NV Customs, LLC.

When the time comes to modify a diesel engine, there are many different options available to increase horsepower and torque. Possibly the most important modification to make in diesel performance is a quality set of gauges. It is important to monitor your exhaust temperature (EGT's) and boost pressure when adding custom turbo setups, nitrous, propane,water methanol injection, and fuel delivery modifications. This allows you to analyze the performance of the engine and make adjustments as necessary. For the H1, which came with a naturally aspirated GM 6.2 liter diesel, I went with the autometer NV series Pyrometer and Turbo boost gauge. The first picture is a stock Hummer gauge cluster - not mine, as I failed to take a picture before tearing into the dashboard. The smaller gauges from left to right are as follows: Voltmeter, Oil pressure, Engine temperature, and Fuel. Notice how underneath the gauge cluster to the right of the steering wheel, there is nothing mounted - the controls for the CTIS (central tire inflation system) belong here, but mine was not equipped with this feature.

My goal was to move the engine temp gauge to the stock location of the voltmeter, and relocate the voltmeter and fuel gauge to the stock location of the CTIS controls - these are the two gauges I monitor the least, and these will be the least visible gauges with this setup. The pyrometer and boost gauge will occupy the cluster to the right of the steering wheel. While it may seem ridiculous to put a boost gauge in a more visible location on an NA (naturally aspirated) truck than the perfectly functional voltmeter and fuel gauge, the turbo will be going in shortly - and I would rather not relocate gauges twice.

In order to move the temp gauge to the opposite side of the steering wheel, I needed to dismantle the entire dashboard. It is nearly impossible to work under the dash with the driver seat in place, so it was removed. I then took the top dash panel and the "dog house" cover out of the truck. I also removed the "dog house" itself, as it made running wires into the engine bay a bit easier. The panel that houses all of the gauges, switches, etc. is held in with 4 7/16" bolts - two through the firewall to the left of the steering wheel and two through braces underneath the steering wheel on either side. To free this panel, I also had to disconnect my cable-style heater controls from the heater assembly. I believe that 1992 models were the only civilian models with these cable controls, so most should not have to contend with this issue.

Once it was all apart, I had free access to the wiring behind the gauges. All of the the Hummer gauges (exc. speedo) are electric, and have a gray wire on one side terminal and a black on the other side. The gray is ignition power, and the black is a ground. Each gauge has a center terminal for the appropriate electrical sending unit except for the voltmeter, which only needs ignition power to read. This made swapping the engine temp gauge to the other side a snap - I only had to extend the sensor wire, as I was able to use the stock voltmeter ignition and ground. There was plenty of play in the wires to relocate the fuel gauge to its lower position, and I hooked up the voltmeter to the stock temp gauge ignition and ground and was good to go. I used a dremel to cut the holes in the CTIS control cluster to mount the two gauges.

Now I was ready to mount and plumb the new gauges. Mounting was a snap - they fit right into the stock locations where the temp and fuel gauges used to be. Conveniently, both the pyrometer and boost gauge needed and ignition and ground wire - I simply ran jumper wires from the terminals on the fuel gauge to the new gauges. They also needed a dash light, so I spliced into the purple wire running to the fuel gauge (all of the purple wires behind the dash go directly to illumination bulbs). I then routed the pyro leads and the mechanical boost line through the grommet that houses one of the heater controls. At this point the gauge install was done - the dash board went back together with slightly less effort than it had taken to get it apart.

Since I have yet to have a turbo, I coiled up the excess boost line in the engine compartment and left it in "storage," for the time being. I had two options for installing the pyrometer probe - drill a 1/2" hole and weld a 1/8" NPT bung into the exhaust, or drill a 7/16" hole and use the hose-clamp mounting system provided with the pyro. I went with option B, as the kit did not come with the bung I would have needed for option A. Using a right-angle drill, I was able to drill the 7/16" hole in the collector of the header on the driver side, about 1" above the flange that connects the rest of the exhaust. The hose clamp mounting system worked well - other than the 30 minutes I spent looking for a dropped screw that retains the probe.

Once it was all back together, it had a stock appearance - other than the fact that the NV gauges are considerably brighter than the factory gauges. Once the turbo is installed, I will include a brief section of mounting the engine side of the mechanical boost line. Overall, the install took about 4 hours - well worth the piece of mind that the gauges provide.

Stock gauges (different Hummer)

Interior from driver side - no dog house

Passenger Side

Backside of Temp and Fuel gauges - stock location

New gauges mounted!

Close-up of NV's - 60lbs, huh? I smell Cummins...

Gauges to the left of steering wheel

Probe install

Boost lead rolled up for later...