The miata has been in need of a cold-air intake since the day I turboed it. The intake breaths hot air directly from the radiator. I want to do one of those sectioned off intakes behind the driver headlight. Creating a box will help keep the hot engine bay heat away, and the box can be fed with air from around the headlight which should be cold than the air behind the radiator. Eventually I might even try making a replacement blinker that allows for even more air to enter from outside.
Before going all out on fabricating something, I wanted to prove it out with some cardboard testing. I create a piece that sections of the header light and used a 90deg elbow to relocate the intake inside the box.
I then took the car for a drive and measured the intake temperatures in three different configurations.
- Intake directly off turbo (original)
- Intake behind headlight (no cardboard)
- Intake behind headlight w/ cardboard
I made sure to take my measurement at roughly the same speed and load. The car was driving at 60mph on a flat section of highway. The measurements were all ~10-15mins apart from each; long enough for me to get off the highway and change configurations. Here are the results.
| Test Case | Pre-Intercooler Temp (F) | Post-Intercooler Temp (F) |
|---|---|---|
| Intake directly off turbo | 132.0 | 83.0 |
| Intake behind headlight | 124.0 | 83.0 |
| Intake behind headlight w/ cardboard | 114.0 | 82.0 |
The results are interesting. I was honestly expecting to see a bigger improvement in intake temps. Overall, it looks like a drop of ~18deg from the original intake to the cardboard intake. I’m thinking the results could be better if the box was properly sealed against the hood (I cut the box out in less than an hour). Overall, I think this proves the concept is worth doing, especially if I eventually bring in more cold air from the blinker.
-Dan
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