curious question...

[ALTRNTV]

I currently have a pretty much stock 240 except an Apex'i N1 exhaust and an Injen intake. When I'm in 3rd gear at around 3k rpms, I'm around 37-40mph. If i had more horsepower and if I was in the same 3rd gear, would my mph be higher, or would it stay the same?

[Sundi240]

It would be the same unless you changed your gear ratios.

[fastpace]

i believe that it will stay the same because all horsepower and mph equates to is you getting to a speed faster. Just think about it, if you can get from 0 to 60 in 2nd gear at 6500 rpm at 8 seconds one can also get from 0 to 60 in 2nd gear at 6500 rpm at 6 seconds if performance modification was done to the car. This is just an estimate so don't quote me on it. You will just be shifting faster due to the extra hp.

[s13rookie]

if youre trying to go faster, dont be driving along at 37mph in 3rd

[Jeff240sx]

Sundi - Nice.
The engine turns at a fixed speed, RPM on the tach. That engine speed is transfered to the tranny via the clutch assy. The tranny has a gear that turns 1 time for every x RPM (x is determined by the gear ratio. 4th is 1:1 ratio). That 1 time goes to the differential via the driveshaft. Then, for every 4.08 times the differential turns, or 4.08 times the engine turns (in 4th), your wheels turn once. Find the tire circumfrence (75" or so for stock 16" rims) and you can find the distance your car will travel per rotation of the tire. In 4th, at 4080rpm, your tires will rotate 1000 times in a minute, moving about 6250 feet. Multiply that by 60 (for miles per hour), and you'll get 375,000 feet in an hour, or a fixed 71 miles per hour.
So, the only variables are gear ratios, and tire diameter.
-Jeff