usually much more accurate than the speedometer. My speed reads about 2-3mph fast over 60 mph but my odometer seems to be right on the money.

 

so just buy yourself some 20" rims and now you can get about 13,183.56 miles a year instead of your normal 12,000. By the way i just pulled that figure out of my a$$.

 

i hav a 00 tl and was clocked buy a buddy of mine who works for the sheriffs dept, we went out on a big country road by my cottage and he had me clocked at 156 and my spedo showed 161-2ish we also toped his 99 maxima out at 147. we both have cai's and exhausts.
just my .02

 

This thread sounds too much like my physic class. We're doing centripedal and centrifugal force and that friction too.

 

Odometer and Speedometer both use different speed sensors. My odometer is dead accurate. My speedometer is off approx 8% at 75mph (which the dealer verified through their methods). I cannot get Acura to fix because their specs allow plus or minus 10%. Not sure if the 8% error is linear across all speeds. I think they prefer to have speedo's read high for obvious reasons.

 

Stop worrying about triple-digit speeds cause anything usually over 65 mph is illegal.

 

well said

 

guyz,
if your doing 145+, does it really matter? all you have to say to your friends is "yah, spent 3 days in jail last week" lol!

 

All you need is a stopwatch and an expressway. Time yourself at various fixed speeds between mile markers. Divide 3600 by the result in seconds and you will get the actual speed. Conduct several runs for accuracy or track time for several miles and average the results.

My speedometer reads high.

60 indicated = 57
70 indicated = 67
80 indicated = 76

The assertion that a TL's speedo could be off by several miles per hour at 150 is consistent with my experience. Tire size and wear can affect the results as well. Running smaller diameter wheel/tire combinations will increase the error.

rw