Airbox Mod explained

hopefully this will come in handy for some of you.

 

Can you show me a good air box mod for a 99 F-150 with a 5.4L

Thanks,

 

Interesting stuff... do you have any diagrams of stock airbox and modified air box at the same throttle setting? The pics you have are mixing apples and oranges, and I'd like to see the effects of the air box mod at the same part throttle as the stocker.

Thanks

 

it's not mixing apples and oranges if you understand the assumptions.

when the engine is @ WOT, the 2 diagrams are similar to stock airbox vs. chopped air box.

 

when I get my truck, i'll get a pressure transducer and video tape what happens before and after the mod.

 

I updated it with a few more examples, re-worded some of the text, and a conclusion.

 

Corpsie,

Thanks for the info, very interesting. I have to agree with BeastRider about the "apples and oranges" thing. Maybe I'm missing something or don't understand the assumptions but wouldn't it be better to show the graphs of modified and stock airbox at WOT and part throttle. Please explain. TIA

 

I have a much easier air box mod explaination. Take a look at my gallery and do what I did to your truck, then start it up, point it in a safe direction, and FLOOR IT! That's all the explaination that I need. :-)

cajun

 

I'm a little confused. Looking at your diagrams, as I recall, specific volume is the reciprocal of density. At BDC, both diagrams indicate the same specific volume, the air would, therefore, have to have the same density in both cases.

The pressure in "a" certainly is higher than the pressure in "b."

From the ideal gas law we also know that density=pressure/(specific gas constant x absolute temperature). If density a = density b and pressure a >pressure b, then temperature a > temperature b.

So I must be missing something, because to me, "a" is just hotter than "b."

Don't get me wrong I generally agree with logic in the text, I just think the exhibits don't acturately demonstrate the text.

I think of it when the engine is off - atmospheric pressure at the entrance to the airbox and at the throttle body.

When the engine is on - atmospheric pressure at the airbox entrance and less than atmospheric pressure at the throttle body for 2 reasons. static pressure energy is converted to kinetic energy and energy losses in the air box system. the 2 causes for the losses are friction beween the air and the pipe walls and losses caused be changes in flow direction and changes in flow area. By modifing the airbox you eliminate a portion of both of these energy losses. therefore less static energy is used and the pressure is higher at the throttle body. there is more available pressure to push more air into the cylinder.