Update Air Intake

[smokeeater]

I have a 2011 Itasca motorhome on a Ford F-53 chassis with a Ford 6.8L V10. I am thinking of upgrading the air intake to increase hp, torque and possibly mpg. I would like to hear from anyone who may have done something like this pro and/or con. I have roughly 59,000 miles on the coach. I have also installed a 5 Star programmer to the engine with good results for the first two items but not so much for the mpg. I appreciate any and all comments.

[twinboat]

More air flow = more gas flow. More gas flow = less MPG.

[Busbreath]

Way I see it - I'm on vacation. What's the hurry? I always get where I'm going towing either my Jeep or tracker and a half hour won't matter to me...
Just my 2c...

[Fiesta48]

Originally Posted by twinboat

More air flow = more gas flow. More gas flow = less MPG.

SORRY Wrong. Automotive engineer here.
Increased air flow = easier for engine to suck in air. Engines are vacuum pumps. Only more gas is used if you push the accelerator more. Otherwise the engine is working less hard at any given rpm.
I've opened up the intake tract on every car, truck and rv since 1985. I avg at least 1 to 3 more mpg on cars and .1 to .3 on RVs. Every one has better throttle response and more seat of pants power such as in hills.
I track mpg very closely.
I use gauze filters and enlarged the intact tract into frontal area for a cold air intake.
Even my wife notices the difference.
Under rated intake tracts cut power and increase mpg because the engine has to work harder sucking air.

[Fiesta48]

If you have an F-53. Use semi rigid alum dryer vent hose before the air filter. Bend it down facing the front as far back as possible close to the radiator. Use a opened outside vent facing forward to act as a funnel. Total hose min 2' long. 3' better.
Use a gauze filter inside the filter housing. Paper filters do absorb water. You will not get water into the engine in pouring rains. I did this on 2 F-53s.

[TeJay]

Fiesta48,

Here's a link about an improved air intake that some of us did a few years back. It's another look at what can be done.

My intake funnels are just made out of plastic bowls. I've got them set up so when it rains they can be moved. On two ocassions when it started raining I forgot to do it and we still didn't have any water ingested into the system. The next time it rains I'm not going to move them and will check when we stop to see if there's any water inide the air cleaner housing.

I'm almost positive the height of the tubes (4" & 2") is a just to much of a climb for the rain to get into the cleaner housing. Even if some water gets in it still has not given me any performance indication that the water is causing any issues. Believe me I'll know it when it happens. We had it happen several times on our 1999 Dutch Star.

We had issues when the dealer used dryer vent flex hoses to re-route my intake to stop the water. We lost power climbing hills. It might have been ther way of doing it. They maybe used to much of it. I can't remember it was back in 2000. The semi-rigid being smoother would work much better.

https://www.irv2.com/forums/f23/perf...-359077-4.html

[twinboat]

Originally Posted by Fiesta48

SORRY Wrong. Automotive engineer here.
Increased air flow = easier for engine to suck in air. Engines are vacuum pumps. Only more gas is used if you push the accelerator more. Otherwise the engine is working less hard at any given rpm.
I've opened up the intake tract on every car, truck and rv since 1985. I avg at least 1 to 3 more mpg on cars and .1 to .3 on RVs. Every one has better throttle response and more seat of pants power such as in hills.
I track mpg very closely.
I use gauze filters and enlarged the intact tract into frontal area for a cold air intake.
Even my wife notices the difference.
Under rated intake tracts cut power and increase mpg because the engine has to work harder sucking air.

Sorry, but if you believe it, good for you.

[Bobby F]

Originally Posted by Fiesta48

SORRY Wrong. Automotive engineer here.

And I'm decidedly NOT an AE, so take this as a "huh?" instead of a disagreement.

I've done the same to many vehicles over the past 40+ years, flipping AC covers on old 283's, piping in CAI systems to my goat, upping throttle body sizes, you name it.

I've always gotten better performance, better quick response, and a much cooler sound - but I've never noticed a bump in mpg.

Are some engines - that I haven't tried this on maybe - so bad at aspiration that they're losing 5-10% of their power by having to expend it on sucking air hard? I guess that would make sense, but that would seem like a very poor design to begin with. If you haven't found a way around the stoichiometry, I would think that the more air = more gas idea has to be true.


Like I said, not an auto engineer, so looking more for enlightenment than anything else.

[TeJay]

I'm not an AE either. Lets apply some common sense and look at this way.

Todays vehicles can monitor air flow, air temps and meter fuel to maintain a stociometric air fuel ratio of 14.7:1 which is supposed to be the most ideal air fuel ratio for proper exhaust emissions.

We are driving down a level road with calm winds at 2,000 RPM and 60 MPH. The vehicles computer system maintaines everything to achieve the desired results. We are receiving the right amount of fuel and air to effectively burn the metered fuel (14:1 AFR) and control our desired exhaust emissions.

Now modify the air cleaner so we can provide a smoother, lower resistance air flow into the filter container along with some funnels to force (RAM) in the air. Now lets again drive the same vehicle down the same road under the same conditions and see (guess) what happens?

Keep in mind when we step on the gas we are first actually controlling intake air flow and not gas. It could be called an air pedal but that's not nearly as exciting or dramatic.

Who ever heard a criminal shout as they leave the bank robbery? "Lets get out of here. Step on the Air." Even when we had carburetors allowing more air flow resulted in more fuel flow. So it was still an air pedal and not gas.

The vehicle is moving at 2,000 RPM's and 60 MPH. With more air flow based on lowered restrictions and funnels or RAM air will the computer add more or less fuel to maintain the speed and air fuel ratio?

There should/could be more molecules of oxygen per cubic feet of air based on the RAM air effect. The result might be a lower throttle angle and less fuel to maintaine the 60 MPH.

Just my thoughts!! Anybody else care to give it a go???

[twinboat]

All engine need a proper air fuel ratio to combust properly.

Add air, it goes lean and looses power. But wait, they measure the air flow AFTER the restricter plate, we call the throttle. More air flow, more fuel injection, more power.

You guys must have seen vacuum guages on gas engines. Higher vacuum means more MPG.

[tderonne]

Originally Posted by TeJay

The vehicle is moving at 2,000 RPM's and 60 MPH. With more air flow based on lowered restrictions and funnels or RAM air will the computer add more or less fuel to maintain the speed and air fuel ratio?

There should/could be more molecules of oxygen per cubic feet of air based on the RAM air effect. The result might be a lower throttle angle and less fuel to maintain the 60 MPH.

Just my thoughts!! Anybody else care to give it a go???

You were almost there.....(in bold above)

It takes a certain amount of power to move a vehicle down the road at 60 MPH. Even in motorhomes, on flat ground, we don't have to use wide open throttle.

So what TeJay said about the pedal is true. If we free up the intake, to go 60 MPH will take a little less pedal. BUT, the engine will still be making the exact same amount of power. You just traded some air filter restriction for additional throttle restriction. Same airflow, same fuel flow, same MPG.

[Fiesta48]

There's s big difference between air pressure before and vacuum after the butterfly.
Add pressure (or less vacuum) before the engine, it has to suck less hard. Meaning more power. This is a 70 year old HOT RODDERS trick.
A restricted system can not get enough air (oxygen). Almost all intakes are restricted to reduce noise especially at full throttle. But we run at full throttle maybe 1% who cares?
Getting rid of the restrictive intake on my Accord gave it incredible throttle response, almost too much, its jerky if you dont modulate the accelerator.

[CC38EL]

Not an engineer, nor do I have test data or the tools to get data. All my results are from the 'seat of my pants' and manual MPG calculations at the pump.

Like Fiesta48 and others, I've been obsessed with MPG forever. In all, probably 5 RVs and 50 different cars/trucks.

I've used all the air filters and most of the CAIs....but the thing I found most productive was increasing the diameter of the exhaust and installing a MagnaFlow style muffler. I've used FLowMaster and MBR with great results.

Example: Chevy 454 in a class A. Doghouse hot enough to cook on. And noisy!......after the mod, much quieter (noise actually moved from doghouse to middle of RV exhaust) and much cooler. Drove like a Corvette.

Another example was our Cummins ISC 350. Expanded exhaust and added MBR flow thru muffler. MPG went up .7 and engine temp down 15degrees. Boost also went up 5psi. Might have been a little louder... but campground folks never said anything.

Alas, most of my MPG results were never near my expectations...BUT they all performed better, ran cooler, responded better and the MPG was never WORSE than when I started.

So I would suggest not only looking at the air intakes and filter setups but also the exhaust. These things are just big air pumps and if you push more in the front, it's gotta go somewhere.

Just my .02 worth.

[VanDiemen23]

You don't get much pressure recovery (ram air effect) until you get up to about 90. It's going to be next to nothing on a RV. Regardless, the best place for the intake is where the highest static pressure is when under way. That's usually just below the front bumper

The longer the intake duct the more restrictive it is, regardless of diameter.

Your best modifications will be in eliminating any tight right angle turns.

Be careful with oiled air filters. Pretty easy to goober up the MAF with those.

More people create hot air intakes than successfully make a cold air intake....