"modded" my air intake :)

[DoomTrooper]

I understand that a smaller pipe makes the air move faster, this is proven by the fact that if u blow through a cardboard tube or a straw, the air comming out of the straw is faster, but if u turn that around and now try and suck through the straw and the cardboard tube, which one will be easier to suck through, the cardboard tube, now if u suck hard enough then the air will travel just as fast through the cardboard tube as it would through the straw except your sucking alot more air, however if u applied this same amount of suction to the straw you wouldn't breathe nearlly as easily, you would recive less air, hence why a larger tube in and out of the engine helps airflow

[DoomTrooper]

i should mention of cource there is an upper limit to the size of the tube, when the engine doesn't suck hard enough to create a fast enough flow through such a large pipeing and of cource the air will get hotter etc, but since my tube is the same size as the pipe that goes actually into the airbox, just that i continue that size the whole way to the bumper instead of it geting smaller like the stock one

[macquered]

You are making a few basic errors in your assumptions. Of course there is a compromise and thats why there is a stack of engineering in these setups. There is a hell of a lot more science in a modern inlet tract than just pipe diameter and you'd need a degree in fluid dynamics to understand and therefore improve it, hence my backyard engineering call.

[DoomTrooper]

funny thing is that i am an engineer and i do study fluid mechanics, just trying to provide an example ppl can identify with

[macquered]

So then you should be able to tell me exactly how much restriction the standard setup is imposing on the motor.

An engineer at age 20? You must be pretty damn smart.

[DoomTrooper]

well buy me a wind tunnel and we shall test away won't we,
ok so i may have overexaggerated a little, i'm a member of the AIE, but i have yet to finish my degree but i am studying fluid mechanics this semester so it is pretty much right up my alley, but i'm not saying your wrong but the only point you've made is that because it was designed along with the car therefore it must be right, but you see that when they design a car they factor in more than just performance, also fuel economy and durability, whilst it maybe more efficient to have a bigger tube it may also effect fuel economy or make it wear faster, so to compromise they choose a happy medium, the springs that came with my car arn't as good as the ones that i put in, but holden would never use them as stock as they're too harsh for the average go from A to B commuter

[macquered]

I'm not saying you're wrong either but one trend I just can't understand is saying that one solution is better than X without actually measuring X in the first place. People say 'oh my derestricted airbox is better because it flows more'. How the hell can you tell? One bright spark here told me he could *hear* more air going in. Well I'll be damned if that is a recognised measure of air flow.

I don't see how durability and fuel efficiency come into it either. Durability? I've never seen durability of an air intake affect flow. Fuel efficiency is measured by use of fuel. How does a restrictive intake affect this?

[DoomTrooper]

surely u know that if u put more air in then the ecu will put more fuel in to keep to the ratio?
durability of the engine as a complete unit, not just the tubeing

[NUTTTR]

Well, the actual pipe itself (hence why in a few weeks i'm going to get a bigger pipe made up) has almost 20% less surface area (at it's smallest point) than the throttle body....
That's part of the reason, to smooth the airflow and stop the turbulence.... It (to my ears) is now louder... but it might not be, i have an spl meter but didn't measure it before i changed it....
Aaron

[macquered]

surely u know that if u put more air in then the ecu will put more fuel in to keep to the ratio?

Yes of course. So how does that make it less or more efficient?

In a nutshell, there are many other factors that determine fuel efficiency and I would be surprised if the intake is starving the engine of air as you are suggesting.

I think you'll find that a lot of modern naturally aspirated intakes actually generate positive pressure in the manifold, giving the engine very impressive volumetric efficiency. Why do people think they can better that by cutting off bits and pieces in the inlet?