Quote:
Originally Posted by AtomicLabMonkey
The big decision is mechanical gauges vs. electrical... mechanical ones actually run capillary tubing inside the driver's compartment right up to the gauge on your dash, and the capillary tubing is filled with whatever fluid you're measuring, oil, water, etc. This means you have hot oil & water in lines under your dashboard... up to you, and I've seen plenty of people do it on street cars, but I myself am shying away from that for street use due to the potential leak they represent. Electrical gauges have a sender unit under the hood hooked into whatever line or engine part you want to measure, and then just run an electrical wire inside the driver's compartment up to the back of the gauge. The thing that's nice about mechanical gauges is that they have full-sweep (270 degree) readings that are nicer and have more precise markings than most electrical gauges which are only 90-degree sweep. You can find some full-sweep electrical gauges however, they're usually just harder to find and I think might be more expensive than standard sweep electricals.
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All that's true until you start talking about the Japanese gauges. Japanese companies like GReddy, Defi and Omori have full sweep electrical gauges that are probably more accurate than mechanical gauges due to their stepper motor design. The problem is that you have to pay serious bling to get them.
For example:
Autometer Mechanical Boost Gauge: <$50
- run a tube into the cabin and measure the boost directly w/ a pressure gauge
Autometer Electrical Boost Gauge: ~$120 (IIRC)
- sender measures boost in the engine compartment, sends a voltage to the cabin, gauge is a mechanical voltmeter
Defi Electrical Boost Gauge: $275 (Including control unit that is used w/ other gauges)
- sender measures boost in the engine compartment, sends a voltage to the control unit, control unit sends ditigal instructions to the stepper motor to make the gauge point right at indicated boost. Control unit allows for recording/playback of data, along with peak values.
If you want to spend less than $1000 on a complete gauge setup, then you pretty much have to go with Autometer or another domestic company. The gauges are pretty decent, especially considering their lower prices, but there are some limitations: As LabMonkey mentioned, the electrical gauges that are based on voltmeters usually have lower sweeps, like 90 degree, and the gauges don't usually have a linear scale.
I don't know if you checked out Arthur's setup (they used to be mine) but he's got the full-on Autometer suite: Mechanical Boost, Electrical EGT, Oil Pressure and Oil Temp. Plus a nifty clock! When I had them, I found they worked really well (esp. the EGT gauge, since it had the high-end racing sender unit that gave it a *very* quick response time) but I decided they were just too busy... too many dials and stuff in the cockpit.
Now I've got a Defi boost gauge, and I'm slowly saving up for the Defi digital display so I can wire up Oil Temp / Pressure and EGT w/ having a specific gauge for each one.