Mechanical or Electrical

[imwlw83]

I am getting ready to put some gauges in my 95 TA, I plan to use Autometer Sport Comps, would the mech or elec oil pressure gauge be better. At present i am having issues with my stock one. I did the test that , I think Shoebox mentioned, and pulled the sender and started the car. It shot oil everywhere in about 2 secs, the car was cold. Its only when it warms up and at idle when the needle doesnt move. So, which should i get , mech or elec. Thanks you guys, yall help out so much when i cant make up my mind or need tech. advice.

[MN6WS6]

Mechanical gauges are more accurate with sudden changes, not to mention cheaper, but they are not NHRA legal unless you use the isolator kits with them, which costs even more money. The isolator uses a non-flammable fluid between the sender and the actual gauge, so that if something were to happen and the tube come loose, you wouldn't have hot oil spraying in the car and causing a fire problem (not to mention burning you up).

For street use (aka daily driving) you'd be better off going electric, like your factory gauges are. No hazards, and while they don't react as quickly, they still do the job very well.

[Rob B (shoebox)]

Whoa! I never told anyone to pull the oil pressure sender and start the engine!

(I don't even know what thread this was in reference to)

[Injuneer]

As far as I am aware, the NHRA limitiation applies to fuel only, not to oil. The flash point of oil is actually very high, and the probability of an oil fire inside the cockpit is next to "0". I do recommend that you use only braided SS tubing for the connection, because the nylon tube that the AutoMeter gauges comes with doesn't leave me with a warm feeling.

[MN6WS6]

I stand corrected. I thought the rules prohibited the use of "live" mechanical gauges.

IMHO, I still don't want 200 degree oil having the possibility of spraying onto my body in the event of an incident, so I'll stick with electric gauges.

[imwlw83]

Sorry shoebox, maybe i miss quoted you, or someone I thought was you. I will go with the electric, this gauge sitting on 0 at idle is really a pain in the neck. I know there is pressure there, its just not right ...... Thanks for everyone's help. Oh on a side note, i guess i will have to pull out the check gauges light to make it go away?

[Injuneer]

There are precautions that need to be taken with mechanical gauges, even if not required by the rules. Using a restriction orifice in the line to a nitrous pressure gauge is a good idea. AutoMeter includes it with the gauge, but I wonder how many people realize what its for and actually use it?

I also wouldn't use a mechanical fuel pressure gauge, even WITH the isolator. I had one - the AutoMeter #5280 - and it failed, allowing fuel into the lines in the passenger compartment. They recalled the gauge and replaced it with #5821.... which was also eventually discontinued due to poor performance, and then replaced with the current #5282, which includes braided lines and costs over $100.

[fastTa]

Sorry shoebox, maybe i miss quoted you, or someone I thought was you. I will go with the electric, this gauge sitting on 0 at idle is really a pain in the neck. I know there is pressure there, its just not right ...... Thanks for everyone's help. Oh on a side note, i guess i will have to pull out the check gauges light to make it go away?

Have you even verified that your oil pressure sensor is in working order? It is fairly common for them to malfunction or even have a bad ground. Start by verfying that you have constant power to the actual sensor itself. If you do then I would replace the sensor and go from there.

Disconnecting the SES light = bad idea.

[imwlw83]

I have oil pressure, not sure how much, but the gauge does move. Shows 40psi at startup, then as it the engine warms up it goes lower. Once it is warmed up when you come to an idle it shows 0psi and when you start to give it throttle it only goes up to about 15psi. I replaced the sender and it got worse readings. I really think the gauge is messed up. The light i was talking about pulling out is the "Check gauges" light.

[imwlw83]

Also, i have another question. What is the best path to take in routing the wires and lines through the firewall. I was thinking about the hole underneath the PCM. Would that be to long of a run for a SS braided line for the oil gauge going to one of the A/C vents? And how long of a hose that would be? I am sorry about being a pain in the butt, but i will get the hang of it and maybe be able to help someone else. I plan on taking pictures of the vent install job, maybe we can post them someplace.

[Injuneer]

I have my nitrous pressure gauge braided hose routed through the grommet behind the PCM, then to the center A/C vent. The oil pressure braided hose runs through what used to be the hole in the firewall for the clutch master cylinder.... that hole became "unused" when the TH400 went in. The hole is covered with an aluminum plate, and there's a rubber grommet for the hose.

In the case of the oil pressure, shorter is better, to minimize any "damping" of the pressure in the line.

I would first temporarily connect a mechanical gauge to the port above oil filter, to assess the accuracy of the stock gauge and sender.