I like seeing data, I’m not a big fan of black boxes. And my WRX dearly needed to give me more dials and numbers to look at. Also, it’s not a bad idea to monitor your engine closely after doing a complete rebuild, which I did, so here’s my writeup on picking and installing gauges in your Subaru. So this is all about getting gauges on your EJ2xx series engine.
There’s plenty written about different gauges (like the Gauge FAQ on NASOIC), but there are the ones I like:
- Oil Pressure – when this drops, something catastrophic is about to happen. You can’t drive without lubrication.
- Oil Temperature – over 285 Farenheit and Oil doesn’t lubricate, so you know when to back down. Under 210 and it won’t boil off water or fuel, and does not clean your engine.
- Inside/Outside Temperature – I find it helpful to know whether the roads are starting to freeze, especially in California where you get widely varied temperatures as you drive from the Bay to the mountains, and many people assume that the road is fine.
- Exhaust Gas Temperature – gives you some insight into the combustion process
- Air/Fuel mixture – great for tuning purposes since a leaner mixture gives more power but can also cause cylinder knock. You need a wideband A/F sensor for this to get useful readings.
- Boost – you do have a stock gauge for this, but replacing it with a bigger one or something that has an easier to read scale is useful.
Electric gauges are much simpler to work with – you measure data at the source and run wires to your gauges – so I will take the liberty of assuming that you’re working with electrical gauges.
Terminology and Parts
People sprout all kinds of jargon for guages, plenty of which I think is poorly chosen, but that’s usually the case with these “bolt-on” modifications. To get data into your car, you need the following:
- Pod: the enclosure you mount your gauges in – replacing the stock clock, putting them on the A-pillar or mounting them behind the steering wheel is probably the most widely used mounting locations with plenty of pods manufactured for it.
- Sender: really, a sensor, that measures data from a source and convert this into, usually, resistance values on a wire.
- Gauge: something to display the data from the sender.
- Wire: since you need the gauge hooked up to the wire
- Sender attachment: This is a complicated one. You need a way to “tap” what you want to measure and get your sender in there.
Senders tend to be built for a specific gauge and specific manufacturer, since the resistance response of different senders to their environment is different between manufacturers, and gauges are calibrated to a specific sender.
Sender attachments depend on what you want to measure and how you want to do it. Here’s the list I’ve come up with so far:
- Oil pressure and/or Oil temperature:
- Gallery Plug (front or rear): Screw a bolt right into your engine block, and have your sender screw into this bolt so you can measure oil data right on the block. The front gallery plug has the car’s built in oil pressure sensor that lights up the little “needs oil” light. It’s a useless light, so it’s completely acceptable to replace this with an oil pressure sender. The rear gallery plug cannot house most sender itself due to lack of space, so you use a remote sender kit that runs a braided tube from the gallery plug to a sender, and you can mount the sender anywhere in the engine bay
- Sandwich Adapter: Screws on between your oil cooler and your oil filter, giving you two or four plugs that you can screw senders into. It’s down at the bottom of the engine and makes your oil filter stick out slightly further, and you need to find one that fits the thread type f your car, but pretty useful and easy if you’re planning to run both oil pressure and temperature – both senders sit next to each other.
- Exhaust Gas Temperature
- Outside Air Temperature
- Boost / Vacuum
Where to get Gauges and Gauge Pods
There’s tons of manufacturers, but as of 2010 there’s a few places that has everything and sells you decent stuff for cheap:
Prospect Gauges has all the hardware you need and has a great reputation, while GlowShift has lots of mounting options and cheaper gauges. The expensive stuff that’s all digitally controlled from a central controller allowing for data recording and playback is available from Defi.
There’s plenty more info on the NASIOC forums gauge FAQ, here.