CAI’s...do they actually work?

[77cruiser]

Have you thought about tuning your cruise AFR to run in the 15.5-17 range?

[BOOT]

I'd look to see if you can maybe trim the factory opening, most oem air intake are designed for noise reduction. I've herd modern airboxes are not that bad but not as old as a 99. The one thing I H8 bout aftermarket CAI's(other than most are HAI) is when they use an alum tube but peeps like shinny.

Seems to me that the shiny metal tubing would actually conduct heat better...which I couldn’t see that being a good thing.

I’ll investigate the air box for any baffling or restrictions. It could have some sort of silencing in it.

That's why I said I H8 the alum tubing. Lots of good aero tips and that ecomodder site is good! Someone else suggested fuel line insulation but with FI the higher PSI, submerged cooled pump and constant circulation kinda defeats any insulation in my opinion. If no1 already brought it up Taller tires could help, they make ECO tires that have tread that helps or stiffer sidewalls to reduce bulge for less rolling resistant.

[travis]

I’ve got a front valance/air dam on order...should arrive tomorrow.

Unfortunately I have no way to tweak the a/f ratios, nor do I know of anybody reasonably close that could do it either.

I had approximately 2” taller tires on it until recently. The problem is that a 350 in a 5700 pound brick is just struggling going down the highway at 1800-2000 rpms unless there is a tale wind. The slight rpm increase at 65-70mph from the shorter tires actually helped it quite a bit more than you would think.

I’m also going to run the valves on it, as I have never touched them since I have owned it. I suspect they may be a little tight. I have seen 1+ mpg gains on a number of my personal vehicles from running them about 3/8 turn down from 0 lash, versus the full turn from 0 that a lot of repair manuals recommend.

[gruntguru]

A CAI can definitely improve performance but I have never heard of a CAI improving economy. If economy is the goal, a hot air intake or a heated intake manifold (if its carburetted) is a better way to go.

[groberts101]

A CAI can definitely improve performance but I have never heard of a CAI improving economy. If economy is the goal, a hot air intake or a heated intake manifold (if its carburetted) is a better way to go.

CAI's can reduce pumping losses due to straighter and larger ID tube designs. Plastic resin is best but if it's aluminum?.. just insulate it and you're still far ahead of the OEM stuff. And the better ones will have filters or adapters with venturi's(velocity stack style openings). Where some guys will confuse the matter is when the intake tubing ID has jumped considerably and they feel less bottom end torque output with a boggy sensation from idle to heavy throttle but that is only because the MAF tables and rest of the tune has not been optimized for the different tube velocities. Some systems remedy this by using reducers or necked down sections around the MAF to reaccelerate the air speeds past the sensor. However it's done it can be remedied and net gain is the end result.

The OEM's do it to protect their asses from warranty work and keep the CAFE and emissions standards in check. The colder the induction temperatures the more aggressive the tune can be. The more aggressive the tune.. the more manifold vacuum(higher BMEP) and light throttle torque can be made. The more light throttle torque you have available the less throttle will be needed to accelerate the vehicle and maintain steady state cruise. THAT.. is where the savings and net gains come from. Works best with carb'd motors using an annular or downleg booster but also works with EFI as well. Ask why a cold motor with cold unheated induction runs stronger than a hot one and see what extra tune can be put into it. NOx be damned.. lawnmowers to race engines works on everything I've ever put the effort into and the trends are quite obvious.

[Belgian1979]

A CAI can definitely improve performance but I have never heard of a CAI improving economy. If economy is the goal, a hot air intake or a heated intake manifold (if its carburetted) is a better way to go.

X amount of HP is needed to run a car at a certain speed. At this speed Y amount of fuel needs to be mixed with Z amount of air to create that hp.
If the air is cooler (more dense) it contains more airmolucules, so when you install a CAI, that air contains more air molecules and so more power can be produced for the same volume of air inhaled.

What happens in practice is that you will reduce you throttle opening to maintain the same speed. So in effect a CAI will not reduce your need for fuel, but it will do so at a lower throttle opening. At cruise nothing will change in terms of fuel consumption or power produced

It all changes when you're accelerating or at WOT. At that moment you can burn more fuel in the same amount of time and thus produce more power.

[MadBill]

When the throttle opening is reduced to make the same cruise power with colder/denser air, the manifold vacuum increases and so more work is required to pull the pistons down on the intake strokes, i.e. more 'pumping loss' is incurred, which must be 'paid for' in additional fuel consumption. https://www.quora.com/What-is-meant-by- ... on-engines

[gruntguru]

When the throttle opening is reduced to make the same cruise power with colder/denser air, the manifold vacuum increases and so more work is required to pull the pistons down on the intake strokes, i.e. more 'pumping loss' is incurred, which must be 'paid for' in additional fuel consumption. https://www.quora.com/What-is-meant-by- ... on-engines

Exactly. Thanks Bill. This is one reason a heated air intake will improve fuel economy. Another is greater vaporisation of fuel droplets leading to better combustion, another is higher TDC temps producing faster combustion (slow flame speed is a negative aspect of throttled operation.)

[cjperformance]

My daily hack is a 4.0L 6cylinder stock standard. Economy is as predictable as the sun rising! Its efi and has a factory pickup for cold air. The pickup can be easily removed so engine bay air is picked up instead. Its winter here now. 10/14°C days. I have just filled it so i will remove the cold air pickup and do a comparison over the next 2 tanks. About a week and a half driving for me.

I’d be really curious to see how this works out for you

I can also , as per midnightbluS10 suggests, check IAT with a scan tool when I do this CAI on and off test.

Ok so far my car likes the CAI. Typically i get 12.2 to 12.8 liters per 100km (sorry you'll have to convert to your local/preffered figures) , with cai intake removed i have gotten 13.3 and 13.1 liters/100km respectively.
Difference on hills is probably the most noticeable as in places where it would normally maintain (4 spd auto with lockup in 3rd and 4th) top gear and maybe just unlock the convertor , with no CAI it has to go back to 3rd then the convertor will relock and maintain but of course at a higher rpm. Out of aprox 460km of driving i may cover aprox 90km of light hills where this scenario takes place. I tried to drive as "samey" as i normally would so as not to change too much.

[cjperformance]

Just so you can see what im reffering to ,, on my dusty work pig (i use some dirt road most days!) The CAI gets air right at the front over the radiator.

20180730_154904-600x800.jpg

2 screws out and the CAI 'snorkel' pops out easily, you can see the screwdriver resting in the hole where air is now taken from engine bay . There is actually room for some air to get around the side of the radiatior so its probably seeing a blend of cool air and engine bay air.

20180730_154947-600x800.jpg

[Circlotron]

When the throttle opening is reduced to make the same cruise power with colder/denser air, the manifold vacuum increases and so more work is required to pull the pistons down on the intake strokes, i.e. more 'pumping loss' is incurred, which must be 'paid for' in additional fuel consumption. https://www.quora.com/What-is-meant-by- ... on-engines

Exactly. Thanks Bill. This is one reason a heated air intake will improve fuel economy. Another is greater vaporisation of fuel droplets leading to better combustion, another is higher TDC temps producing faster combustion (slow flame speed is a negative aspect of throttled operation.)

+10

[BigBlockMopar]

Just so you can see what im reffering to ,, on my dusty work pig (i use some dirt road most days!) The CAI gets air right at the front over the radiator.

The front of the radiator is most likely a higher air pressure zone, compared to the engine bay itself, which might have an impact too.

Since your CAI seems easily accessible, how about wrapping some reflective bubble-insulation around it to shield the black plastic from the engine-bay heat a bit more?

[Geoff2]

Bill,
Do not agree with your blanket statement that cold[er] air resulting in reduced throttle opening causes...ultimately greater fuel consumption from increased pumping losses. What about the extra power than can & is generated from the denser air? This can result in the t/blades being closed even further to maintain cruise speed, reducing fuel consumption.

[Belgian1979]

Bill,
Do not agree with your blanket statement that cold[er] air resulting in reduced throttle opening causes...ultimately greater fuel consumption from increased pumping losses. What about the extra power than can & is generated from the denser air? This can result in the t/blades being closed even further to maintain cruise speed, reducing fuel consumption.

Pumping losses due to a couple of % more closed throttle is minimal and not in comparison to the additional hp created.

On my efi set up I've run it with underhood air and with CAI. The difference is that at the same throttle openings the car runs faster/injects more fuel. At the same speed it runs at lower rpm and the amount of fuel injected per unit of time is the same with the lower TP. The amount of pumping losses couldn't be noticed when looking at the numbers so it seems they can be largely disregarded.

[mk e]

When the throttle opening is reduced to make the same cruise power with colder/denser air, the manifold vacuum increases and so more work is required to pull the pistons down on the intake strokes, i.e. more 'pumping loss' is incurred, which must be 'paid for' in additional fuel consumption. https://www.quora.com/What-is-meant-by- ... on-engines

Exactly. Thanks Bill. This is one reason a heated air intake will improve fuel economy. Another is greater vaporisation of fuel droplets leading to better combustion, another is higher TDC temps producing faster combustion (slow flame speed is a negative aspect of throttled operation.)

And the last is a version of the pump loss theme. The throttle works by expanding the air which causes pumping losses but it also means the air is expanded which effectively reduces the compression ratio, 2hich reduces efficiency.

This is the whole point of the tiny turbo engines.....the engine runs at near full unboosted power which is its highest efficiency point a lot of the time, the boost is used to give adequate acceleration. Improved mileage with acceptable performance is the result.