OILED vs DRY FILTERS w/ PLOT TWIST: IAT

[Cory S]

You may wanna take of you intake tube and see how dirty it is inside.

It’s spotless.

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[WildHorse]

Cotton is much lower than oil, more like 0.023 W/m*K. Its really good at not allowing heat transfer and why it makes good clothing or insulation, as long as it is dry. Once wet/oiled it is not a good insulator. Heat will transfer to it quicker, but also away from it quicker.

My man.. the observations I've been making 100% contradict what you are saying. With my car in my weather conditions with my driving style oiled most certainly have lower IAT when driving, and cool much quicker than plain cotton. Try it if you don't believe me.

 

[Red65]

It’s spotless.

I would still be worried that it’s been constantly pulling in fine dirt and dust. If there’s no oil film or anything on the inside of the intake from the PCV, then you won’t really see it stuck to the inside. Better oil that filter, fine dirt is like straight sand paper to cylinder walls

 

[FreePenguin]

I would still be worried that it’s been constantly pulling in fine dirt and dust. If there’s no oil film or anything on the inside of the intake from the PCV, then you won’t really see it stuck to the inside. Better oil that filter, fine dirt is like straight sand paper to cylinder walls

kinda funny. I had something done at dealership at like 100k miles, in my Scion tC, (last time hood was opened) at like 150k I noticed I looked in engine, and realized the airbox wasn't even closed, half the box was completely exposed, like they forgot to clamp it, and such.

I looked at filter, looked spotless, which means all the dirt was just bypassing from engine bay past filter, whatever though, car drives no different in the 50k of unfiltered air.

 

[markmurfie]

My man.. the observations I've been making 100% contradict what you are saying. With my car in my weather conditions with my driving style oiled most certainly have lower IAT when driving, and cool much quicker than plain cotton. Try it if you don't believe me.

With out the oil being constantly replenished it can't cool anything down, it's just a heat sink that requires more airflow to cool it down. It's effect is going to be minimal over all.

 

[Dave2013M3]

My man.. the observations I've been making 100% contradict what you are saying. With my car in my weather conditions with my driving style oiled most certainly have lower IAT when driving, and cool much quicker than plain cotton. Try it if you don't believe me.

Agreed, not to mention the oiled filters are cotton with an oil film.

 

[WildHorse]

With out the oil being constantly replenished it can't cool anything down, it's just a heat sink that requires more airflow to cool it down. It's effect is going to be minimal over all.

I showed pics/proof dunno what else to say except just try it.

 

[Dr. Norts]

Could the oil possibly have already coated your MAF causing it to display a lower temp than the air actually is?

Just throwing ideas out there.

 

[WildHorse]

Could the oil possibly have already coated your MAF causing it to display a lower temp than the air actually is?

Just throwing ideas out there.

Gimmie 10 mins I'll check

 

[Dr. Norts]

Gimmie 10 mins I'll check

Might as well spray the thing with MAF cleaner while it's out. Get two birds stoned lol.

 

[WildHorse]

Clean buddy

 

[friedmud]

With out the oil being constantly replenished it can't cool anything down, it's just a heat sink that requires more airflow to cool it down. It's effect is going to be minimal over all.

At steady state I agree - but in a transient (like accelerating from a stop) a material that can transfer heat to the air better could be cooled more rapidly. This would actually result in higher IAT for a moment… then lower over time. That is really more of a function of surface area than it is material though.

Because of conservation of energy, all heat removed from the filter into the air flowing through it will go into the engine. There are a couple of ways this could be different between dry/oiled.

1. Higher thermal conductivity could allow the filter to more rapidly pull heat in from the engine and deposit it in the air (meaning higher IAT over all). Oil is a better conductor than paper - which would make it easier to pull in more heat from the engine.

2. Higher heat capacity could lead to more “heat soak”. A material with a higher heat capacity will be able to absorb more heat as it comes up to the same temperature as the engine. Oil has a higher heat capacity than paper, so when sitting idle this would mean you could “load” more heat into it. When you start accelerating that heat will be transferred to the air - ultimately giving you over all higher IAT.

However: it’s tough to make general statements like these. It depends on how much (the mass) paper vs oil is used. The heat capacity of oil is not that much higher than paper… so if you just used more paper then you could reach the same or even higher heat capacity.

Similarly: while oil has a higher thermal conductivity - the cotton it is on does not. How well the oil droplets are connected on the strands of cotton will play a role in the ability for the filter to soak up heat from the engine.

Finally: a lot depends on how the heat is getting from the engine to the filter. Is it conducting in? Does the box heat the air and then the air deposits the heat on the filter? Is the temperature of the box high enough that it is radiating a lot of heat toward the filter?

Basically: this system is pretty damn complicated. Just by looking at the materials you really can’t say which would be “better”. It is going to depend a lot on the engineering of the filter and the box.

The ONLY way ensure IATs stay low is to keep heat from getting into the box in the first-place. Heat shields / reflectors could work. Thicker plastic can help (will lower conductivity - but raise mass that can hold heat).

Trying to make it easier for the air to “cool” the filter is folly… “cooling” the filter means bringing heat from the filter into the engine…..

 

[Whitedevil95]

LOL how is this even a discussion topic

 

[WildHorse]

LOL how is this even a discussion topic

Then unwatch it. Simple.

 

[Whitedevil95]

Then unwatch it. Simple.

It was interesting to read all the discussion about what a 4 degree IAT difference will do on near stock mustangs , but I think im good now.

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