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projector 03-26-2010 09:19 AM

air cleaners
 
Hey all. I'm hearing different theories on air intake for my 454. One theory is an aftermarket open air cleaner to get more volume to the carb
and the other is a remote duct to get cooler air and more volume to the carb. The other reasoning for the first is to draw air from the engine compartment thus keeping it cooler. Basically using the engine as a giant air pump, something that's used in calculating air flow in boat bilges.

Any opinions would be appreciated.

wmarsha 03-26-2010 09:39 AM

compromises...
 
The cooler the intake air and the faster it flows will yield the best air flow to maximize the fuel usage. This increases horsepower. you have to jet to control the fuel air mixture. racing carbs are set up to utilize cool, fast flowing air-they have adjustable air bleeds for each venturii as well as jets to control the fuel flow. Such carbs are plenty expensive. a Braswel modified Holley will cost around $1000.00. You still have to tune the carb for the conditions present while "racing". in a MOHO, you may not be able to keep up with the changing conditions. But, Isolating the intake air is a good first step. but it increases the noise of the intake system. an air cleaner also muffles the noise created by the carb.

Watch your investment $ closely when modifying air intake-you may be better off with a programmable ignition system coupled with programmable electronic fuel injection. you have to comply with emission rules, too. you might be better off reducing the weight of your rig.

kmpro 03-28-2010 05:42 PM

air cleaners
 
454 Big Block Chevy engines use about 600-700 CFM of air at full throttle and certainly modifying the air intake by drawing air in front of the radiator area is a good first step. Getting someone to rework your Quadrajet carburetor is another way to improve performance and mileage. Finding the Tech who will overhaul the Q-jet and making all the adjustments during the rebuild is a tall order in this age of bolt-on throwaway. In addition, the Tech must pay attention to proper setting of the choke, Fast Idle, and curb idle to properly give you help on the carburetor. A good speed shop in your area may have a tech who speaks Quadrajet or might know someone who does.
Rather than buy a high dollar racing holley, you might consider swapping the Quadrajet for a 650 CFM Electric Choke Carter 4BBL which is an out-of-the-box bolt on. No linkage changes either. Improved my performance and fuel mileage on a coach I did the swap on. Cost was very reasonable too. I got about a 1.4 MPG increase overall in mileage, but starting and idle was much better.

Mike

bkahler 03-28-2010 06:53 PM

Quote:

Originally Posted by projector (Post 829528)
Hey all. I'm hearing different theories on air intake for my 454. One theory is an aftermarket open air cleaner to get more volume to the carb

This is a bad idea. All you're doing then is pulling in the hot air from the engine compartment. You want cool/cold air coming into the carburetor for maximum fuel engine efficiency and mileage. So stay far away from these "open" type air filters. They are worthless.

Quote:

and the other is a remote duct to get cooler air and more volume to the carb.
This is what we did above. As a prime example was our old 1983 Winnebago MH with a 454. It had the factory air filter assembly on it and our mileage was always in the 5.5 to 6.0 range. Part way through a trip we stopped at a Walmart and bought one of those aluminum dryer vent hoses. We attached it to the snout of the air filter and ran it down to in front of the radiator. Our mileage immediately jumped from the above numbers to 6.5 to 7.0 on the same trip, same terrain.

Quote:

The other reasoning for the first is to draw air from the engine compartment thus keeping it cooler. Basically using the engine as a giant air pump, something that's used in calculating air flow in boat bilges.
It actually does just the opposite. Your engine has to work harder because of the poorer engine efficiency caused by the warmer air coming into the engine which contains less oxygen.

Race car builders go out of their way to get the ram air intakes from the front of the race car to the carburetors so they can get the cool air for better power.

Brad

GlenCoombe 03-28-2010 07:14 PM

Take the time to do a DIY job with very little expense and you'll be a happy camper.

I sourced my hose from Rockleer Woodworks and the upper and lower parts of the canister from Summit Racing. I added the body by wrapping about 4 layers of flashing aluminum and then cutting the hose opening. Sealed all with gasket maker and this system is then fronted with a reusable cone filter.

Performance gain was noticeable and has stood the test of time well.

http://www.airforums.com/attachments...60756fde3d.jpg
http://www.airforums.com/attachments...14b3f49602.jpg
http://www.airforums.com/attachments...f8b9a94080.jpg

projector 03-29-2010 09:36 AM

Thanks for all the imput. GlenCoombe, I saw you're photos in the tune up thread and that's what really got me thinking about all this.

I'm looking at a "carb hat" on ebay that's basicly a cast aluminum elbow that fits the carb and a 4" duct to a remote filter. The casting and filter are about $65 with shipping. Also there's a guy at work that has a K&N filter on a tube that I can have if it's the right size. So it's a matter of figuring out the routing and a place to mount the filter.

thanks again.

easyride 03-29-2010 11:29 AM

Quote:

Originally Posted by GlenCoombe (Post 830635)
Take the time to do a DIY job with very little expense and you'll be a happy camper.

I sourced my hose from Rockleer Woodworks and the upper and lower parts of the canister from Summit Racing. I added the body by wrapping about 4 layers of flashing aluminum and then cutting the hose opening. Sealed all with gasket maker and this system is then fronted with a reusable cone filter.

Performance gain was noticeable and has stood the test of time well.

http://www.airforums.com/attachments...60756fde3d.jpg
http://www.airforums.com/attachments...14b3f49602.jpg
http://www.airforums.com/attachments...f8b9a94080.jpg

Really like that system,wonder if I could make that look right oon my GTO.Dave

projector 03-30-2010 08:08 AM

So where are the batteries on an Aistream Motorhome? GlenCoombe's air filter is where my batteries are.

kmpro 03-30-2010 08:14 AM

Air cleaners
 
GlenCoombe, your aircleaner is great! Looks like I have to go to work on building one similar to yours. Mine is stock except for 4 1" holes drilled in it that draws air from inside the engine compartment. What did you do with the crankcase filter that was inside the aircleaner?
Mike

GlenCoombe 03-30-2010 09:05 AM

I just used a regular push on filter directly to the valve cover.

If you're doing this you might also consider putting a spacer between the intake and the carb. Lifting the carb a half inch will isolate it a bit from the heat and help to mix the air going into the intake.

kmpro 03-30-2010 06:30 PM

Air cleaners
 
Thanks Glenn, that sounds like a good idea to get cooler air in for more power.
BTW, your work on this is beautiful.
Mike

bkahler 04-04-2010 09:02 AM

Quote:

Originally Posted by kmpro (Post 831314)
GlenCoombe, your aircleaner is great! Looks like I have to go to work on building one similar to yours. Mine is stock except for 4 1" holes drilled in it that draws air from inside the engine compartment. What did you do with the crankcase filter that was inside the aircleaner?
Mike

Mike,

You probably already know this but you should cover those 1" holes and go with a ram effect from the front of the MH like Glen has done. All those 1" holes are doing is drawing hot air into the carburetor. My experience has been that is bad for mileage and performance.

Brad

jhenry 04-04-2010 01:13 PM

Hi to all hope everyone enjoying holidays! Very intersesting topic! What size of tubing is best to install on air cleaner and does it mater how long? and is lower or higher up on grill better? Jonathan

GlenCoombe 04-04-2010 07:02 PM

I used 4" ducting and this fit the height well as shown in the open photo. I've not actually measured how much clearance I still have above the top but so far so good.

I mounted the cone filter high so as to be out of the way of direct debris coming into the front of the rad and to be out of the way of the cooling flow.

There is enough dam effect to push air up into the filter area and though this likely diminishes the ram effect it seems to be effective so far.


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