Dans88stang

Hey everyone, in my previous posts i stated that i just bought an 04 GT 5 speed. There are mods done to it already CAI, full exhaust,underdrive pully's, diablo sport, 75mm throttle, polished plenum. I have a question about my RPM's when I am in 5th. At around 75mph on the highway my RPM's are at 2100. Should they be that high or is there something wrong that i need to do. Thanks for the help.

cliffyk

That's right on the money for the OEM 3.27 gears (2055 rpm @ 75 mph), you must be used to driving a V-6 Park Avenue or something to think that's "too high" (BTW, my '92 Miata spins 4k rpm @ 75)[/align][/align]I have 3.73 gears and 75 mph = 2340 rpm; 4.10s would make it 2575 rpm @ 75....[/align]

BleedinBlue

Yup.

lol, at 75 mph I think* I am right on 3K rpms or a tad higher.

massmustang02

What about 55 mph? Where should they be at?

cliffyk

Assuming stock tire sizes (25.7" diameter, 811 revs/mile) anda 3650 tranny; 1 mph = the following rpm:[/align][/align]gears rpm/1 mph (k)[/align]3.27 27.40[/align]3.55 29.75[/align]3.73 31.26[/align]3.9032.68[/align]4.10 34.36[/align][/align]rpm @ x mph = (x * k)[/align][/align]So, 55 with the stock 3.27 gears = (55 * 27.40) = 1507 rpm[/align][/align](note: if you have a T-45 transmission multiply thecalculated rpmby 1.097--so for a T-45 with stock gears the rpm @ 55 = (1507 * 1.097) = 1653.)[/align]