9 replies to this topic

[AndyM]

Hi all. I've got a major oil leak under load so I'm going to fit an oil pressure gauge to see if the pressure's spiking at any point. Is there any real difference in accuracy between the electric type and the mechanical type? Is there one type to avoid? I believe the mini oil pressure should run around 50psi, is that correct?
Any advice gratefully received, as ever! Andy.

[Dan]

Modern electrical gauges are pretty much as good as mechanical ones, it's a throw back to the older racing series that make speople think they arren't. But if you buy a cheap gauge it's just as likely to be a bit vague whether it's mechanical or electric anyway. Mechanical ones are cheaper though as you don't need to buy the transducer which are expensive parts.

The oil pressure you should run depends on which engine you have exactly and how used it is.

[AndyM]

Thanks for that. I've just picked up a Smiths mechanical gauge from Ebay, just need to source some oil pipe and fittings now.
Andy.

[Pavel]

Or you could do as I did and buy a fancy electric one that comes brand new in box, and doesnt work

[TimS]

iv got an oil pressure guage, seems to be around 70psi at cold and 50when up to temp... but also depends on rpm too

[Guess-Works.com]

IMO, 70 when cold, 50 hot is about right... you dont need to over pressurise the system as your just waisting horses.

You can get the necessary bits to connect the guage from minispares, but also from shows etc...

CAM6431

C-AHT9
(this is a bit overkill but I can't find the standard pipe )

I would also consider getting one of these...

OIL PRESSURE REGULATOR KIT means you can actually adjust your running oil pressure.

[AndyM]

Thanks for the tips, and the parts info. Andy.

[dklawson]

You can make the adjustable pressure relief valve as shown above. There are several web sites that discuss this. I think it's even under the technical section at Mini Spares web site. You can also replace the standard relief valve with a ball bearing from a CV joint and a shortened relief spring... also discussed at length on the web. (Less likely to jam and provides very consistent opening pressures).

The target oil pressure should be considered 50 psi. However, a lot of that depends on the operating temperature and condition of the engine. On older "stock" engines it's not unusual to see pressures close to 25 psi when they're at hot idle. Depending on the relief valve type and setting, pressures around 70 psi cold would not be unusual. Remember, this also depends on the grade of oil and ambient temperature.

For oil pressure, I'm still of the old school and prefer mechanical. As Dan said, you don't need the separate sending unit. However, I've never trusted the resolution of the Smiths gauges. Most of the common ones have about 90 degrees of needle sweep. I prefer VDO instrumentation. They have several mechanical styles with 270 degrees of sweep. Though not an absolute, this generally results in higher mid-scale accuracy... and better resolution. You can always confirm this yourself with another "known good" test gauge on the bench. Used VDO equipment is always on eBay and a mechanical gauge generally outlasts the car it was originally installed in.

[paulrockliffe]

I've a '93 SPI and an electronic oil pressure gauge that I want to fit. Can someone tell me if it just wires straight in, or if I need a transducer or something? Cheers.

[Dan]

You'll need a sender. There's nothing for you to connect it up to at the moment. You need a tee-pice for the oil fitting in the block, make sure it's got all the right threads on it. You need to get the right thread on the transducer too and it needs to be compatible with the gauge.