Speedo Question

[Boostin88T]

Anyone know what speed I would be going if the needle pointed to the P in the middle of the MPH at the bottom past 150 speedo cutoff?

Or at least know the calculation to find out the speed.

I know it's past 160mph but made me interested.

 

[Supracentral]

Factory speedometers are notoriously inaccurate as you get to higher and higher speeds. When you are operating outside the marked range it would be hard to say with any degree of accuracy. Really freakin' fast would probably a good statement.

 

[xarewhyayen]

r154? what rpm were you @? Whats the gearing of your diff?

 

[Nick M]

Search. The formula has been posted many times.

 

[chriso]

Really, really fast

 

[Boostin88T]

r154? what rpm were you @? Whats the gearing of your diff?

Yeah, R154 at around 6300rpm ish. Don't remember the gearing in my car but it's an 1988 Turbo 5spd. I have a 4.10 gearset sitting next to me that I haven't put in yet.

 

[Boostin88T]

Speed Range according to the calculator that I just found was 171mph to 178mph. My friend in his 540 6-spd was suprised because he was crusing at 160mph and I blew right past him.

 

[NDBoost]

Speed Range according to the calculator that I just found was 171mph to 178mph. My friend in his 540 6-spd was suprised because he was crusing at 160mph and I blew right past him.

with a stock differential and trans setup and stock factory tires Top speed is approx 171mph.

Tirewidth: 225
Aspect Ratio: 50
Wheel Diameter: 16
Rev Limit: 6500
Overdrive Gear: 0.753
(89+ Turbo Differential) Final Drive Gear: 3.73

http://www.mysportscar.com/tools/topspeed.htm

 

[antman]

Speed Range according to the calculator that I just found was 171mph to 178mph. My friend in his 540 6-spd was suprised because he was crusing at 160mph and I blew right past him.

iam sure glad i don't live near you. iresponsable driving like that gets people killed.

 

[NDBoost]

iam sure glad i don't live near you. iresponsable driving like that gets people killed.

oh get off your soap box hippie:naughty:

 

[Jeff Lange]

With stock tires and the stock rear end. 6300rpm is 158.28MPH. If you blew past someone doing "160MPH" at 6300rpm in 5th, chances are his speedometer is off too, lol.

Even if you had the 89+ gearing, you'd still only be doing 166MPH.

(Unless you have an unholy tire size... what tires are you running?)

 

[Boostin88T]

With stock tires and the stock rear end. 6300rpm is 158.28MPH. If you blew past someone doing "160MPH" at 6300rpm in 5th, chances are his speedometer is off too, lol.

Even if you had the 89+ gearing, you'd still only be doing 166MPH.

(Unless you have an unholy tire size... what tires are you running?)

275/45/17 Tires and 3.91 rear w/R154.

Oh, my speedo is probably waaaay off...I was laughing when it pointed to the MPH at the bottom.

Btw this was done on a closed off highway with no one there.