CAI indepth.....

[hampsterzone]

I have heard many arguments on CAI. Gotts mod, CAI, ect. Well, a very good friend who is a mechanic of 25 yrs, gave me the low down. CAI's are the best for adding horsepower. The Gotts mod is cheap and effective but not as much as CAI. Moving the MAF sensor doesn't cause lean codes. It reads air flow no matter where it is. Lean codes come from custom exausts not CAI. Low back pressure cause the lean codes. Which makes sense cause I never had a lean code with my edge and CAI alone. But when I did headers and true dual exhaust I saw lean codes on bank #1 and bank #2. We did find that the Gotts mod is the cheapest, easiest mod you can do. But again, it is in my opinion that it depends on what you want and how much you are willing to spend. Hope this helps. Oh and by the way, removing cats could be the worst thing you could do as far as causing our engines to run lean. I am not an expert but my friend has worked on many F150's and says they are great trucks to modify if you take your time and do it right. Thanks guys.

[DarkShadowSTX]

Moving the MAF sensor doesn't cause lean codes.

I have always read that the reason you get lean codes is because you move the MAF.

Low back pressure cause the lean codes. Which makes sense cause I never had a lean code with my edge and CAI alone.

Backpressure is supposedly just a myth. I never had a lean code with my EDGE and CAI but I did get other codes because the truck wouldn't run correctly since the CAI changed the MAF location. Custom tunes on my Gryphon fixed that. A lot of people with EDGEs and 5.4Ls got lean codes with CAIs though.


:hmmm:

[hampsterzone]

Yeah, it seems to be a complex system that varies upon application and truck setup. Idk, but I can say that if you are going to do mods you better be prepared to do them right. Thanks, I appreciate everyone's opinion. As far as the MAF and exhaust causing lean codes. :confused: Probably both! I do believe my mechanic on the exhaust though. Not sure if I believe MAF being the reason. More like more air from the CAI. I am sure we will figure it out soon enough.

[Longshot270]

I have heard many arguments on CAI. Gotts mod, CAI, ect. Well, a very good friend who is a mechanic of 25 yrs, gave me the low down. CAI's are the best for adding horsepower. The Gotts mod is cheap and effective but not as much as CAI. Moving the MAF sensor doesn't cause lean codes. It reads air flow no matter where it is.

If your wanting to add power, a blower is the best. A CAI can't compete with boost. :hehe:

The CAI's are slightly more effective at increasing power because of the slight lean condition they cause. I've seen 30 horsepower on a dynoed mustang just by going from slightly rich to a leaner A/F ratio. The ratio was then tuned back to stoic out of conscern for the motor.

Those horsepower numbers that the companies advertise also is not across the entire power band. That is the peak horsepower marks. Below about 2200 rpm you could have an intake the size of a trash can but the engine will not be bringing in any more air than it was before.

The commercial "cold" air intakes use a larger diameter pipe than the stock sensor housing.
This is a picture that demonstrates what a cross section would look like. The blue area is what the truck calculates for and the red area is what is not calculated because of an aftermarket intake that is larger than the stock housing.
http://forum.gopowerhungry.com/members/longshot270-albums-pics-picture908-pipe-diameter.jpg

The MAF sensor in these newer trucks is a heated wire. As the engine pulls in air the wire is cooled by the "breeze". The resulting temperature of the wire increases or decreses its resistance to electrical current which is read by the computer. With the larger diameter, the air will flow at a different speed. If you were to bring in 60 grams/sec of air it will flow faster in the narrower tube. Higher air speed, lower wire temperature.
On a stock truck the sensor is calibrated for the stock fluid area (blue). Any result you get from the MAF sensor can be calculated into an accurate physical volume. If you increase the diameter, you change the air speed, you change the reading and in doing so, you change how much air an electrical value represents. This is where custom tunes come in and we've got plenty of threads about that. :thumbup:

So the sparknote version:
Yes, the MAF sensor will read airflow no matter where on the intake track it is located, but that does not mean the reading will be accurate.
When you increase the diameter of the pipe the air does not need to move as fast to move the same volume. The slower air velocity will read on the sensor as the wire being slightly warmer, making the resistance slightly different. When the value is different the truck fuels different.

The gotts mod does not have this issue because it does not impact the MAF sensor in any way. All the gotts mod does is allow more of the shielded fender air than the stock system.

[hampsterzone]

Excellently put! I appreciate your response. Any thoughts on exhaust causing the O2 sensors to relay lean conditions?

[ticopowell]

My question about the CAI's and the MAF is that on the 2 K&N CAI's that I have installed, the MAF sticks around, and so did the pipe surrounding it. here is a picture (http://www.autoanything.com/GenericPages/ProductImage.aspx?GroupID=567&ImageID=4546&ProductID=1951) here is another (http://www.aa1car.com/library/maf_sensor_ford.gif)
the pics are for different sensors which may or may not be different than what we have, but my point is the same. That specific diameter where the MAF is located stayed the same in my trucks where I put in a CAI versus stock because that piece, even though it moved up or down the intake track, was exactly the same diameter.
The only thoughts that I have that would make it different is that if the pipe or filter right in front of the MAF made air flow faster through the pipe where the sensor cant read, such as the other side of the tube, then there would be a lean condition.
any thoughts? :cheesy smile:

[hampsterzone]

I have to say I believe it is the amount of air going past that causes the lean condition. Makes sense because a lean condition is caused by too much air to fuel ratio. Just like exhausts being opened up and less restrictive causes lean conditions. I can't seem to agree anything other than the more air means leaner conditions regardless of MAF location. Simply put, more in & more out means the computer has to account for than it is initially set up for. Fuel seems to be the missing ingredient. Or Bill for that matter. LOL I seriously can't wait to install my gryphon and see the difference. Hope my thoughts help. :)

[Longshot270]

My question about the CAI's and the MAF is that on the 2 K&N CAI's that I have installed, the MAF sticks around, and so did the pipe surrounding it. here is a picture (http://www.autoanything.com/GenericPages/ProductImage.aspx?GroupID=567&ImageID=4546&ProductID=1951) here is another (http://www.aa1car.com/library/maf_sensor_ford.gif)
the pics are for different sensors which may or may not be different than what we have, but my point is the same. That specific diameter where the MAF is located stayed the same in my trucks where I put in a CAI versus stock because that piece, even though it moved up or down the intake track, was exactly the same diameter.
The only thoughts that I have that would make it different is that if the pipe or filter right in front of the MAF made air flow faster through the pipe where the sensor cant read, such as the other side of the tube, then there would be a lean condition.
any thoughts? :cheesy smile:

Tico, I'm not sure what to say with the After Market MAF sensors. That would be a question for Bill.

I can say that having the higher flow gotts mod and AM filters that the stock MAF can easily account for it. The stock sensor can handle over 200 grams/sec of air...or the amount of air my truck consumes at WOT around 5400 rpm. No basic intake mod can overwhelm the stock sensor. On my truck I got gains of about 10 grams/sec. Things might be a bit different for turbo/supercharge kits but for a basic stuff you're good on that sensor.
Here is a chart I made a while back comparing the gotts mod to the stock intake set up. http://forum.gopowerhungry.com/members/longshot270-albums-pics-picture768-maf-vs-rpm.jpg

That also brings up another factor for a lean condition because over oiling can cause it to acumulate on the sensor. This would help insulate the wire. Just one of the many reasons you should properly oil AM filters if you dont still use the traditional paper ones.




Hey...that looks like 2k posts, thanks for reminding me Ticopowell :thumbs up yellow:

[hampsterzone]

Any thoughts regarding exhaust causing leaner conditions? I would love to hear your opinion. (anyone's for that matter).

[Longshot270]

I dont really have an opinion on exhaust because I've never really messed with it besides dropping empty cans into a friend of mine's diesel stacks. :hehe:

I did find that a flowmaster 40 would only add .1-.07 seconds to my 1/4 mile time (even that is questionable when I compared the 60' and 1/8 mile times). So all those heated arguments over theories and physics and them being restrictive are pretty much a load of bull IMO.

Bill does advise custom tunes for certain headers, high flow cats and other mods.

In regards to a lean condition, if it is done right you shouldn't have any trouble...that is my opinion, so me and your mechanic agree on that part.

[hampsterzone]

Opinion considered! Forced air induction is too risky and potentially harmful to engines. With all that being said, what do you think of my mods? Have you done the same? I don't like under drive pully's because of the alternate problems and higher idle rpms needed. I don't think I have anything else to do performance wise. All I want now is an 8" lift. LOL

[Longshot270]

Low boost can be done with no problems. Even small amounts of spray can be done to a stock engine. You just run into the problems of using it too often. An engine doesn't like to run at WOT all the time when it is connected to a 5000+ pound truck.

Your list is more impressive than I can afford, so no, I haven't done many of them. :giggle:
Stuff like the intakes can be experimented with at a minimal cost and a little common sense. Take anything I say with a grain of salt because I'm no mechanic and certainly not an expert. I just type my best opinion and am willing to learn from the parts that are wrong. That is why these forums are so great. Technically I should be asking you for opinions, I'm one of the youngest members of this forum. :hehe:

[hampsterzone]

Thanks... I hope I don't ever come off as pompous or seem to brag about my mods. It has literally been a dream of mine to have done everything I have. I have never owned a new truck! And trust you me, I would love a new Raptor w/ the 6.2 liter. It has become quite addictive being a member of this forum. May I inquire how you became a moderator? I would love to be one. LOL Seriously! I am very interested in helping others out on this forum. ;)

[Longshot270]

Oh no you didn't. I would love to have a raptor version of my truck...but it means I'll just weight the options for mine because I can't even afford to rebuild my dirt bike. :giggle:

We all got here just by helping out. Us moderators are volunteers, we dont get paid a penny.
Read this, things will make more sense (hopefully)...Power Hungry Performance - About Us (http://www.gopowerhungry.com/_about.shtml)

[hampsterzone]

I know you guys are volunteers, and I see that you guys are always quick to reply and help out. I think it would be super cool to be a moderator. But then again, I can help much the same w/ or w/out the title. My beautiful wife says I can have a new Raptor after I pay off this one. Which means, less mods and more principle payoff. Is that before or after the 8" lift? Haha!

[Skip_1074]

I wanted to post on this topic from the minute that I saw it, but haven't been able to actually get on a computer to do it, so here it goes which is actually better for me. I hope that I have enough understanding to help, but we'll see. Sorry if I chopped something out of your posts that was important, but I was just trying to get the points/details.

Well, a very good friend who is a mechanic of 25 yrs, gave me the low down. CAI's are the best for adding horsepower. The Gotts mod is cheap and effective but not as much as CAI. Moving the MAF sensor doesn't cause lean codes. It reads air flow no matter where it is. Lean codes come from custom exausts not CAI. Low back pressure cause the lean codes.

Which makes sense cause I never had a lean code with my edge and CAI alone.

But when I did headers and true dual exhaust I saw lean codes on bank #1 and bank #2.

While I don't mean to discredit your friend, I would like to know what he is basing his information off of. I've been studying, working on, mod-ing, planning vehicles for over 10 years now (import cars and trucks to domestic gas and diesels) and it just seems a little different from the norm from my research. I admit my lack of understanding is in the electronic aspect of engines and how some of the sensors play a role, but

I think Longshot addresses the movement of the MAF sensor and/or its coexistence with a CAI as well as the lean environment in the next quote very nicely. I will expand more in a few.

You never experienced a lean code with a CAI and the Edge because even though the Edge wasn't calibrated specifically for the CAI that you were using, it had altered your fuel trim already thus providing more fuel to the engine. That being the said, without actually knowing the strategies, or understanding them for that matter, that Edge uses (and many other factors such as tune used, octane used, CAI brand and tube diameter at MAF sensor in comparison to stock), I believe that your the Edge kept your A/F ratio with CAI somewhere around the what the stock programming had.

I will also try to explain the exhaust setup's existence in a few. I'm trying to keep to one point at a time.


The commercial "cold" air intakes use a larger diameter pipe than the stock sensor housing.
This is a picture that demonstrates what a cross section would look like. The blue area is what the truck calculates for and the red area is what is not calculated because of an aftermarket intake that is larger than the stock housing.
http://forum.gopowerhungry.com/members/longshot270-albums-pics-picture908-pipe-diameter.jpg

With the larger diameter, the air will flow at a different speed. If you were to bring in 60 grams/sec of air it will flow faster in the narrower tube. Higher air speed, lower wire temperature.
On a stock truck the sensor is calibrated for the stock fluid area (blue). Any result you get from the MAF sensor can be calculated into an accurate physical volume. If you increase the diameter, you change the air speed, you change the reading and in doing so, you change how much air an electrical value represents. This is where custom tunes come in and we've got plenty of threads about that.

So the sparknote version:
Yes, the MAF sensor will read airflow no matter where on the intake track it is located, but that does not mean the reading will be accurate.
When you increase the diameter of the pipe the air does not need to move as fast to move the same volume. The slower air velocity will read on the sensor as the wire being slightly warmer, making the resistance slightly different. When the value is different the truck fuels different.

As I stated, I think this is a very good explanation. I honestly can't explain it better, but can only maybe elaborate upon it. I know that it is more technical then what I am about to explain. My mind thinks in numbers, so please forgive me.

If you have a two hoses and pretend that the small one is stock and the larger is a CAI...lets say a 3" (7.07 square inch cross section) and 4" (12.57 square inch cross section)...and a sensor that is 1" by 1" (1 square inch) that extends into them. The sensor is designed to take a sample from 14.14% of the 3" hose and that is needed to provided accurate flow calculations, but when placed in the 4" hose, it only takes a sample from 7.95%. That means only 56.22% of the required sample is being provided for the calculations.

If this doesn't make sense, let me know, but I hope that it helps better explain the situation. I have a post from another forum that is about 880 words that really breaks it down if anyone wants to read it.


Any thoughts regarding exhaust causing leaner conditions? I would love to hear your opinion. (anyone's for that matter).

Okay, on the the exhaust and addition to an Edge and CAI. "A chain is only as strong as it's weakest link." This works two ways on an engine:

1. You can only suck in as much air as the exhaust system can expel.
2. You can only expel as much air as the intake can suck in.

My understanding is the first was the case with your truck. The addition of a free flowing exhaust freed the engine's ability to take in more air from the CAI already installed. As stated before, I believe that the Edge held your A/F ratio similar to stock, but I also believe that the tune did not provide a large enough increase in fuel for both the CAI and exhaust system you added, thus causing the lean issue.

Where I am not sure how O2 sensors play into the equation. I know that some vehicles (don't remember which ones right now) are very sensitive to changing them as well as changes in their placement. I don't know if this played any part in your situation or not, but I figured that I would toss that out there too.


Take anything I say with a grain of salt because I'm no mechanic and certainly not an expert. I just type my best opinion and am willing to learn from the parts that are wrong. That is why these forums are so great. Technically I should be asking you for opinions, I'm one of the youngest members of this forum.

Longshot, don't be bringing age into the equation here. We each have one goal here, to exchange information and learn from the information someone else provides that we didn't already know. But since you brought it up...I'm only 27.


I've spent well over an hour typing this and I think I confused myself now, or maybe its just the fact that I have been up all night working and still have another 4+ hours to be up. If I missed anything, you have questions, or whatever, please let me know. I'm off to go play with some numbers to waste time. After I've slept, I'll try to post some interesting just for :censored1: and giggles facts that I'm going to try to derive, now I've just got to find the excel files I have.

[Longshot270]

Good post Skip :thumbsup:
But I want to add to a few of your points.

You never experienced a lean code with a CAI and the Edge because even though the Edge wasn't calibrated specifically for the CAI that you were using, it had altered your fuel trim already thus providing more fuel to the engine. That being the said, without actually knowing the strategies, or understanding them for that matter, that Edge uses (and many other factors such as tune used, octane used, CAI brand and tube diameter at MAF sensor in comparison to stock), I believe that your the Edge kept your A/F ratio with CAI somewhere around the what the stock programming had.
That is a good observation. One thing that is recommended for people with CAIs are the canned tow tunes. They are written with a richer A/F ratio and it helps counter act the lean effects.

But you also have to remember every truck runs a bit different so there is a bit of luck involved. He was lucky and no codes came up.

If you have a two hoses and pretend that the small one is stock and the larger is a CAI...lets say a 3" (7.07 square inch cross section) and 4" (12.57 square inch cross section)...and a sensor that is 1" by 1" (1 square inch) that extends into them. The sensor is designed to take a sample from 14.14% of the 3" hose and that is needed to provided accurate flow calculations, but when placed in the 4" hose, it only takes a sample from 7.95%. That means only 56.22% of the required sample is being provided for the calculations.
I bolded the part that I usually find important. Air is a fluid and fluid dynamics is a tricky subject. A more important comparison would be the velocity of a specific amount of air through different sized pipes. The engine is nothing more than an air pump so the air flow that is entering can be calculated mathematically. With the narrow pipe the sensor might read 65 grams/sec but with a larger pipe it might only read 55 grams/sec. That difference is what causes the lean condition because the truck fuels for 55 g/s instead of 65 g/s.

Here is where the O2 sensor comes in. Their purpose is to make sure the truck is running around stoic for emissions purposes. The O2 sensor will attempt to correct the issue but it does not have nearly as much influence when the MAF sensor is still operating within the predetermined parameters of "working sensor". When these two sensors do not agree enough you have rich and lean codes. But there are many other sensors that contribute to the codes.


Okay, on the the exhaust and addition to an Edge and CAI. "A chain is only as strong as it's weakest link." This works two ways on an engine:

1. You can only suck in as much air as the exhaust system can expel.
2. You can only expel as much air as the intake can suck in.

My understanding is the first was the case with your truck. The addition of a free flowing exhaust freed the engine's ability to take in more air from the CAI already installed. As stated before, I believe that the Edge held your A/F ratio similar to stock, but I also believe that the tune did not provide a large enough increase in fuel for both the CAI and exhaust system you added, thus causing the lean issue.

Where I am not sure how O2 sensors play into the equation. I know that some vehicles (don't remember which ones right now) are very sensitive to changing them as well as changes in their placement. I don't know if this played any part in your situation or not, but I figured that I would toss that out there too.

I can't say for sure but this echos the same effect as the CAI to the MAF sensor if you go to a larger pipe diameter with the same O2 sensors.


Longshot, don't be bringing age into the equation here. We each have one goal here, to exchange information and learn from the information someone else provides that we didn't already know. But since you brought it up...I'm only 27. Only 27? You guys crack me up. Try being 19 a month ago, being 18 when I got promoted to a jr mod. :hehe: You have to realize that, regardless of it being important or not, many people think age does make a difference. Doesn't help that I look 16 and have no official mechanical experience. My dad still refuses to let me work on my truck when I'm home. :really-lmao: I was using the age as an example why the forums are good at building intelligent discussions because you can't assume somebody doesn't know what they are saying based on appearances, as I've encountered many times in face to face discussions.


I've spent well over an hour typing this and I think I confused myself now, or maybe its just the fact that I have been up all night working and still have another 4+ hours to be up. If I missed anything, you have questions, or whatever, please let me know. I'm off to go play with some numbers to waste time. After I've slept, I'll try to post some interesting just for :censored1: and giggles facts that I'm going to try to derive, now I've just got to find the excel files I have. Thats ok, I spend a few hours typing that long post too because I was watching a movie.
I usually go fishing to waste time...but whatever floats your boat. :hehe:

[Jackpine]

Now that you youngun's have finished talking - and making VERY good points, in my opinion, I want to throw in this one last observation:

The MAF sensor is nothing more than a heated wire whose resistance changes as its temperature changes. As air flows over it, the wire is cooled and the voltage drop across it is modified. This voltage drop is what is interpreted by the PCM as a quantity of airflow - more air molecules hitting the wire, more cooling (which is what Longshot said in a different way). Notice if the area around the MAF sensor is increased, more air gets by without changing the number of molecules hitting the wire, and, the mixture is potentially leaner.

But, we have O2 sensors in the exhaust that report the result of that leaner mixture to the PCM and it tries to compensate by adding fuel. As long as the mixture is not TOO lean, it can do this and you don't get codes, but, you're now operating near one end of the design envelope (instead of near the center).

However, as Longshot also said (not bad for a "fish guy"), fluid flow is tricky stuff indeed. As flow velocity increases, static pressure decreases, so, the air becomes less dense. The effect of having a constricted intake snorkel forces the airflow velocity to increase to fill the cylinders at a reduced pressure! This is essentially the effect you get when driving at altitude. The MAF sensor "sees" all the flow though (as long as it fills the throat), so all is well. Opening the intake snorkel to 3" (an increase in diameter of 1" in my truck), changes the "choke point" cross sectional area from 3.142 sq inches to 7.069 sq inches! This doubling+ of the intake area greatly reduces the intake flow velocity and increases the density of the air charge - without "fooling" the MAF sensor since it still "sees" all the air flowing around it. (Effectively, we've suddenly taken the truck to below sea level atmosphere conditions and it can make more power.)

Anyway, this is how a 70-year old sees things. :geezer:

- Jack

[ticopowell]

Haha well I am not the oldest or the youngest here(25), but I do think its great that we can all have fun joking about ourselves while learning stuff :D.
I just wanted to add a clarification to what I posted before, I am not interested in aftermarket MAF's, mine works fine and im never gonna have a monster machine that needs that much airflow. I was just pointing out that the diameter around the actual sensor stays the same on the CAI's that I have dealt with, therefor the fact that the rest of the pipes change wont have a huge effect on the reading. :)

also another thought... just because you arent getting a lean code doesnt mean that you arent running slightly lean... or the same with a rich code :thumbs up yellow: just my thoughts :D

[Longshot270]

Haha well I am not the oldest or the youngest here(25), but I do think its great that we can all have fun joking about ourselves while learning stuff :D.
I just wanted to add a clarification to what I posted before, I am not interested in aftermarket MAF's, mine works fine and im never gonna have a monster machine that needs that much airflow. I was just pointing out that the diameter around the actual sensor stays the same on the CAI's that I have dealt with, therefor the fact that the rest of the pipes change wont have a huge effect on the reading. :)

Are you sure they weren't larger or a different shape around the sensor? If not then you aren't gaining anything running them besides the looks. You must consider your point of peak restriction as that will slow down air movement and change the absolute pressure from there to the cylinders.

[ticopowell]

It was the same diameter right next to the MAF, but it did remove other restrictions like in the fender, and it was a smoother path between the filter and the throttle body. Here (http://thegasmisers.com/img/K&NCAI.JPG) is a good example of what I am saying about the CAI's I have dealt with. both were exactly this same idea.
the only think that I can think of that would affect airflow is that the air maybe be relatively faster or slower in that part of the tube versus what the stock tube would read. since this can affect that area without the MAF reading it (because like someone said the MAF covers only about 14% of the circle of air in question), that is why any adjustments would need to be made. :cheesy smile:

[Longshot270]

It was the same diameter right next to the MAF, but it did remove other restrictions like in the fender, and it was a smoother path between the filter and the throttle body. Here (http://thegasmisers.com/img/K&NCAI.JPG) is a good example of what I am saying about the CAI's I have dealt with. both were exactly this same idea.
the only think that I can think of that would affect airflow is that the air maybe be relatively faster or slower in that part of the tube versus what the stock tube would read. since this can affect that area without the MAF reading it (because like someone said the MAF covers only about 14% of the circle of air in question), that is why any adjustments would need to be made. :cheesy smile:

Well if the inside diameter of the housing is the exact same as the stock housing then you should be fine. The pipe after it doesn't matter and the open filter before it only affects performance through air temps. The issue is not that the MAF only covers 14% of the cross section, the issue is the air speed through the cross section. You are not measuring the actual mass of air, you are measuring a part of the cross section to determine the rate at which air enters. From there you can calculate the overall rate and then the mass of air passing through. You dont measure flow rates of a river by channelling it into a big cup. You find an area that has uniform flow, measure the rate there and the rate at which water is moving through the area. Increasing pipe diameter with the same air consumption rates causes the airspeed to lower and tell the computer to fuel less.

We are dealing with vacuum rather than pressure so the concepts are much simpler.

[hampsterzone]

I'm glad that I got the down low on everything from just about everyone. Makes since and I have learned a lot. I love being the first domino, Haha.

[Skip_1074]

That is a good observation. One thing that is recommended for people with CAIs are the canned tow tunes. They are written with a richer A/F ratio and it helps counter act the lean effects.

I bolded the part that I usually find important. Air is a fluid and fluid dynamics is a tricky subject.

I usually go fishing to waste time...but whatever floats your boat. :hehe:

When I read the OP, the combination of the Edge and CAI caught my eye while I was still on the first sentence, and I was actually surprised that nobody else mentioned it.

I understand fluid dynamics, but not to the point that I can confidently speak on it. You are definitely right about air being a fluid and it being tricky. I have searched a little today and I can't seem to find an article that I read on Banks Power, specifically addressing air being a fluid, but here a chunk borrowed from one of their articles:

Courtesy of BANKS POWER:

In the confines of a stock motorhome or truck, your gas or diesel engine’s inherent power is limited by factory restrictions in the intake and exhaust. With your engine starved for air, a tremendous amount of power traveling through the power-train is unnecessarily wasted before it gets to where it matters—your vehicle’s rear wheels. Airflow restrictions make poor engine efficiency, which soaks up fuel, runs a hot exhaust, compromises performance and shortens engine life.

http://assets.bankspower.com/tech_article_images/131/Use_of_Power.jpg

How airflow restrictions waste power

* Intake restrictions cause engine to labor (“pumping losses”)
* Exhaust backpressure generates a tremendous engine heat-load
* Power is robbed from the crankshaft to expel exhaust
* Cooling fan runs often, wasting power and making the cab noisy
* Hot, overworked lubricants degrade faster and increase friction
* Gasoline-vehicle makers mask poor-airflow problems (eg. detonation) with overly-rich fuel
* Excess fuel is wasted, worsening mileage and emissions
* Inadequate airflow chokes engine’s potential

Think of an engine as an air pump that produces power. To run it, fuel is needed. In a typical stock vehicle, a gasoline engine produces only about 250 horsepower for every 1,000-horsepower’s worth of fuel put in. Diesel engines are more efficient—they put out about 320 horsepower for every 1000 in, only wasting 68%—still leaving lots of room for improvement!

Hampsterzone, you discussed backpressure in one of your earlier posts. As you notice, backpressure actually creates heat excess heat in the engine acting as a "parasitic loss" in power.

As for the time wasting that I did this morning, I was trying to do some calculations in regards to engine CFM airflow requirements in comparison to the ability of air systems to move them, but unfortunately I was unable to find the capability of the stock air system. But just for :censored1: and :giggle:, the max CFM flow of the 5.4L 3V engine at 5500 RPM is 628 based on the calculator that I have.

I would have gone fishing, except for a few things...its was only about 3:30am when I started the post, around 5:00am when I finished it and I'm pretty sure you can't get your line wet until first light. It was about 25 degrees outside and the closest place to go fishing is a GOOD hour plus away. The only reason that I was still up was my daughter had late start at school and I had to take her so my wife could go to work.

This discussion has been great and I only hope that we can keep the information flowing. If I find the article of air as fluid, I will definitely pass it on.

[Longshot270]

When I read the OP, the combination of the Edge and CAI caught my eye while I was still on the first sentence, and I was actually surprised that nobody else mentioned it.

I understand fluid dynamics, but not to the point that I can confidently speak on it. You are definitely right about air being a fluid and it being tricky. I have searched a little today and I can't seem to find an article that I read on Banks Power, specifically addressing air being a fluid, but here a chunk borrowed from one of their articles:



Hampsterzone, you discussed backpressure in one of your earlier posts. As you notice, backpressure actually creates heat excess heat in the engine acting as a "parasitic loss" in power.

As for the time wasting that I did this morning, I was trying to do some calculations in regards to engine CFM airflow requirements in comparison to the ability of air systems to move them, but unfortunately I was unable to find the capability of the stock air system. But just for :censored1: and :giggle:, the max CFM flow of the 5.4L 3V engine at 5500 RPM is 628 based on the calculator that I have.

I would have gone fishing, except for a few things...its was only about 3:30am when I started the post, around 5:00am when I finished it and I'm pretty sure you can't get your line wet until first light. It was about 25 degrees outside and the closest place to go fishing is a GOOD hour plus away. The only reason that I was still up was my daughter had late start at school and I had to take her so my wife could go to work.

This discussion has been great and I only hope that we can keep the information flowing. If I find the article of air as fluid, I will definitely pass it on.

In scientific terms, a gas IS a fluid just as a liquid IS a fluid. The confustions arise when things are translated to common speak because words are not the same. :giggle:

If your wanting flow bench results, we have some in an ancient article...
http://forum.gopowerhungry.com/2004-2008-f-150-mark-lt/808-flow-bench-test-results.html

At the current state of technology, our engines are pathetic on mechanical efficiency.

Back pressure also reduces engine efficiency because not all of the exhaust gasses are expelled. For gasses, pressure is equivalent to mass. Here we work backwards. Instead of trying to increase pressure at the cylinder, here we are trying to reduce it. If there is pressure out side of the cylinder then more of the molecules that make up the exhaust gas will stay in the cylinder. Things also start getting real tricky because the exhaust gasses start acting a little different because now we are pushing them with pressure rather than pulling them. You encounter simple logic problems such as exhaust pipe diameters and configurations that reduce performance rather than increase it, along with true impact of obstructions and such. If you go on the larger forums you can see people (like me haha) get chewed on for running baffled mufflers like the flowmasters. The baffles present an obstruction and logically would stop or hinder the flow to cause a decrease in exhaust flow, increase heat, etc. All of that sounds true and to an extent is true, I did see a loss in performance because I tested it at a local drag strip. I lost .07 seconds on a quarter mile run. Exhaust requires more advanced understanding of fluids under pressure because it is very easy to overeastimate and undereastimate the effects of a modification without having a solid understanding of the numbers that cause it. I try to not discuss anything unless I'm able to test it because without facts everything is a WAS guess, epecially for this. :hehe:

[88Racing]

To put it simply a cai alters the original path of air in which the MAF was calibrated for......
Also
Larger diameters of tubing cause the air intake to move slower across the MAF at a set rpm thus less fuel is delivered bring in a lean condition.....

[88Racing]

Excellently put! I appreciate your response. Any thoughts on exhaust causing the O2 sensors to relay lean conditions?
The lean codes from the o2 sensers can be atributed to a vacuum leak occuring after the maf up to the point of combustion......after combustion the exhaust may cause these but before the o2 senser if there are......broken welds, broken header studs, cracked manifolds, bad gaskets.......