"I would think that the range of each sensor would be linear"
Yep, felt the same way. That's why I'm not too worried about it.
Hey, on the eng mount issue, I am using the ones from a S12 V6 . They are near indentical to the one's that came with my motor. I believe they are the silicone filled style, so I bought new from Nissan because I know over time the rubber cracks and lets the goo out. Think they were about $80 ea even with my Z-Club discount from Courtesy Nissan.
On the oil pressure front, I am using the sensor from my old eng, and I have very good oil pressure with the new motor. Sensor looks to be in good shape, but can't remember if it is factory or aftermarket.
Running 10W-30 (conventional oil), on a 70 deg day, with a cold eng, I show about 2/3 guage, coming back down to 1/4 guage at idle when warm.
I recently put in 20W-50 Valvoline Racing (conventional) oil in the car and now I have CRAZY oil pressure. With a little cooler air temp (50 deg), a cold eng at idle almost PEGS the guage. It will read 2 needle width's past the upper mark (so past 90 psi). I have been letting it idle until the temp comes up, but the pressure stays probably mid guage at idle when warm, and will still edge up twards the 90 psi range when rev'ed.
I plan to switch to synthetic this summer, but I wanted to run some conventional oil through it for a couple of changes to 'get the gunk out' since it was a used eng and sat for a bit.
You might want to try out an aftermarket one as Careless says, I have had 2 Nissan guages go out on me (in the 160K I have run the car, so I guess not too bad...). But both times, it would read low pressure.
Oh, if you get bored, I fiinally posted some pic's of the car on the "Lets see your RB Z..." thread. http://forums.hybridz.org/showthread.php?t=97930&page=8