My opinion is..
I'm starting this thread so that newcomers to the forum can learn about alternatives to glass panels. With most RV's being flown VFR, and moving map GPS's at such a high.
Before talking
old school analog/mechanical (nothing wrong with that), one thing electronic brings to the table is the conditional alerts for all systems, oil temp, oil pressure, low fuel level, low fuel pressure, volts, CHT, EGT....etc. The conditional part is based on RPM, like low oil pressure alert is conditional on low idle RPM, the higher oil pressure limit is at normal flight RPM, avoiding nuisance alerts. You can program your own high/low limits.
Looking at accident stats, its clear pilots don't look at their gauges. Having warning of high oil / CHT temp or low oil / fuel pressure or volts is a good thing to have. Most true analog gauges are just a needle and that is it. If you don't look at it, it does not tell you anything. Having the electronics be your flight engineer is a safety thing.
This is what I have, the GRT EIS4000. A full
EIS4000 system with OT, OP, FP, Tach, fuel levels, 4 x EGT, 4 x CHT, volt and even more stuff than you can shake a stick at, starts at $900. I know it does not look as classy or have "analog" emulation but it works well and totally programmable. You can add manifold pressure, amps and about a dozen other options. A central engine monitor is also going to save space and weight, and I think it adds safety.
ANALOG
Most all analog gauges are really electric gauges which is NOT old school. It's
middle school.
If you want real analog, than its mechanical. Tach, MAP, oil pressure, oil temp and fuel pressure can be mechanical. Most older Cessna's and Pipers have mechanical tachs with mechanical tach cables spinning, like an old car or bicycle speedometer cables. Even Cessna and Piper have gone to electronic tachometers. Almost all cars have electronic speed-os and tachs. The display may be analog but the drive is electrical wire. Most home builder use electric tach's. They are lighter and a tach cable is a pain (heavy and costly).
Modern or
new school is really just the electric senders for the electric analog gauge to a fancy microprocessor and digital display. Some digital displays can display numbers and graphics and "emulate" a sweep analog needle or vertical/horizontal bar graph reading. Bottom line it is taking something that is analog, pressure, temp or RPM and converting it to an electric voltage or one step further digitizing it.
For real
old school there is nothing like classic military 3-in-1, OP, OT, FP mechanical. It would look just right in the panel of a B-17. They are more rare now or all but gone, but in the 80's you could buy them overhauled with the dial face redone, with out the radioactive iridium markings. I like iridium. Its safe if you don't lick it or hold it next to your skin; now its a no-no. No electric power needed, very accurate and built for the military. You have to routed small fuel & oil pressure lines to the gauge. There pressure is measured mechanically with a Bourdon tube. The oil temp is "mechanical" as well with a capillary tube. The "bulb" is heated and the pressure change in the capillary tube connecting the bulb and gauge makes a bourdon tube move. The bourdon tubes are linked to the needle via a gear. The nice thing, totally mechanical, very reliable and accurate. The down side is routing fuel/oil lines, albeit tiny diameter with flow restricts. The temp capillary tube can not be cut. If you want a mechanical tach and map you have to route the tach drive cable and manifold line to the gauge. That is they way it was done, old school.
The 3 in-1 gauge can still be had at spruce aircraft in an all electric version (middle school). The price has gone up 5 fold since I bough mine. I had one and loved it. It looks classic and works. It's all electric so there are not tubes routed to the gauge.
http://www.aircraftspruce.com/catalog/inpages/threeOneGauge.php
They use to be cheap, like $150, now they are $530, plus the $160 mil-spec temp sender and cannon plug. That's over $700 by the time you plumb it. For about $200 more you can get and electronic engine instrument with 20 gauge functions. The draw of the analog gauge is strong. Even though some electronic engine monitors can do a pseudo analog digital gauge, it's not the same as a needle.
CHEAP IS NO BARGIN:
There are a lot of "inexpensive" analog electric gauges (middle school) from Vans Aircraft and Westach
(edited). I am not going to make a specific comment but one thing is for sure, I hate gauges that are inaccurate, unreliable or cheaply made. I am not saying any of the above are bad. Research before you buy. Also you have to find a way to placard the limits, green, yellow or red line.
I'll comment on Van's analog gauges. They look good, have the cool logo, have proper limit lines, priced right and work, but they have a reputation for occasional odd EMF or RFI issues; some builders find when you key their radio mic some gauges dance and peg (the MAP and VOLTS seem especially prone to this). Some builders do and some don't have this issue. For the money they are very inexpensive but be ready for the above issue to pop up. If you are careful routing the wires and twisting wire pairs or using shield cable, you can minimize you chance this will happen.
Consider automotive gauges:
Autometer ,
Stewert Warner,
VDO The hot rod and race car guys have a ton of gauges; typ sizes are 1.5", 2-1/16", 2-5/8" and so on, with wild styles from retro to modern. Cost is not bad and depending on brand quality if good. Check out JEGS Performance Parts or Summit racing. They even have "pyrometer" gauges that might work for EGT? You could have for sure Tach, Manifold (vacuum), oil temp, oil pressure, fuel levels, volts and amps. That is 2" x 8 gauges! Impressive! The only down side I see is the Tachs all go to at least 4,000 or 5,000 rpm, but that will work. The tachs tend to be larger 2-5/8" dia. There was even a CHTgauge I saw, but peek was 340F, a little low. This was just a quick look at one brand and one product line.
FLIGHT INSTRUMENTS
As far as flight instruments its almost the same thing, you will spend more for mechanical/analog than for glass. Vacuum is a story unto itself. Electric gyros are crazy expensive unless you go with those China made "Falcon" models. Their quality is subject to discussion and debate. I have heard they are not repairable or rebuildable. For the cost of a Dynon EFIS10A with 10 flight instruments, you will get may be one high quality 12 volt electric DG or AI gyro. High quality vacuum gyros and pumps are expensive as well, no doubt to pay for their liability insurance and the STC seal of approval.
I'm not anti-analog; I'm just cheap and want more bang for the buck. Electronics clearly gives more bang for the buck, tends to be accurate, reliable, giving good utility, saving space, weight and cost, while doing things analog can never do, like the aforementioned warnings.
For those wanting old school I say more power to you, but don't go cheap. Get high quality (which means expensive). There is nothing wrong with mechanical whirling wheels and needles but you will be unhappy with cheap gauges. Check out Mitchell
Mini gauges.
http://www.aircraftspruce.com/catalog/inpages/1002730.php