ok guys i was driving out to skool last nite and i noticed that my rpms were pretty high on the freeway..my speedometer was only reading about 80-85 mph and i was seadily rite under 4k rpm between 3900-4000 id say the whole time.. is this normal..this doesnt sound rite because i thought our cars were supposed to top out at about 140 mph at 7k...seems off ..could my mph be off possibly? o yea i have a 10ae 1988 turbo II

 

baisicaly as long as your clutch isn't slipping, there could be any "real" problem here. get out a calculator and go to the mazdatrix webpage and calculate what your rpm based mph is, use the info provided on trany and rear end ratios, you'l also need to know how many rptations per mile whatever tire you have gets (check tire rack) if all the calculations are off by the same amount in aech gear, then someone probobbly put in a 4.33 rear end. if the numbers still dont work have your speedo looked at and recalibrated if necissary.

 

Hard to say. I can tell you though that in my '87 TII (when it was running, hehe) at 80mph, I was at about 3500rpms in 5th gear. At about 90mph I would be at 4000rpms.

 

so this is very not normal..maybe its just my tires may be a little flat? that doesnt seem substantial enuff though..dam now im worried. doesnt really feel lik my clutch is slipping..its a centerforce dual friction.and this things grips hard and clean..so i would guess its not that.

 

85mph 3500rpm, its fine, FLOOR IT, it takes that tach a very long time, very long time to start moving, the mph climb but rpm doesnt follow suite.....120mph at 4200rpm.

 

No way.... 120 at 6200 maybe.... thats a little off unless you got a 3.9 but then again i doubt an auto would go that high.

 

then if your clutch isn't slipping check out your speedo, Easiest way is line up with some one with a reliable speedo and see if you both read the same if you do then what size tires do you have ?? stock after market etc... you can find out your rear end gearing by lifing up one side of the rear so i rear tire is off the ground put the car in neutral and turn the tire while paying attention to your drive shaft, turn the wheel one full turn and see how many times the drive shaft turns.. i have a 3.90 rear so my driveshaft turns 3.9 times for ever full turn my wheel does.. chances are if your speedo and clutch are fine you might have a higher rear gear ratio

 

i cruise all day long 80mph at 3000rpms exactly. than again, i'm running 225 50 15's... suppose to be 205 60 15's

-Markus

I can usually tell when i'm at 3-3500 rpms, i get massive Exhaust DRONE inside the car

 

132 with my auto before I blew second gear band

manual driveline parts are on the way, less the rearend, keeping 3.9

 

Me go 80mph at 3k exactly also. 225/50/16 in the back, 205/50/16 in the front...

 

tire size has nothing to do with speed vrs RPM.. your speed will be wrong vrs the speedo. but the stock speedo vrs rpm will always be the same.

4000 at 85mph doesn't sound far off. your tach is probbaly off a bit. most are.

and FYI. if you are doing 85mph at 4000rpm. you would be doing 148.75 at 7000rpm... to answer your "shoudln't it be 140 at 7000" so yours sounds fine.

 

4th gear @ ~3krpm = 50mph
4th gear @ ~4krpm = 70mph
5th gear @ ~3krpm = 70mph


Thats the way it is for me at least...