Short Ram vs CAI.

[alphalanos]

someone just told me that a short intake tube is better than a CAI. how could this be? the air inside the engine bay is really hot. (especially my car) which is why im running CAI as opposed to short ram.

I know for some cars this varies and you have to experiment, but in general...

[-Jayson-]

they make no difference. And when your driving the air inside the engine bay isnt hot, its the same as the outside air.

[Auto_newb]

Why don't you try using a hairdryer blowing towards your face on "high heat", then set it to "cool". You will feel a difference

[Evil Result]

Depending on whether your car uses a Carb or FI. A short intake that would be pulling air from the inside of the engine bay, which will be hotter will help keep fuel atomized which helps in creating more power even though the desity of the air may be lower. For FI its already fairly close to the intake valve so it isn't given much time to cool and condense so using a short intake or a CAI might not make much of a difference.

Not that either of these will, unless its winter or something.

[-Jayson-]

ok its not the difference of a hair dryer or not. So you mean to tell me that air going into your engine at 45 MPH is going to be just as hot as if your engine was sitting still? i dont think so. When your moving air is constantly being circulated around in their, faster and more volume than what is able to be heated up. Not to mention that with cold air the air travels a longer distance and through more bends in a pipe which will cause drag and turbulanc ein the air slowing it down.

[Auto_newb]

Won't the engine get hotter as the revs go up?

[v10_viper]

Originally Posted by Auto_newb

Won't the engine get hotter as the revs go up?

Not Necessarily, Good example is my truck, which has a 195 degree thermostat runs right at about 190 traveling down the highway at say 60 mph. But when I stop and let it sit and idle for 10 minutes temp goes up to around 250, which really pisses me off, because the fan on is spinning slower which is moving less air, and i can open the hood and hot air just flows out because as hot air rises it really doesn't have anywhere to go so it stays hot in there. So i dont really know if an engine is hotter at higher revs, more heat is produced but with i'm assuming the coolant traveling around faster and such and the fan moving faster might help a lot, but driving at higher speeds DEFINATELY helps keep it cool. To help this though i wanna get a lower thermostat and a two speed electric fan.

[cshky04]

For every 11 degree drop in intake air temp, you gain 1 hp....you figure it out

[SaabJohan]

The air under the hood is quite hot, especially during a hot summer day. It doesn't matter if the car is moving the temperature will be higher under the hood anyway, remember that the air is first heated by the radiator and in some cases oil coolers, A/C condensor, and intercoolers before it gets into the engine where it's heated further, probably with the same amount it was heated by the radiator. 60-70 degC isn't uncommon under the hood, which means that you will loose some power.

Basicly, if we can take air that is colder and denser the better it will be. Rarely any new cars take hot air from under the hood.

The length of the itake pipe has also a tuning effect on the intake.

The gain from colder air will depend on the engine power, it's a percentage number so to speak.

[burly]

The air unde the hood is indeed quite hot. The air isn't flowing through there at the rate as you are moving for one. Second, its getting heated as it enters the bay and crosses over the radiator. Third, the engine itself is over 100 degrees, the exhaust is several hundred and there are dead spots for air movement within the engine bay. Underhood temps are often 150-175 degrees F and when in heavy traffic, spots can see well over 200. So even "hot" 90 degree ambient air is an improvement. And as cshky04, for about every 11 degree F drop in temp, you can about 1 hp.

[lazysmurff]

get either. the HP gains you see will result in you free-ing up your intake, not in whether its hot or cold. think about it, your intake manifold is going to heat whatever "cold" air you bring in, so the difference between the two will be neglegable. especially

you wont find any difference in the way it drives if you switch to a shorter intake. so dont bother

[Auto_newb]

So you guys are saying that if I bought a $300 cold air intake, I just wasted money?! And I don't even get as much HP compared to a short ram which only costs slightly above $100?

[Sluttypatton]

Chances are that you will not notice the power increase made by either, let alone tell the difference between the two.

There is however a difference between hot air and cold air, and while the intake manifold may become heat soaked and heat the intake air to some extent, that effect is far superior to simply sucking in the hot ambient air in the engine bay. The heat transferred by the intake manifold will be fairly negligible when compared to the heat of the ambient air in the engine bay.

I have always thought that $300 for what is essentially a shaped tube is excessive, however they do increase your power...just not by enough of a margin that you can expect to feel the increase. Although, the effect of modifications is cumulative, and having a better positioned and less restrictive intake will help to make the most out of any future modifications.

[Auto_newb]

So you are saying that the heat in the intake manifold wouldn't make the air coming through, hot?

"intake manifold may become heat soaked and heat the intake air to some extent, that effect is far superior to simply sucking in the hot ambient air in the engine bay."

What does this mean?

[Sluttypatton]

Basically what I'm saying is that although the manifold may get hot and heat the intake air a bit, it is still better to locate your air filter at the coldest possible location than just leaving it in a hot area of the engine bay. Sometime I'll get around to measuring the manifold temperatures with my CAI and factory airbox, so I can provide some firsthand numbers. It might take a little while however, I'm pretty busy during the days right now.