When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
At low speeds of course the shroud works. At those speeds conduction plays a bigger role than convection. But as soon as you get up to speed (real speed, where your CAI is arguably a more important upgrade), the temperature differences are going to be minute.
Let me use your example: with shroud the highest temps you saw was 95ºF (308 K), 120ºF (322 K) without the shroud.
Now let's use the ideal gas law to figure out density of air. After all, the goal of a CAI is to have colder (more dense) air enter the combustion chamber to increase our volumetric efficiency.
Let's see how these temperature differences really affect the final density of the air as it is entering the intake:
Ideal gas law: PV = nRT
P= pressure, V= volume, n= quantity (mass) of air, R = constant, T= temperature, n/V= density, p = density
Rearrange to get on the order of density (mass per unit volume):
(n/V) = (P/(RT))
But pressure in the atmosphere is relatively constant, and the R is also constant so we can transform to:
p=(1/T)*k; where k is some constant
Now the goal is to figure what 1/T is at both temperatures measured above:
1/308= .00325; 1/322 = .00311.
So what was the increase in density? .00014 g/ml or 4.5%.
Now this may sound like a huge improvement, but at traffic speeds there is usually an easier, cheaper way to increase your volumetric efficiency: depress the accelerator further.
Note that this density improvement only decreases as your speed increases, because convection due to the rapid relative velocity of air will maintain your intake temperature closer to ambient with or without a shroud.
In any case, this is just a simplification of a much more complicated problem. Thanks for reading.
.
At low speeds of course the shroud works. At those speeds conduction plays a bigger role than convection. But as soon as you get up to speed (real speed, where your CAI is arguably a more important upgrade), the temperature differences are going to be minute.
Let me use your example: with shroud the highest temps you saw was 95ºF (308 K), 120ºF (322 K) without the shroud.
Now let's use the ideal gas law to figure out density of air. After all, the goal of a CAI is to have colder (more dense) air enter the combustion chamber to increase our volumetric efficiency.
Let's see how these temperature differences really affect the final density of the air as it is entering the intake:
Ideal gas law: PV = nRT
P= pressure, V= volume, n= quantity (mass) of air, R = constant, T= temperature, n/V= density, p = density
Rearrange to get on the order of density (mass per unit volume):
(n/V) = (P/(RT))
But pressure in the atmosphere is relatively constant, and the R is also constant so we can transform to:
p=(1/T)*k; where k is some constant
Now the goal is to figure what 1/T is at both temperatures measured above:
1/308= .00325; 1/322 = .00311.
So what was the increase in density? .00014 g/ml or 4.5%.
Now this may sound like a huge improvement, but at traffic speeds there is usually an easier, cheaper way to increase your volumetric efficiency: depress the accelerator further.
Note that this density improvement only decreases as your speed increases, because convection due to the rapid relative velocity of air will maintain your intake temperature closer to ambient with or without a shroud.
In any case, this is just a simplification of a much more complicated problem. Thanks for reading.
.
LOL....I think you need to hook up with some of those guys in the oil threads. They're pretty good at throwing out some of those fancy thing-a-ma-jiggy moon rocket calculations themselves. Me....i'm just grabbin another beer.....
The debate over "worth it or not?" from a performance standpoint notwithstanding... the issue over pricing is indeed BS and probably not a good idea to deal with that particular company.
In regards to "bang for the buck" performance increase, based on CAI experiences with other rigs... I would concur that there is a nominal increase in bhp - and even that won't really happen unless you open up the other end and help the exhaust gasses extract easier too. So there is that to consider... gotta do both ends.
Wow, I guessing none of you would like to take a wager then on a Mamba and your car on a dyno????
First off you don't have to be going 120+ for any of them to work, and I can't really talk about ones I have not tested but I can talk about the Mamba. The comment was made that the car will compensate. That is not true and you are missing the point of what a CAI does, a good one anyways. You are getting better VE with it and when you do that you make more power. It is the same effect with headers, when you introduce the scavenging from the headers, you get clean air and fuel in the cylinder and that alone makes more power. The CAI is the same thing, we are increasing the pressure in the intake manifold thus getting a better VE.
So who want to talk about legal advice or medical recommendations??
Since we have a bunch of everyone guessing at what works and what doesn't maybe you would like to take some legal or medical advice from me since I am neither a lawyer or a doctor.
JA
Well said. Of course, doing the exhaust too does add more, but a well engineered air-intake system can do a lot. If you think of that increased pressure at the intake as "reserve", you can see where it will not starve out under heavy throttle. My experience is more in the turbo field, but all is the same basic principle. Splatter the fuel with higher pressure and more air and it burns more efficiently. Kind of in layman terms, but it works for me. :-)
LOL....I think you need to hook up with some of those guys in the oil threads. They're pretty good at throwing out some of those fancy thing-a-ma-jiggy moon rocket calculations themselves. Me....i'm just grabbin another beer.....
Well said. Of course, doing the exhaust too does add more, but a well engineered air-intake system can do a lot. If you think of that increased pressure at the intake as "reserve", you can see where it will not starve out under heavy throttle. My experience is more in the turbo field, but all is the same basic principle. Splatter the fuel with higher pressure and more air and it burns more efficiently. Kind of in layman terms, but it works for me. :-)
I'm thinkun maybe a CAI might compress the air in the man. by maybe....what.... .00005 PSI ? Thats got to be good for at least .0003 HP at the studs......
I'm thinkun maybe a CAI might compress the air in the man. by maybe....what.... .00005 PSI ? Thats got to be good for at least .0003 HP at the studs......
But I think that's only true at 187+MPH, and my car has an advertised top end of only 186.
I really love the LS2 airbox small tubes going into the main body and then air needs to make a 90 degree turn towards the MAF and engine. I'll take my chances
with a vararam and toss out the stock box!!! Just looking at a LS3 or LS7 I wouldn't bother with a CAI, I would just shroud the top, and prop the bottom open.
I really love the LS2 airbox small tubes going into the main body and then air needs to make a 90 degree turn towards the MAF and engine. I'll take my chances
with a vararam and toss out the stock box!!! Just looking at a LS3 or LS7 I wouldn't bother with a CAI, I would just shroud the top, and prop the bottom open.
That's the correct approach to an intake. It should function to improve airflow through better streamlines. 90 degree bends are definitely a bad for intake design.
I remember reading this article a long time ago on Super Street answering the question of "wouldn't an intake function better without a filter at all, just an open pipe?". The answer was "no". This was shown on the dyno results. Not because the air was colder or compressed (ram air), but rather the small slits in the filter help to smooth the airflow, which reduces eddies and actually increases mass flow rates at the micro level. As a result, more air, not less, went down the intake pipe due to the filter, which is contrary to intuition.
LOL....I think you need to hook up with some of those guys in the oil threads. They're pretty good at throwing out some of those fancy thing-a-ma-jiggy moon rocket calculations themselves. Me....i'm just grabbin another beer.....
Well said. Of course, doing the exhaust too does add more, but a well engineered air-intake system can do a lot. If you think of that increased pressure at the intake as "reserve", you can see where it will not starve out under heavy throttle. My experience is more in the turbo field, but all is the same basic principle. Splatter the fuel with higher pressure and more air and it burns more efficiently. Kind of in layman terms, but it works for me. :-)
The engine works like an air pump..The more air you get into it you need to get it out.
I'm thinkun maybe a CAI might compress the air in the man . by maybe....what.... .00005 PSI ? Thats got to be good for at least .0003 HP at the studs......
CAI does nothing if your stock intake pulls cold air, but if it pulls underhood air then it works to add HP maybe 1 or 2% 400hp maybe 6 -8hp. The ram air will drop vacuum psi in the intake box allowing the engine to work easier to suck in air. Corvette engineers thought it would work also
Below is a write-up from a fellow forum member regarding his real-world experience with using an intake shroud to provide ambient air to the intake opening on his GS. It's kinda long, - but some of you may find in interesting.
"The Intake Shroud is working well.
Here are examples of the past two mornings coming into work.
1.) I park my car in a garage, and it’s been getting in the high 80’s here in Daytona this week. At about 5 am as I am leaving, both the ambient temp and the intake temp is about 90 degrees (the engine bay and garage are still warm from parking the hot cars in it from the day before).
2.) When I back out of the garage, the ambient temp drops first (as expected) to about 65 degrees.
3.) Within the first mile of 25 mph driving (about 2 minutes) the intake air temp has also dropped to within 5 degrees (about 70 degrees) these past two mornings. This is very good, it shows cool air is getting to the intake air sensor, and cooling off the entire intake, even though the engine is heating back up from driving. After this first mile, my coolant temp is close to 190 degrees, as a fyi.
4.) As a comparison to the OEM setup (meaning without anything on the air intake), the intake air temp rarely drops at all from the temperature it is at in my garage. Meaning the intake air temp will stay near the 90 degrees, and never drop for this same mile of 25 mph driving.
Next, within the first 10 minutes, the intake air temp drops (and stays) within 2 – 4 degrees of the ambient temp. Meaning, if the ambient temp is 65 degrees, the intake temp is showing 67 to 69 degrees. This is very good.
1.) As a comparison to the OEM setup, the intake air temp eventually settles in at about 10 degrees higher than the ambient temp. Meaning, if the ambient is 65 degrees, the intake temp is 75 degrees (or higher).
Now, to stop and go traffic in the morning, because I go thru several red lights on the way to work.
1.) During the mornings, it is still dark, and the intake air temp has not risen more than 2 degrees, even when stopped for long light changes. Meaning, if the intake air temp is 67 degrees when I stop at a red light, it will only rise to 69 degrees.
2.) It will then quickly drop back to the 67 when I start moving too, which is showing the fresh air is cooling the sensor.
3.) As a comparison to OEM, the intake air temperature would rise at least 10 degrees, and sometimes as much as 20 degrees during a red light stop. Meaning you are now 20 to 30 degrees higher than the ambient temp. So using an ambient of 65 degrees (and an intake temp of 75 degrees) the intake air temp would rise to 85 - 95 degrees temp during the red light stop.
Now, about driving home after work, in stop and go traffic.
1.) Both the ambient and intake air temps have been about 90 degrees, when I start my car and pull out onto the highway. The water temp of the engine is around 100, when starting, meaning the car has not fully cooled off during the day. This is telling me that even when stopped, if there is a breeze (which there is most days where I work), some of the cooler outside air can make it to the sensor to cool it.
2.) As I wait to get out into traffic, the intake temp has never risen above the 90 degrees, even though the engine temp may rise to 150 degrees while I wait.
3.) I’ve noticed that I spin easier when I get on it (to get up to speed with traffic), more about this later.
4.) Compared to OEM, the intake air temp would be 100 degrees or so. Which makes sense, it is matching the engine under hood temp.
5.) If I sit and wait, the intake temp will rise to over 100 degrees, as the engine temp rises to the 150 degrees.
6.) I’ve noticed that don’t spin when I get on it (to get up to speed with traffic), and that tells me that the OEM is pulling some timing, due to the intake temp being above 100 degrees.
7.) As I go home thru more red lights (and more traffic), with the new CAI, the intake temps have stayed within 5 degrees of the ambient. Meaning, if the ambient is 90 degrees, I’ve never seen the intake air temp rise above 95 degrees.
8.) You will get some heat soak from the engine, because the engine coolant temp will get close to 200 degrees when in stop and go red light traffic. But your CAI is keeping the intake air temp very close to ambient. It shows when I punch it at red lights too, I break traction, even with hot sticky Nitto Invo tires.
9.) As a comparison to OEM, the intake temp will rise to over 120 degrees easily, due to the heat soak of the engine bay. And, as I play at the red lights by romping it, I can also notice reduced power by not being able to spin when punching it."
I think most vette owners have their favorite way to play with their car. Maybe it's the track, car shows, or long cruises. For me it's a few special 'on' ramps, country roads and city stretchs with stop lights. I like to idle away from a light then mash the throttle until the tires break traction. It's in these situations that I want max performance. The shroud seems to help with the off-the-line perf. That's enough for me.
