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  #1  
Old 07-18-2003, 01:42 AM
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FearThe4Doors FearThe4Doors is offline
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Default Mechanical vs Electrical gauges

Aside from fuel level and amps/volts (obviously)... what are the goods and bads with running electrical or mechanical gauges. I guess mostly oil press and water temp.

Electric are easier to hook up, and loom the wires. Are mechanical more relieable? More accurate? Consistant? or are mechanicals mostly intended for racecars where charging systems arent really high powered, or even existent.

Electrics cant be TOO bad since just about every car made came with them stock. Good stuff like vipers, hemi cudas, and other HiPo cars (not just camerys and civics.. hehe)
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Old 07-18-2003, 02:56 AM
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Default Re: Mechanical vs Electrical gauges

[QUOTE]Originally posted by FearThe4Doors
[B]

Electric are easier to hook up, and loom the wires.
Yes! They are rather easier to hook up than mech.s.

Are mechanical more relieable? NO.

More accurate? NO.

Consistant? NO.

or are mechanicals mostly intended for racecars where charging systems arent really high powered, or even existent. NO. But they do come in handy there. But then again most all race cars use a charging system of some sort. Dyno will show some hp lost just running on a battery abd will gain if it has the volt push from an Alt. Course we are talking msd boxs and such. Magnetos dont count since power will increase with there rpm.

Hope that helps.
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Old 07-18-2003, 02:43 PM
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The "mechanical is better" theory goes back to the 60's & 70's when it was actually true. Electrical guages at the time were known for their innacuracy & slow response. (oil pressure fluctuations not showing up at all, for example as the sender/guage was to slow to react.)

A lot of this was due to the fact that the "quality" instrument makers of the day (such as Stewart-Warner) never really put much R&D into electrical guages, prefering to stick with mechanical. Factory guages of the muscle car era were all electric & were HORRIBLY innacurate & prone to failure. This also helped reinforce the "electric guages suck" theory.

These days, Manufacturers such as autometer & VDO have put a lot of effort into making fast, accurate electrically-sent instruments. They claim they are every bit as good as their mechanical guages. Add to that fact that, as you said, they are easier to install & you don't have to pipe engine fluids into your passenger compartment risking soaking your carpet with hot oil in the event of a line rupture.

Me? I got mechanical autometers, 'cuz I'm old n' set in my ways....

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Old 07-18-2003, 05:16 PM
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The way I always do it is to install a mechanical oil pressure guage for its quick response and accuracy.Then a electric water temp for its long life. It seems that about all i would get is two years out of mechanical water guages before the capilarry tube would leak.
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Old 07-18-2003, 08:46 PM
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Lots of debate here but one thing you can not argue elec gauges do not have all that hot some volitile fluids in the cab with you
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Old 07-19-2003, 02:38 AM
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I would probably use elec in a streeter, but like the mech's in the race car. The tranny oil, engine oil, and coolant temp guages are live, no need to reach in and turn the ign on to check cooldown between events.
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Old 07-20-2003, 08:36 PM
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Default oil

oil pressure guages would be the only ones that have actual fluid in the line.
temperature guages work off of air in a copper tube that expands as it heats, increasing the pressure in the tubing and moving the needle in the guage appropriately. there is a solid bulbous tube inserted into whereever the temperature is needed, you can cut the line and nothing will leak, its just air.
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Old 07-20-2003, 11:03 PM
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I have a question. Why are the electrical fuel pressure qauges so damn expensive? I have mechanical water temp qauges on all my race cars and have not had any trouble with them but you do have to handle them carefully. One nice thing about them is that you can read engine temperature with the power off. The amount of electrical power it takes to run electrical gauges is next to nothing so I don't think that's an issue.
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Old 07-20-2003, 11:48 PM
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the only electric guage in my car that i trust, is my autometer tach. all my other guages are mechanical. IMHO mechanical guages are very easy to install, and are very accurate as you don't have to worry about shorts sending incorrect signals...

the only time my tach is wrong is when/if my battery goes dead or my voltage reg goes out, my tach is very inconsistant and very incorrect...as is everyother electrical guage. i KNOW i can trust my mechanicals, especially oil pressure.

aftermarket electricals are probably a lot better than the old stock ones, but i'd rather rely on a mechanical guage. just run everything correct, no kinks etc, and everything should be fine.

as for the fuel pressure guages, i think the main reason for the price on inside mounted guages is because of the isolator. i'm not sure how those work, but i guess it keeps the fuel out of the cab and still gives accurate psi readings...not sure though. i don't know why you couldn't run an 'outside mount' inside? i did actually...for my nitrous. just keep everything clear so nothing will happen to the line and it should be fine.
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Old 07-22-2003, 01:52 AM
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well, some of us wouldn't prefer the fuel line splitting and shooting fuel all over us as we are flying down the track, that's probably one of the reasons.
yes, the isolator is the big bucks. and all it is a diaphragm with a sensor on one side and gas on the other. why not just run an outside one to your cowl and look at it there? easiest way to do it i figure.
plus looks like you mean business with guages everywhere =)
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Old 07-23-2003, 04:21 PM
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one thing, with my psi guages i use copper line only, i don't like fooling with platic lines that get brittle after a little heat, and especially not with NOS or Fuel Psi.

also, i don't have a psi guage for my carb yet (only NOS psi and it's only on with NOS, which i haven't used yet), but when/if i do get one, i would want one inside so i can watch the psi as i got down the track/street/whatever. it's kinda hard to check the pressure while your driving if it's on the carb itself...
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Old 07-23-2003, 04:54 PM
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My question was, why are the ELECTRICAL fuel pressure gauges so expensive? Why should they be any more expensive than an electrical oil pressure gauge. Case in point: Jeg's lists an Autometer electrical oil pressure gauge for $53.99. The fuel pressure gauge sells for $189.99. Both gauges include the sender. What's up with that?
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Old 07-23-2003, 06:33 PM
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OH! electrical! hmm, dunno, maybe supply and demand? there might not be a lot of people buyting fuel psi guages...

have no idea, call em!
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Old 07-23-2003, 10:31 PM
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i dont know if id put a mechanical fuel pressure guage in my engine compartment, I do have a mechanical oil pressure guage that when i was using the cheap plastic tubing leaked on me, ICK!!! oil all over the inside of my car. Luckily i havent finished my interior yet so not that big of a deal. I replaced it with braided steel line from autometer, very nice stuff if you dont mind paying the extra bucks. I think it was worth it.
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Old 07-23-2003, 11:09 PM
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It's illegal to put a mechanical fuel pressure gauge in a car unless it has an isolator. We put one of those in my friend's Super Gas 'Cuda and the thing never worked right. Was a waste of money and it wasn't cheap.
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Old 07-24-2003, 04:41 AM
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illegal as on the strip, or on the road? or both??
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Old 07-24-2003, 08:55 AM
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Illegal at a sanctioned drag strip. Just plain stupid anywhere else.
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Old 07-24-2003, 04:19 PM
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lol stupid? i don't see how 7 psi fuel can be any worse on copper lines etc than 80+psi oil. oil is heavier and hotter than fuel as well! one thing though, if i ever get a fuel psi guage and mount it inside without isolator (expensive), and i smell fuel, i have an electric pump....jus shut it down and fix the problem. cap off the line for the guage and see what happened...

anyhow, to each his own
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Old 07-24-2003, 05:03 PM
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How you gonna do that after someone pulls out in front of you at an intersection hits your car, your pinned in and knocked out cold. Fuel leaks from that solid copper line cause it cant flex like the nylon that comes with the gauge. Simple spark ignites fuel under 7 psi pressure from electric pump that's running that no one knows about but you so you burn to death. Yeah, that's real smart there. Not to mention in that scenerio that you put safety personel at risk along with many other peolpe. Even n20 has no business being inside the cab. Any substance that increases oxygen will certainly feed a fire just the same as fuel will.

Bad choices there. You should rethink this before someone gets hurt.
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Old 07-25-2003, 04:58 PM
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as i said i don't have one. and i disagree about the copper lines, they do flex easily, but don't get as fragile as nylon lines from heat. as for my NOS psi guages, i use plumbers goup on all the fittings and tighten, then recheck after a while.

BTW: the bottle isn't filled and i don't have my fuel cell plumbed in so there isn't any fuel or NOS in those lines yet.

to each his own!
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