Evil Aviator

The implication is that the aftermarket "cold air intake" will supply the engine with colder air than the stock intake. I don't think the aftermarket dealers would sell as many units if they called it a "same temperature as your stock intake but more expensive" intake.

At least in the 80's the high performance filters were marketed by their improved flow rate, which is actually true in almost all cases, despite being barely measurable on an otherwise unmodified engine.

Some are scammers, but they are all rich, lol. Some Hondas do actually draw air from the hot engine bay in their stock configuration, so I think the origins of the "CAI" were most likely honorable and technically correct.

Yes, those lame internet tests tend to show that. Fortunately, that correlation is actually quite applicable for the majority of the readers. I guess it just bothers me that all other aspects are ignored while the articles focus on their simplistic agenda.

phoenix7

stock airbox, better pipe?

NZConvertible

Well in some cases that would be true. As you point out, many car's stock intake systems draw air from the engine bay. But before you said it implied colder than ambient, not colder than stock. The former is silly, the latter quite plausible.

The tests I'm referring to are far from what I'd call lame. I'm referring to the ones done by Autospeed. Using sensitive pressure testers (a water manometer or a Magnehelic gauge) to measure the pressure drop at various points along the intact tract is a perfectly valid test. What exactly is your criticism?

RB_eater

iTrader: (1)

Cheers to a nice scientific argumentation, it seems so rare nowadays.

RotaMan99

Though the stock snorkle is out of the engine bay, its not directly in the outside air. The radiator panels block the air from the snorkle. So I bet its just sucking in cooled air that reaches that point from the bay and a little air the seeps by the plastic panels.

Designing the right cai placed in the right spot should work better then the complete stock intake system. Im not saying you will gain much or anything to notice, but in theory, should work better at getting the outside air into the intake then the stock system.

Evil Aviator

Yes, if an aftermarket "cold air" intake were marketed to replace a stock intake that already fed from ambient air, then the "cold air" description should indicate the air would be colder than ambient. I agree that this is silly, and I wonder why retailers are allowed to use this terminology. I think that may be why some of them redesignated their products as "ram air" intakes.

Also, my original quote in this particular thread was "The implication from the naming convention is that an aftermarket "cold air intake" would supply colder air than the stock intake. With a Honda, that may be true. With an FC RX-7, that is not true".

1. Their testing does not even remotely follow the scientific method.
2. Their testing does not follow SAE guidelines.
3. Their testing assumes stock engine flow rates.
4. Their testing of only one parameter while ignoring and not even controlling the other parameters is just plain lame.

While I understand that magazine type articles need to be brief and dumbed-down for the general public, and it is not practical for the journalist to consult a scientist or engineer in the subject's field, it does not mean that I will give them the same value as an SAE paper or similar well-written technical journal.

At least the Autospeed articles are not as bad as that hideous Revspeed air filter infomercial running around the internet.

The stock system works just fine. Its main problem is that it has some pressure issues just like every other stock intake, as already stated by NZConvertible. The pressure issues become more of a problem as the engine's flow rate increases. For those of you reading this who do not have a strong background in this subject, you can think of it the same way a square-shaped car would have no problem traveling along at 10mph, but when you try to take it up to 150mph the drag is going to become a big problem. Just like there is no point in adding fancy aerodynamics to a 10mph vehicle, there is no point in adding a fancy intake to an engine with a flow rate that is within the efficiency range of its stock intake system.

Yes.

NZConvertible

They're not a scientific experiments and are certainly not intended to be. They were before and after tests of modifications to see what worked. Given the purpose of the testing, I can't see any reason why they'd need to be any more "scientific".

Who said anything about it being an SAE test? What's wrong with the method used? Why would anyone who wants to test the effectiveness of simple mods to their car go to the trouble of following SAE guidelines?

Well most of the vehicles in question were already modified, so I don't see any assumption about stock flow rates. How is that even relevant?

Dude, are you serious? This is real-world DIY modifying and testing. Take a measurement on the road, change something, take a new measurement on the road, compare results. The whole point of those articles was to show how anyone can test to see which parts on an intake system are worth modifying and which aren't, and to make worthwhile improvements based on that knowledge. Nobody's selling anything here.

Your comments are very broad and don't actually explain what's wrong with the way the testing was done. Are you saying the results are worthless? Are you saying they proved nothing? So many people make baseless claims about the effectiveness of the mods they perform. You should be encouraging people to test their work, not rubbishing the practical methods for doing so.

Let's not forget that I brought up these tests because they all shows that the pressure drop through the stock filter was tiny compared to the rest of the system. Are you disputing that? Do you have better evidence to the contrary? Evidence the SAE would accept?

You're talking about two completely different types of articles and it's a bit silly to even try to compare them. Nobody's ever going to write an SAE paper on the results of non-OEM modifications to the intake system of an MX-5 or WRX (two Autospeed examples).

RotaMan99

I do agree the stock system works just fine for a stock engine setup. I am simply pointing out that the stock intake is not sucking in outside ambiant air directly like a well designed custom cai would.

I would like to see a comparison of the pressue drop in the stock intake vs a well designed custom cai on a stock port n/a engine with stock exhaust and a stock port n/a engine with a high flow exhaust. Considering with a high flow exhaust, the engine is able to injest more air, the pressure drop may increase to a point where replacing the stock intake setup may actually give you a little gain.