oil temperatur gauge - anyone?

[don.hasi]

I wonder whether someone has already installed an oil temperature gauge? I have searched the board but not only one hint found... could this be?

If there is anybody I am interested how and where...

I am thinking about the place of the clock which doesn´t work anyway

Thx

[Lotus-e-Clan]

The usual way is to either drill and tap the sump plug nut for the sender OR you can buy a ready tapped sump plug from places like "Demon Tweeks" online but best phone them to see if they have one for the EXcel /Esprit sump ...I'm sure they'll have some info....or ring Lotusbits...

The sump oil temp will demonstrate that the oil gets most of it's heat from the underside of pistons at high engine speeds /WOT. If you can't keep the oil below 95C on the motorway in summer then you need to uprate the oil cooler or properly duct-in cold air directly.

You'll soon start worrying more about the length of time you have COLD oil temps than hot temps though. This is why modern cars have oil/water heat exchangers...you get a quicker oil warm-up and the oil is kept close to water temps most of the time.

[don.hasi]

I would have thought, that at the sumpplug is also the most fresh/cool air on the car incl the cooling fins at the bottomof the sump... Is this at all the best place for taking the temperature or is there another one? Perhaps at the oil cooler entrance?

[Lotus-e-Clan]

The oil cooler input is oil drawn from the sump ...so not much better. The bottom of the sump is coolest for sure, so if the temp rises above 95c you should be concerned.

I you can fit one toward the top of the sump level but you will read the hot oil falling from the pistons/bores and of course that doesn't tell you how efficient the cooling system is. But it could warn you if the oil temp is so high that a piston ring might pick-up in the bore...

For this reason, in the Clan which has an oil to water heat exchanger, I have two sensors which I can switch between to read off the same gauge. One reads the return oil temp from the heat exchanger so I can see both the warming and cooling effect of the heat exchanger. The other sensor is in the sump plug.

The oil in the sump is (nearly) always cooler than the oil coming from the exchanger because the heat exchanger oil is heated by the water from the head which gives a quick warm-up and if the oil from the sump gets very hot (on high speed motorways), the exchanger passes this heat back into the water which is then cooled by the water rad which has a high air flow.

The important thing for me is that I know the oil delivered to the engine bearings is nearly always at water temp (once everything has warmed up). The oil temp in the sump is of secondary importance to me now. As long as I know the heat exchanger is keeping the temp of the oil delivered to the bearings stable between 80 - 95C I'm happy.

[don.hasi]

For this reason, in the Clan which has an oil to water heat exchanger, I have two sensors which I can switch between to read off the same gauge.

This sounds super clever Is this a stock feature of the Clan?

95C sounds very low... all my other cars reach 130 easily when under full throttle and only if you get over 130 once, the water parts in the mix will go out.

[Lotus-e-Clan]

Not a std feature.

I use an after market Laminova heat exchanger but you could easily adapt one more cheaply from another car.

The oil temp gauge is std. The two identical sensors are simply switched using a "change over" relay...easy to do.

I would be very unhappy with 130C SYSTEMIC oil temperatures. Maybe you need a better oil cooling system (unless the 130c temps measured @ a hot spot in the system?).

Porsche engine builders, for example, say that long engine life much depends on oil temps that are maintained in the 75C -95C range. Of course modern oils can withstand high temps without the film breaking down completely but the difference in oil pressure between oil @ 75C and oil @ 130C would mean you would suffering a large drop and the possibility of increased bearing wear ..assuming ALL of the oil is at 130C and not just a local hot spot.

Are you sure your gauge is reading C not F?

[don.hasi]

Yes, it is 130°C

Like I have already said, I don´t know any car -modern, youngtimer, oldtimer doesn´t matter- that not does reach this level. Also it is not a matter whether it is a diesel, turbo/SC or NA. Perhaps it is a matter of our Autobahn but you will get this also on a track.

In opposite... I would mean the most are desgined to get a 130° at an average time and all other parts are desinged to hold this (oilcooler, oil/water exchanger,aerodynamics, air ducting etc.)

Like I have already said, I don´t know any car -modern, youngtimer, oldtimer doesn´t matter- that not does reach this level. Also it is not a matter whether it is a diesel, turbo/SC or NA. Perhaps it is a matter of our Autobahn but you will get this also on track.

In opposite... I would mean the most are desgined to get a 130° at an average time and all other parts are desinged to hold this (oilcooler, oil/water exchanger,aerodynamics, air ducting etc.)

I have had last year a 5cylinder Audi Coupe GT from 1987 which at full throttle easyy goes up to 140/150 when you have to lift up the pedal a bit... but this was the kind it was enginered and so it had to be. Stock!

Pretty clear, the complete system has to be seen as one... the oil pump have to be strong enough etc. But I never heard that any pump had failed. If there were a failure then most cases -and these only on track- have had bad designed sumps without any splash plates, and the higher corner forces beaten the engines...

[MrCoolA]

I wonder whether someone has already installed an oil temperature gauge? I have searched the board but not only one hint found... could this be?

If there is anybody I am interested how and where...

I am thinking about the place of the clock which doesn´t work anyway

Thx

If i remeber correctly mine is drilled in next to the oil pressure sender and runs to my water/oil/volts electric box of tricks mounted in the dash area, it enables me to adjust the temp my fans come on and is set to warn me is any of the three drop or raise to high. I would reccomend that in terms if reducing the oil temp you change your oil rad for a larger one i have a 15(?) row uprated and make sure you have an air flow to it, some of the Excels have no direct flow on to it with the sump gaurd in place (some do) i manufactured one to channel the air to it and she runs pretty much the same even during a thrash...i will post some pic if i havent already.

[don.hasi]

i will post some pic if i havent already.

This would be very nice

And btw pics of your magic box would be nice as well

Thx in advance

[MrCoolA]

i will post some pic if i havent already.

This would be very nice

And btw pics of your magic box would be nice as well

Thx in advance

[Lotus-e-Clan]

Ah ...I wonder if we're talking cross purpose here? Forced induction oil temps will be more difficult to control....they run very high air intake temps, even with a charge cooler, so obviously pistons (and oil) run hotter than an n/a engine.

I run mine on track @ 95C max. There is no need to run temps any higher in an n/a engine. I would suggest an n/a 912 engine would prefer a sub-100C max oil temp too. Interested to hear from anyone who regularly sees 130C in a 912 engine and its still in tip top condition. Historically, classic engines don't last long for many reasons and control of oil temp (both hot and cold) is one of the constants that kill engines early.

An oil water heat exchanger keeps oil temp equilbrated to water temp + or minus 10C and that equals a happy long lasting engine. I can see no advantage running temps any higher. Water /sludge in oil is only an issue with oil temps below 65C. ie the sort of oil temp every one gets on very short journeys in cold weather /rich mixtures...even with an oil heat exchanger fitted.

[MrCoolA]

Ah ...I wonder if we're talking cross purpose here? Forced induction oil temps will be more difficult to control....they run very high air intake temps, even with a charge cooler, so obviously pistons (and oil) run hotter than an n/a engine.

I run mine on track @ 95C max. There is no need to run temps any higher in an n/a engine. I would suggest an n/a 912 engine would prefer a sub-100C max oil temp too. Interested to hear from anyone who regularly sees 130C in a 912 engine and its still in tip top condition. Historically, classic engines don't last long for many reasons and control of oil temp (both hot and cold) is one of the constants that kill engines early.

An oil water heat exchanger keeps oil temp equilbrated to water temp + or minus 10C and that equals a happy long lasting engine. I can see no advantage running temps any higher. Water /sludge in oil is only an issue with oil temps below 65C. ie the sort of oil temp every one gets on very short journeys in cold weather /rich mixtures...even with an oil heat exchanger fitted.

Peter
Probably my fault, i just read the first post..................

[don.hasi]

Probably my fault, i just read the first post..................

No, this was just I wanted to hear about sth


Peter:

Ah ...I wonder if we're talking cross purpose here? Forced induction oil temps will be more difficult to control....they run very high air intake temps, even with a charge cooler, so obviously pistons (and oil) run hotter than an n/a engine.

No. Please read it again. My words are: every car I have ever driven (!) NA, SC, Turbo, Diesel, ... ALL have reached 130°C. To get these temperatures in Germany is easy: drive on the Autobahn at >120 mph for a few minutes.

Interested to hear from anyone who regularly sees 130C in a 912 engine and its still in tip top condition.

I dont know... I don´t have any oil temp gauge

Historically, classic engines don't last long for many reasons and control of oil temp (both hot and cold) is one of the constants that kill engines early.

Depends on: what is historical for you?
My 5cylinder Audi was engineered in 70s (as the 907/912) My Audi has had 270.000km and was still running in These engines reaches also easily 750.000km with often temps over 130°C. No problem at all! At these 270.000 the car has proven more power than stock

I don´t want to run the engines that high... they get this high... and to control it, i want to measure it.

[Lotus-e-Clan]

I don't doubt you findings. But I'm in no doubt about the advantage of maintaining stable oil temps @ water levels of 80C -95C either.

Much depends where oil temp is measured and if indeed 130C is a stable terminal oil temp or an escalating one. Obviously unlike cooling system water, oil does more than one job, it cools and lubricates. Engine design, power output and rev limits dictate how much heat the oil has to dissipate and how much external oil cooling is required.

Some engines splash more oil up into the bores than others. But here is a law of diminishing returns with oil splash. Too much splash means too much oil is recirculated from the sump surface oil into the bores without a pass through the cooler. This oil WILL get very hot very quickly under power at sustained high engine speed and a high quality oil is required to maintain the integrity of the oil film in the bores @ piston ring level. My race engine has a knife-edged crank designed to throw less oil under the pistons so the ratio of splash-heated oil to circulated oil is reduced so my sump temps are VERY slow to rise. No doubt relatively low revving Audis are built to cope with occasional high oil temps. My race engine held @ 8k rpm would not last long with 130c oil temps and I doubt a 912 would cope well either.

[smithersoli]

Am thinking of going down the oil to water cooler route, any ideas what sort of area cooler would be required on the 912 engine. Mine isn't going to be full race, but properly modified for about 210 hp I hope, once its running. (if i ever get there)

Would approximately 54 cm2, be enough, got a small cooler about 30 cm long, 45 mm diameter with a small oil pipe through the middle.