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What gauges do you *really* need? Or another way to ask it: A driver needs continuous updates of which information? And, what information only needs to be known before a problem occurs?

Could you imagine replacing most of your gauges with only indicator lights?

For example, at this moment...today...(tomorrow could be different), I'm leaning toward having a single gauge: Speedometer with odometer/trip odometer. Then, use indicator lights for Tach, Oil Temp, Oil Pressure, Water Temp, Alternator, and yes, even Fuel Level.

The indicators could [theoretically] be somewhat intelligent using some homegrown, small, & inexpensive circuits, such as a progressive shift light array, and for temperature/pressure, define a window that indicates either safe or unsafe operation and turn on the indicator accordingly. Lights could be single LEDs, arrays, multi-color, etc. For example, have 3 LEDs or a 3-color LED for Fuel Level to indicate Full, 2/3 Full, 1/3 Full.

Am I crazy?

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On a slightly related note, I found myself looking at some of the consumer development boards, like Arduino, Raspberry Pi, and BeagleBone Black, and people are starting to use CAN bus interfaces with them, which means you could take the sender outputs from the various sensors on a car, inject them into the CAN bus, and then use something like the Android Torque app for data logging...all for much much cheaper than the $$$$ aftermarket data loggers. Or, if you were ambitious, write your own data logger and drive an LCD screen with the development board. I personally won't go this way, but it's an interesting idea to use a [removable?] Android Tablet as the only gauge display in the car.

IMHO, you would need a tach, a speedo with odometer(typically a requirement by law), oil pressure gauge or read out, water temp gauge or read out, an ignition warning/charging lamp, signal lamp, and if needed a low fuel warning lamp. Personally I don't like gauges that don't tell me exactly whats going on, ie. an oil pressure gauge that reads low, normal and high. I like to know what the oil pressure actually is as well as what the water temp actually is. On the Eleven I built, the tach, water temp and oil pressure gauge were in front of the driver, while the speedo and ammeter (was an originality thing) were in front of the passenger seat. If it were a race car, I would only have the tach, water temp and oil pressure gauge along with a giant low oil pressure warning lamp (think something like 2" in diameter).

Almost forgot, I also prefer mechanical gauges, mostly because I'm a luddite.

As already said, I believe a speedometer is required as is a high beam indicator (not a gauge). For me, the most useful gauges are water temp, oil temp, and oil pressure. I've been running my car for years without a tach on the race track. My personal feeling is that if you are staring at a tach while racing, your eyes aren't in the right position. You need to use your ears as a tach and have a rev limiter as a backup.

The temp and pressure gauges give you an indication of oncoming trouble.

Ken

With the gauges (other than speedometer & odometer), what action will you take based on the information presented? What I mean is, will you mentally follow the pattern of the needles and then take action based on something in the pattern that concerns you (without the needle crossing a specific numerical threshold)? Or, will you watch the needle, and regardless of what it does, will you only take action once it crosses a specific threshold?

I can say with certainty that I do the latter. For example, if the water temp gauge was fluctuating, I probably wouldn't do anything until it either showed the engine was too hot or too cold. Similarly, with oil pressure, if it's fluctuating, I probably won't take action until it's too high or low. That tells me that all I need is an alert for those thresholds, i.e. warning lights. Plus, for oil pressure, I may not see a quick flick of the needle if I have a momentary loss of pressure, especially if it's in a turn on the track where I can't really afford to glance at the gauge.

Tachs do seem truly pointless to me. On the track, there's a tiny argument for them because it's useful to know that you're shifting in the proper range. But, I would say that it's much easier to see a series of different colored lights rather than the needle position, especially if you have a narrow shifting range.

What really got me thinking is when I was shopping gauges, I told myself that I definitely wanted the ones that had the integrated warning lights. Then, as I imagined driving with them, it occurred to me that I was likely going to ignore the gauges until the lights turned on, which led to me asking what was the point in having the gauges if I was going to ignore them.

I guess if I think about the gauges in terms of cost, dash real-estate, aesthetics, and value to me as a driver, the justification just isn't there. Now, keep in mind that's based off my experience of not yet encountering an issue which a gauge could have helped prevent that a warning light would have missed (knock on wood).

The CEL/MIL is an interesting analogy...look at all the parameters modern ECUs monitor, and we have a single light, not gauges, for all of those. They are mission critical parameters, but somehow we manage without gauges...

Lots of options here depending on how you run your engine.
If you go MegaSquirt, TunerStudio for android gives you your tablet dash. I like my little TrailTech Vapor dash, its pretty minimalist but covers all the legal bases and then some. I did add an oil pressure gauge just because I like to know if its losing pressure anywhere, but not so much that it kicks the idiot light. I also installed a AFR meter, just to aid in tuning. I could delete that now, but its fun to watch. Its also telling me that I could probably wring a few more MPG out of this thing if I felt like doing more tuning.

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Parts left out cost nothing and cause no problems!!

Can't say what you really need. A lot is dictated by rules and more, by personal preference.
However, having raced and flown competitive aerobatics, I am a firm believer in analog gauges. As someone mentioned, your eyes need to be outside, but a quick scan of an analog gauge cluster gives more information in a fraction of a second, than any digital display. Furthermore, analog gauges convey a rate of change much better than any digital read outs. In aerobatics altitude is your friend and safety, and nothing can tell you better what's going on, than an analog altimeter, that is unwinding at a rapid rate, while your eyeballs are bugging out, as you're pushing -5 G's going from vertical down to inverted. No tablet or android will give you that info at a quick and rather blurry glance. Not suggesting to invert the 7, but analog information is still quicker for this old brain to process.

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Martin


My build log:
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Analog rocks. I used to like that when I walked away from my race car, the gauges still read correctly. They work even when it's turned off, what could be more magic than that! They read correctly when your alternator or electrical system is limping or dying.

Having an idiot light for oil pressure and other items makes sense. It's worth plumbing the extra sensors or programming/building something for that. I connected the idiot light to a red trailer taillight on the center of my steering wheel...

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Marcus Barrow - Car9 an open design community supported sports car for home builders!
SketchUp collection for LocostUSA: "Dream it, Build it, Drive it!"
Car9 Roadster information - models, drawings, resources etc.

While analog may work, the digitial dash in the S2000 works better.

The big speedo numbers are tough to miss and the big sweep of the tach across the whole gauge takes a nanosecond to see where in the rpm range you are.

Just an opposing viewpoint. I guess the point is that it just depends upon what kind of analog and what kind of digital.

A small round digital gauge with a number like temp or oil pressure might not be easily read, but there are others than can be read as quickly or quicker than analogs.

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mobilito ergo sum
I drive therefore I am

I can explain it to you,
but I can't understand it for you.

My old VW-Devin had a speedometer. No coolant to worry about, and you figured the oil pressure was okay so long as you had oil. And since the car only had 36 hp, I actually didn't need the speedo.

In a regular car, I think water temp and oil pressure are needed, and a tach is nice to have.

Here's something I didn't realize before. A long row of gauges on the dash looks cool, but doesn't always give you the quickest read. If you're driving along and glance over at a row of gauges that all look about the same, and one of the needles is swung left or right, you may need to look over a second time to determine which gauge that was. Manufacturers seldom line up gauges in a row, and there are no doubt other reasons for that, but I've noticed that having gauges in different locations around the dash makes it immediately obvious which gauge you're looking at.

It sounds like you can do a fair bit of design work. So that is good. You can have it any way that you want. For me, a speedo, and a fuel gauge and a BIG RED "shut it down now" light are the minimal ones, that is unless you want to go back to the early VW Bug days/ They had no fuel gauge and a "reserve" valve to switch over when you run out; sort of like motorcycle tanks. Everything else is just clutter. This could be the low/high oil pressure, high engine temp, and any other signal "and'd" together. It needs to be BIG and BRIGHT to catch your attention even when not looking for it. I have, from my donor, a low brake fluid and low oil level light. They have come in handy a time or two.

BTW, fluctuating water temp gauge could be an indication of low coolant. So if you are monitoring that analog gauge, it will tell you BEFORE you do permanent damage to your engine. Analog gauges can be very helpful in monitoring engine health and diagnosing issues. I wouldn't discount them.

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Chuck.

“Any suspension will work if you don’t let it.” - Colin Chapman

Visit my ongoing MGB Rustoration log: over HERE

Or my Wankel powered Locost log : over HERE

And don't forget my Cushman Truckster resto Locostusa.com/forums/viewtopic.php?f=36&t=17766

A big oil pressure light and a rear view mirror to see if you are outrunning the red and blue lights!

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Honey anyone?

I have thought about which gauges could be replaced by indicator lights too, and haven't yet come up with a steadfast answer. As noted, just about everything could be replaced with simple indicator lights except for the speedometer on a street car. But should they be? Does the driver actually gain anything from it? It really comes down to personal preference, which is going to be dictated in large part by personal experience.

When I think about how many LED's would be scattered across my dash to convey all of the information I personally would both need and want, I think it would get to be too much to take in at a glance any better than analog gauges, and possibly be worse. I also don't know that such an array of LED's would ultimately save all that much space on the dash either, if laid out in a coherently spaced manner...Especially when one starts using multiple LED's in an attempt to partially replicate the functionality of analog gauges.

For me personally, part of this car is trying to keep a bit of 'vintage' feel to it. So analog gauges it will be, and probably mechanical over electric for the most part as well. Of course, when going for a British feel, the gauges don't even have to be connected to anything in the first place!

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-Justin

"Orville Wright did not have a pilots license." - Gordon MacKenzie

I've found putting the really important stuff right in front of you and in/close to your line of sight helps. Normally I'd put the oil pressure gauge and tach in this category; both of these prevent immediate engine death. I'd say coolant temperature is the next most important followed by oil temperature since both prevent slow engine deaths. The speedometer goes where ever real estate is available. If its half blocked by the steering wheel it isn't a big deal.

I hate digital tachometers. I've driven one car with one and it was worthless since your mind couldn't process the numbers from just a quick glance at it. Fortunately it had a built in shift light so you knew when it was time to change gears.

I'd avoid dummy lights only. For instance your oil pressure light may come on at 10 psi but if you're at 12 psi the light will be off and you're doing damage. You can set the light for 25 psi but how do you know if you have 24 psi or 1 psi? I didn't even bother with an oil pressure dummy light on the Sprite since I'm running a mechanical gauge (more reliable than electrical) and the light only confirms your engine is trashed.

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-Andrew
Build Log
Youtube

If you decide to design something, consider the fault modes of a single idiot light. What happens if your circuits loose +12 to your circuit or if the sensor wire becomes disconnected or any number of possible problems. If you have gauges, pretty much, you know if the gauge (and sensor, if electrical) is working or not. With an idiot light, how do you know that the circuits are functioning properly? Modern ECU's go thru a lot of checking against expected responses. A flaky sensor is detected and sets the fault. Not so much with a roll-your-own solution.

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Chuck.

“Any suspension will work if you don’t let it.” - Colin Chapman

Visit my ongoing MGB Rustoration log: over HERE

Or my Wankel powered Locost log : over HERE

And don't forget my Cushman Truckster resto Locostusa.com/forums/viewtopic.php?f=36&t=17766

This is good stuff, keep 'em comin'.

rx7locost, yes, fault modes are something I'm thinking about.