I was chattin with a friend the other day and we got onto the subject of basic engine efficiency modifications, one of witch was the CAI.

He mentioned something that made me think,
Most CAI intake systems are made from Aluminum, which conducts heat rather well. So, how efficiently is the thing working?.
I know its a short distance from the wheel well inlet to the throttle body, but the air around it is very hot. So, would a pretty aluminium pipe really be working efficiently to deliver the air at its coolest state?.
Perhaps some kind of heat shilding, or cladding, would a plastic work more efficiently than a polished aluminium pipe?

What are your thoughts?

 

you can just heat wrap the intake

 

when you buy that intake. It usually comes with a good powdercoating or something of the like. This will reduce the amount of heat it does conduct. However, the alternative is the stock restrictive system or a ram air unit. The ram air stays UNDER the hood. In either instance, the CAI is still by far cooler than sucking up the already REALLY hot air, than sucking up cooler air and having it warm up slightly with its short pass through your CAI.

So, even though the unit can heat up, it wont heat the air to the same point as air Underneath the hood is with how long it is coming in contact with the unit.

 

Remember that the stock unit is actually a CAI. Plastic absorbs less heat than aluminum or steel. So, yes, the aftermarket systmes are probably less thermodymicly efficient. You could wrap them with the same heat tape that is used for headers or foam for heating pipes. The fact that the air is at low pressure due to the vacuum of the engine means that the air in the intake tract is even colder. This increases the delta between the under hood and the air in the tube allowing for a higher rate of heat transfer. That said it's still going to be a small number. But little changes (lots of them) make the big difference. I was thinking about my new CAI and how I was hoping for better gas mileage from it but then I thought here's this high flow filter and straight tubing that go right up to this big butterfly that, lets face it, usually 80% closed. Talk about a restriction. With that in mind the free flowing filter makes nearly now difference until that butterfly is wide open. Bottom line don't buy a big filter for the mileage. I think my mileage has actually declined since I put the CAI on, just because I always want the throttle open (so I can hear that wonder sound when the car hits 5K.

 

Lets be honest, the only real reason for a CAI system such as my K&N is no longer ther persuit of massive HP but really it is just the sound. Just think about the FRAM Boost commercials what are they selling most the HP the mention it but they sell the sound. Manufacturers are putting in the time and effort to ring out that last ounce of performance they can while being QUIET. There is no longer much left on the table. So it is the Sound we like most that is what we are after.

 

I think there's something left. The sound may be confusing me but the car feels a bit better to me. (no dyno data). I think when you are at WOT you may be gaining some but any other time your TB is creating a larger restriction than any filter can create.

 

Unless your dragging, theres always going to be restriction at the throttle body. How often do you run the throttle Wide Open?

Its about letting the engine breath as easily as possible when it needs to right?
If you can take away the effort of "Sucking" air into the system your making the engine run smoother right?

 

Lets all remember the engine does not suck in air, your engine is a pump, plain and simple. It operates the same way a vacuume cleaner does, it creates a lower area of pressure...since this area is lower in pressure than atmospheric pressure, the outside air is forced into the engine. All a cold air intake does is relocate the filter closer to the source of the air, theoretically allowing colder air into the engine. It doesnt allow for a larger volume of air, it only allows for better flow through the intake section, but since its the same diameter at the throttle body your not getting any increase in air volume to the engine. Your just getting slightly colder air, nothing more...

 

If it doesn't suck in air then how does it get in there? Air pumps "suck in air". It creates a low pressure area by drawing the piston down with the intake valve open. It sucks. The lower we make the delta P between the ambiant air aid that intake tract the less work the motor has to do to get that air. Hey I have a great idea. Let's push the air into the motor with a fan driven by the spent exhaust gases. Nah that would never work.

 

Let us see to suck--- to expand our belly/lungs with muscles creating a low pressure in our abdomen and chest cavity cause the higher pressure air to rush in.

Hmm....Piston moves down creates vacuum and thus air rushes in. Sounds like SUCKING to me... Just a thought. YEAH YEAH only moves from high pressure to low big whup. Everyone understands it suck in air.

However in response to those above is it mroe efficient??? Well at Wide Open Throttle it is marginally better and since this is the only time it matters at all there is essentially no efficiency gain over most modern intakes. Just feeds the sole sounding like Horse Power thus the placebo effeect takes over and you think it is better.

The effect was demonstrated by ford back in the early 90's when the released the 5.0L Thunderbird in response to Car & Driver, Road and Track, and others that the supercoupe was not that good. Well after running all day with the new V-8 Thunderbirds they were marvelling at how great it was how much faster it was so they had them pull out the test mules they had been driving for the last year or more and proceeded to have the Supercharged V-6 hand the V-8 it's lunch even though they(Some professional drivers t00) were convinced the V-8's were faster. Placebo effect sound like HP must be even if it is not.