Why is stock air intake gasket shaped like this?

[pcdangio]

I'm debugging some high IAT2 temps (air intake temperature), and curious why the stock gasket for the intake has this large opening on the right side (see pic attached).

I would think this is bad, as one could imagine a lot of hot air from inside the engine compartment gets sucked in there (red arrow) as opposed to the colder air coming in through the main inlet in front of the radiator (blue arrow).

I'm sure there's a good reason for it that I just haven't imagined... anybody have any thoughts?

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[Byron Sexton]

using that noggin up there in that head of yours...im interested to see the responses.

 

[bbeem]

Good question. Not to hyjack but on the same line of thought, why do they block the first 4 inches of the si intercooler with plastic? Won't this raise IATs also? I don't know if other models are like this? I noticed it a few months in and took it out. When I did I had 4" of virgin intercooler waiting for cool air and bugs.

 

[TypeRNY]

My feeling is, Honda has to sacrifice some power or sacrifice something for protection. That would be the only reason I can imagine plastic being there. Plus plastic doesn't really retain that much heat, so I dont think it would be too detrimental

 

[SDAlexander8]

Extra protection against water being sucked into the intake is my guess. People are stupid about driving through high water

 

[bbeem]

My feeling is, Honda has to sacrifice some power or sacrifice something for protection. That would be the only reason I can imagine plastic being there. Plus plastic doesn't really retain that much heat, so I dont think it would be too detrimental

But what is it protecting? Why would the intercooler fins be more fragile on the left than anywhere else. I don't think it heat soaks but I definitely had virgin radiator behind it. Now that part looks trash like the rest after a year but I think it makes sense to get rid of it. Doesn't provide any additional protection I figure unless you like the first few inches of your cooler clean and hidden.

 

[pcdangio]

Extra protection against water being sucked into the intake is my guess. People are stupid about driving through high water

Looking at it I don’t think it’s for water protection... that big gasket gap on the right is only like 4 inches higher than the front inlet in front of the radiator (which is already reallly high above ground)

 

[Learn2turn]

Think air movement...

You will not get air to FLOW through the inlet consistently without allowing some way of escape, that is where/why the gasket is open on the side.

 

[pcdangio]

Think air movement...

You will not get air to FLOW through the inlet consistently without allowing some way of escape, that is where/why the gasket is open on the side.

With the turbo, my understanding is that the intake operates under a total vacuum and pulls all the air it needs in through the intake... and air isn’t forced into the intake by the speed of the vehicle. If you look at the intake inlet tube in front of the radiator, it points straight down as well (and air can’t be forced into it).

If my understanding about the vacuum is correct, then the only thing that gasket gap could do is allow more air to get pulled into the intake from within the engine compartment?

 

[Phy]

If you're sitting in traffic, you might get some hot engine air, but when you're driving forward all that air is getting replaced and pushed around so much that I would guess there isn't any appreciable difference and it has an exit for excess air coming from the front.

 

[pcdangio]

If you're sitting in traffic, you might get some hot engine air, but when you're driving forward all that air is getting replaced and pushed around so much that I would guess there isn't any appreciable difference and it has an exit for excess air coming from the front.

Appreciate all the thoughts on this so far guys...

I'd like to put an ambient temp sensor under the hood to see how hot it stays even while driving at speed. My guess is that the air in the engine bay stays wellllll above ambient even while driving at speed.

I've been monitoring my IAT2 (intake temp before turbo). After a cold start, with engine cool, IAT2 stays within 10degF of ambient, whether im driving at speed or sitting still. After driving for a while and heating the engine up, my IAT2 will be +30degF over ambient while driving at speed, and +50degF when sitting still. So even at speed, the IA2 temps are still way hotter than ambient because the engine is hot. So either hot engine compartment air is getting sucked in through the intake, or the intake airbox itself is getting so hot from being next to the engine that it heats up cool ambient air as it flows through.

Based on how fast that air is moving through the intake box (and the fact that the IAT2 sensor is 2 inches downstream from the airbox itself), I don't think that there's any way a hot airbox is enough to raise the fast moving air up by 30degF. It's gotta be hot air from the compartment getting pulled in. I'm trying to figure out if that hot air is coming in through gaps in the airbox lid, or if its getting pulled in through that gasket gap I showed in the pic.

 

[Phy]

Appreciate all the thoughts on this so far guys...

I'd like to put an ambient temp sensor under the hood to see how hot it stays even while driving at speed. My guess is that the air in the engine bay stays wellllll above ambient even while driving at speed.

I've been monitoring my IAT2 (intake temp before turbo). After a cold start, with engine cool, IAT2 stays within 10degF of ambient, whether im driving at speed or sitting still. After driving for a while and heating the engine up, my IAT2 will be +30degF over ambient while driving at speed, and +50degF when sitting still. So even at speed, the IA2 temps are still way hotter than ambient because the engine is hot. So either hot engine compartment air is getting sucked in through the intake, or the intake airbox itself is getting so hot from being next to the engine that it heats up cool ambient air as it flows through.

Based on how fast that air is moving through the intake box (and the fact that the IAT2 sensor is 2 inches downstream from the airbox itself), I don't think that there's any way a hot airbox is enough to raise the fast moving air up by 30degF. It's gotta be hot air from the compartment getting pulled in. I'm trying to figure out if that hot air is coming in through gaps in the airbox lid, or if its getting pulled in through that gasket gap I showed in the pic.

How hard would it be to cover that hole and check temps?

 

[pcdangio]

How hard would it be to cover that hole and check temps?

wouldn’t be too hard, I’m more worried about seeing that it does lower intake temps without any immediate negative effects, but then finding out later that it has some sort of long term negative effect that winds up screwing me over haha... why I wanted to ask on here first

 

[Joe1986]

Extra protection against water being sucked into the intake is my guess. People are stupid about driving through high water

Lol nah

 

[dwag0588]

Good question. Not to hyjack but on the same line of thought, why do they block the first 4 inches of the si intercooler with plastic? Won't this raise IATs also? I don't know if other models are like this? I noticed it a few months in and took it out. When I did I had 4" of virgin intercooler waiting for cool air and bugs.

This is often done to prevent intercooler icing in cold climates. If you live somewhere warm, you can probably remove it. In Iowa, I don't think I would.