okay, I'm joining the party a little late here...
I skimmed through this thread and didn't see any mention of the Taurus fan (from a 90s 3.8 v-6 Taurus). These things are sweet! Two speeds, massive airflow, and very thin.
I have one on my 88 Trooper with an adjustable thermostatic switch (the kind with the little probe that goes into the upper rad. hose).
Initially, I had it wired up so that high speed was constantly hot. I now have it on low speed only, constantly hot, and it's working fine at keeping the engine cool, even in 100*+ Sacramento.
Ideally, I'd like to have both speeds available, depending on temperature, but I just haven't gotten around to figuring out the wiring of it.
As far as increased HP goes, well, I'm obviously not going to take my 88 Trooper to a dyno. But, the Taurus fan and a new exhaust system are the only performance upgrades I have and I pass plenty of 1G Troopers whenever I drive up into the Sierras. It used to be a struggle to keep it at 50-55 on some hills; now I can pretty much maintain 60-65.
here's a great thread on it.
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