oil temp/pressure gauge

[moosehead]

I too thought about the merits of oil temp vs oil pressure gauges on a non-oil cooler Airhead. Besides, I don't like the factory oil pressure sensor (digital output: red light or no light) and prefer the analog output of a pressure sensor on a gauge.
I choose pressure over temp, mainly for the one reason that I couldn't measure the oil temperature where it counts, at the piston. I.e., I could not figure out the relationship between oil temp in the sump (or wherever your sender is) and at the piston (linear/non-0linear etc). I did play around with it: I sometimes had 120C oil temp with the deep sump (pre-GS) and was very scared how that would translate into oil temperature at the piston. At the same time, the oil pressure was still above 40psi (60psi was "normal") which was a better piece of information.
The oil pressure represents the sum of various engine conditions, oil temperature being only one of them. Health of your oil pump is another.
My 0-160psi oil pressure gauge shows very high oil pressure when starting cold in Fall or Winter reminding me not to flog the engine when its cold. It takes a while even for an Airhead to get to operating temperatures (which results in oil pressure values around 60psi). I learned a lot form the oil pressure gauge and how to read it and utilize the information. It provides you with trends rather than accurate values.

Here is mine on my home-built R100G/S:




My vote: oil pressure gauge all the way.

Stephen that's a very slick oil pressure measuring system. I remember you had a nicewrite up on how you built it over on ADV website. I'm sure some guys would like to see how you did it..perhaps post the link to your how-to here?

[StephenB]

More than happy to post it here:
Well, I had a new idea for a gimmick, but in reality, I only wanted to replace the BMW OEM oil pressure switch. I am a visual kinda guy and like mechanical things, so with an analog oil pressure gauge I would be able to eliminate the OEM oil pressure switch. The gauge would show me the health of the oilsupply, if not the engine health. Now, when looking at prices, an automotive 2 1/16" gauge with a reasonable mounting cup sets me back about $100-$120. Not too much for knowing the engine health at all times, but there must be a cheaper way. Also, that gauge requires some space to mount, which, on an unfaired bike, is a luxury. So, one must buy for a total of not even $30:



a 1 1/2" oil pressure gauge from your local hydraulic supply, 1/8NPT fitting, 160psi range, 270deg sweep (my preference) => $5.50
a tubing kit with 3ft-4ft of 1/8" nylon tubing and at least a 1/8NPT Male and one 1/8NPT Female fitting (e.g. EQUUS #9801) => $9.10
one adapter fitting M12x1.5 Male to 1/8NPT Female (to fit the original location of the OEM oil pressure switch) => $9.40
one 7/8" hose clamp => $3.50
some scrap aluminum to fabricate a bracket => $0

I used some silicone to waterproof the gauge (I left some areas for venting should the gauge require that). I also fabricated a very small aluminum bracket from some scrap material and JB-welded it to the gauge, together with a "JB Weld"-nut.



Final product:



Note from first actual run on the bike: easily 150PSI on cold engine on higher rpm, that however changes with the engine being warmed up properly to 20PSI at idle, 60+PSI @ 4000+rpm, all working well despite my first doubt.

[twist]

Stephen, good to see you post! Been a while. hanks for the great information on the gauge. I think that your application is what I'm looking for. An oil pressure gauge seems more useful that a clock, if gauges are being used. The clock can be a battery operated thing that doesn't need to be connected to the bike systems. I like gauges better than warning lights. The lights come on when something is wrong. I had always thought the pressure switch could be used for a gauge instead of a warning light. Looks good!

By the way, I was one of the early buyers of the omega electronic ignition you imported. It's been years since I installed it and haven't experienced any trouble. Through the heat of Death Valley and the cold snows going over the mountain passes. I've become so confident I've removed the point system for a cleaner alternator case, (I keep point plate and points with me on long trips as a back up).