Vented Tailgate - (Dodge Ram '07)

That it is a waste of money on a stock truck.

If you are talking about a cowl induction from days gone by I'd venture that the cowl induction is better. Direct shot of coldd air into a carb.

If you are talking about today, by the time the "cold" air travels through the filter and through the hot tube to the tb it is no longer "cold" and not of much if any benifit to a truck running along at 2500-3000 rpm that is having it's air fuel mix controlled by a 'putor.

Here's the thing Miles, the air is not pulled in it is forced into the filter by the speed of the truck. If the speed of the truck isn't in excess of 80+mph there isn't a whole heck of a lot happening.

That simply isn't true at all. For that to happen heat would have to conduct rapidly through whatever material was used for the duct. You would be correct for some of the cheaper thin walled plastic that could conduct heat. However, the better styles are double walled or made of thicker materials that don't conduct heat all that well. The air is traveling through the duct much too fast to heat up appreciably.

What type of truck are you talking about here? Very few trucks have forced air intakes. We are talking about stock trucks. They are not forced. Cold air drawn in is preferable to hot air from inside the engine compartment. A proper duct will not conduct significant heat to the air being drawn in.

Really??

Let me try again. The material that the tube is made from is going to aquire the same temp. that the rest of the engine does, or darn close to it. That heat will transfer through the walls of the tube so that the inner wall that the air is passing through is also the same temp. Now you introduce air that has already been slowed by the hot filter and then has to proceed through the tube to the tb. Seeing as it isn't a forced air induction there isn't a heck of a lot of velocity moving it. What makes you believe that this air is moving so fast that it won't pick up heat from whatever it travels through? The air will pick up a bunch of heat as it passes through the filter and tube. Thus the gain in performance or mpg compared to factory is going to be nil imo.

Exactly !!

Sure it is. But you aren't going to get there by changing the tube and that is pretty much what you have done. Heat is heat whether or not it is the factory tube of aftermarket

You are saying that a tube heated for a hour or so in a stock truck in normal driving won't transfer the heat to the air that passes through it with zilch for velocity?

Miles, I played with forced air on drag car's years ago. True it is now old tech, but pretty much the same deal.With a hood scoop and a velocity stack sealed to the scoop, good for maybe 1/2 second in the 1/4. That is on a modified engine at wot. That is with cold air being stuffed dirctly into the carb through a cold 6" tall velocity stack with no filter at at all.

You won't see that on a stock truck under normal use with a your tube and filter. You won't notice a mpg change that will offset money spent on the tube and filter imo.

No Roy. The engine metal temp is much hotter than the compartments air temp but I assume you meant air temp.

With that logic your homes A/C would not work. It travels through duct work often through attics that can get quite hot. Here in Phoenix my attic can get well over 120 degrees yet I have nice cold A/C coming out of the ducts which travel through that temperature.

It takes time for the air to heat up. How long does air take to travel through the duct in your view? Again, with your logic your homes A/C would not work very well. The velocity produced by the A/C's fan on say low isn't very much. The engine does draw in air more than fast enough.

Tell me Roy. Why do so many auto manufactures install ducts to the outside of the engines compartment when doing so costs extra money if according to you there is nothing to gain?

I change the duct from one that draws air inside the engine compartment to one that draws it from outside.

zilch velocity? Hmm. Guess again.

What does the tube cool it??

It is already hot from the air that it surrounds it.

You would be correct for some of the

I'm talking about the air in the engine compartment, under the hood where the tube is surrounded by air which is well over 120 degrees.

WTF is this thing part of the space shuttle? If the tube is under the hood for a hour at at normal operating temp are you trying to tell me the inside of the tube is cool?

And at the filter the air is slowed down.

Okay, for the sake of this mindnumbing exercise let's say it is 80 degrees outside, you have been rideing around for 45 minutes with a/c on driving at

35-45 mph, the engine compartment is well over 120 degrees, what would you figure the air temp is when this 80 degree air upon entery to the filter is when it hit's the tb?

Tom your talking nothing but bs here. It is a stock truck, with stock tb, stock cam, stock 'putor all stock. The "less restiction" means nada to it. as does this so called "cold air". If it was a race car modified to handle a fater mix then everything matters. But it isn't.

Answer the question. Is there or is there not heat transfer?

From experience with a bunch of hi performance cars, street and drag cars. You?

At the entrance of the tube, in it's box is a pretty restrictive filter, slowing things down. Does the air somehow get sped up after it goes through the filter? Or does the noise tell you something?

While we are at it go to a few of sites, you can buy a cai used all day long. I wonder why? Could it be that it doesn't work all that well on a daily driver.

Many years ago I was real good at what I did. Or maybe I just got lucky. I also did a whole bunch of jet and heat range changing to handle the cold air. So it wasn't all with the scoop and stack, which I hope you would agree is a much better system, although not for street use, than the current cai being offered for a truck. But since you think that 1/2 second gain is huge. What do you think the gain would be in a stock truck with a cai?

Thinking about this does a stock putor note the change if you somehow managed to get cooler air to the tb? I think it would require a reflash.

Also wouldn't you need a to go to a different heat range plug to accomodate all this cold air you and miles are stuffing into the fuel/air mixture?

On a stock truck at operating temp I think I am. But if I'm wrong then you must have one of these performance delivering, gas saveing toys on your truck. Right?

Yup!

We aren't talking about a/c. We are talking about the benifit of this setup on a stock daily driver truck.

I disagree.

For the same reason they put big assed decals on them and tell people they are fast.

Some do, some don't.. DC didn't with the Charger SRT8, and the SRT boys were after all the go that they could get.

But this is a stock truck, remember.

Hmmm. Answer the question. No heat transfer after the truck has been operated for a hour or so.? Where are you getting all this velocity after the filter?

>

Are you trying to tell me that the air coming from outside the engine compartment through the tube is the same temp as the air outside the tube? That would only be true if the air sat still in the tube for that hour you are talking about.

. 80-90 depending on the vehicle and duct used. Measure it if you feel thats not possible.

What you are missing Roy is the rate of heat transfer. Ok, lets say that tube sat at 120 for an hour and the inside is also 120. Now start a constant flow of 80 degree air through it. The inside of the tube will cool which does mean heat was transferred to the air....but only for the first few minutes. Plastic does not conduct heat very well. It won't be able to continue heating that air significantly.

The length of time is irrelevant. Heat is heat and the ability of that heat to transfer through the plastic enough to heat the air running through the tube is negligible especially if per you it would take an hour.

Your splitting hairs miles I said the drive the truck for a hour. Drive it longer. The continueing heat transfer is still there. No where is the velocity comeing from.

It still won't help a stock truck.

The heat would have to transfer through the tube wall fast enough to be able to heat the air passing through it in the time that air spends in the tube. It makes no difference if you drove an hour or 5 hours.

Miles you continue to ignore the question. You say it is moving fast enough to cool the tube and keep it cool. Where are you finding all this velocity?

Pardon me for butting in here, but let's take your stock, run-of-the-mill

360. Let's give it an 85% volumetric efficiency ratio. Therefore, every 2 revolutions, it's moving 85% of 360 cubic inches of air, or 306 cubic inches. Round that off to 300 cubic inches.

Typical highway cruising RPM is about 2,000RPM, so we're moving 300,000 cubic inches of air per minute.

Now - here's where it's going to get a little tricky, but let's assume a K&N-style cold air intake. That tube is about, what, 4" in diameter, and about, oh... 4 feet long? Calculating the volume of that cylinder, we get about 603 cubic inches? (Pi * 2" squared * 48"). That means we have to empty that cylinder about 498 times over per minute to feed the engine's demand for air. Therefore, each molocule of air has to make the 48" journey in .12 seconds (60 seconds/498). That works out to about 22.7MPH.

So... how much heat do you think the cool, 70-ish degree outside air is going to soak up from a thermoplastic tube, going almost 23MPH, and sitting in there for just over a tenth of a second?

I'm betting... not too much.

I'm on vacation this week and there's no way I'm going to the shop to get a scanner but if one of you guys with a scanner in your back pocket would check the reading of the intake air temp sensor you'd have an answer to the question. I'm betting its hotter than you think..

Denny

All of which explains why a cold air intake works.... with damn near anyone using one finding at least a difference in engine temp, if not power as well.

Dang Tom! I was gonna do all those calculations but couldn't find my slide rule.

I've done this. I see about a 5-10 degree differential.

run-of-the-mill

I'm sure that it is with a stock setup but lets not forget that the factory CAI is not normally the most efficient on the planet. The plastics that they use are based more on a cost / endurance ratio with the main influence being on the cost. That same cost factor also sometimes leads to a fairly restrictive setup and in most of the factory setups, the filter is contained in a box on or near the engine where it is subjected to much more heat transfer.

I never said that it would give huge improvements in every truck but you cannot validly say that no improvements would be made in any stock truck either. And then again, there is the bling factor that to some people, is worth every penny that these things cost.

Let me explain it then. In order for K&N or any of them to legally make those claims, they have to have done it. They could have found that in one model and year of truck A that they were getting a 12 HP increase (factory filter was way too small) and in completely different truck 'B' that they managed a 3 MPG gain (highly restrictive ducting). Now they can say that with their product you could get up to 12 HP and up to 3 MPG gains because they have seen it but nothing in the wording claims any specific vehicle and in most cases, you will not get close to either one of these increases while otherwise stock.

Probably because their HP increases did not occur with the Vette, especially since it is a sports car and probably already has enough air flow capability because HP is the name of the game for a car like that but for most passenger cars and trucks, max HP at any cost is not exactly a priority for the manufacturer.

Fair enough but for a while the group had some life in it again.

They make no such legally binding claims. Read the way they word it. It is very misleading. Here is an example copied from the K&N website describing their "High Performance Intake Kits".

"Designed to increase horsepower and acceleration by as much as 10% ..."

Even if it results in a huge power loss they are only claiming they /designed/ it for an increase. What happens after you install it has no bearing on this "claim". The only way you could bring legal action is if you can prove it increases horsepower and acceleration MORE than 10%, and that they /designed/ it for more than a 10% increase. I suspect that will never happen. I bet K&N's lawyers suspect that will never happen either.