Improved Mileage with CAI Mod

[FutureHoldsNoBounds]

Hi All,

It is known that cold air intake (CAI) provides more horse power (HP) than short ram intake (SRI), and is relatively easy to custom make and install yourself. A custom made CAI is a cheap alternative (as low as $10) compared to OEM (hundreds of dollars). My question is, what sort of mileage improvements can be expected from a CAI versus stock air intake? extra 50 km per tank full of petrol?

Your opinions are welcome.
FutureHoldsNoBounds

[PhatRoyale]

It depends on a lot of factors and your driving habits. There is no set answer for this question.

[FutureHoldsNoBounds]

I agree that it would depend on many factors. As for myself, I mainly drive in the city and metropolitan area, to and from work. But based on your response, it appears that a CAI doesn't make any significant improvements in mileage. I'm not going to bother putting in a CAI as yet until there is evidence for mileage improvements. I'll await for other opinions.

[PhatRoyale]

AFAIK, it's more of a performance modification rather than one that's done for economy.

It's supposed to help the engine breathe easier and help increase the throttle response a bit.

Downside is that you have to watch out for large puddles in heavy rain or risk hydrolocking your engine.

[Rdkill]

You will get ZERO gas mileage improvements from a CAI most likely, this is because it will let your car breathe easier...BUT use colder air which will take more fuel to burn because of power increase. Now you MAY see noticible gas mileage improvements with a hot SRI, since it will still be sucking hot air, you will burn less fuel, and on top of that it will again breathe easier.

[FutureHoldsNoBounds]

RdKill, you made an interesting point. You say that a hot SRI is more likely to improve gas mileage than CAI because sucking in hot air burns less fuel. I don't undestand the science behind that, as i don't see the diffrence in hot vs cold air with burning fuel. Can you further explain?

[PhatRoyale]

Some reading for the OP:

Could a CAI decrease MPG?

[Rdkill]

To sum it up, even though we run with an EFI engine, the same rules apply that a carbed engine would follow. That being when the air is hotter, it is less dense and less dense air needs less fuel to meet a certain Air/Fuel ratio. The opposite is true with colder air, it is more dense and more fuel is thus needed to burn at the needed A/F. So instead of turning a needle to compensate, EFI will detect this and make the changes.

To sum it up
Hotter air = less fuel, more MPG, but less power (overall)
Colder air = More fuel, less MPG, More power. (potential)

Put into the fact that the stock intake draws hot air, it gives you good fuel econ, but may be slightly restrictive. Add an SRI with a less restrictive filter and still sucking the hot air, then you get the capability of possibly increasing MPG.

Its complicated :-D

[PhantomS]

imho, neither cai nor sri will make a truly noticeable difference, other than making one feel good that they did this ot that "mod" ....... truly, if one or the other provided measurable mpg benefits, do you not think that Toyota would not have made that the stock design ? I mean, c'mon .....
Keep it stock....keeps insurance co and warranty happy

[midnightmach]

SRI will show better MPG because it uses warmer engine bay air

[Rdkill]

They could have made the car run on three cylinders to save on fuel too...:-p I guess its just a matter of all the little things adding up. Anyways its all theory...as none of us have dynos lying around to test such things :-(.

[FutureHoldsNoBounds]

I've been doing some research on the matter, and i seem to get contradicting views. One report states the following:

1. "Hot air is MORE dense than cold air, and therefore has less oxygen it in. Oxygen is required to burn fuel and since there is less oxygen then less fuel will get burnt"

2. "There is no noticeable/significant difference in performance and mileage between SRI and CAI".

3. "The mass air flow sensor (MAI) on CAI can cause detonation when too much air enters the engine"

My conclusion from all this is don't bother with SRI or CAI if you want improved mileage.

[Rdkill]

1 - flat out wrong...lol air is a gas and as such must follow the laws of physics. Unless we are referring to different types of density.
2 - agreed....but it sounds cool :-D
3 - Not sure.

Yea I agree, this is mostly done for performance. But if you did want to put one in your car dont bother buying one for several hundred dollars when you can make it for less than $60.

[thebrokeenthusiast]

I don't now why people are so caught up n the mileage hype. Drive your car how you want and do what you want to it. Let the greenies worry about driving clean diesels and hybrids. Me? I'll stick to my V6 and beating the ever living snot out of my wife's corolla.

[impulseRED]

Originally Posted by FutureHoldsNoBounds

I've been doing some research on the matter, and i seem to get contradicting views. One report states the following:

1. "Hot air is MORE dense than cold air, and therefore has less oxygen it in. Oxygen is required to burn fuel and since there is less oxygen then less fuel will get burnt"

2. "There is no noticeable/significant difference in performance and mileage between SRI and CAI".

3. "The mass air flow sensor (MAI) on CAI can cause detonation when too much air enters the engine"

My conclusion from all this is don't bother with SRI or CAI if you want improved mileage.

.........ummm isn't it the fact hot air is LESS dense than cold air, because if im not mistaken when things are heated the molocules spread out and when things are cooled, the molocules get closer together. Thats why if u get oxygen cold enough it turns into a liquid....??? correct???