Hi guys. I have an 02 xjr 100 with 115k miles. At 70 MPH. I'm at 2,500 rpm on the highway. One tire fire, so pretty sure it has the factory diff gearing. Verified RPM with my Bluetooth scanner. It doesn't matter if I keep the trans in sport mode or normal mode. I can feel a shift at around 50 mph, which I believe is torque converter lockup. All that said, car shifts fine and moves out when you punch it.

Only asking because I had a 2002 xj sport before this. I know, different trans in the NA cars. But at 70 mph, that car was 2,250.

Any ideas?

 

That sounds about right. I'll look again on my drive to work tomorrow

 

Thanks good sir!

 

I believe mine runs right at 2500 as well. My understanding is that Sport mode causes the car to start in first gear vs. second, and upshift later. It should not affect the rpm at highway speeds.

 

Yup verified today, seems to be right around 2400-2500 around 70mph. Didn't compare gauges against OBDII data to be sure, but it's probably pretty close.

 

XJR and XJ8 have the same diff ratios (3.06) but XJR has the top gear ratio of 0.83 and XJ8 has 0.80, thus the difference in rpm at the same speeds. If, at a certain true speed, the XJ8 is running at 2250 rpm, XJR will be running at 2334 rpm. The difference can be higher than this due to inaccuracies (tolerances) of the speedometers.

 

That'll work. Thanks for clearing it up guys!