Videos of this ram scoop design that you engineered please.

Cause it sounds like you are figuring out the math to make improvements but if you believe your thesis to be correct then you should build a unit and test it. Now that you've worked in class it's time to hit the lab. If you can produce results and build a working unit that provides positive results you could then start building one at a time and sell them. This is how little guys gets bigger in the corporate world.

 

I don't understand it all but appreciate you taking the time to write it. I'm a VERY different kind of scientist!

 

I might just make a ram air intake for my skyactiv just for kicks. I wonder whether I should use plastic, some sort of metal, or just try to make a cold air intake instead. I'll think it over, but I'm definitely doing something with this!

 

I'm trying to remember if someone in here said that the MS3 hood would fit or not on a Sky but if it did you could retrofit a ram scoop into the existing port hole normally used for the inter cooler you would have a ram scoop.

Technically the upper part of the opening of our cars (above the bumper) rams air and compresses it in that area so we already get a form of compressed ram scoop especially since the opening is much bigger than the intake port that sucks it in. Air is compressed in that area and more air is rushing in it too. The header and CPU programming are the restrictions. The 4-2-1 headers would have helped evacuate heat build up quicker where our header needed a cpu program that adapted to it. I keep hoping an aftermarket 4-2-1 header that would fit our cars would be engineered but perhaps that's wishful thinking.

 

Since some of you have requested that I continue this thread (and there may be others as well) I feel that I should continue to provide more information about ram air induction for those who might want to experiment with it on their own, and not leave anyone hanging. And, as one poster has pointed out, if you dislike a thread or actively hate it, why not just ignore it or at least wait until it plays itself out before attacking it?

A word about my first post. I don't particularly enjoy number-spinning but I don't believe in posting a formula without providing information about what it's based on and how it's derived. I think most people would rather have that information and not simply blindly accept someone's word that this is the way things are - take it or leave it. In any case, that's the way I work. Anyone who wants to skip the derivations and work directly with the formula is, of course, free to do so. There is no "higher math" involved here, just simple arithmetic of the kind we all learn in elementary school.

Measurement
For those of us interested in improving the air flow in our intake system, what is needed is a highly sensitive, low-pressure measurement instrument, capable of both direct and differential readings, and able to read both positive and negative pressures. With such an instrument, the degree of intake restriction as measured in terms of negative pressure can be plotted for such elements as the air inlet, the duct leading to the air box, the air filter element, the air box itself, the MAF sensor and screens (where applicable) and the throttle body. Any part of the intake system could be measured simply by installing a port at any point you wish to sample. Any mod that reduces intake restriction will show up as a reduction in negative pressure, or an actual positive pressure on such an instrument, compared with the stock layout. Additionally, measurements of aerodynamic pressures across the front of a car for discovering the best location for a ram air intake would also be possible. Fortunately, such a device exists: the Dwyer Magnehelic Differential Pressure Gauge. Dwyer is an American company located in Michigan City, IN. For more information, go:
Dwyer Instruments | Dwyer Instruments

The gauge of interest for us is the Series 2000. These gauges are available in a wide variety of measurement units among which are the following:
"water with a range of 0-.25" to 0-500" (30 models)
"Hg with a range of 0-.25 to 0-60"
kPa with a range of 0-.1 to 0-200 kPa (33models)

The reason that such a wide range of measurements is needed is because the more extended the range, the lower the resolution of each measurement point. For example, the most sensitive "water model with a range of 0-.25" has a resolution of .005"/division while the "water model with a range of 0-150" has a resolution of 5"/division. Clearly one size does not fit all situations. Imagine, for example, trying to measure the pressure drop across a new air filter element designed to have a pressure drop of 1.5" water when clean with a gauge whose most sensitive resolution is 5" water. Accuracy for most models is 2% of full scale, and the best news is that they are available from Dwyer at a cost of only, in most cases, US $63.50.
Probably even cheaper on ebay.

Which Dwyer Magnehelic Differential Pressure Gauge Should I Buy?
Given the wide variety of measurement units and ranges possible, the question becomes which of the many gauges available would be the most useful for our purposes, assuming that we only want to buy a single model? Julian Edgar of the great Australian online auto magazine, Autospeed, about whose work we'll extensively cover starting in the next post (the man who, BTW, made me aware of the existence and utility of these instruments) tends to measure negative pressure in "water or kPa, and positive pressure in psi owns a selection of gauges but recommends an instrument reading 0-10 kPa as having the most all-round utility for our purposes.

This is the Dwyer Model 2000-10KPA with a resolution of .2 kPa per division, more than sensitive enough to measure the pressure drop across a clean air filter. Using an online converter, we can easily convert these figures to "water or psi with 10 kPa = 40.146 "water or 1.45 psi. For those of you who prefer to work with "water, Dwyer's gauge with a range of 0-40 is virtually identical to the 10 kPa gauge.

Using the Dwyer Magnehelic Differential Pressure Gauge
Using the gauge is extremely easy. the instrument is equipped with two high-pressure and two low-pressure ports and a zero adjust screw. To measure a positive pressure, connect tubing from the source of pressure to either of the two high pressure ports, plug the port not used, and vent one or both low-pressure ports to atmosphere. To measure a negative pressure, connect the tubing from the source of negative pressure, or vacuum, to either of the two low-pressure ports, plug the port not used, and vent one or both high-pressure ports to atmosphere. To measure a differential pressure, connect tubing from the greater of two pressure sources to either high-pressure port and connect tubing from the lower pressure source to either low-pressure port. Plug both unused ports. When used in a dusty atmosphere, an accessory filter vent plug can be installed in the open port(s) to keep the inside of the gauge clean. That's all there is to it and NO ARITHMETIC IS INVOLVED.

In the next post, if there is a next post, we'll get to the meat of the topic of maximizing ram induction in vehicles.

 

Looking forward to the next post. Thank you for not dropping the thread.


Sent from AutoGuide.com Free App

 

I think my nose is bleeding from reading this thread. LOL

 

Before proceeding further, we might ask what benefits might accrue from improving ram air induction in terms of performance and everyday driving. The answer to the first question is an increase in power output. In order to demonstrate this will require me to utilize another formula which may further increase the wrath of certain members of this Forum but at least I promise you no numbers.

Most of you know that indicated HP (IHP) is the power developed in the cylinders from the combustion of the A/F mixture while Brake HP (BHP) is the power available at the crank. The difference between the two is the friction HP (FHP), the power consumed by overcoming the mechanical friction of the engine. But FHP has two components: mechanical friction between moving parts (especially piston motion in the cylinders), and fluid motion in the intake and exhaust systems including the flow through the valves and motion within the cylinders. This second type of friction is known as pumping work or pumping losses. Any restriction to flow in the intake or exhaust system will increase these pumping losses. Now, since BHP = IHP - FHP, any reduction in pumping losses should provide a commensurate increase in BHP. It's for this reason that increased ram induction, by reducing pumping losses, may increase BHP output. Granted, the effect will be small though it can be added to by also utilizing a less-restrictive exhaust system, but why not make use of it if you can? Additionally, a reduction in FHP should reduce fuel consumption and we know this because Mazda has gone to great lengths to reduce both mechanical friction and pumping losses in the Sky.

The answer to the second question, based on my own experience with my Protégé, and that of others who have experimented in this area, is that a noticeable increase in throttle response occurs along with a freer revving engine particularly in the higher rpm ranges, resulting from the increased intake air flow through ram induction. The difference is not overwhelming but it is definitely there. I don't drag race my car on the street but high-speed passes on two-lane country highways are certainly easier now with less time spent out in the opposing lane. Hill-climbing ability is also improved and since I really enjoy driving the twisties, acceleration powering out of turns is noticeably enhanced. In other words, the car is just more fun to drive. For me, reason enough to do it.

Locating a High Pressure Intake
As previously mentioned Julian Edgar of the online Autospeed magazine has done considerable work in exploring the benefits of ram induction. A big fan of maintaining the factory air box (although he will modify it in certain instances) to avoid the ingestion of underhood air, he has written extensively on modifying all parts of the induction system to reduce negative pressure throughout the inlet tract. As Edgar has demonstrated, creating a positive pressure in the cold air intake, or at least reducing the negative pressure, will result in an increase in performance. But achieving that goal requires that the inlet of the cold air intake be situated in an area of high aerodynamic pressure. But just how are these areas to be found?

In his article, "More on Siting Cold Air Intakes," Edgar explains how he measured the pattern of pressure distribution across the front of a car.
AutoSpeed - More on Siting Cold Air Intakes
When the car is stationary, the air pressure all around it will be at atmospheric. In motion the air pressure at the front of the car will increase above atmospheric due to ram. To summarize, using a Dwyer Magnehelic Pressure Gauge calibrated for 0-1" water, at a road speed of 60 km/h (37 mph), the distribution of pressures was recorded at various locations across the front of a 2003 Lexus RX330 SUV (according to the author, previous testing of a first-generation Lexus LS400 found similar patterns of pressure distribution). The figures with a + sign represent pressures above atmospheric in " water those with a negative sign indicate pressures below atmospheric in " water. A table provided in the article lists the recorded pressures from a high of +.55" water above atmospheric at the middle of the front license plate, decreasing to +.3" at the leading edge of the front undertray , +.2" at the middle of the Lexus badge in the grille (where the Lexus air intake is located), and +.2" in the middle of the headlight. As the sides of the car are approached, pressures tend to decrease even more or even become negative. According to Edgar, this is because as the air starts to wrap around body curves, pressure falls off. Accordingly, the pressure at the base of the windscreen was down to +.1", below the foglight on the bumper it fell to +.05 to -.1" and switched to a negative pressure in the front wheel arch (-.1"), at the outer edge of the headlight (-.45"), and reached its lowest point at the top of the windscreen (-.6"). Interestingly, the wheel arch recorded a negative pressure and this is the location for many CAI filter placements. Obviously not a good outcome and suggesting that those who have filters placed there might want to check the pressure to avoid a possible loss.

To ensure that the pressure distribution didn't change with speed as other aerodynamic effects occur, Edgar also tested the vehicle at higher speeds. Since the 0-1" water gauge was too sensitive to measure pressure at higher speeds, he substituted a 0-150" instrument. Using the front tow hook blanking plate on the front bumper as a measuring point (which had previously recorded +.4" water at 60 km/h), he found that pressure rose smoothly with speed from +.4" water at 60 km/h (37 mph), to 3" water at 120 km/h (75 mph), to 10" water at 150 km/h (93 mph).

Obviously, not all locations on the front of a vehicle are available for intake placement but by carrying out this kind of testing, the best available entry at the highest available dynamic pressure can be chosen for the best possible results.

In the next post, we''ll look at how some ram air mods provided a measurable increase in performance.

 

@goldstar You know, reading through this thread again the math needs to be explained in closer to layman's terms. It's good info but definitely more advanced than any other mathy thread here so far, and needs more context to walk the kids into the topic.

 

I don't think I have the ability to simplify the formulas and math beyond which I've already done, which undoubtedly is a failure on my part - I'm probably not a very good teacher. My suggestion for those who don't want to follow the numbers or formulas is to forget about them or ignore them. I only provided the background material to demonstrate that there is a scientific basis for the utilization of ram air. I thought some of our readers might want to know about the physics involved in the process but that knowledge isn't necessary if one just wants to experiment.

To cut to the chase, we're talking about using the forward velocity of a vehicle to ram air into the intake system to provide a slight increase in the amount of air drawn into the cylinders, over and above that possible by the downward motion of the pistons alone on the intake stroke. The faster the vehicle speed, the greater the ram effect.

For those who don't care about the why and how of ram air but just want to give it a try, all you have to do is to locate the air inlet on a high pressure part of the vehicle front (suitably protected against the ingestion of standing water or heavy rain) and duct it to the air box. With luck, there will be some benefit that you can feel.

 

Measuring the Effect of Ram Air Modifications
One of the things I like about the work of Julian Edgar and his associates in regard to ram air modifications is his ability to achieve high-tech results from low-tech materials such as PVC pipes, flexible hoses from various sources, and even kitchen utensils. Ideal for people like us who have to homebrew installations in this area since no commercial products exist. Here are some striking examples of the positive effect that ram air can have in road cars:

The first article is, "Eliminating Negative Boost, Part 5" by Julian Edgar.
AutoSpeed - Eliminating Negative Boost - Part 5
Although the car in question is turbocharged, this is irrelevant to the discussion since the article discusses air flow on the atmosphere side of the compressor. By locating the air inlet in a high pressure area, the author was able to maintain atmospheric pressure in the system all the way up to the air box and, at anything less than full-throttle, a measurable POSITIVE pressure as indicated by the Dwyer Magnehelic Differential Pressure gauge. In fact, he was able to eliminate the entire 9" water (.325 psi; 2.242 kPa) pressure drop that was previously recorded in the air box before the filter. Edgar was able to make use of a highly efficient OEM scoop used to funnel air to the stock oil cooler to also serve as an air scoop. I think you'll agree this is an outstanding result. BTW, if you have the inclination and the time you might want to read parts 1-4 of the article for an excellent tutorial on improving the induction system in general.

The next article is, "Ram Air Revelations" by Michael Knowling.
AutoSpeed - Ram-Air Revelations
Here, the OEM snorkel was replaced with a homemade duct that picked up ram air from the fog light opening. Before modification, the Dwyer gauge recorded a 10.4" water (.376 psi; 2.591 kPa) pressure drop (negative pressure) in the air box and 27" water pressure drop after the MAF sensor. With the new ram air snorkel, the air box now recorded a POSITIVE pressure of 4" water (.145 psi; .996 kPa) at 62 mph cruise and a total system reduction in negative pressure from 27" water to 23" water at full-throttle. Again a marked improvement. However, the author cautions against such a close-to-the-roadway location of the air inlet because of the possibility of ingesting standing water and the resultant potential of hydrostatic lock. In both the above articles, the authors noted the significant increase in throttle response that was obtained.

Finally, the last article I want to cite deals with the lowest minimum pressure drop ever achieved after the air filter in a modified system. The article is, "We Have a Record! Reducing intake flow restriction to the absolute bare minimum" by Julian Edgar.
AutoSpeed - We Have a Record!
The car in question is a hybrid Honda Insight with a 1.0 L 3-cylinder engine. Who says that a pokey economy car can't be modified like the big boys? The standard air intake system is the usual air box connected to a snorkel that crosses the front of the engine bay. The air inlet is positioned inside the engine bay and therefore not located in a high-pressure region. To obtain a baseline figure, rather than measure the intake system at a variety of points, the measurement port was located on the engine side of the air filter to measure the total intake restriction of the snorkel, air filter, and air box. As usual, a Dwyer gauge was used.

Results (stock configuration): At peak revs in 2nd gear (max power), the total pressure drop was only 4" water (.145 psi; 996kPa). This was the lowest pressure drop that the author had ever recorded in the last 15 years of his investigations.

Ever on the lookout for improvements, Edgar speculated about the effects of connecting the snorkel to the front of the car thus allowing it to be pressurized by the vehicle's forward motion. Utilizing a truck radiator hose that had the right bends, the original intake end of the Honda's snorkel was cut off and heated and shaped until it was round. A bellmouth was made from the middle of a plastic cake dish, fitted to the intake, and foam rubber was used to seal off the gaps. Contact cement was used to hold the bits together.

Results (with ram air): At peak revs in 2nd gear, Edgar found the maximum pressure drop of the snorkel, air filter and air box combined decreased to just 2" water (.072 psi; .498 kPa). Even more importantly, at any constant throttle cruise above 40 km/h (25 MPH), there was in fact a POSITIVE pressure on the engine side of the air filter, typically about .5" water (.018 psi; .125 kPa). In other words, at cruise conditions the intake system is generating less than zero restriction. Another way of looking at this is that ram air was actually providing a mild form of supercharge at cruise, but even at maximum output flow, the throttle sees 99.5% of atmospheric pressure. Talk about phenomenal throttle response!

If ram air is so good, why didn't Honda utilize it? Edgar speculates that with ram, in very dusty conditions, the air filter would have to be changed more frequently (which he says is a no-no in modern cars, especially hybrids), and now there's a just audible induction sound at full-throttle with the windows down that might prove bothersome to the average driver.

Conclusion
The above examples are a very dramatic illustration of how effective ram air can be in enhancing performance. In most cases the performance gain won't be nearly as significant as seen here, but obviously some potential exists and experimenting might be worthwhile. It's interesting to note that an adequate air filter element should have no more than 1.5" water pressure drop at the maximum rated CFM air flow of the engine. As we've seen, at as slow a speed as 55 mph, assuming perfect ram, the ram air pressure is 1.5" water exactly balancing the maximum allowable pressure drop of the filter element. At the very least, even a small amount of ram could effectively eliminate the air filter as a restriction. Even if atmospheric pressure can never be obtained anywhere in the intake system due to ram, any substantial reduction in negative boost in the system should have some beneficial effect on performance.

 

You'll have to move all the A/C lines and cut into the firewall a little bit (/hammer). It's not geometrically out of the question last I looked at it but a massive pain.

 

i find it difficult to get excited about a gain of .145 psi

this thread only talks about increasing delta P, but keep in mind the ultimate goal of all this work is to increase flow (CFM). while it is true that flow is directly related to delta P, and that there can be no flow between 2 points without a pressure difference between said points.
but there are simpler ways to increase flow than to rob your moving car's kinetic energy, which you paid for with prior acceleration using fuel and time, to get yourself minimum gains on intake flow.

it's late so i'm not going to crunch the numbers, but an increase of 0.145 psi is not gonna do anything meaningful for your intake flow. the weather from day to day can give you that amount of variation, just pick a better day to go to the track.

 

Ram air, or air compressed from forward motion doesn't get interesting until you hit 0.3 Mach, or about 230MPH at sea level on a 60°F day. Below that speed, air is effectively incompressible outside of a closed space.

The real benefit of a ram air intake is that it pulls in cooler outside air. If placed correctly, it can do so from a stagnation point, and breathe air at roughly ambient pressure.

 

Instead of ramming air into the nose on our cars I wish that the nose would be pointy and closed and sample air rushing over the car through a port hole. Same deal for heat dissipation in the engine bay and motor. Many race cars use this methode . Why are they not applying it to all cars... trying to cut through air while ramming into it makes things harder at higher speeds. For example, a lifted Jeep Wrangler cuts through wind like a space shuttle entering our atmosphere. Such elegance while dancing in the wind.

Now... a Hennessey Venom however... true definition of Zoom.

 

Actually, the 2012-13 SkyActiv-G models have excellent aerodynamics for a passenger car. The coefficient of drag has been reduced to .27 which is an excellent figure. While making fun of the "smiley face" visage of these models, keep that in mind. That being said, there are still stagnation points on the front surface of the vehicle that lend themselves to being a good source for ram air induction. Why not make use of them?

 

In previous posts I mentioned how there is a air ram feature already designed in the front of our nose. In another thread I mentioned how the front side fake grills could be compressing air and cause flow around the body in the effort of drawing rushing air away from the body. I`m thinking that you`re saying that people in general talk about the smiley face.

The fastest car in the world has a small nose that cuts through air and the body is designed to have minimal down force on it and some body designs get rid of pressure that would build up under the car. This was a big issue in the racing world with super light cars with high powered engines. Cars could loose their down force because the air pressure on the top of the car would be challenged by the pressure build up under the car and once there is too much pressure build up under the car, it would just lift up and throw the car into the air making it flip in mid air sometimes in a 360degree rotation. Obviously that won`t happen to our cars however, this is the reason why Mazda engineers have installed a plastic plastic panel under the engine bay to help reduce drag and air build up on the underbelly of the body. When you lower your car with lowering kits you`re actually reducing this effect even more plus cutting through less air.

Now, if you were able to sample the air rushing under the car to send it to the engine intake port, it would be a win-win situation. You simply need to create a system of pipes to make sure no water can reach the MAF sensors and throttle assembly. This could be installed right under the front nose so that it would make a smooth run going to the engine.

The pointy nose thing has been around for years. Richard Petty`s Charger is still an iconic design that is now seen in Fast and the Furious and the anime movie CARS. It looks kinda silly but the old idea is still there.

 

That's a interesting idea you have about piping underbody air into the air box considering the aerodynamics involved. I'd also like to measure the air pressure at the OEM point of entry to the duct leading to the air box using a Dwyer Magnehelic Differential Pressure gauge and compare that with the pressures found in other locations at the front of the vehicle.

Sorry, I never meant to imply that you would laugh at the smiley face look since you're obviously aware that it has an important aerodynamic function. As you said, I meant people in general. As someone who writes for a living, I should have been more careful in the way I phrased my statement.

 

I remember seeing a formula 1 topic a few years back about how they added a blower in the back of the car to rush the pressured air out from under the car to try to cause less positive pressure and they were successful at doing so.

As for the smiley face, I saw it for what it was meant for. No biggy.

 

Yes.

nvm PSI gains, think volumetric, and think how fast the cylinders gets filled up.

15psi on the speed3 in the manifold IS NOT 15psi in the cylinder. Force induction in short is to fill up the cylinders with air faster than the engine itself can.

So with ram air, the cylinder does get fill up faster, but if the ECU aint tuned right, you just end up running lean.

been there, done that.

 

So the extra air sent through to the MAF doesn't make the CPU adjust the fuel sent to the cylinder or cause timing changes?

 

Go dyno again JM

 

The intake air sensors which message the PCM (baro, temp, and MAF) have a wide range of latitudes in which to compensate for expected variations. For example, the temperature of the intake air determines its density yet whether the ambient is 100* F or 0* F, the A/F ratio is adjusted accordingly. Likewise for air pressure the A/F ratio is adjusted appropriately for sea level driving conditions or driving around Denver, CO. In similar manner, the MAF sensor meters on density. Ram air, unlike FI, provides a minimal, but worthwhile change to the air flow, but certainly within the range of the adjustment capabilities of the PCM. Therefore, even under the best of circumstances no amount of ram air would ever cause the A/F ratio to be too lean.

 

This is my logic also.