Everyone with oil temp issues

TheWeatherman · 05-13-2009, 11:21 AM

[QUOTE=ricer333;72272

Weatherman, you are correct, but still the heat is going to be much higher down south than up north. Not that the north will not have issues, but I'm just pointing this out because down here we are already hitting 90+ degree weather. Vermont was in the 50's this past weekend. QUOTE]

Ricer, you're definately right about the southern states getting hotter and are right about them having the more frequent problems. That is totally the issue. (Again, sorry to be that guy.)

wstar · 05-13-2009, 11:50 AM

Humidity does in fact affect cars multiple ways. In the case of intake air, it changes the air's density, and more importantly changes the oxygen density (how much available oxygen to burn in a liter of 'air' at a given pressure). As for cooling, humidity in the air changes the heat-transfer properties of the air, which again affects cooling (it makes your car hotter for much the same reasons it makes you feel hotter).

Edit: I'll give you that the car doesn't rely on evaporative cooling like skin does, but still, the heat-transfer properties of humid air are going to be different.

TheWeatherman · 05-13-2009, 12:00 PM

Quote:

Originally Posted by wstar

Humidity does in fact affect cars multiple ways. In the case of intake air, it changes the air's density, and more importantly changes the oxygen density (how much available oxygen to burn in a liter of 'air' at a given pressure). As for cooling, humidity in the air changes the heat-transfer properties of the air, which again affects cooling (it makes your car hotter for much the same reasons it makes you feel hotter).

Edit: I'll give you that the car doesn't rely on evaporative cooling like skin does, but still, the heat-transfer properties of humid air are going to be different.

We're not talking about the intake part of this. This is a radiator issue, not an MAF issue. Elevation & pressure is the biggest factor in what you're talking about, not so much humidity.

After numerous thermodynamics classes, the humidity you speak of for cooling is totally different. You're talking about latent heat processes which pretty much don't affect your radiator. Radiators rely on the movement of air over the exchangers which is a conductive process, not a latent process. Your A/C works on latent heating/cooling, not radiators. Actually, humid air can hold more heat than dry air, which would make it better to have humid air running over your heat exchanger. It's similar to a moist adiabatic process vs. dry.

Don't give people ideas about humidity causing this issue. It is completely irrelevant. Any engineer or atmospheric scientist knows this.

wstar · 05-13-2009, 12:06 PM

Quote:

Originally Posted by TheWeatherman

We're not talking about the intake part of this. This is a radiator issue, not an MAF issue. Elevation & pressure is the biggest factor in what you're talking about, not so much humidity.

After numerous thermodynamics classes, the humidity you speak of for cooling is totally different. You're talking about latent heat processes which pretty much don't affect your radiator. Radiators rely on the movement of air over the exchangers which is a conductive process, not a latent process. Your A/C works on latent heating/cooling, not radiators. Actually, humid air can hold more heat than dry air, which would make it better to have humid air running over your heat exchanger. It's similar to a moist adiabatic process vs. dry.

Don't give people ideas about humidity causing this issue. It is completely irrelevant. Any engineer or atmospheric scientist knows this.

Our numbers indicate that our radiators aren't doing much for our oil temps. Water temp in the radiator is fine, but the radiator water isn't getting enough heat out of the engine oil (not enough transfer between the two). Therefore the cooling of the block itself is a factor (engine bay heat). You don't think there's an effect there?

TheWeatherman · 05-13-2009, 12:12 PM

Quote:

Originally Posted by wstar

Our numbers indicate that our radiators aren't doing much for our oil temps. Water temp in the radiator is fine, but the radiator water isn't getting enough heat out of the engine oil (not enough transfer between the two). Therefore the cooling of the block itself is a factor (engine bay heat). You don't think there's an effect there?

Yeah, with pure heat, not humidity. If anything, humidity would help, but in way so small that it would barely register. Again, heat conduction vs. latent heat processes.

spearfish25 · 05-13-2009, 12:46 PM

Quote:

Originally Posted by TheWeatherman

adiabatic process

I LOVE IT!!! I haven't heard (or read) the word adiabatic in almost 10 years since my engineering days

TheWeatherman · 05-13-2009, 01:03 PM

Quote:

Originally Posted by spearfish25

I LOVE IT!!! I haven't heard (or read) the word adiabatic in almost 10 years since my engineering days

Ha ha! Thanks for understanding Spearfish, but you know as a scientist, that's how it really works with a car! I just wanted to make it clear so people who go outside and think it's humid think it's going to make your car overheat faster than a dry day. Another common misconception is the thought of a car feeling a wind chill. Sure, it rids heat faster when it's cold, but when you have a windchill of -80F, your car only feels the outside air's temperature. Good stuff, good stuff.

joeyz10 · 05-13-2009, 11:34 PM

Quote:

Originally Posted by TheWeatherman

Ha ha! Thanks for understanding Spearfish, but you know as a scientist, that's how it really works with a car! I just wanted to make it clear so people who go outside and think it's humid think it's going to make your car overheat faster than a dry day. Another common misconception is the thought of a car feeling a wind chill. Sure, it rids heat faster when it's cold, but when you have a windchill of -80F, your car only feels the outside air's temperature. Good stuff, good stuff.

Weatherman no wonder it feels so hot when the temp is over 100 f on a low humidity state like ca and las vegas compared to 85 f humid states. i can't stand 118's in vegas on summer...

05-13-2009, 11:50 AM	#2 (permalink)
wstar A True Z Fanatic Join Date: Mar 2009 Location: Houston, TX Posts: 4,024 Drives: too slow Rep Power: 3595	Humidity does in fact affect cars multiple ways. In the case of intake air, it changes the air's density, and more importantly changes the oxygen density (how much available oxygen to burn in a liter of 'air' at a given pressure). As for cooling, humidity in the air changes the heat-transfer properties of the air, which again affects cooling (it makes your car hotter for much the same reasons it makes you feel hotter). Edit: I'll give you that the car doesn't rely on evaporative cooling like skin does, but still, the heat-transfer properties of humid air are going to be different. __________________ 7AT Track Car! Journal thread / Car setup details

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05-13-2009, 11:21 AM	#1 (permalink)
TheWeatherman Enthusiast Member Join Date: Mar 2009 Location: Milwaukee, WI Posts: 265 Drives: 2009 370Z 6MTw/Sport Rep Power: 17	[QUOTE=ricer333;72272 Weatherman, you are correct, but still the heat is going to be much higher down south than up north. Not that the north will not have issues, but I'm just pointing this out because down here we are already hitting 90+ degree weather. Vermont was in the 50's this past weekend. QUOTE] Ricer, you're definately right about the southern states getting hotter and are right about them having the more frequent problems. That is totally the issue. (Again, sorry to be that guy.)