Cylinder Head Temperature Gauge

[Vlad Soare]

Hi,

Just out of curiosity - is the CHT reading in the gauges real, or is it just calculated based on other parameters? Is there an actual temperature sensor in the cylinder head?

Thank you.

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[EFI]

CHT is a sensor in the head, so yes it's the real temperature.

 

[Vlad Soare]

Thanks.

 

[engineermike]

I was logging with hptuners and the dash CHT tracked identically with ECT, not the CHT PID in the logger.

 

[Vlad Soare]

How does the oil temperature relate to the CHT? Sadly, there's no gauge for the oil temperature. Can it be approximated based on the CHT? Or are they completely independent on one another?

 

[engineermike]

CHT is a function of ECT and load, mainly. I’m sure the oil temp is related but not nearly as influenced.

 

[opengl]

How does the oil temperature relate to the CHT? Sadly, there's no gauge for the oil temperature. Can it be approximated based on the CHT? Or are they completely independent on one another?

Once fully up to temperature they'll be similar under normal driving conditions. But oil takes a lot longer than coolant to get there. Figure twice as long as a rough estimate.

If you have a PP1/PP2 car you can easily swap in GT350 center gauges to get an inferred oil temperature gauge. It's pretty spot on even though it doesn't have a real sensor.

 

[Vlad Soare]

But oil takes a lot longer than coolant to get there.

Exactly. That's why I was wondering how to figure out when the oil is up to temperature. I know that a coolant temp indicator in the middle of the scale is no guarantee of that, but how about CHT? Is it safe to assume that the oil has reached its normal operating temperature when I see the CHT at, or around, 200° F?
But if the CHT is a function of coolant rather than oil temperature, then I take it the answer to my question would be no.

 

[opengl]

CHT is going to track really closely to coolant temp.

 

[Idaho2018GTPremium]

Exactly. That's why I was wondering how to figure out when the oil is up to temperature. I know that a coolant temp indicator in the middle of the scale is no guarantee of that, but how about CHT? Is it safe to assume that the oil has reached its normal operating temperature when I see the CHT at, or around, 200° F?
But if the CHT is a function of coolant rather than oil temperature, then I take it the answer to my question would be no.

Hmm, I have a digital oil gauge in the center screen in the gauges section. If you are in the gauges list view it shows as low, normal, or high. If you click on that it gives you an actual digital gauge (without numbers, though). Do you not have that feature? Just go by that if you have it. Once it settles in it's normal spot about half way on the gauge, it should be good to go.

 

[Zooks527]

Exactly. That's why I was wondering how to figure out when the oil is up to temperature. I know that a coolant temp indicator in the middle of the scale is no guarantee of that, but how about CHT? Is it safe to assume that the oil has reached its normal operating temperature when I see the CHT at, or around, 200° F?
But if the CHT is a function of coolant rather than oil temperature, then I take it the answer to my question would be no.

No, you can't assume oil is at temperature when CHT is at 200.

I have the GT350 gauges with oil temperature installed and have CHT displayed on my dash. Oil lags CHT by 15 - 20 degrees during heat up of the engine pretty consistently on a 40 - 70 degree day (I don't have any really cold data yet). At highway speed, oil temperature doesn't reach it's stable maximum until about 5 - 10 minutes or so after CHT hits and stops at 200. On my commute to work (2 miles on a residential street followed by straight highway miles) it takes the better part of 20 minutes to fully heat the oil on a pleasant day.

FWIW, I try to keep under 3000 rpm while I'm below an oil temperature of 160F, unless I have to do a highway entry, in which case I'll shift at or before 4000 rpm.

 

[Vlad Soare]

Hmm, I have a digital oil gauge in the center screen in the gauges section. If you are in the gauges list view it shows as low, normal, or high. If you click on that it gives you an actual digital gauge (without numbers, though). Do you not have that feature? Just go by that if you have it. Once it settles in it's normal spot about half way on the gauge, it should be good to go.

No, I don't have that. I have a gauge for oil pressure there, but not temperature. That may be a PP1 feature. European cars are a mixture of PP1 and Premium, we get a bit of both. Apparently not this bit though.

I have the GT350 gauges with oil temperature installed and have CHT displayed on my dash. Oil lags CHT by 15 - 20 degrees during heat up of the engine pretty consistently on a 40 - 70 degree day (I don't have any really cold data yet). At highway speed, oil temperature doesn't reach it's stable maximum until about 5 - 10 minutes or so after CHT hits and stops at 200. On my commute to work (2 miles on a residential street followed by straight highway miles) it takes the better part of 20 minutes to fully heat the oil on a pleasant day.

Thanks, that's great info. I can use that as a rough approximation.

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