Two identical EF's, both do different rpm at 100, any ideas?

[JG3282]

Mine had a 3.45 and sat at 2200 @ 100 km/h with 16/55's

Although I know of two identical cars that raced at the drags and one was remarkably faster so you never know with the laws of science, maybe they could be wrong :

[toby123]

It definatly will not be tyre size as if it was your speedo and tacho willl read right but your actual speed will be slower ie. cars will over take you and not keep up with you like you have stated.

It will most likely be diff gears or convertor problems

Toby

[Deanodriver]

I have noticed lately that when the engine is off, the tacho needle sits at slightly above 0, which could be the cause of some of it.

[Deanodriver]

It's still happening, and given that fuel prices are going up, and I'm trying to get more k's from my tank, I'm still wondering how to fix it.

I've taken the car (the high revving EF) to the mechanic since then, and the auto is leaking a little, but that shouldn't affect it, should it?

On the highway between Geelong and Melbourne, under the bridge with the speed detector, it does 97 when my speedo says 100, so it's accurate enough. I've got a 3.08 diff in it, like my dad's car, and I have a feeling it's different in other gears too (also revs higher at 70km/h in 3rd).

Generally, I'm doing about the same amount of revs at 85-90km/h as my old man's car does at 100.

Any other ideas?

[EFFalcon]

torque converter sounds like its not locking up.

[Deanodriver]

That doesn't explain the higher revs in 3rd at 70, and it will go to ~2300rpm at 100 sometimes when accelerating, and I don't think that's 3rd gear either (3rd's about 2800rpm at 100, i think), could that be the 4th with unlocked torque converter?