I thought of 1 more way to explain it.. If you add the restriction of the stock paper air filter and the throttle body it would equal the restriction of the K&N and the throttle body. The only difference, is that the K&N's throttle body will be closed slightly more, thus equaling out the gains...

Values at straight level cruise @55mph with stock air filter

outside air------after air filter------ after throttle body
1atm------------.8atm--------------.4atm



Values at straight level cruise @55mph with K&N air filter

outside air-------after air filter------after throttle body
1atm------------.9atm-------------.4atm

 

Sorry chester but you are incorrect. I have been in operational side of the nuclear power generation field for 10 years. My whole life is about thermodynamics, fluid flow, and system efficiencies both closed and open loop. An engine is an air pump that operates in an open loop. If you lower the suction side head losses it is easier for the air pump to operate at all levels => less energy input per power output => the pump is operating more efficiently at all levels not just wide open.

 

I don't doubt that you're intelligent to do what you do, but there must not be any GASOLINE engines in a nuclear power plant.

Do you understand COMPLETELY how a gasoline engine works? (it's different from a diesel in a lot of ways)

If you answered yes to the above question, then you'll be able to tell me how a (fuel injected) gasoline engine's power output is regulated.... The throttle body. Right?

And what does the throttle body do at any throttle setting besides Wide Open Throttle?.... It induces a VACUUM on the intake side of the air pump. A RESTRICTION. It PLUGS up the air hole! It CLOSES the air supply. It LIMITS air intake volume. Thus limiting power.

Well, since IT is the LIMITING factor, how is a "better" filter going to help it at ANY other setting besides Wide Open Throttle?

(Wide Open Throttle is the point at which the throttle body is no longer the limiting factor for air intake volume) eg. Wide Open Throttle is the point at which the comments in your post begin to come true.



Most people just can't believe that their engine is designed to choke itself in order to regulate power output. But it is true. The intake restriction is NECESSARY, or the engine would run wild. All the air filter does, is add a little bit more of an intake restriction than the throttle body alone. Thus requiring you to open the throttle body a bit more to maintain steady flow. No undue loss of efficiency there, its designed that way!

In a diesel, you regulate fuel. In a gasoline you regulate air.

 

Well, I'm glad somebody else is backing me up here, thanks Ken.

I'm going to say this again, and it applies for both performance and fuel economy. An air filter is a restriction in the intake track which requires your engine (aka. a large air pump) to work harder to get air in. A throttle body is a flow restriction, while the air filter is primarily a pressure restriction. Those are very different things when speaking in terms of fluid flow.

You hear people talk alot about back pressure and gas velocity in exhaust systems being two very differnt things. The same principles apply to the intake side.

And just an FYI, quoting your past posts does not help in your defense. You need to reference somebody else's statements if you want to get credit

 

No they're not. They're identical. They both restrict the flow. The lack of flow causes the vacuum. How are you not understanding this? Do they both cause a reduction in pressure? YES!!! The ammount of power your engine makes is DIRECTLY related to pressure in your intake. Reduce the pressure - reduce power. It's that simple. It doesn't matter how you do it. It's just as hard for the engine to pull a vaccuum through 50 filters, as it is through a cracked throttle body! Same net difference.

When that piston is trying to go down, a .5 ATM intake vacuum is a .5 ATM intake vacuum, the engine doesn't care what caused it. Just because somebody agrees with you, doesn't mean you're right.

 

In a gasoline engine you regulate both. Disconnect your TPS and open your throttle body all the way. You won't get WOT rpms without the TPS sensors input to add fuel. The position of the vane alone is not enough.
Better flowing inlet systems are always better.

 

I know you can take it apart, and it won't work right. Whatever. I give up. One day I'll build an animation of what I'm talking about. Everyone is thinking about flow efficiency, but that's not the issue with a throttle body at part throttle. It doesn't care about that. It's just interested in regulating a volume of air. You can't decrease intake restriction and expect intake volume to stay the same. And if you want to increase intake volume, just open the throttle body.

And no, you don't regulate both. Only air. The fuel part remains a constant. It is added in direct porportion to the air volume. (at part throttle driving) (please don't get technical. I know this is not always true, but for the sake of the argument....)

 

Sorry but an air pressure loss is not the same as a an air flow loss. Again, this is based on physics and fluid dynamics and isn't debateable. Some of your points are valid and I agree that putting a better air filter will be more noticeable at WOT than at part throttle. But no matter how many times you say it, less restriction is still not a bad thing.

At this point this thread is a lost cause. I think I know how to end it: you are right, and everybody else posting here is obviously wrong. We good to move on now?

 

Nope don't take anything apart. Just remove the voltage from the TPS and your engine will not speed up when you open the throttle plate. This is because it takes fuel to speed up not just air.
Pressure, flow and volume are 3 seperate items. Flow is volume over a period of time. The throttle body does not change volume but it does change flow. Any restrictions in the inlet (not just throttle body plate) will increase the vacuum drawn by the engine. The less restriction the better.

Yes Ford does regulate both in our trucks. The duty cycle (on time) of the injectors and the frequency (how often they are on) are both controlled by the PCM which rely on input from the MAF and the TPS and probably a few other things as well like cam position sensor etc.

 

Air pressure and air volume are EXACTLY related. You need to go back to school. Remember the ideal gas law?
This isn't the exhaust pipe we're talking about. It isn't limited by the same principles. We're talking about a governed flow. An exhaust system is not governed, therefore flow velocity, pipe diameter, and flow restriction play a HUGE part in efficiency. But such is NOT the case on an intake at part throttle. You are getting 2 things confused. Airflow characteristics BEFORE the throttle body, and AFTER the throttle body. (talking about part throttle here, NOT WOT) Since the airfow is governed at the throttle body, the flow characterisics BEFORE it do not apply to the airflow AFTER it, unless the flow before the throttle body doesn't meet the requirements of the throttle body. eg. WOT or a VERY VERY stopped up air filter.

Norm, You know that our engines are controlled by an intake restriction. Why are you even saying this? You are getting WOT and part throttle confused. At part throttle, the restrictions before the throttle body are not important, as long as they aren't the limiting factor. (Eg. A completely stopped up air filter.) Pressure and volume are inversely related to the QUANTITY of air. So you can't have a higher pressure, and expect the volume to stay the same!


Yes, both are regulated, but YOU don't control them in the least. Do you have a mixture screw? Do you have a choke? NO! All that you ,as the operator, control is AIR. Nothing more. Now the truck has inputs to see how much air you are requesting, but you do not control anything else. You know that!

It's hard to argue about something when you can't keep wide open throttle, and part throttle separated. It just confuses the issue.

Let's say your are running 55mph in closed loop. You ride through a dust devil, and the air filter gets stopped up a little. Well, that would increase it's restriction right? Logic would say that you would have to press down on the gas pedal a little to offset the restriction right? (thus reducing the restriction of the throttle body, and giving the engine the same level of airflow/cylinder pressure as before) Well, the throttle position sensor will notice that you are pressing the pedal more, but since you're in closed loop, it's maintaining a/f ratio based on the Mass airflow sensor and the O2's. And it maintains the same air fuel ratio as before you entered the dust devil. So, you are getting the same gas mileage as before, EVEN THOUGH your air filter is slightly stopped up. Because you offset the air filter restriction with the throttle body. Now, if you stomp the gas, (thus taking the throttle body out of the equation) you won't have as much power as before, because the engine won't be able to get as much air as it did before you rode through the dust devil. But we're not talking about that. We're talking about fuel mileage.

 

This is a pretty touchy subject for you isn't it? You have some bad experiences you want to share

And no thanks on the going back to school, I've got plenty of that under my belt.

Pressure and volume are related by the ideal gas law (even though this is not an ideal gas, but thats besides the point) but that is not what I said. I said that a flow restriction is not the same as a pressure restriction, and that is most certainly true.

 

Please explain. This is a vague statement. And it is not very accurate from a mathematical standpoing. Your engine's cylinders are not concerned with flow. They are concerned with the actual quantity of air molecules in the combustion chaimber. IF you increase or decrease the ammount of molecules, you change the pressure. So, power output is mostly related to the ammount of air molecules in the combustion chaimber. You are trying to apply the principles of flow restriction to this argument. Which is fine, if I was arguing that a throttle body spacer didn't help. But I'm talking about stuff that happens BEFORE the throttle body. It doesn't have ANY bearing on what happens after it, because that "restriction system" starts AT the throttle body. (at part throttle...)

 

To be honest with you I really don't feel like debating this anylonger. Its obvious we have different opinions, so lets just agree to disagree. I doubt anybody else on an F150 board cares about the details of fluid dynamics.

I think we both agree that a better air filter will help you at WOT. Thats what most people care about anyway. Does it help you at part throttle??? Well we'll just leave that up to the person deciding if they want to buy one or not.

 

Yes you can. Volume is the space you are filling. In order to increase the quantity of gas in the same volume you have to increase the pressure. If you have an empty nitrous bottle it has a fixed volume. That volume does not change when it is filled only the pressure changes along with the quantity of gas in that volume. To fit more gas in you have to increase the pressure. Consider our intakes as a fixed volume. We cannot change the volume. It is a physical dimension from air filter to intake valve. Think of flow as the number of times we can fill and empty this volume. The difference in pressure is a factor in how much we can flow. Yes, the throttle body is what controls that flow. I never disputed that but if there is any restriction in the inlet tract your flow will suffer. A free flowing filter is always going to be better than a restricted filter. A free flowing manifold is better than a poorly ported one etc. Intake valve size, duration it is open etc.
I am not the confused one. I know the difference between WOT and not.
I think you are confusing amount of gas with volume (the space the gas occupies).

but you said before they weren't. Glad you came around
My foot is on the pedal which opens and closes the throttle body AND moves the TPS. That is human input into the fuel equation. Like I said before without the TPS to request FUEL it doesn't matter how much air you let in. It is not going anywhere. The engine is an air pump powered by fuel.
By the way a choke only regulates air. Yes we are talking about that exactly. As you just said "you won't have as much power as before, because the engine won't be able to get as much air as it did before you rode through the dust devil." proving that a free flowing intake is better than a dust devil (dirt) filled one.
This also illustrates that a higher flow filter like the Amsoil is going to perform better than a cheap paper one. This will help at all throttle positions except closed.

 

Norm, How do you figure this? If there is a restriction BEFORE the throttle body, it can be offset by opening the throttle body more, thus reducing its restriction.

Now at WOT, there is no more throttle body left to offset the restricton, but at any other throttle setting...

That's why superchargers/turbochargers DON'T help gas mileage. (unless you're trying to get a small engine to do a big job...) You may be running 10lbs of boost, but after the throttle body you will have a -5lb vacuum! So net result = same as N/A. Forced induction gives probably even less economy due to the exhaust restriction / supercharger belt.

I'm a retard. I meant the acc pump.