Although cfm does not DIRECTLY translate to the volume of air getting into the engine, increased cfm produces similar effects to forced induction. Similar to RAM type induction where the speed of the car helps "shove" air into the system. This effect creates denser air.

Also, I agree if we ASSUME the stock box provides enough air to the engine there won't be much of an increase. Now, look at the huge increase in cfm compared to stock.. this is a huge indication that the stock box was not letting enough air into the system.

I'm not sure if you know but gravity is the weakest of all forces. Air pressure is a much stronger force than gravity.. This is a known and proven scientific fact. Gravity is orders of magnitude weaker than air pressure.

don't know what you mean here.

First of all, it is impossible to have no compression in the system if you've closed off the intake unless you have ZERO air in the system. And second, compression uses energy but the expansion releases energy. So, the NET effect will be the same as having no compression.

yes, you will pull more air with less restrictions. But that's what I've been saying all along. MORE AIR. The engine is still doing the same amount of work because that system is fixed. And yes, TECHNICALLY, the engine will have an easier time of pulling in the SAME amount of air as stock filter through a K&N. This is not what I am arguing. We are talking about where the power comes from when installing intakes (and headers/exhuast). And it is certainly not from any miniscule gains from "easier suction".

First, an engine can't "reduce" it's "suction" because that system is fixed. Suction is created from the pistons cycling. So, in the end there is no power gain. The engine is still doing the same amount of work but pulling in more air on that same stroke. So if the engine is doing the same amount of work, how does installing an intake improve power? where is the extra power coming from? It's coming from the extra air.

Second, the amount of power "saved" (assuming the engine could reduce its suction), is miniscule because the force of the expanding gases in the combustion chamber are on many orders of magnitude greater than the "suction" forces. Your straw example with you sucking on it is again not an accurate analogy. When you "suck", your chest expands to allow air to enter the cavity. This air is again, only at atmospheric pressure or a little higher if you suck hard to increase air flow. But this increase is at best what? 2 times? 10 times better? The engine produced pressure that is 100's of times greater than atmospheric pressure. Basically, I'm saying the vacuum effect is negligible because of the large disparity in forces inside the engine compared to the forces at the intake.

I'm glad we agree on this point. I'm not sure what SRI means though (short ram intake)?
There are tradeoffs between CAI and SRI. CAI gets colder air but SRI gets faster moving air (supposedly). The net effect of both these intakes is denser air. I'm not sure which will produce more dense air but they are trying to achieve the same goal.

Since we agree that air flow is increased with K&N filter compared to stock, this is where the "compression" comes from as stated before. Fewer restrictions allow faster moving air.

yes a 30% increase in air will yield a 30% increase in oxygen into the system. You're right, I took the wrong %. But that still doesn't change the fact that you aren't gonna get 30% more fuel into the system. Using the 14.7 to 1, you will only get 2% more fuel into the system.

Edit: just an aside, the oxygen-fuel ratio is not 14.7. I remember this number too and I know it is the AIR-fuel ratio. oxygen-fuel is lower (nobody uses this ratio)... but since oxygen and air increase by the same ratio, it is safe to use this in this case.

 

Maybe we should all go out and test it????

 

holy crap. i dont know what to say. i dont mean to be rude, but i dont know how to make you realize what im saying. its getting annoying cutting and pasting replys and all of that. oh well, let me try this again.

no, only if the cfm is less than the demands of the engine will it increase the air quantity in the engine. im sorry, but i refuse to believe that a company with the quality of engineering such as honda, would use an air filter that flows so little as to cause such a noticeable drop in air getting into the engine.

the huge increase in cfm is in a test. it is not done taking into account, the needs of any given engine. its simply put under a given vacuum pressure. and what do you consider "much of an increase"? i dont think from 1-3 hp (lets be serious here, and im talking drop ins, not CAI or SRI. comparing intakes to stock tubes would just expound on the dilema we are in.)is much of an increase. when you look at the hp increase seen in some larger engined cars, they can see from 10-20+ hp from a good filter. much of that can be attributed to poorly designed and tested (for production, not performance testing) stock pieces.


I dont see what this has to do with the argument. any force that pushes/pulls on the object in question is comparable. whether it be gravity pulling water down through a straw, or the force of expanding combustion pushing down on a piston in turn pulling down on the piston in question. yes the force is smaller, but if you pulled the water out by sucking on it (and for this example, lets say its a steel straw) the water would not move down unless air was allowed in the other end. or the pressure of the water would drop, but that movement would be miniscule. i only used that as an example because you said the only force was that of the air on the straw, which isnt true.

what i mean is, it wont turn without expending power. try turning over an engine with the compression working. turn it over by hand, then take the spark plugs out and turn it over. it turns much easier. which takes me to my next point.

not if the heads are off, or some such thing. and yeah, the compression will push down with the vacuum pulling, but in an engine, this isnt the way it works, this is due to our little friend, Valve. because an engine is an air pump, it will push what air it has in, out, causing a huge vacuum inside, and unless increasing force is applied, it will not continue to turn. much of what im saying is hypothetical, you arent thinking outside the box. try to see what im TRYING to say, not just what im saying, its hard to put some ideas into words.

no, you wont pull in "more" air. unless the pressure is increased, the engine can not pull in more air than its actual displacement. it defys the laws of physics. and i dont see where a couple of horsepower is this groundbreaking gain to you. not to start up an old debate, but back to the underdrive pulleys in the other thread, reducing the power an engine uses on extraneous things can give a small amount more to propel the car. and actually, the gains from underdrive pulleys and a drop-in filter are very comparable. as well as the means of getting them, by reducing resistence to rotation.

the engine is not reducing its suction. the new filter is reducing the resistence to its suction, which is where power comes from, as an engine is basically an air pump. actually, thats a good example. take a shop vac, when it is flowing freely, the vacuum stays at a steady rpm. but when it gets caught on something, like your pants while you are trying to vacuum out your car, then the engine speeds up considerably. this is due to it attempting to continue pulling air in at the same rate, so it raises the rpm, which in turn raises the HP, all to accomplish the same amount of work (moving X amount of air).

the laws of physics are pretty consistent. yeah the engine produces more pressure than i can with my chest, but the effect is the same. and when you suck on the straw and your chest expands, it is imitating what the combustion chamber is doing on the intake stroke. and again i say, the power gains are minimal. and they shouldnt be comparing the force driving the piston down to the resistence in the air, but to the resistence of the stock filter to that of the aftermarket filter, so its possible that there is what, a 1-5% difference in vacuum pressure between the two filters (as relates to hp gain)

[quote] I'm glad we agree on this point. I'm not sure what SRI means though (short ram intake)?
There are tradeoffs between CAI and SRI. CAI gets colder air but SRI gets faster moving air (supposedly). The net effect of both these intakes is denser air. I'm not sure which will produce more dense

 

the posts are 2 long. so, I'm just gonna mention the points that you have a trouble believing.

(1) Increasing air flow over the same area has the potential to increase air density through piping design (which apply to stock pipes as well). It is a basic principle of fluid dynamics. So you are basically saying adding a K&N does not increase air flow? I don't know what to say to that.. I think you should talk to some other people about this cause no matter what I say you aren't gonna change your mind.

(2) You still don't understand that the engine power is orders of magnitude stronger than the power required to "suck" air. Do you agree that the expansionary forces produced from combustion are huge compared to the "parasitic loss" due to suction inefficiencies (prolly 100 times+ more powerful)?? So would it not make sense that only a small amount of extra fuel being burned will produce MORE power than even completely eliminating parasitic loss due to suction inefficiencies?

this is why the straw example doesn't really work because your sucking and the air holding the water are on the same order of magnitude in strength. And when talking about gravity, that can even be considered zero. In your straw example, gravity is more analogous to the suction losses in an engine because it is such a small force compared to you sucking through the straw. Do you even notice gravity when you are sucking on the straw? NO. And that is the same with the engine and the "parasitic losses" due to suction inefficiency. The engine doesn't "notice" it because it is such a weak force compared to the forces produced in combustion.

I think the biggest problem you have is that you can't seem to understand that "parasitc losses" due to suction is very small. Only about 5% of an engine's theoretical power is lost due to ALL "mechanical" losses like friction, your suction losses, etc. Like 60% is lost due to thermal losses.. and what you are left with is about 35% of theoretical power.


Again, if you don't believe me ask around. More air and more fuel is generating the power increase on an intake. Not reducing "parasitic losses" due to inefficiencies in suction.

 

principles of physics are constant. it doesnt matter what the ratios of force are. it is still the same effect. its just not as noticeable. and yes, i realize the difference between intake restrictions and the force the engine is making with combustion is huge. but if it wasnt, then there would be no power to move a car. the power gains are on the order of about 1-3%. this shows how obvious it is that its not even close to equal power forces. and the cfm wont increase without expending power SOMEWHERE. nothing is free. nothing. you cannot make the density of the air go up wihtout expending more force. a SC uses crank horsepower. a turbo uses (otherwise) wasted exhaust energy. the energy has to come from somewhere.
I KNOW. thats why the gains are so small. if it incresed the air going into the engine by 30% as you stated earlier, then you would get roughly the same power gain (this is variable due to outside parameters) of apx. 30%. and you would expend the same amount of extra fuel. and if a k&n filter could manage to somehow jam 30% more air into the engine, then if you ran without a filter, imagine what you could do. 35? 40? 50? geez, what was i thinking? wanting a turbo so that i could add 5-6 psi to the atmospheric pressure adding about 30-40% more air. ill just go take off my filter. i should see about 60-80hp.

 

no point arguing this. you don't seem to understand that the disparity in the ratio of forces is so great that it can be treated as zero.

increasing cfm is exactly where the energy comes from. by slowing down the air before it enters the intake manifold, you achieve compression. Look at airplane wings, they are designed to change the speed of air flow so that there is unequal pressure on the wing to produce lift. It is the same principle. don't take my word for it, go look it up.

first of all, I was just pulling numbers out of the "air" And what I meant by 30% increase in air was the air flow. I just used the same 30% for simplicity in an example of how more air would increase fuel consumption (which was the original question). The actual number I don't know. I've already stated this. Reread my first post and I have always talked about air FLOW. Please, dont pick and choose quotes from different places out of context to create a point so you can pick on it. And before you say it was edited, check the time stamp...

this is my point. more air = more power. adding 30-40% more air into the system generates 60-80hp. So, taking your ratio, 30% more air = 60hp roughly... on 1% more air you will get 60/30 or 2hp gain. Which is exactly the type of power gains an intake gives you... the only problem is that you don't believe more air can get into the system with an intake.. i encourage you to look up how intakes work and ask other knowledgable people. Like i said don't take my word for it. Just know that an air intake's function is to push more air into the engine, not to reduce suction inefficiencies (although it may be an added benefit).

 

this is the main thing i dont agree with. an intake CANNOT "push" air into the engine. the most i will ever agree is that there is a VERY small gain in air simply by the reduced vaccum after the filter. there is no way that the air can be FORCED into the engine without SOME form of energy being expended.

increasing cfm doesnt make power. yes, more air going through the motor will, but we are talking about the energy being used to pull the air INTO the motor. where is that coming from? there ia a force that pulls the air into the engine. what is it?

hehe, now thats funny.

but your still saying that the increased flow in a test shows that there will be increased flow into an engine. thats simply not true, unless there is a grave problem with the original filter.

so i guess what this comes down to is that we disagree on the main source of power gain. you say the reduced suction is an added benefit and the main power improvment is from added air, and i say that its the other way around. since you cannot have one without the other, there is no way for us to PROVE, inarguably, which is the greater benefit. i can leave this part of the debate at that.

However, i still have a huge problem with you stating that an intake speeds up the air going into the cylinders. if the piston is moving at a constant rate downward, then the air cannot speed up, unless it is through a smaller path.

 

Don't you agree that cfm increases? If you have increased cfm, that means more air is moving through the intake tube in the same given time interval. Hence, the air is moving faster. Like i said in the previous post, the air is slowed down the line which increases the pressure and produces the compression effect.

the engine intake valves are not open 100% of the time. when the intake valves close, the air has nowhere to go. Intakes are "tuned" by varying the pipe length so that they take advantage of this fact, timing it with the opening and closing of the intake port. When the port closes, the suction stops but the air inside the pipe still has momentum and continues forward. As the air continues forward towards the closed port (essentially a wall), it gets compressed. The kinetic energy of the air moving at a velocity X is transferred as the velocity reaches 0. This is where the energy comes from to compress the air. This is the "pushing" effect I mentioned before, as the air piles up on itself. Thats why as air increases in speed, the compression effect also increases.

I hope this clears it up but don't take my word for it. Look it up.

 

absolutely not. the potential for cfm increases, but if there is nowhere for the extra air to go, then it will not enter the intake.
how does it slow down? if it is slower, then it must be taking up a bigger area. there can not be 2 different speeds of air in the same pipe that retains the same diameter.
not in one cylinder, but they are open in one OF the cylinders, so when one door closes, another one opens. this disproves the "pushing" effect you mention down the line.

 

i have nothing to say if you think air flow is not increased after putting in an intake. you are missing some fundamentals of how stuff works in a car.

like i said, go look it up. There is no point continuing this conversation. You are unable to understand or unwilling to accept the concepts of fluid dynamics. Please, go look it up before continuing to post.