ol"blue

The point we're trying to make is the difference in airflow "through the rad". with & w/o the shroud. I think you would accomplish this more accurately if you were to put the telltails on the engine-side of the rad. core, and on the bottom trailing edge of the rad. on both Jeeps. While putting the telltails anywhere in the airstream behind the fan might not be altered by the presence of a shroud, it doesn't settle the discussion on whether or not the air was in fact flowing through the rad. faster or just being drawn to the fan by the path of least ressistance. That path, as we both know, would not be through the rad. and AC condensor, but from underneath, avoiding the rad..
My point might make more sense to me, but since you're the engineer, and this is your experiment, proceed my friend.

Mike1998XJ

Now that's what I'm talking about! Socrates and Plato coming up with a good experiment! You are absolutely right... I will screw an old antenna mast into a block of wood so I can position it in various places in front of the Jeep. We will see what effect the draw of the fan has on pulling the string towards the radiator. That way I can do the experiment with the hood closed simulating actual operating conditions! Even better yet!
I am the Engineer but you are the Man'

ol"blue

That's more like it. To keep it legit, leave the AC off, and/or unplug the aux. elec. fan so that it doesn't adversely affect the test results.

Rmart30

good luck on finding one at pullapart... i looked for about 4 months and finally bought one off Ebay new for $24 shipped a cpl of weeks ago.
Local dealer wanted like $40 for it.

Mike1998XJ

Ol Blu'
Here's our setup. I may need to reposition the strings or trim them or use yarn instead but this is the apparatus we will use. I will do as you said... Apples to apples...
It's funny but I'm looking at the other cars I have sitting around and their shrouds look more functional that the one on the Jeep. Just as a hypothesis... I'm almost wondering if the Cherokee shrouds were more for protection than flow... Legal issues and all. I will do the experiment tomorrow and talk to the Engineers at Chrysler next week, they love it when I have technical questions on the Cherokees. We all know it was one of the best trucks Chrysler ever built. Especially the 4.0l.
The biggest problem these days is the bankruptcy and actually finding an old timer that is left that knows about the Cherokees. And if the results show better air draw I will go to the Dealer tomorrow and order a fan Shroud!

ol"blue

I've seen vehicle's where the shroud was basicly a shield for the top of the fan. I've never owned an XJ, but both my ZJ and WJ have fan shrouds that covers the full circumference of the fan. Also on both, the fan is set into the shroud so that the trailing edge of the fan is about 1" inside the shroud.

littleblueman

I ordered mine last weekend from partstrain. The PO did away with it and ive ran without it for a year, but its time to slide one back on to insure cooling for the hot sticky summer.

http://www2.partstrain.com/store/ind...ND(universal:0)

Schmoozer

Venturi, the word is venturi.

Get me a job, please, I'm an employed MI engineer.

Please. PLEASE!

Mike1998XJ

Sorry to rain on your parade Schmoozer but Venturi is not the correct term. Our Cherokee Fan Blades work the same way propellors do utilizing Bernoulli's Equation. They do that by generating thrust not a venturi.

a1racer

Do all the teat you want. but know this it is there for a reason. and people smarter then any of us have a reason for it being there. So if that is the case thinking that you are smarter then them by doing a test with a string is pointless. If you disagree that is fine but when you over heat don't come back asking why on the tech section

Mike1998XJ

Sorry you feel that way a1racer. You should stick with hacking holes in your hood and center console. Maybe a little duct tape on that CB mount of yours would make it look better...

ol"blue

Okay, let's all have another cup of coffee and enjoy this day the Lord has given us! Lots of poor unfortunate folks didn't wake up this morning!

Schmoozer

Right, but its the same general shape of a venturi tube, but yeah I still had a but too much last night . . .

Mike1998XJ

Yep I hear you...

a1racer

i was not taking personal shots at you man just telling you that there is a reason for it being there and that your test while it might show i tiny bit of movement is not accurate. but i guess that the manufactures of the jeep must of wasted there time on building the piece to just put it on. i am sorry for busting your ego to the point you had to attack my simple project in defense. that was not my intention