Good point.

Don't waste your time. It's been done. The open filter loses. Do a search here.

 

My friend said the same thing. Problem is I was one of the idiots buying every intake I could find, as I couldn't find one to be happy with. Now I have 4 intakes sitting in my garage including a modified factory one. Not to mention a cold air feed from the front. I believe you that the open air inake will lose, but I want to see why I wasted so much on intakes and what kind of variances there truly are, so I know with first hand experience.

 

Well, lets look at aftermarket CAI's that have enclosures. They are typically made out of aluminum or metal which absorbs heat. That defeats the purpose of sucking in cold air since the shield surrounding the CAI is absorbing heat from the engine. Thats why IMO the open air is better. When you accelerate the cold air is being forced through the grill or underneath into the engine bay displacing the cold air into the filter.

 

By just adding 3 more holes at the bottom of the box I think will just allow the hot air in the engine compartment to enter the box which would defeat the whole purpose, now if there were three more vaccum hoses connected to the holes for the rammed air set up then that would be effective, but space to run those hoses are limited.
Open air filter elements no doubt have larger surface areas hence it should allow more air to pass through but most open air filters are just that, open...in the engine compartment where it's exposed to the tremendous heat generated by the engine and headers even with a heat shield thus allowing mostly hot air to enter the supercharger (horsepower killer) especially in Florida. As Tim already said the only true cold air set ups are the ones where the filter is entirely enclosed away from the heat and the extra hoses ramming more air through the K&N is just gravy.
I think, and this is my opinion only, that the stock black power tube with the rings might flow cooler air than the after market ones although those look a lot nicer, the rings and indentations should act like cooling fins similar like the ones on an aftermarket transmission pan.

Just my thoughts,

Bert.

 

yes, it would and yes you would want to duct it. I had 4 two inch holes in my stock box ducted to the front.



here is a pic of my 15 inch Air Force One open end cone filter , that I enclosed,with a duct running out the end of it through the fender to the front of the truck...plus three more two inch hose running to the front of the truck (which you can see in the pic if ya look close)....good luck with your CAI

 

Very nice work!

 

The argument still makes no sense.

First, the metal cannot be any hotter than the surrounding air. And the metal has WAY less than perfect heat transfer to the air coming through the box. So the air cannot be heated to the same temp as the air that heated the box in the first place.

Remember, we are talking hundreds of cubic feet per minute here. You would have to heat the box up red hot to heat the incoming air as much as the hot air under the hood (once again, due to imperfect heat transfer). Ergo, while a nonconductive enclosure would be preferable, that the box is metal does not establish that it will not work.

And your acceleration argument is also flawed. The temp of the metal in the box will lag behind the temp of the engine compartment. So, let's just say that the box, while sitting at idle, gets 100% as hot as the engine comparment air. It will cool down quickly as the airflow around it cools. But assume that it would still be hotter than the engine compartment air for a few seconds (I don't believe that for a second, but I'm just making a point). Now the truck slows back down. It will take some time for the box to heat back up. During that period of time, the box is supplying air cooler than that in the engine compartment.

But at the end of the day, while interesting, none of this matters, as it has been conclusively proven that enclosed filters are better.

From a previous post here by Soap:

Was helping a friend this weekend work on his L. He has the full PSP Fast Air kit. I wanted to check out how it worked so when work was done we took a ride up to the local parts store and I did a little data logging. We drove 3 minutes to the store and parked. In the 12 minutes we idled in the parking lot the IAT rose from 82* to 146*. 11 seconds after pulling out on the main road (45mph) the IAT dropped to 82* . . . 1* warmer than the outside temp reading of 81*.

FYI . . . I logged another friend's L the same day. All he has is a open element cone filter, no ram air or fresh air kit. On the freeway cruising at 70MPH his IAT never got below 92*. The outside temp at that time was 78*.

Lots and lots of similar documented results are collected on my Web site.

Finally, as well said by Kenne Bell:

"Right there on the list [of most ridiculous products] has to be those "underhood exposed filters" that suck in 200° underhood air instead of ambient (70°-100° air from the fenderwell). 10° air temp rise is -1% HP. That's how dynos are calibrated for temperature changes. Does anyone really believe that all those OEM manufacturers designed expensive plastic inlet systems - for the last 20 years - that pull cool air from the fenderwell, hood or grill because they didn't have anything else to spend their money on?"

Case closed. Next topic.

 

And good thoughts they are, Bert (except for that whole stillborn "cooling effect" business ). Cutting holes in the box without ducting is counterproductive. From a previous post here:

"I'm recording just 2 to 10 degrees over ambient in the same temps w/ the stock airbox. . . . w/ the modified stock airbox [holes drilled in the stock airbox] I'm seeing anywhere up to 50 over ambient in traffic and low speed cruising. When on the highway or interstate I'm getting +20 over around 55 to 60 and about +10 over at 80."

 

Tim, great crusher of egos.
The stock airbox (with a K&N filter?) is 2 to 10 degrees above ambient while the PSP fast air is only 1 degree above ambient. Has anyone tested the stock airbox, K&N filter, and proper duct for cool air? This seems like it would keep the coolest tempatures. I'm just looking for true tested results, fact beats fiction every time. Since I bought my truck and it had an open filter installed, the PSP fast air kit may be best. My stock airbox awaits the test results.

 

Thanks for that post Tim, you answered a lot of my questions.

 

I also have an open-end cone filter. I have been data logging ever sense I first got the truck. I designed my own force air kit that forces ambient air to the filter when moving. However the problem that I discovered was that when at a stoplight, with the ambient temperature in Houston of 98F the filter would climb up to 150F.

Once I started moving the temperature would quickly go back down to ambient temperature. Therefore, my real problem was how to introduce colder air to the filter while stopped.

My solution, I went to Radio shack and purchased two 12-volt fans one was 3” square and the other was 6”
The 3” puts out about 40 cfm and the 6” about 90 cfm. I installed the smaller one inside the fender well centered in the current opening, and then installed the larger one on the out side larger hole. I spliced them together, and tapped on to the brake light fuse, that is the fuse box mounted on the fender wall.

Now whenever I apply the brakes, the small fan sucks air from the inside fender wall and the larger fan continues the flow right in to the filter. I’m still conducting testes as to its effectiveness.

I had a cone filter that was capped at the top; so the blowing air would have to go around to the sides to be effective. I went ahead and purchased a new filter with the open cone on the narrow end. This way the air would be introduced in to that opening.

 

The problem with a stock airbox vs. aftermarket argument is that it's not universal. The Ford factory box does look very efficient. My application is not the same scenerio, so an aftermarket was the way to go. Volant finally made a kit for my truck that looks factory but uses a bigger enclosed plastic box, cone filter, and very straight/smooth flowpath. I figured this had to be the best option finally. I heard the Volant is not so great on the Ford though?

Tim is correct on the heat transfer issue. You are not pulling heat across an intake housing, so there is not the heat transfer like as radiator. The hotter air molecules residing on the surface of an intake box will be very minimal compared to a mass of hot air from an open filter. Plus I would like to know how much cool air is making it's way across an open filter even when moving on with the location of most filters. The headlight blocks most of the mass air unlike the radiator location.

 

OH OK, Tim. You win.

But, the huge difference in price doesn't warrant the insignificant difference in the air intake temp.

 

I'm not a areospace engineer but, I would think the type of hood you are running has a lot to do with an open/filter too! Whether it be a ram-air hood , shaker-hood , or vented cowl-hood . Just my 02 .

 

Excellent post! Oldfrmtrk, I have the Air Force One open air 15” filter. I have been looking at installing a small 12 volt fan. Great idea with using the brake light fuse. Installing a small fan in the fender would bring in the cooler outside air. This set up along with an open air filter, would give you much more air then the enclosed filter with the tube and scoop method. More air more power.

Here is some more info on this never ending debate.

https://www.f150online.com/forums/sh...hreadid=113663

https://www.f150online.com/forums/sh...threadid=85409