Ram Air Nets 5.1MPG gain...

[markweatherill]

Every little helps, as they say. But to be of benefit, the air entering the intake must be going fast enough to compare with the rate at which the engine is sucking it in, I feel. And that must equate to 'rather fast' in terms of road speed, although I can't work it out in my head.

[Frank Lee]

Oh look! My F150 came with RAM AIR (just to the left of the radiator cap) from the factory! No wonder it's so freeking awesome!

[Christ]

Hm.. My 96 had the intake snorkel (big one, for a I6) on the physical left of the radiator, facing out the 3 left most slots of the grille.

[mcrews]

I was speaking in general.

But specifically, since your second post made me re-read your first......

:....The ram air intake scoop gathers and forces somewhere in the area of 11 times more air than the engine can ingest at 70 MPH.

help me with this sentence.
1. a-b-a. how much air can the engine igest?
2. does it matter past the MAF/ECU
3.how much air prior the this supercalafradulist scope was installed.

Toyota is not Ford. (and I like ford) Ford allows a lot of room for improvement in the engine design and use. See all the bolt-ons for the 5L & 4.6L mustangs.
Toyota tends to enginnner closer to the limit. I worked for toyota in the early 90's.

[highwaylizard]

Originally Posted by Christ

I would like to ask if you have any sets of data or repeatable testing protocols from which we can make our own inferences?

And I'm fairly certain he didn't mean you.

I do have data recorded in a spread sheet that needs to be organized. I pulled a trailer (3,000 pound parachute) for my landscaping business and tree service for the first couple of years I owned the truck. I need to better organize it to reflect which miles are pulling a trailer, which are unladen, which are city and which are highway.

I have been doing fuel economy research as it relates to my truck for years. I test devices, theories, aftermarket modifications, and build my own prototypes. I publish my findings on my blog. I believe my protocol is pretty good but am always open to constructive criticism.

My ram air intake scoop is connected directly to the air box and so I would guess the repeatable testing protocol would be to disconnect and run without it which I have done several times. The ram air scoop only provides significant measurable benefit on the highway.

[highwaylizard]

Originally Posted by tjts1

Ram air is a misnomer (thank you GM marketing) but a large forward facing intake helped improve FE on 3 cars so far vs the stock intake setup. There is less down shifting involved in normal driving and I can use WOT or near wot in high gear at low RPM more often. The tradeoff is that the airbox accumulates more dirt.

My ram air intake scoop is located below the bumper on the passenger side of my truck. At that location it does tend to collect a lot more grit and debris than would normally be found there. I clean out the air box every couple of thousand miles. I have decided redesign the scoop and move it further up and locate it in the bumper. This should make the feed tube less convoluted and the location in the bumper will be in a higher pressure area. It is my hope that by locating the scoop in the bumper it will accumulate less debris. Although I have never done it I worry about the scoop getting ripped off the bottom of the bumper by a parking curb or road hazard. I have managed to fill it up with snow from cutting through a snow bank.

[highwaylizard]

Originally Posted by markweatherill

Every little helps, as they say. But to be of benefit, the air entering the intake must be going fast enough to compare with the rate at which the engine is sucking it in, I feel. And that must equate to 'rather fast' in terms of road speed, although I can't work it out in my head.

I agree. I approached this in simple terms of providing more air than the engine draws in.

• My engine is a 4.7 liter V8 which is 285 cubic inches. At 2200 RPM it draws in 313,500 cubic inches (2200 x 285/2).
• My scoop has a face area of 48 inches (4 inches tall x 12 inches wide)
• At 70 MPH the truck moves 73,920 lineal inches per minute (70/60*5280*12)
• 73920 (lineal inches) X 48 (opening of scoop) = 3,548,160 cubic inches
• 3,548,160 (volume of air the scoop gathers at 70 MPH) divided by 313,500 (volume engine consumes at 2200 RPM) = 11.3

Originally Posted by mcrews

I was speaking in general.

But specifically, since your second post made me re-read your first......

:....The ram air intake scoop gathers and forces somewhere in the area of 11 times more air than the engine can ingest at 70 MPH.

Originally Posted by mcrews

help me with this sentence.
1. a-b-a. how much air can the engine igest?

I calculated the air consumption by taking the cubic inches (285) and multiplying it against the RPM's (2200) at 70 MPH and dividing by 2 since each piston only draws air every two rotations of the crank. This gave me 313,500 cubic inches.

Originally Posted by mcrews

2. does it matter past the MAF/ECU

I do not think that it does. I am not actually pushing 3,548,160 inches of air into the engine - what I am doing is overcoming an intake restriction and keeping pressure in the air box/intake tube/intake plenum. With the first generation Tundra there is a flow restriction in the fender well where the stock air box draws its air from. By doing this I eliminated that restriction.

Originally Posted by mcrews

3.how much air prior the this supercalafradulist scope was installed.

Under perfect conditions the engine would have only been capable of drawing 313,500 cubic inches of air per minute - but as I explained above it was not possible to operate at 100% efficiency due to the restrictions in the fender.

[Phantom]

Not to offend but I highly doubt that there is a real ram air effect, more likely what you are experiencing is a less restrictive intake since there is now more area to pipe in the air and cooler temps allowing for more power.

To start the calculation using my car a 3.8l V6 @ 2000rpm consumes about 67CFM assuming 50% VE. For a straight Flexable 3inch pipe to flow 67CFM the velocity of the air in the pipe would need to be 1364.91fpm (Air Duct Calculator - EfficientComfort.net) or the speed of the air needs to be 930.62mph. Even if the speed of air is 11 times faster than the speed of the car I would need to be moving 84.5MPH.

<s>Your truck</s> The 2.2l car in the first post at 2000rpm 50% VE uses 39CFM with the velocity needing to be 794.5 fpm or moving at 541.7MPH going by the 11 again (highly doubt the air would be moving that much faster than the car) the speed needed is 49.25MPH.

One thing that is not included in my calculations is the extra restriction produced from bends in the pipe see ZZ Performance

[Christ]

Anything over atmospheric would be helpful, actually, even if not a positive boost. Think about turbo applications... If you start at 14 inches of vacuum, the turbo is working through all that vacuum before applying boost. Even if it never makes it into positive pressure, its still lowering the negative pressure in the intake tract, thus reducing pumping losses in the intake. Same theory for ram air, in reality. Doesn't require measurable positive pressure, only a decrease in negative pressure.

! Fixed a bunch of mistakes that swype made. !

[tjts1]

Originally Posted by Phantom

Not to offend but I highly doubt that there is a real ram air effect, more likely what you are experiencing is a less restrictive intake since there is now more area to pipe in the air and cooler temps allowing for more power.

Thats why I said ram air is a misnomer. Most stock intakes are designed to reduce noise and prevent dirt and water ingestion first and foremost at the expense of some fuel economy and power. Theres plenty of information on how to modify the intake here.
Reducing intake flow restriction to the absolute bare minimum
If you do a search you'll find a bunch of intake articles using several different vehicles.