Jeep Wrangler aerodynamics - yea I know - Fuel Economy, Hypermiling, EcoModding News and Forum

DonR · 03-18-2009, 02:30 PM

Yea I know.

I have a Jeep Wrangler that does get driven off road somewhat. Most of the driving is on road. To aid with slow speed cooling I was thinking about adding a set of hood louvers to allow hot air to exit the engine bay. I have a the option of putting louvers on the side of the hood also.

I know there is an eddy that sits in front of the windshield.

I was wondering how will "injecting" air into this eddy affect dthe flow around the windshield/roof area. Do you think it will increase or decrease drag?

Thanks
Don

gascort · 03-18-2009, 07:58 PM

You probably have such high pressure there that air would go down into the hood vents - like the interior air vents - you can get a breeze from them without the fan on at highway speeds.

wagonman76 · 03-19-2009, 01:03 PM

A Wrangler would be a great vehicle for aero improvements, I think. Having a detachable top would give you the liberty to make a perfect kammbacked top that you could use whenever.

aerohead · 03-20-2009, 03:03 PM

If you've actually got an over-heating problem,I'd do some back-tracking first.You need the fan shroud if you don't have that,and a good thermo-actuating coupler for the fan if it's given up the ghost,along with a properly operating thermostat and bug-free radiator.-------------------------------------------------------------- If after all the bits and pieces are restored,and she's still overheating,she may have oil lining the cooling galleries of the block and head.If the coolant was ever left in the engine too long,the ethylene glycol could have bio-degraded back into the petroleum from which it is derived.Heat can't penetrate an oil film and it acts the same as 10-inches of solid cast iron that the water see's before it can transfer.You might need to do a chemical flush/rinse/fill.

44Dan · 09-03-2010, 11:24 AM

I went to Home Depo and bought a couple of chrome vent covers, matched them up side by side on the hood and cut some holes. The covers look sharp and it gives the air coming off of the fan some place else to go besides down. I didn't have overheating problems but doing slow steep crawls in extreme temps while running the A/C (I'm old ya know) made the engine run better, I'm guessing because it was running cooler. You can put your hand over the vents and feel the blast of superheated air, but you can't hold your hand there long

This worked great for me and several other friends that did their Jeeps after I did mine.

Good Luck

winkosmosis · 09-04-2010, 05:36 PM

You don't want to push air in from the high pressure spot in front of the windshield because it will probably just fight the radiator fan.

I saw a writeup on proper Wrangler hood vent placement with tuft testing but I can't find it now. The guy concluded that the best spots were along the left and right edges of the hood.

winkosmosis · 09-04-2010, 05:39 PM

BTW, check out what I did with my XJ... I put a 10" fan in front of the radiator to help out the OEM electric fan behind it. It does help somewhat.

comptiger5000 · 09-04-2010, 06:15 PM

For offroad slow-speed use, it doesn't really matter where the vents are. However, for highway use, a bit farther forward is better, as you don't get the high pressure pushing into them. Take a look at the hood vent placement on the Grand Cherokee 5.9 for ideas.

44Dan · 09-04-2010, 11:21 PM

You don't want to push air in from the high pressure spot in front of the windshield because it will probably just fight the radiator fan

The air can only flow one direction and that is out. It actually takes pressure off of the fan if any giving the air continual flow, even when stopped. I mounted my $2.29 chrome vents where I had the most open area and they worked very well as did the others. Our rolling bricks can use all the help they can get to run cooler and more effecient

Nice 10" Fan

winkosmosis · 09-05-2010, 04:14 AM

Quote:

Originally Posted by 44Dan

You don't want to push air in from the high pressure spot in front of the windshield because it will probably just fight the radiator fan

The air can only flow one direction and that is out. It actually takes pressure off of the fan if any giving the air continual flow, even when stopped. I mounted my $2.29 chrome vents where I had the most open area and they worked very well as did the others. Our rolling bricks can use all the help they can get to run cooler and more effecient

Nice 10" Fan

If you put a vent right in front of the windshield, on the highway air will go inward, increasing pressure and forcing more air to have to exit out the bottom