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EJOUIE"s 2005 Impala



Thats more of what is was getting at. Why would the HAI get better mpg? Wouldn't I always want the coldest air available? Sure, colder air means more fuel to match BUT that would mean the same amount of bang at a lower rpm. Low rpm means less rotating mass which means more efficiency?

I know there are many threads on this issue, but not contained to hwy cruising only. Thats why I am curious.

Grimsin, did you go back to stock due to noise?

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Wamer air takes less energy to burn that cooler air. It's not that it's going to take more fuel because there isn't any more air coming into the engine at the same rpm. The computer is doing everything is it's power under closed loop conditions to achive stoich and the best mpg possible. I feel that it doesnt matter if the intake is directly in an cooler air path or if it's sitting in the warmer engine bay at cruising speeds.
 
IIRC the general concept is that the cold air is more dense, and therefore provides more oxygen for the combustion process...

Other than that, the difference, if there is any, is mostly for boosted applications where lower temperatures are desired to help prevent detonation.
 
Wamer air takes less energy to burn that cooler air. It's not that it's going to take more fuel because there isn't any more air coming into the engine at the same rpm.
Not sure on the science behind that. The pistons moving downward create vacuum with a certain volume to fill with air/fuel. Colder air will have the same volume but will be denser. Thus more air molecules so to speak. Then to maintain stoich the pcm sends more fuel.

The other consideration is how effectively the engine can use that volume, as in can it suck in enough air to fill that volume. Less restrictions increase air velocity which then increases the engine's ability to fill that volume with air.

So, the questions are:

How restrictive is the Hot Air Intake?

How restricive is the stock air box?

How restrictive is the Fender Well Intake?

What are the IATs for each?

I can start collecting data for the stock setup now. Will hopefully be able to find data for the others.
Proposed the question initially to see if anyone has already done this before and could save me the effort.

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More air means more oxygen, which in turn means a more complete burn, thus more power for the same amount of fuel.

That's where the better gas mileage comes from. At highway speeds, the engine compartment will cool down enough to make the difference between fender well and engine compartment negligible.
 


Thats what I am curious to confirm. If so, then the least restrictive HAI will be the best for this application.

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Every car also can be different so I will record my current IATs with the stock airbox and see for a base line.

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I have. 4" hai intake, I got bored of swapping the intakes as i never noticed a difference between the two.
When I got my bigger throttle body that was a noticeable difference, I even got a running lean code and had to get it retuned, so a bigger tb for the n/a 3800 does make a difference
 
Hmmm might have to add the HVL36 TB to the list....

Anywho, I fired up torque for the first time with the impala. IAT never went more than 10*F above ambient while cruising at 75mph. That is not enough reason to move away from the quiet stock airbox.

However, it did not address the potential restrictions of the airbox. That needs to be measured.

Also noticed some kr spikes of up to 6*. That a little high for stock?

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Kr isn't a problem when stock, the PCM does it to prevent detonation. Once the engine is boosted, that's when it becomes an issue, the added stress of higher pressures and more heat will make detonation more prevalent and damaging, and makes chipped pistons a real possibility.
 


Got it. So kr for my setup isn't a problem. It is an area I can work on though to improve performance.

Going to see if I can use torque to get a reading on the MAF. Going to take the measurement at 2000 rpm.

If anyone has a HAI on an otherwise stock l36 and could post their MAF reading at 2000 rpm that would be very helpful.

That comparison should shed light on air velocity and intake restrictions.

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Got it. So kr for my setup isn't a problem. It is an area I can work on though to improve performance.

Going to see if I can use torque to get a reading on the MAF. Going to take the measurement at 2000 rpm.

If anyone has a HAI on an otherwise stock l36 and could post their MAF reading at 2000 rpm that would be very helpful.

That comparison should shed light on air velocity and intake restrictions.

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get a tuner, then play, your chasing your tail here ^^^^^
 


Mine's actually a FWI, made out of 3in PVC... And I need a new filter. Lol

I know it will be different, all of the sensors are in the intake tube instead of the throttle body, everything but the tps.
 
Idle: ~35 cfm
2000 rpm: ~120 cfm
Full WOT, 5800 rpm: ~14,500 cfm.

Intake air temps hovered around 80-90 degrees at 35 mph, 65-70 degrees at 65 mph. Ambient air temp was 62 degrees.

If you want to look at my intake, I can post some detailed pics. My sensors do sit right behind the headlight.
 
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