Others have experienced that the 2771 seems to stay locked in longer , if I'm remembering reading this thread correctly .
Should you get a heavy duty fan clutch?
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I don't remember any such thing but I could have missed it, it's a long thread. I went with the 2791 because when it engages it turns faster so it cools better.
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It's also winter in eastern NC so maybe it's not squealing because it's just not engaged. I'll try to remember to report back in July when it's actually hot out again.
Locked longer might not be the best way to word it . It could be that the 2771 turns the fan 25 to 35% of shaft speed disengaged while the 2791 turns the fan 20 to 30% of the shaft speed disengaged . I would think that would help keep air moving while putting around thus pulling more air over the ac condenser and radiator and moving more air over the engine bay .
I had the 2791 and replaced it with the brushless Camaro electric fan for better idle performance with the AC on during hot desert summer days.
It’s nice not sounding like a commercial truck when I’m accelerating and revving higher with the turbo, but that’s a bit of a cherry on top.
It’s nice not sounding like a commercial truck when I’m accelerating and revving higher with the turbo, but that’s a bit of a cherry on top.
I dunno about the 2791, but the 2771 pulls a hell of a lot more air for my driving style - it stays locked until about 3200. As I seldom rev higher than that, it stays locked practically all the time. I really noticed a difference in how fast (slow) the temp rises once the t-stat opens. YMMV and all that...
Except while you're putting around in hot weather it would more likely be engaged, in which case the 2791 is moving more air. I don't need the fan turning faster when I'm driving 70 mph on the interested (disengaged) but I DO want it turning faster when I'm off-road or in stop and go traffic (engaged).
I'm ok with it pulling more air when disengaged. There probably isn't much real world difference between the two .
Has anyone seen a major difference in airflow when testing the 2771 vs 2791 ?
Has anyone seen a major difference in airflow when testing the 2771 vs 2791 ?
Zorba seems to be having good results with the 2771 moving air under the hood . I am going to give it a try and see if I like it , if not I may try the 2791 . Not doing anything with the fan clutch until Spring . I'm not having a problem with overheating , but I welcome the increased airflow time under the hood .
When is the last time his changed 100’ of elevation though? Just to add context.
Why do you think driving style and RPM matter? A thermal fan clutch locks when the engine reaches a certain temp and when locked the 2791 moves more air. The 2771 moves less air when the engine is hot and more air when the engine is cool, if that's what you want then fine.
Since that's the part number than every parts catalog says goes on a TJ then I'm sure there's millions of people that have used them with "good results". I figured while I was replacing the game clutch anyway I'd go for the best possible option and not just good enough. That's the whole point of this thread, pointing out that there's a better option.
It's only a better option if you need what it provides. If you don't then there is no discernible benefit and it's overkill.
As far as I'm aware, the 2771 is a step up from stock duty. Given mine lasted 115k, I suspect the 2771 will do just fine.
The one I took off (I assume factory but it could have already been replaced) looked almost identical to the 2791, I wish I had taken photos before trashing it. Others on this that have had similar observations leading them to the conclusion that stock was an extreme duty part. Either way, the 2791 will cool better while crawling, either over rocks or through stop and go traffic.
As mine would appear to run at the correct operating temperature with the 2771 installed, regardless of driving conditions and OAT, I fail to see how additional cooling would be a benefit in my case.
If you feel you benefit from using 2791, great. If you feel you've installed a better part than the rest of us with the 2771, great. You clearly feel very strongly about fan clutches. Between this exchange and the fact that this thread now has 13 pages and has been going on for 4+ years, I might suggest we're...
Maybe not, but no one is suggesting you should replace your working fan clutch with a 2791. The point OP was making was that if one is replacing the fan clutch anyway there's a superior part vs the 2771 available for essentially the same price so why not use it?
Does anybody have any actual proof/data for these claims or is this like using a butt dyno with your new CAI for HP increase readings? 
p.s. Don't get me started on the gas savings and HP increase with my Tornado.
p.s. Don't get me started on the gas savings and HP increase with my Tornado.