Debunking tuning myths
As the summer heat continues to build, very few tuners are feeling it worse than those in the SoCal area, where triple-digit temperatures all but mandate a re-evaluation of what last few tricks can be pulled to keep engine and coolant temps down. Ironically, the subject of this month's investigation is a controversial trend that many argue began in SoCal, for the sole purpose of doing just that: the "JDM hood prop".
Proponents of the prop will argue that it allows built-up, hot air in a car's engine bay to escape easily, allowing more air to be drawn in through the radiator. Opponents say that at freeway speeds, propping the hood acts as a cowl, actually pulling air in through the opening rather than letting it out. To put the prop to the test, we secured Auto Meter temperature probes to monitor intake air and under-hood temperatures before and after performing the modification to our project Miata (step-by-step install on importtuner.com), and put it through some road-testing paces. Here's what we found:
The Verdict:
Propping the hood did lower temperatures. By Earth-shattering amounts? No. But temps did drop an average of 13.5 degrees Fahrenheit all around, especially during stop-and-go traffic and highway driving. Also important to note is the placement of the Miata's intake: right near the header, and toward the back of the engine bay-the changes in intake air temperature we found in this instance were almost guaranteed to be an improvement. And keep in mind that these benefits were found by propping the hood of our naturally aspirated 1.6L Miata-we can only imaging how doing so (or adding a properly engineered, vented hood, for that matter) would benefit a more powerful turbocharged car, or an engine that runs hotter altogether, like a turbo rotary.