...I hope I'm not beating a dead horse here. I'd also like to thank all those who have helped me here over the last few weeks.

I have a 99' F-150 with the 4.2L V6. I have removed the airbox silencer and cut away the fender side of the airbox down even with the two posts that hold it in place. I noticed a surprizing increase in throttle response.

I have a few questions about the different types of setups:

- Does air actually flow in through the fender wall, or is it just used as a place to "suck" in air with the stock setup?

- If air does flow in, about how much air actually flows in through the hole without the airbox silencer in place?

- Doesn't it make since that only "so much" of the airbox (without silencer) needs to be removed to increase performance? It seems that too much, would really be an unnecessary waste.

- Imagine your stock intake, without the fender side airbox half, and silencer. Is the air in this area, that would be taken in, really warm? Plentiful? Is their any airflow in this area?

I've considered several options on modifying the airbox...here are my thoughts:

- Pulling the silencer: This would allow "inside" air to be taken in, as well as whatever blows in through the fender well. However, it seems that if you've done this, you may as well sut some more back as well. Just how much, and where from, is the question.

- Cutting sections out of the box: This would allow you to half way control the amount of "hot" air being taken in from the engine. If you cut a hole in the upper section, toward the front, it seems as though only cooler, moving air would enter the airbox. In this case, would you want to keep the air silencer in place? How about the rest of the airbox? Wouldn't their be any benefits to using the combo? Where ever the airbox is cut, you have to keep in mind the distance between the box, and the hood, and airflow in that area.

- Removing the silencer and airbox: (fender side)[/i] It seems as though this would offer the most flow, but who knows where most of the air is actually coming from, and how warm it is. IMO, the "best" way to do it, is to cut the box even with the two posts that secure it in place...this way it half way "blocks" the warmer air coming directly off the engine. (Kind of like a 2" sleeve around the filter.) Would it make more since to cut the box so that the entire bottom side (toward the engine) is blocking the warmer air? Seems that there would be cool air blowing up through the engine compartment from the ground though.

4.6L & 5.4L throttle body silencer removal: Is the larger, "outer-box" sufficient for taking over the air flow that the "silencer" was responsible for? It seems as though their could be some "circulating air" (swirling) in the oversized box. Wouldn't this actually disrupt air flow? Cause a vaccume?

Well, what are your opinions?

-AR

 

So, right now, you are basically running an open element in the engine compartment similar to the setups available from K&N and Airaid. Correct?

If this is the case, then you are pulling the warm air from the engine compartment as opposed to the the cooler air from the fender. I think the air is sucked through the filter regardless of the setup. No ram air affect with the air coming through the fender, unless you make your own system.

Personally, I think the best setup is one that still draws air through the fender, but through a larger opening than stock. This increases airflow, while still pulling the cooler air. Do a search on air box mods to see what others have done.

I don't know how the V6 intake is setup, but with my truck has a removable piece that fits between the fender and the airbox. It can be replaced with a larger diameter hose that significantly increases the area of the opening. Definitely remove the silencer if you have one inside the fender. The 5.4L doesn't have anything there.

Hope this helps.

------------------
2000 F150 XLT 4X4 Off Road 5.4L Reg. Cab
K&N, WMS Velocity Tube, and Gibson Sweptside...

(For now)

 

Just a clarification:
The "silencer" is a small tube inside the elbow that goes from the MAF to the throttle-body. The tube that goes from the fender to the airbox is just part of the airbox.

It would be really interesting to see the difference in temps between the fenderwell and under the hood at 60mph.

Seems to be the only way to actually settle the debate.

 

That's right F150Sven. The 5.4's don't have the AB silencer? Is it still connected to the fender well? If so...how? It seems that "fender drawn" air would be better, but it's still quite a bit more restrictive. I'd think that the FIPK "home-job" would be better for performance, regardless of the warmer air, but that's what I'm here to discuss. It just seems as though the gap between the fender wall where the air is drawn from, is still too narrow unless the air actually has some force behind it.

-AR

 

Nomo.
Just how would a person pull the silencer out of the air hose (tube) whatever they call it. and would it make a difference? Thanks

 

I installed the Airraid intake system yesterday and even though it looks good, I'm a bit concerned about it taking in only HOT air from the engine compartment. I talked to the guy who sold it to me and he said that the air sensor will adjust for the warmer air and that it has no negative impact to the motor. Do you guys know if this is true?

The Airraid only leaves about 1/2" gap from the end of the filter to the hole in the fender. Doesn't seem like that's much room for large amounts of air to blow in. Even if some does, it has to make it around the filter into the intake. I wonder also if, when driving, cool air gets rammed into the engine compartment.

Thanks

------------------
2000 5.4 Expedition -Eddie Bauer 4x4. Wedgewood Blue.

Mods include:
-SuperChip
-Airraid intake
-Gibson Sweptside 3" Catback

 

As long as the inlet is as larger of larger than the openings in the throttle body and the MAF, then there should not be any restriction.

The piece I am referring to is about 7 inches long with a inlet diameter of about 2 1/2" and an oulet into the airbox of about 3 1/2". It snaps onto the airbox with two tabs, probably the same way your silencer fits on. Here is a quick picture of it:
http://homestead.deja.com/user.svensett/air_inlet.html


Nomo, you are correct about the silencer being incorporated into the stock pipe going from the airbox to the TB on the V8s, but I think there is a different silencer included with the V6s.

There is a formula that gives amount of HP lost per degree of temperature increase, but I'm not sure what it is. Every degree counts. Look at how many guys will ice the intake at the strip to get a little bit cooler air charge. The more you can isolate your air inlet from the engine compartment, the better. Remember, you're not always running 60mph

 

I haven't confirmed by checking my Y2K F150, but supposedly, Ford removed the silencer in '99. In the '97 & '98 V8s, you could remove the ducting from the TB and the MAF then reach up inside it. Doing this revealed the silencer tube which narrows as it bends around towards the throttle-body. On the Expedition, I had to do some cutting with a Dremel tool to exctract the silencer. Others say they were able to just pop it loose and pull it out.

There was no neck-snapping performace gains, but a noticeable improvement in throttle response when passing (for example).

Overall, I don't know that I'd do it again. Just getting rid of the airbox made the biggest difference.

------------------
1997 4x4 Expedition- 4.6L, true dual exhaust w/glass-packs, K&N air filter, SuperChip, airbox mods, Edelbrock shocks, 285/75R16 BFG ATs, 2000 "XLT" wheels, 4.10 gears, Auburn LS, Clarion In-dash CD player, Smitty Bilt push bars and nerf bars.

2000 4x2 F150 XLT Reg. Cab LWB- 5.4L, Tow Pkg, 3.55LS, CD player,Remote Keyless Entry, Sliding back glass, Special Appearance Pkg., tinted windows, Line-X bedliner, K&N air filter, SuperChip, airbox mods, 285/60R16 Goodyear Eagle GT IIs and Prime #155 wheels.

http://members.visualcities.com/NoMo

 

Nomo,
I a 99 Ford F-150 and I removed the piece of rubber hose from the air box to the fender and it made some improvements like better sound and more get up and go... But I am going to take of the Air hose to the TB and look inside it and if there is anything in there I'm riping it out Wish me luck

 

Headless-

You'll probably have to "feel" around. I honestly couldn't see or tell where the silencer started on the Expedition. Finally, I stuck my arm up inside the tube and found a "hole" in the wall of the pipe. Stuck my finger in it to find the thickness of the silencer (V8 version) and cut accordingly. The point being that I couldn't SEE anything... had to feel for it.

Again, the newer trucks have been rumored to not have this. If you find something, let us know.

 

Nomo,

Mine has a side compartment off of the main runner that's molded into the whole assembly. I can feel the opeening from one end with my finger, but not the other end. I'm guessing this is where the silencer is now. The WMS tube took care of that, though

Sven

------------------
2000 F150 XLT 4X4 Off Road 5.4L Reg. Cab
K&N, WMS Velocity Tube, and Gibson Sweptside...

(For now)

 

That's exactly the way the '97 Expedition "was". I guess the silencer IS still being used on the new trucks. I just don't know if I want to wrestle with it again????

 

I pulled the hose from the fender wall last night. My quetion is, however, does sucking in hot air bad for the engine? How much hotter is the air under the hood compared to the air on the outside? All I know is that its been 100+ degrees around here lately and I want the best fo my engine.

------------------
2000 White sport
4.2l V6 5spd
K&N filter
e-mail: XLR8@f50guy.com
Superchip
Single in dual out 40 series Flomaster

As soon as i can afford it: Airaid FIPK

 

I definitely suggest removing the restrictor from the fenderwell. Replace this piece with a flexible dryer duct.

You do NOT want to take in underhood air. I did, in fact, modify the filter side (fender side) of the box, but I reshaped it to allow a better flow path around the K&N. The K&N has no cone to direct the air flow around it.

Rather than cutting out the silencer, I suggest removing the flexible duct between the throttle body and filter housing altogether. Use a 4" "Street Elbow" and a reducer to adapt it to the throttlebody (3"). This setup will flow plenty of air to feed my blower, and it worked well in normally aspirated trim. The best part is I am still pulling in outside air.

There is no ram-air effect through the fender; the only benefit here is cooler, denser air. Yes, the IAT (air temp sensor) will compensate for warmer air, but you will see a much more efficient mixture when using cooler air.

You can see the finished product at the following link, and the entire thing cost less than $40.00. This setup will fit the first time you bolt it up!


Magnacharger! https://www.f150online.com/f150board...ML/002050.html

Link to my e-mail if you have any other questions.

[This message has been edited by crash1 (edited 08-17-2000).]

 

Crash, when you find the time, could you please be a little more specific on the dryer hose and 4" elbow applications? This sounds like what I want to do, and I'll need as much info. as possible. Thanks man.

-AR