Rb25det 240sx Differential

[r33240sx]

Hey Every one I am new here and i have a problem with my 240sx its a 1992 with the Rb25det swap. The problem is that while im driving on the express way im only going 55mph and my car is at 4000rpm in 5th gear does anyone know why it does this or has anyone had the same problem. Any pointers will help. Thanks.

[Carryl]

is you ka tach calibrated correctly for the 6cyl?

[s13point5]

is you ka tach calibrated correctly for the 6cyl?

i bet thats the problem

[BoostFab]

Hey Every one I am new here and i have a problem with my 240sx its a 1992 with the Rb25det swap. The problem is that while im driving on the express way im only going 55mph and my car is at 4000rpm in 5th gear does anyone know why it does this or has anyone had the same problem. Any pointers will help. Thanks.

you can also swap out the diff w/ a j30 or a q45 for a higher top speed final gear.

[silviasgp06]

wow, if this is just the tach not being calibrated for the 6cly cause that would make me really worried for you since you missed it while researching what is needed for an RB swap.

........you did research first right? cause this one thing that is discussed that happens, but maybe you just missed it(makes me wonder what else you might of missed). I sure hope its just a small thing you missed..... and not that you knew nothing about the swap going into it.

if its something completely unrelated then ignore my bs above.

have fun!

[r33240sx]

im not sure about the tack calibration cuz i never heard or read about that but i can hear the engine reved up so i figured it would be something else.

[r33240sx]

thats wat i was thinking but i didnt know which diff to get r they both the same or which one is better. and if its not that i was planing on getting it anyway cuz the one i have isnt that good.

[WhatsADSM]

Wow...

Yea it really sounds like it is the tach. Put a real tach on there or adjust your stocker.

What you think is 4000 is really more like 2666.

Have you ever hit the revlimiter? If so I'd bet you wrap the tach before you hit the limiter... That should be a clue that it is off