Normal oil temp and pressure for M20???

[Emre]

Hi, guys.

I'm installing a set of gauges in my track car. It's got a 100% stock M20B25 at the moment. I'm trying to figure out what ranges I need for the gauges.

For those of you who track your cars (and have gauges installed), can you tell me what oil temps and oil pressures you usually see on the track? I figure temps should be around 165 degrees and pressure should be around 55 psi. But I really don't know :???:

[backtrail69]

I am of course measuring my built 2.8 w/ a turbo... But my oil temps with an aftermarket cooler are in the neighborhood of 200-210 F and aprox 60 psi (when the bypass kicks on) max oil pressure and around 10ish at idle.

[jlevie]

An oil temp gage that goes up to 230F and a 80psi oil pressure gage seems about right to me. But since an M20 doesn't have problems with oil temp, I'd substitute a water temp gage. Or just have the oil pressure gage.

[Emre]

I am of course measuring my built 2.8 w/ a turbo... But my oil temps with an aftermarket cooler are in the neighborhood of 200-210 F and aprox 60 psi (when the bypass kicks on) max oil pressure and around 10ish at idle.

Thanks very much for that! The standard VDO oil temp gauges run all the way to 300 degrees, but in a non-linear way: most of the range is from 200 to 300 F. That stuck me as way too high. But it sounds like it's not totally off the mark.

As for oil pressure, there are 80, 100, and 150 psi gauges. Sounds like 80 psi would be a good choice.

BTW, I forgot to ask earlier, but what are you getting for water temps?

[Emre]

But since an M20 doesn't have problems with oil temp, I'd substitute a water temp gage. Or just have the oil pressure gage.

I'll be adding gauges for oil temp, oil pressure, and water temp.

This is pretty much a dedicated track car that I use when instructing with various chapters of the BMW CCA and BMW CC. When you're instructing, you really don't have much time to properly warm up the car before each session: you basically jump right out of a student's car into your own.

I'd like to make sure the oil is up to temp before wringing out the engine. Your coolant will reach normal operating range much, much quicker than our engine oil ... so you can't really rely on water temps to tell you when then engine is ready to go.

[jlevie]

This is pretty much a dedicated track car that I use when instructing with various chapters of the BMW CCA and BMW CC. When you're instructing, you really don't have much time to properly warm up the car before each session: you basically jump right out of a student's car into your own.

Things might be a bit different that far north, But I find that if I allow the engine to idle long enough for the coolant to reach normal temp before the first session each day that it won't cool down to the point where I need to worry about temps for subsequent sessions. Worst case, I'll have to take the first two-three laps at a reduced pace if I've had to go directly from a student's car into mine.

[Emre]

Things might be a bit different that far north, But I find that if I allow the engine to idle long enough for the coolant to reach normal temp before the first session each day that it won't cool down to the point where I need to worry about temps for subsequent sessions.

Well, we usually have 3 student groups and 1 instructor group, which means the car isn't running for 3 sessions of 20 minutes each. That's one full hour that the engine's off in between instructor runs. More than enough time for the engine to cool way down (especially during events in April/May or Sept/Oct when it's pretty cold out).

Worst case, I'll have to take the first two-three laps at a reduced pace if I've had to go directly from a student's car into mine.

Right. But I'd prefer to know my oil temps since water temps are very unreliable for this purpose. Your coolant might be up to temp, but that doesn't necessarily mean your oil is. On my Evo, the oil took MUCH longer to reach operating temp.

Anyway, I really don't see the big deal. I need an oil pressure gauge anyway. It's just a matter of sticking one more $30 gauge in the cluster and screwing a $10 temp sender in place. What's the downside

[jlevie]

Well, we usually have 3 student groups and 1 instructor group, which means the car isn't running for 3 sessions of 20 minutes each. That's one full hour that the engine's off in between instructor runs. More than enough time for the engine to cool way down (especially during events in April/May or Sept/Oct when it's pretty cold out).

Three to four student groups is the norm here too, so the idle time between instructor sessions is an hour or a bit more. Unless there's a strong wind or the temp is really low, the block (and oil) will still be pretty warm. The "finger test" suggests to me that even after an hour the block is still hotter in 50'ish temps than it would be for the first session in the summer time. So there may not be much of a problem.

I presume that you are running a lighter weight oil for the colder events. I run 20w50 (dyno oil) from March through October and switch to Mobil1 0w40 or BMW 5w30 synth from November through February.

[backtrail69]

My water temps never get above 195-200 max. Usually around 180-185. This is via my MS logs.

[Emre]

Three to four student groups is the norm here too, so the idle time between instructor sessions is an hour or a bit more. Unless there's a strong wind or the temp is really low, the block (and oil) will still be pretty warm. The "finger test" suggests to me that even after an hour the block is still hotter in 50'ish temps than it would be for the first session in the summer time. So there may not be much of a problem.

I guess you're right. I'm just paranoid about oil after having lost a couple of engines over the last few seasons. I'm planning to put a fresh M20 (maybe a mild stroker) into the car this winter and I want to take care of it.

I presume that you are running a lighter weight oil for the colder events. I run 20w50 (dyno oil) from March through October and switch to Mobil1 0w40 or BMW 5w30 synth from November through February.

Well, November through February means freezing temps and snow up to your knees in Quebec. The only track driving that gets done is ice racing and winter rallycross ... but I don't use my E30 for those. That's what the Evo was for ;)

Our track season really only goes from mid-May through the end of September. Maybe as early as late April or early Oct if you're lucky. I usually run Castrol GTX 20W-50 in the summer months.

[Emre]

My water temps never get above 195-200 max. Usually around 180-185. This is via my MS logs.

Thanks very much! I'm going to order a set of VDO Vision series gauges from Summit Racing but I realized that I didn't know exactly what I needed.

All the information you've provided in this thread has been very, very helpful :up: