Basically you can do it the long way, and calculate your tire size in inches, calculate the gear ration based upon engine speed versus trannys ratio, then against the rear-end, and this is how many times the tires are spinning per minute, multiply by 60 (per hour, obviously), then you can divide the distance 1 mile is in inches, and it yields the MPH value. Or you can just find a calculator that already has this all programmed in for you. Any questions?

 

Yeah if I saw 137mph and your calculations say 142mph using the info provided is it even possible? I mean the info I provided was correct but is my car capible?

 

If you have been around this long, you'd know the following.

The stock tach reads high. This is obvious, watch with any standalone, s-afc, or timing light, and you'll see it's off. As for your speedometer being calibrated, that still doesn't change the fact that it will and CAN read off. As for broken '80's N/A. '89 GTUs, speedometer and speedo cable with gear replaced @ mazda dealership within the last year, all verified to function up to 90mph on the dot. As for my innaccurate numbers, they were innaccurate in the sense that I was giving you a higher reading that what you'd actually yield. Just because you are incapable of accepting the fact that you were proven wrong, and did nothing more to prove that you were right (such as stating that you may actually have been an idiot and had 20 inch rims), there's not much else you can do but make yourself look like more of an *** because you're arguing against math, and well, the numbers don't lie, unless they're made up or incorrect, which yours were.

 

Depends on if the car was actually in 4th gear, and how far your tach/speedometer are off. Generally N/A's run out of steam around the 130 mark (with radar)

 

Whats the difference between the 5th gear on a TII trans and a N/A trans? 5th gear in a N/A doesn't pull worth a **** but in a TII it pulls quite well. Also I'm close to the salt flats so I plan on getting an actual reading once I put in my TII manual. And it was in 4th because I maxed out 3rd around 115mph at 7200rpm I believe it was.

 

sonic i have been just siting hear reading, all this math would b easer to understand if it was in front of me. i for beleve u. i have 16in rims so if my rpm was at 5k in 5th then how fast was i going. and thanx alot

 

flamin just for the record what r u driving

 

Well, here's a simple sight to check it all out for yourselves. http://www.f-body.org/gears/ Just enter in all the info and have at it. I've been doing it manually which is why it's taken me a bit longer, but I never trust those online ones

With 16" rims you'd be around 127mph @ 5k rpm.

The gearing between an n/a to a tII is something like
.756 for a tII
.711 for an n/a
.720 for an automatic (4th gear)

 

thanx again

 

so what does a t11 top out at and where did u get the numbers for the gears and **** like that anyway

 

I'll agree with SonicRat on this one, i know my Tach is off. My SAFC reads 2700-2800 when the tach says 3000. While that may not seem like much, when you throw in gear ratios that can be a difference of 10 miles an hour.

 

1989 GXL with a ****-o-matic transmission. I've got a TII trans and I'm waiting for a crossmember bracket to install the stupid thing.

 

again sonic, this is why real rotary enthusiasts and racecar builders don’t come to message boards like this.
And you’re incoherent rambling proved nothing but that you can contradict yourself very well.

 

Is there any way to calibrate the stock speedo?

How about the Tach?

Side: Calm down man, no one is attacking you. Why does it even matter if somone you dont even know, belives or doesnt belive you did a certain speed?

 

So thats why you're here right?

 

Talk about contradiction.

 

this is my first post, i would also like to know what the top speed of a s5 TII is. i have a 1990 TII, and in forth gear at about 7k rpm, the speedo said 120 mph, i ran out of road so i backed off. (after reading all the posts, i want to make sure that everyone knows that these numbers were just what the speedo and tach said, so if they are weird, im just saying what they said) next time im just going to take my dads gps and find the exact speed and compare. my dad said its really accurate and it would probably be one of the best ways to find exact actual speed.

 

My speedo is funky, its showing me going faster then i am below 70 and its showing slower then im really going above 70, ive had all of it measured, i have done 135-140 b4, that was when it was completely stock.

 

Your thing shows my auto ratios all wacko, its saying im running 60 at 3500 rpm's when i do 60 at 2300rpm's, and if i calc it for that it shows i can make 162mph.....??

thats not right at all.

 

Well it seems that we have to have one of these about every 6 months. Just because you're speed reads something doesn't mean you're traveling that fast. indicated DOES NOT equal equivalent, or even Calibrated, which ofcourse is different from Actual.

IF you're a Pilot you know what i'm talking about.

There's a reason SCTA & ECTA use multiple traps to read your velocity. They just don't take the guys word, "yeah i broke 200mph, now give me my jacket"

C'mon kids grow up, you look like a bunch of amateurs.

 

my spedo said i was doing 90 when i got a ticket for 90 ;(

but on my spedo I got up to 145 and backed down -TII

 

Btw, weres a LEAGAL place to top your car out in indiana? If cops can give you a ticket and tell you to keep it on the track, i wana see what track they are talking about.

 

redlined 5th gear......redline=8500rpms to me...cant go to much faster than that without some extra goodies.

 

No you didn't.



If you redlined 5th gear, you would theoretically be going over 200mph, and you undoubtedly weren't.

 

Or the clutch was slipping.