High rpms!?

i have a 94 325 IS and when i am doing 80 mph my rpms are about 4,250 give or take 50... this just seems like lot to me, so i dont know if someone changed the rear end out of a four banger (if the gear ratio is different) but i dont know?.. My car is a five speed. My mustang is a five speed as well with a v8 pushing 450hp with 3.55 gears and it doesn't even spin that fast at 80mph. so i am just wanting to know if what the I6 five speed gear ratio is to an I4 gear ratio??

maybe it was a swap n you have an auto rear diff...the 4 cyl one wouldnt fit

Crawl under and look for a tag on the rear diff to see what gear ratio it is.

http://www.bimmerfest.com/forums/sho...rpm+calculator

Look here. Specifically posts 8 & 9.

Your on spot man ! My 318ti is the same way, these are super high revving "performance" 4 cylinder engines. So your reasonable power area is around 4000 rpm

I might have written the reasonable power area starts around 4000 rpm.

Thanks John -_-

i can read what is left of the tag on the rearend and it looks like is says 3.90 and then it is not readable so im not sure if the auto read is the same gear ratio standard...?