Improved Engine Air Intake

sailor man

Well-known member
Jan 12, 2021
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Palmetto, FL
IMG_2973.webp
We all know that the original cool air intake is the one on the right, with the open air dimensions of 3"x8 1/8". It has an open area of 24.57 sq in feeding a 4' dia (12.57 sq in) flexible hose with two 90° turns that increases air resistance substantially. The compression ratio is 1.97.
The stock opening is 2 1/2" so visualize the modification to cut out the entire flat section to get the full 4" opening for the air hose.

My proposed 11" x 8" eliptical air intake has an unrestricted area of 276.5 sq in feeding the 4" dis tube with no turns. The compression ratio of this arrangement is 21.99, almost 11 times the original design.
This must help both engine with carbs and fuel injection engines.
IMG_1687.webp
This is my COOP 455 with the old carb.
IMG_2932.webp
This is it now. Quite an improvement.
IMG_2963.webp
The filter has been moved to where the old air intake used to be.
IMG_2981.webp
It will soon be inclosed and protected with this assembly, but what is it?
IMG_2980.webp
The screen cage is........IMG_2975.webp
A stainless steel kitchen strainer and .......
IMG_2976.webp
the elliptic scoop is a heavy duty gasoline and diesel funnel.
Both a readily available and inexpensive.
The filter is washable, so it can be cleaned and reused. Rain water will not affect it.
The screen will protect the filter from debris and bug juice.
The filter can now be service from the front of the coach.

What do you think of my new "AIR RAM".
 
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Creative use of COTS hardware :)
Not to be a jerk, but those reuseable air filters are barely better than that sieve. If you want to keep sand out of your engine you need a paper filter
 
You would be better to find a filter from a 2000s GM Truck or Van, yes it will take some fab work. It will filter better and be a lot quitter.
 
The filter was Jim Bounds recommendation.
A quick search didn't have great things to say about Spectre filters.


This video compares "performance filters", as a techie guy you won't be surprised that increased performance HP is directly related to airflow... and inversely to better filtration.

Regardless of the old chestnut saying, "12,000 pound hot rod with plumbing", these ain't hot rods and the performance gain from a "performance filter" would never be noticeable in our GMCs.

Go for longevity. You and the next owner will be happier.
 
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I had a K&N filter like that on my former 91 Honda Civic 1.6L. Oil samples came back with high silicone numbers. I switched back to stock air filter and the silicone numbers to came down. I'm with Keith on this one. JMHO
 
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I had a K&N filter like that on my former 91 Honda Civic 1.6L. Oil samples came back with high silicone numbers. I switched back to stock air filter and the silicone numbers to came down. I'm with Keith on this one. JMHO
Good feedback, nice to have that data. This is something that's been on my list and is getting closer to the top. I had to go to a carb-hat for the TBI with my Toronado intake and whatnot. Stock air cleaner is a no-go at this point. The easiest path to just getting something going was using one of these oiled cone filters. I'd like to get a nice and quiet OEM airbox rigged up at some point.

Wasn't someone on here using a 2500HD airbox or something like that? I forget the details.

It'd be neat to get cold, ram-air fed to the airbox like @sailor man is showing. I like the resourcefulness of the funnel and the screen--always nice to keep leaves, twigs, mice, bugs, etc out of the airbox. Any details on the funnel you found?
 
One of the auto repair YouTube channels was showing a vehicle that was running rough that used an oiled air filter. The oil residue from the air filter was coating the Mass Airflow Sensor and throwing the AFR out of wack. They don't recommend the oiled air filters on EFI vehicles as it messes with the sensors.
 
Good feedback, nice to have that data. This is something that's been on my list and is getting closer to the top. I had to go to a carb-hat for the TBI with my Toronado intake and whatnot. Stock air cleaner is a no-go at this point. The easiest path to just getting something going was using one of these oiled cone filters. I'd like to get a nice and quiet OEM airbox rigged up at some point.

Wasn't someone on here using a 2500HD airbox or something like that? I forget the details.

It'd be neat to get cold, ram-air fed to the airbox like @sailor man is showing. I like the resourcefulness of the funnel and the screen--always nice to keep leaves, twigs, mice, bugs, etc out of the airbox. Any details on the funnel you found?
1756209092871.webp
1756209192540.webp
Ring $14.82
1756209301669.webp
$42.99

I think that this pretty inexpensive considering the potential performance increase.
 
A quick search didn't have great things to say about Spectre filters.


This video compares "performance filters", as a techie guy you won't be surprised that increased performance HP is directly related to airflow... and inversely to better filtration.

Regardless of the old chestnut saying, "12,000 pound hot rod with plumbing", these ain't hot rods and the performance gain from a "performance filter" would never be noticeable in our GMCs.

Go for longevity. You and the next owner will be happier.
The air resistance of the screen is barely noticeable because the screened area is about double of the intake area of the funnel.
IMG_2977.webp
The clamp is a standard 4" hose bracket and the white right is a standard 4" marine round deck plate ring mount.
1756210809362.webp
The actual funnel opening is smaller than 4", so the ring becomes the adapter to 4". I will have to trim the outlet end of the funnel to mate it to the ring.
The ring even comes with a gasket.
I might be using 3M 5200 fast set adhesive sealant as well.
 
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A quick search didn't have great things to say about Spectre filters.


This video compares "performance filters", as a techie guy you won't be surprised that increased performance HP is directly related to airflow... and inversely to better filtration.

Regardless of the old chestnut saying, "12,000 pound hot rod with plumbing", these ain't hot rods and the performance gain from a "performance filter" would never be noticeable in our GMCs.

Go for longevity. You and the next owner will be happier.
I think that my design allow one to use any filter that has a inline 4" connection.

These parts cost a total of $89.81. This might be the most economical upgrade, ever.
 
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View attachment 16056
We all know that the original cool air intake is the one on the right, with the open air dimensions of 3"x8 1/8". It has an open area of 24.57 sq in feeding a 4' dia (12.57 sq in) flexible hose with two 90° turns that increases air resistance substantially. The compression ratio is 1.97.
The stock opening is 2 1/2" so visualize the modification to cut out the entire flat section to get the full 4" opening for the air hose.

My proposed 11" x 8" eliptical air intake has an unrestricted area of 276.5 sq in feeding the 4" dis tube with no turns. The compression ratio of this arrangement is 21.99, almost 11 times the original design.
This must help both engine with carbs and fuel injection engines.
View attachment 16057
This is my COOP 455 with the old carb.
View attachment 16058
This is it now. Quite an improvement.
View attachment 16059
The filter has been moved to where the old air intake used to be.
View attachment 16060
It will soon be inclosed and protected with this assembly, but what is it?
View attachment 16063
The screen cage is........View attachment 16061
A stainless steel kitchen strainer and .......
View attachment 16062
the elliptic scoop is a heavy duty gasoline and diesel funnel.
Both a readily available and inexpensive.
The filter is washable, so it can be cleaned and reused. Rain water will not affect it.
The screen will protect the filter from debris and bug juice.
The filter can now be service from the front of the coach.

What do you think of my new "AIR RAM".
IMG_3038.webpIMG_3044.webp
I am still working to optimize the air ram. The old photo showed the 2 1/2" funnel opening but moving the 4" deck ring to the inside of the funnel instead of being outside with be a better design.

These photos show what a gapping maw this inlet is.
 
You can also install a coth dust cover over the filter.
But those reusable filters only get more air flow is by having larger holes for air to go through. You will decrease the life of that COOP Motor. Your best bet is to find a Factory air box from a 3/4- or 1-ton truck or van and use the paper element.
 
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