WRX Top Speed
04-02-2003, 01:39 AM
#17
Registered User
Join Date: Nov 2002
Location: San Diego
Posts: 1,780
Car Info: Boosted Geo Prizm
Originally posted by mario
what does that mean drag limited
what does that mean drag limited
It means that there is not enough HP to push the car past xx amount of speed. Of course that only means build more b00st y0
04-02-2003, 10:04 AM
#19
Registered User
Join Date: Mar 2003
Location: Oak Hill, West Virginia
Posts: 39
Car Info: 2003 WRX 5-Spd,short throw, premium sound, security, yellow... stock... MINE!!
My calculations on top speed on a stock WRX sedan (not figuring in rolling resistance or aerodynamic drag).
With the stock 205/55R16 tires and rims. At 7000 RPM's in 5th gear top speed is approximately 137.07 mph. For the these tires to spin much faster than that you would need a higher redline or a 6th gear.
In case my logic is off, I'll post the formula I used to determine this.
MPH= (RPM*Radius)/(FGR*168)
Radius is determined by by taking your tire measurement, in this case 205/55R16.... 205 is the width in mm, 55 is the percentage of height to width in this case, 55% of 255mm which is 4.83 inches, plus half the diameter of the rim (16/2=8).
4.83+8=12.83
so now we have (7000*12.83)/(FGR*168)
FGR is your final gear ratio, which is 3.9:1 in a stock WRX.
Soooo.... (7000*12.83)/(3.9*168) is what we need to calculate.
89810/(3.9*168)
89810/655.2 = 137.0726 mph
This isn't an exact science as several variables are not taken into account, but this will give a good general idea of top speed in high gear at redline.
Is my logic flawed on this? I'm almost positive I did this correctly.
With the stock 205/55R16 tires and rims. At 7000 RPM's in 5th gear top speed is approximately 137.07 mph. For the these tires to spin much faster than that you would need a higher redline or a 6th gear.
In case my logic is off, I'll post the formula I used to determine this.
MPH= (RPM*Radius)/(FGR*168)
Radius is determined by by taking your tire measurement, in this case 205/55R16.... 205 is the width in mm, 55 is the percentage of height to width in this case, 55% of 255mm which is 4.83 inches, plus half the diameter of the rim (16/2=8).
4.83+8=12.83
so now we have (7000*12.83)/(FGR*168)
FGR is your final gear ratio, which is 3.9:1 in a stock WRX.
Soooo.... (7000*12.83)/(3.9*168) is what we need to calculate.
89810/(3.9*168)
89810/655.2 = 137.0726 mph
This isn't an exact science as several variables are not taken into account, but this will give a good general idea of top speed in high gear at redline.
Is my logic flawed on this? I'm almost positive I did this correctly.
04-06-2003, 10:30 AM
#21
Guest
Posts: n/a
Well...Although top speed is limited to 130 by the ecm...any piggyback or standalone computer replacement will take care of that for ya! Anyways here's a good place to get info. http://www.subaru.net/usproduct/2002/wrx/02wrxspecs.htm
And here's a link for a nice little utility....
http://www.maxxskunkworks.com/SpeedCalcSheet.htm
You'll be surprised what the top speed of a WRX is with it's gear ratio and firguring 7200rpm
Magerum
Anyways here's a good place to get info. http://www.subaru.net/usproduct/2002/wrx/02wrxspecs.htmAnd here's a link for a nice little utility....
http://www.maxxskunkworks.com/SpeedCalcSheet.htm
You'll be surprised what the top speed of a WRX is with it's gear ratio and firguring 7200rpm
Magerum
04-07-2003, 03:26 PM
#24
Guest
Posts: n/a
When I bought my WRX, it didn't come with the rear wing. I was able to drive the car past 135 MPH, but it was a bit twitchy.
After installing the rear wing, I was able to drive past 140+ MPH (based on the speedometer) a couple of times with greater stability but it did take a little longer to do so.
Now, with the few mods I've added, I've been able to drive at about 145 MPH to 148 MPH (based on what was being indicated on the speedometer of a Corvette that was tracking and following me.) On my speedometer, my needle went below the letter "M" of the MPH letters so I couldn't tell how fast I was going.
After installing the rear wing, I was able to drive past 140+ MPH (based on the speedometer) a couple of times with greater stability but it did take a little longer to do so.
Now, with the few mods I've added, I've been able to drive at about 145 MPH to 148 MPH (based on what was being indicated on the speedometer of a Corvette that was tracking and following me.) On my speedometer, my needle went below the letter "M" of the MPH letters so I couldn't tell how fast I was going.
