Diversion Panels

It's hot outside. And your high-performance ride is tuned on the ragged edge of reliability, for maximum power. You're nearly broke from having added the best aftermarket radiator, intercooler, oil cooler, and other high-dollar goods to keep it alive, but it's not enough--you're left searching for any last-minute trick mod to lower its temps by those ever-so-important few degrees. The economic melt-down's heat is doubly bearing down upon you, and as much as you need to avoid catastrophic engine (read: bank account) failure, you'd rather not throw your hard-earned dollars away on some useless gimmick. You're desperate for a solution, but if there's any doubt whether or not a product will actually help, you'd rather not even mess with it.

But sometimes it's hard to tell if a product is actually making a difference. Radiator diversion panels, or "cooling plates", have been on our market for a while now, claiming to increase radiator efficiency by diverting incoming air through a car's radiator, rather than allowing it to pool-up in front of the radiator and escape over its radiator support. The question of legitimacy occurs because diversion panels claim to bring benefits that are important, yet often too small to be displayed by most cars' inaccurate OE temperature gauges--and because they look so damn cool, people often add them for that reason alone.

To put the diminutive diversion panel to the test, we acquired a test car with one of the most turbulent radiator support designs out there--the Nissan S14 240SX--and two differently styled diversion panels, from G-Dimension in City of Industry, CA: a large carbon fiber one (similar to one once made by Renova Auto) that spans the entire open area between the car's bumper and rad support; and a smaller aluminum version that covers a portion of open area between the car's headlights. Monitoring radiator outlet temps via an Auto Meter digital temperature gauge, we put our S14 through three tests with each variation, allowing the car to thoroughly cool between each test. Here's what we found:

The verdict: Fact
At idle, neither diversion panel offered any measurable benefit, as the car's belt-driven fan and large-surfaced radiator were more than adept at warding off heat generated by such low demand on the engine. During our Second gear test, however, the benefits of the large carbon diversion panel began to show, but not so much for its smaller aluminum rival. At freeway speeds in Third gear, the results were more clear: the high velocity of incoming air out-paced what the fan could displace, and without a diversion panel, air began to flow around the radiator rather than through it. Our large carbon fiber diversion panel was able to reduce this overflow significantly more than the smaller, aluminum one, but both increased radiator efficiency as opposed to not using one, just like they claimed.