[HWYSTR455]

Yes, the fan shrouds do need a relief to allow air to pass when on the highway, but another thing I've seen is where the fans and shroud are too close to the core, and the shroud is completely flat. When it's like that, the fans only draw across the core the diameter of the fans. It's like bolting them right to the core and blocking the rest of the rad.

I've also seen some that have louvers on the sheet metal shrouds, completely open. All that does is draw air from the engine compartment, and not across the core.

Those crappy wiz-bang sheet metal rad/fan/shroud combos you get cheap on eGay are notorious for that.

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