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Mechanical or Elec gauges?

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Old 02-17-2014, 08:57 AM
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Default Mechanical or Elec gauges?

I will finally plan on getting into autocross and then road racing when $$ allows this summer.

But before I do I wan to add a Oil Pressure and maybe Water Temp gauges before beginning to race. The Water Temp will most likely be electrical since I don't see it needing to be as reactive and accurate at Oil Pressure.

Oil Pressure I WANT to be mechanical to give me the best "real time" info, and well because it's mechanical and I don't have to deal with grounding issues etc.

I always bounce back and forth between mech/elec. Electric is a more simple install and no worries of hot fluids inside the passenger compartment. BUT my father-in-laws 67 Vette that lives 90% of it's life on road courses has FACTORY mechanical gauges and has had no issues...

Other things I thought about are the SCCA or regional laws in tech inspections etc. if they allow fluids to be run into pass compartment and that this is a DD so any accidents could rupture the line?

I installed some SpeedHut Revolution electric series gauges in my 04 GTO that worked well. I liked having a low pressure warning light that you could set at any psi you wanted.

Mech Pros:
"Live" readings
Low readings = motor problems or leak in line to gauge

Mech Cons:
Fluid inside cabin, possible issue for DD during accident
Tricky running hard copper lines through dash etc (I don't feel comfortable with nylon lines...)

Elec Pros:
"easy" install no dealing with copper lines
Able to have low pressure warning light

Elec Cons:
Possible grounding issues cause faulty readings
$160 SpeedHut elec gauge (has best/smallest sending unit) vs $80 Autometer Mech gauge.

Any advice/opinions from you RR/Autocross guys I would appreciate it.

Thank You!
Old 02-17-2014, 12:13 PM
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I prefer electric gauges. Like you said, easier to install and no fluids in the cab. The down side is that they're expensive.

It used to be that all electric gauges were 90* sweep only. But now you can get them with a 270* sweep, which increases accuracy.

In the olden days mechanical gauges were more reactive, making them more immediately accurate. Today, the difference is so small that you really can't tell.

"Idiot Lights" are also a good idea. When you're on the track, you can't watch the gauges every second. So if you lose oil pressure, it would be nice to have the light come on.

My favorite gauges are Autometer and Speedhut.

If you plan to use mechanic pressure gauges, I would use braided AN lines and fittings, rather than copper. Again, easier installation that won't fail. Copper can vibrate and eventually crack if not supported well enough. And in a race car, I wouldn't want to risk that.

You don't say what kind of car you have, but you might consider something like this: http://www.ultra-gauge.com/ultragauge/ Installation doesn't get any easier.

BUT, as far as I can tell, LS1 powered cars do not send the oil pressure signal to the ECU. So you'd still have to install an OP gauge. You would want to research that for your car.
Old 02-17-2014, 03:11 PM
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Thanks a lot for the input.

I have a 95 Z28 so I can't use all the fancy OBD2 port gauges.

I forgot about the braided line option. That would reduce the issue of vibration as well as installing a hard line.

I'm wondering if there is a way to make a "shield" for a mechanical gauge. If for whatever reason a fitting leaks/pops you can surround the line in maybe a larger tube that can contain the mess? Still...high oil temps at 60psi will be hard to "contain" lol.
Old 02-25-2014, 12:42 AM
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I went with all electric VDO gauges. Truth be told, grounding really wasn't an issue as much as getting the signal lead to stay attached to the water temp sender. All else was solid. Thankfully, I have a separate thermostat trigger for the radiator fan.



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