rear end changed gearing ratio?

[turbonicsperformance]

Originally Posted by cre

It's simple... first off that chart is for a PERFECTLY dialed in FACTORY, BONE STOCK setup... even a difference in air pressure will start it moving off... second, the factory speedometer SUCKS. It can be calibrated but will not be terribly accurate except for the speed at which it was calibrated. and Third... the stock tachometer SUCKS... miles off. Mine is off by about 150RPM at idle and it gets worse the higher you rev... this could be modified so you could calibrate it, but it's not worth it in the least. Also, if you're running a R154 the numbers will be off too... their gearing is a bit different for each gear.

i get what your saying but it says my car at fuel cut will do just at 86 i was like 500 rpm off fuel cut at 87 and my tires are almost 1 inch shorter than stock that means im revving higher to go the same speed so it just doesnt make any sense to me... but its not that important