Installing an HKS boost gauge

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[url=https://imoc.co.uk/app.php/kb/viewarticle?a=2&sid=4ba90fa433dae2254d6977b083766baa]Knowledge Base - Installing an HKS boost gauge[/url]

HKS 46mm Boost Gauge Install

by "Dean M. Fujita" ([email protected])

I got a lot of questions regarding this so I'll pass along the info. Again I was only able to do this thanks to the help of Alex Pun. Just as he was very helpful to me during the install I would like to pass on the knowledge to others interested. These instructions are intended as a guide for the DIYers out there. Whatever you do to your car is your own responsibility etc..etc...

First of all I purchased the HKS 46mm boost gauge from CAP (talked to Stacey). Also get about 10 feet of 4mm (1/8 inch tubing. 3mm works too) and some small zip ties to secure everything and some 1/8 plastic hose barbs (found 'em at Eagle Hardware). The HKS gauge maybe difficult to get as they (HKS) are making some changes to there product line. Omori is introducing a line of 45mm gauges and others have managed to fit Autometer gauges in there.

In the engine compartment attach the vacuum tubing to one of the tubes coming off of the intake manifold. There is also an unused opening (capped) on the right side (look below the RIGHT SIDE OF the intake manifold) that can be used but requires a larger tube (6mm i think) which needs to be reduced to the 4mm one provided with the HKS gauge. I used the T provided and connected to the line going to the stock sensor (this is where the stock boost gauge gets its signal see Photo 1).

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Route the tubing along the back (trunk side) wall and over to the left side of the car. If you have a cone type filter and the stock airbox removed you should be able to see a rubber grommet with wires passing into the passenger compartment (it enters down behind the drivers seat). You could unwrap the wires and push the tube through but I just poked a hole (with a screwdriver) through the grommet off to the side (careful of the wires!). Because I wanted to be able to remove portions of the tubing I installed a plastic hose barb on the engine side of the firewall (Photo 2). I also used the hose supplied by HKS for going through the grommet. The HKS hose has a thicker wall and the nice blue silicone hose I bought would kink in this area. Use the HKS hose in the dash area and going through the firewall, these are the two areas where the tubing is susceptable to kinks.

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Okay you are now in the car. Remove the cover of the box behind the drivers seat (3 screws) and the center tower/cd holder (4 screws - 2 up top and 2 below inside). The center armrest thingy is removed with six screws (2 back, 2 middle, and 2 front - remove the shift boot and carefully pull out the trim around it to see the 2 front screws). You can now lift the carpet on the back wall to see the rubber grommet (it may help to loosen the rear side panel; 2 fasteners and a screw under the engine lid release). Route the hose along the wall (Photo 3) and down the center of the car toward the front. Use the zip ties to secure it (also use zip ties to secure your tubing ends at hose barbs and tees). You are now ready to go into the dash.

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Note: At this point I took a break and connected my HKS gauge to the tubing routed up from the ashtray. I drove around a bit and noticed the big difference between the stock gauge and my new one. I completed the install the next day as this next part requires patience.

Before I started messing with the wires in the dash I disconnected the battery (negative terminal). Don't know if it was necessary but I felt much better about poking around the dash with my screwdriver : ).

The plastic piece under the steering column removes with four screws (I was unable to unclip the fog light switch so I left it hanging - no problem). Pull out the ashtray and remove the two screws there. This removes the trim around the radio. Unclip the wires for the hazard lights and lighter to remove completely. The next piece is the bottom/left side of the dash. Pull out the dimmer light knob and remove the 12mm bolt. Lower the steering column all the way, remove one screw on the right and gently/carefully remove. The plastic trim above the instrument cluster has a screw on each side and needs to be pulled out. The instrument cluster now comes out after removing one screw on the left side. Unclip the wires from the back of it and pull out the assembly. (The '91-'92 models have a speedo cable that needs to be disconnected. It can be reached through the center vents).

The instrument cluster is three pieces sandwiched together. A clear plastic cover, a black piece with the cut out for the gauges and a white piece with all the gauges and circuits on the back (Photo 4). Unscrew the metal brackets on each side and gently pull apart the 3 pieces (an extra set of hands may be useful).

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The next part is irreversable and requires drilling/cutting of the stock pieces. I used a Dremel motor tool but a patient hand and some Xacto knifes and file would work just as well.

Remove the stock boost gauge (two screws) and take your new gauge in hand and try to fit it into the instrument cluster (white plastic piece). Notice all the places where the new gauge hits; these are the areas that need to be cut/filed away. Again be patient and don't break the bulbs in there.

Next turn over the cluster and using a Xacto knife, carefully cut out the green plastic printed circuit around the lower boost gauge screw hole (see Photo 5). This is where the tubing will exit the cluster. It is important to cut the green plastic away (don't cut into adjacent circuits) as you need to take a drill to the hole and enlarge it so that the tubing will fit through. If you don't cut away enough of the green plastic you could tear it up trying to drill out the hole.

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Drill a second hole up the center (between the speedo and tach) for the wires to light the gauge. I got a connector from Radio Shack (Photo 6) so that I could easily remove and install the cluster. See the mr2 page for instructions on how to connect these wires to light the gauge. I tapped the wires to the fog light switch and used a 10mm bolt in the dash frame for the ground. I also used a lot of shrink wrap and electrical tape around the positive wire as it passes over a lot of metal edges in the dash (wouldn't want a short back there)

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The opening of the black plastic bezel needs to be enlarged to fit your new gauge. Start cutting/filing/grinding away at it. Try to keep everything even but don't worry if it is not a perfect circle. The edge of the HKS gauge will cover the hole you're enlarging. Open it up just large enough so that your new gauge can be snuggly pushed through as nothing else will be needed to hold it in place.

Okay put everything back together and leave a few feet of tubing from the boost gauge sticking out the back of the cluster. You need to find a way to connect it to the tubing you routed near the ash tray. I used a hose barb and made my connection near the hole where the wires for the lighter was (Photo 7). I also attached some plastic ties here so that I could "fish" out the barb if I needed to disconnect it later.

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Check your connections, connect the battery and crank 'er up. I get a reading of 500 mm/Hg at idle (just under 1,000 rpm) and about .5 bar with my manual boost controller opened up all the way (stock boost). Check for leaks, if everything looks okay button it all up and enjoy : ).

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Dean Fujita
'93T Steel Mist Grey

The following was provided by Kostas G.D. Chryssos Ph.D.

The front bezel from the HKS instrument can be removed if the metal lip is opened up with care. In this way the complete front with the glass is removed from your gauge. The gauge can then be mounted from the inside of the black panel cover which in this case you DO NOT ENLARGE the stock instrument hole. You will have to do a bit more removal on the inside white stuff and in particular to the side of the left white plastic tube that houses the turn signal lens... [img]