Thanks for the links..

Have a question though.

When dyno testing, the environment is closed and usually a fan is running. Don't all these mods to the airbox yield barely noticeable differences especially when the external conditions to the car are the same every single time? The only thing that's changing is some of the airflow to the MAF and intake.

 

The big difference usually found in dyno testing is having the hood open. This improves the airflow to the air filter on open filter setups. It would have very minimal effect with the stock setup.

The reason for increasing the air PRESSURE to the filter area is that ANY loss in pressure decreases power. On the stock setup the pressure loss begins at the feed over the intake and continues with every turn and bend to the filter, the filter itself, the MAF, the feed from the MAF to the throttle body, the TB itself, the intake passages, the intake valve and seat area. The pressure that actually gets into the engine is substancially less than the outside air pressure. At sea level this pressure starts at 14.7psi. If your engine, after all the restrictions, gets say 12psi into the cylinders and makes 250hp... you are making 20.83hp per psi of available pressure (250 / 12 = 20.83). So, if you can increase the pressure to 13psi you should pick up another 20hp.

 

Thanks for that input, but that's not what I meant..

ok how about..

How do the HP/TQ numbers change when making modifications to the airbox in a controlled (usually closed) dyno garage?

 

What are you asking? Why the power goes up with mods? As I said above, the mods allow more pressure into the engine, more pressure results in more MASS (as in molecular weight) of air (Nitrogen, oxygen, etc) this extra air mass can catalyze (allow to burn) more fuel = more energy released = more cylinder pressure = more power.

This is all because of the mod NOT the ambient conditions. If the air temp, the barometric pressure and or the humidity changes... the relative power will change with the modded engine still making its relative higher power number.

 

Hey Jbrady do you leave the cardboard shield in there all the time? If so how secure is it.

I just did my air box mod and notice some nice results from stop and high revs. Hung pretty close with a SLK AMG at high speeds so Im happy. Gas mileage has improved a bit, I think I am getting around 22-25 mpg on the highway, I cant tell by stop and go driving because I only drive 4 miles each way everyday so it is hard to tell.

 

I am glad you made the mod! Cheap, easy and EFFECTIVE. Sounds great also.

Yes, I leave the cardboard in all the time. The picture shows the first shield I made. It fits snugly between the filter housing, the ABS block and the radiator with the "flaps" cut to help seal around the stock air feed box. Since the picture was taken I made an additional cardboard heatshield that fits around the back of the air filter box and creates a complete seal between the hot engine air and the filter inlet. That piece is held VERY tightly by the air filter housing itself. I intend to replace the cardboard with something more durable but it has been working perfectly for a couple of months now with no heat or moisture problems at all.

When I get a chance I will post more pics.

 

I had tried a metal sheet from home depot earlier, but after a driving it for a while the metal sheet got hot, so I think the metal sheet did not help at all. I think it was heating up the cool air that was being drawn in. I guess I will find a shoe box to tear apart. hehe

 

My concern about metal would be rattle control. I am not worried about the heat of the metal as it would be easy to insulate and the main objective is keeping hot air from the engine from flowing into the filter. I would prefer to use PVC type plastic or the OEM type the stock box is made from but that is not easy to form.

The cardboard piece you see in the photos is the back of a legal pad. The second part I made from good old corregated box cardboard. Durable, function, cheap and UGLY!

 

I never had insulation on my metal shield. I didnt think it worked real well because any cold air that would have entered would instantly be heated up by the warm sheet of metal.

 

Underhood heat can be nearly 200 degrees. Anything over 110 feels VERY warm/hot to the touch (think about hot tub water temp) the HOT metal you touched was probably less than 120 degrees, more like 110. The sheet metal itself does not have much mass and it doesn't radiate very fast relative to the air mass flowing into the filter. If the ambient air was 80 degrees and the metal box was 120 degrees I would doubt it would add even 5 degrees to the inflowing air. The resulting 85 degree intake air is a HUGE improvement over the 175-200 degree underhood heat. Bottom line, ALWAYS use a cold air box that has EXCELLENT access to ambient air flow without restriction.

 

Hey all -

Did a couple more short 0-60 runs. Times have went DOWN with open airbox mod!!

I even ran one yesterday in the middle of the afternoon (high 70's temp) and did roughly 8.6 / 8.7

 

All right that's a nearly a half a second quicker, correct?

Do you have any heat shielding?

 

is this the mod that you get the quicker times with Lee?

 

No,,,, well..kinda

It's the mod, but done the correct way. That picture you see is me putting the filter on backwards (duh) I turned it around so the lipped edge of the filter is in the way it should be - just like if the cover was on.

Jbrady - Well, I wouldn't say the airbox mod is giving me a whole 1/2 second off 0-60 times, maybe 1/4 sec. The numbers are a little lower than with stock box, and alot less than with K&N (booooo!).

 

A quarter second is still a great improvement on a 4000lb car