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Old 09-25-2012, 08:47 AM   #1
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Air Scoops

You just can't provide too much fresh air to a diesel, they run stronger and cooler the more air made avaiable. Would there be any advantage to fabricating air scoops for my side intake system?

I'm thinking with the filter intake on the side it's a pure pull system, i.e. either a neutral or maybe even a little negative pressure at the filter inlet, the engine having to suck all the air it gets. Whereas with a scoop positive pressure would be created, forcing air into the filter.

It still has to pass through the filter, which has a maximum flow capacity, which is the upper limit of air availability, but I don't know that my filter is operating at 100% efficiency.

Increasing filter size to increase avaiability is a no-brainer, and I've read the threads on that, but it seems that air rushing past the inlet at 65mph would create a low pressure situation at the filter head (venturi effect), not the most efficient delivery system.

Thoughts? Pros/cons?

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Old 09-25-2012, 09:16 AM   #2
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Only negative to a cold air intake of any kind is to ensure there is no water intrusion (or snow or hail )

NO engine likes rain water in the air cleaner and some of our northern buds on the deezle sites spoke of blowing snow and /or snow from drifts clogging up there intakes (and melting)

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Old 09-26-2012, 07:35 AM   #3
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While sufficient air availability is certainly a critical factor in performance, you cannot force more air in than the engine can use in cfm.

If a scoop were an improvement to performance, bus companies would have been all over them long ago.

I'm a busnut, and many of my fellow nut's have tried what you propose, but all that is left of those that tried it, only the screw holes remain.

Others have tried larger air filters attached to an air scoop on the roof trying to increase performance and/or horsepower, but again run up against that cfm limit.

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Old 09-26-2012, 09:16 AM   #4
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Old 09-30-2012, 04:27 PM   #5
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don't know where your air intake is. i'd look to see if i could feed it cooler air. cold air is more dense than hot air. cold air equals more power.
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Old 09-30-2012, 04:32 PM   #6
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You're talking about 'ram air' and at your speeds, it wont do a thing..
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Old 09-30-2012, 06:20 PM   #7
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My guess would be that the engineers that designed the air intake did some extensive testing before building. Since they are the ones that must provide the warranty for the engines. I would leave it alone since I can only see things entering the "air scoop" and none of them any good.
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Old 09-30-2012, 07:39 PM   #8
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devils advocate. new ideas and products come from people that think outside the box and figure out how do do something no one else could do (ie chevy 6.0 v8 - after years of after market taking the 400's crank and putting in a 350 block, chevy made the 6.0 basicly the same combination). but when they're figuring things out they tend to use something less expensive than a motorhome. would it work? remember drag racing? prostock and fuel dragsters they run scoops. now they don't run in the rain. only run quarter mile, etc. but if you can figure out the problems rain being one you'll have something to sell. small budget guys not having the money for a wind tunnel took a van body like a ups truck. cut the front out (windshield,etc) and tool the backdoors off and drove in the desert. wind tunnel -- down hill snow ski jumpers who are in the air for seconds using said van (hanging inside from straps ) can drive for hours learning to control their body to get max. air time on a jump. they didn't let not having a ton of money stop them. another is building a windmill. figuring out output in different wind speed. low budget they built a frame mounted to their vehicle to hold the windmill out infront of the vehicle and drive in the desert. 5 - 10-15-20-35mph what's the output. cheap testing. and thinking outside the box. so keep thinking you might be the one and we'll owe you the mpg increases. new things come from peope that didn't know it couldn't be done.
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Old 09-30-2012, 08:01 PM   #9
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Modern diesels have a turbo and usually a waste gate to cut down on the pressure when it reaches a certain set point. Adding pressure to that won't do anything unless you reprogram the waste gate.
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Old 09-30-2012, 08:57 PM   #10
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Look at the side of a Kenworth truck, you will see a air scoop that has a large opening in the front and a small outlet at the back. The rear opening is to let the water flow through.
Make sure you have opened up the grill on the side of your motorhome. Most have air inlets that are very restrictive
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Old 09-30-2012, 09:27 PM   #11
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air scoop

mr_d is right about the waste gate limiting boost pressure. boost presure goes with the amount of throttle (fuel) you feed the motor. at full throttle = max pressure. that being said at lite throttle (cruising down the highway, looking for max fuel milage) the boost pressure is low, adding more cool air in theory should add some horse power and fuel milage at that combination. but remember dragging an air scoop is going to cost horse power and milage. so who's right--- that's the question---- if you make it work you get the prize. i'd like to get 20 or 30 mpg in my pusher (8.3) so keep those brains working. remember before the foreign cars came out? who would have thought we would be getting 40 mpg and more. brothers 2001 400 hp. corvette, when he's trying, can get 33 mpg. who would have thought
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Old 10-01-2012, 06:54 AM   #12
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An air scoop would only scoop up more rain,bugs and dirt. On a diesel the exhaust side is the most restrictive.
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Old 10-01-2012, 07:10 AM   #13
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Old 10-01-2012, 11:35 AM   #14
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Originally Posted by wonderer1 View Post
don't know where your air intake is. i'd look to see if i could feed it cooler air. cold air is more dense than hot air. cold air equals more power.
Actually the cooler air is more dense (more #/ft3) than the warmer air. The CFM or volume flow is essentially the same, but the mass flow increases. With more air mass, you can add nore fuel mass and you get more power from a given fixed displacement engine.


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