I'm probably the only the only 2.8 owner that has installed a boost
gauge in their car. No, it wasn't out of sheer madness, but
because of the addition of the PES G2 supercharger. I wanted to be
able to monitor my boost/vacuum levels so I could make sure the car is
operating normally and safely at all times. The car runs about 8
lbs of boost under WOT conditions and under vacuum, 25 in Hg. At
idle it sits at about 17 in Hg. Just like a turbo car, between
shifts, boost is lost momentarily, but with the bypass valve it recovers
VERY quickly. Unlike a turbo, the supercharger has no lag, and the
power curve is very linear.
The gauge I used
|Where I installed it
I decided to put in right in the console as shown here. I had to remove the 3 blank switches. Once those were out, there are 3 plastic support tabs for them. I used the dremel and just cut those tabs out. Save the plastic switches because you can use half of one to fill in the gap that will be left. Once that plastic is out, you will be required to shave a hair off the gauge to get the face plate to fit. Once done, make sure the gauge fits nicely in the console. You will notice the material you have ground off now shows bare metal and it used to be black. Take the gauge out and get some black paint and touch it up again. The nice thing about the fit is that it is just tight enough to not require you to bolt the gauge in. Pressure alone holds it in place. The other wire you see in the pic is for my V1. Notice the slight notch cut in the switch to allow it to pass through.
|Vacuum line and sensor
The vacuum line I chose to use was the hard nylon type. It is more durable than the rubber lines, and due to it size it fits perfectly through the ECU nipple. On the supercharged 2.8 engine, I placed my T in line with the fuel pressure regulator vacuum hose. That hose gets both boost and vacuum, and it is really easy to place a T fitting there. I then shoved the nylon line through the grommet in the fire wall. I poked the nipple through on the ECU and ran the nylon line through that. After removing the lower trim panel on the car (go here for the FAQ) I mounted the boost sensor underneath the steering column and secured it with a few zip strips. Plug it together and run your power and ground wires. The power can go to one of the wires on the power terminal that is switched on with the ignition. Just use a meter to check which terminal to use because it is different for the 1.8 and the 2.8.
I mounted the oil pressure gauge where the ashtray goes. I used a dremel cutting wheel and cut a hole for it. The gauge doesn't sit flush with the ashtray, but it is more perpendicular with the console. Basically what that means is the bottom of the gauge doesn't mount flush with the tray. But due to it's location, I don't think it looks bad. You be your own judge.
This gauge was fairly simple to install. Cut the hole then run your power, ground and signal to the sensor wires. I ran the wire through the same nipple I poked out of the ECU for the nylon vacuum hose. The sensor was a pain to install though. You have to purchase T adapter from VDO (part # 240 850) for about $5. On the 2.8 the stock oil pressure switch is found right above the factory oil cooler. Undo it, screw the T fitting in, and then hook up the stock switch and the new oil pressure switch. Make sure you crank that switch down in it. If you don't oil will drip from it. Once installed, I would recommend starting the car and watching the T fitting for any oil leaks. Oil pressure according to the Bentley should be between 15-36psi at idle and 44-73psi at 3000rpm provided the oil is at least 80°C (176°F). Mine sits around 26psi and around 62psi respectively.
(click to enlarge)