A larger fan doesn't necessarily mean more air flow, it just usually does.
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What you want to look at is the CFM rating of the fan, that is how much air it pushes. If you get a fan out of a truck it probably won't push as much air as a slightly smaller fan out of a FF car, just because the car has to do much more work to cool the engine.
Saying that, you can probably get an electric fan out of a Geo Metro/Suzuki Swift and have it work fine. Heck, some of the time they even had the same engine.
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