Intakes without boxes vs. Intakes with boxes
Intake Temperature
The intake temperature is one of the most important factors in making power.
Hot Intake Air Temperature
Hot temps have a snowball effect on turbocharged vehicles.
- When the temp increases the air becomes less dense so the car will make less power by default.
- Hot temps heat soak the intercooler and make it less efficient.
- Hot temps cause the car to become more knock prone.
- Hot temps cause the car to reduce ignition timing via the Intake Air Temp Igntion Timing Compensation Table. This is the main reason the cars feel slow and sluggish when it's hot outside. This table is also one of the main reasons most people run less than optimal 1/4 mile times. Heat soaking in the staging lanes causes the IAT to increase and the car is missing 4-8 degrees of timing the whole 1/4 mile.
- Without a box around the intake, the MAF sensor is prone to being disturbed by the airflow from the radiator fans. This will cause fueling inconsistencies when the radiator fans kick on and off, which will in turn cause idle fluctuations. These inconsistencies are from the airflow variances caused by the fans along with the fueling corrections that are incorrect due to not having a box. The tip in and tip out fueling corrections are based on speed density which takes into account the air density and air temperature, so when the intake temps are drastically different than the ambient temp, these corrections are thrown off which will increase the corrections and rpm fluctuations.
- If the disturbance from the radiator fans makes the car run lean it can also make the car misfire, especially during cold starts when the 02 sensor and fueling corrections aren't active yet.
Customer made his own box. Intake temps down 27 degrees
How To Build An Intake Box
Supplies Needed
- One - 3.25 in. x 10 in. x 3 ft. Half Section Rectangular Stack Duct (Aluminum, Lowes item # 100608, $7.99 or Home Depot #RD3.25X10X36) $7.81)
- One - pack of screw w/nuts 10 x 24 x3/8 (Lowes item # 62058, $1.50)
- Approx 2ft of automotive rubber edge trim
- Aviation metal snips
- Black duck tape or similar.
Assembly Instructions
- I cut this thin metal sheet into 3 sections, one at a time as I went along. Be careful it is SUPER SHARP (that's why I ran duck tape along all the edges) and it bends into shape very easily. I used the small screws and nuts to keep the 3 pieces together by drilling a few holes.
- The reason for the rubber on the bottom is to keep it from scratching through the paint, stop vibration and there are 2 cables underneath that will be safe from the sharp edges.
- This will not be a museum piece but, it works great. Takes about one hour from start to finish and looks decent from the engine bay for something that costs less than $15 to make. The hood closes with no problem, it doesn't vibrate/rattle or make any noise. It all depends on how you cut it, fit it and placement of the rubber trim.
Thanks to Bart K. for the pics and write up.