'97 Jeep Cherokee XJ 4x4 overland rig

[mannydantyla]

Ok guys, I need your help.

Which do you think is more aerodynamic? My original XJ mirrors, or the TJ mirrors I put on?

Original XJ Mirrors:


TJ (wrangler) mirrors:


The TJ mirrors can also be folded in while still being usable as side mirrors (not just folded and pointed at the cabin)

[freebeard]

Too late to make an adapter plate and reuse the original mounting holes

[mannydantyla]

Originally Posted by freebeard

Too late to make an adapter plate and reuse the original mounting holes

If I did that the TJ mirrors would sit too high and would block my view out of the winow

I can put the old mirrors back on but would have to deal with the holes I drilled in the door. Not a big deal just not something I really want to do. The TJ mirrors are better looking but worse in every other way (they're manual, old ones were powered; they don't reflect as well; etc) and if it's agreed that they're definitely worse for aerodynamics then I might just have to swap them back out.

BTW I haven't yet but I am definitely covering those exposed holes in the door where the old mirrors were bolted to

[iikhod]

I'm not an expert in aerodynamics, but those TJ mirrors seem to be bigger, also that "arm" is quite big.

As an former off roader i still would keep the TJ mirrors, would suppose that they are better for reversing?

[slowmover]

I’d pay the penalty for the TJ mirrors. In fact I’d add a 4” tall or taller convex also the width of those TJ mirrors.

Convex is for what’s next to you. Higher importance.

On big trucks the “aero money” goes into the arms. Otherwise, the housing is rounded.

[Hersbird]

Uhaul trailer

[mannydantyla]

Anybody have an opinion on whether or not a rear spoiler like this would help with aero and FE?



They're on EBAY right now for like $152. I would just make my own. https://www.ebay.com/itm/JEEP-CHEROK...%257Ciid%253A1

Originally Posted by mannydantyla

Note that he says at the end that the underbody skid plates did NOT help is fuel efficiency and may have hurt FE in the city due to their weight. Hmm....

I found another ecomodder who claims that a front skid plate (he calles it the aero-skid, I like that) moved his 6.5-inch-lifted (that's a lot!) Jeep Cherokee XJ from 15.8 mpg to 22+ mpg at 65 mph ...

WHAT?!?!

http://ecomodder.com/forum/showthrea...tml#post292536

[freebeard]

I was looking for a quote on Faschenfeld tearing edges when I found this:


http://ecomodder.com/forum/showthread.php/random-wind-tunnel-smoke-pictures-thread-26678-17.html#post544437

This is a similar shape. The vertical edges are 'hotter'. two triangular fins from the outer edges down toward the taillight would be a good start on a boxed cavity. Here — according to the text is an explanation, if you can see Photobucket images: http://ecomodder.com/forum/showthrea...tml#post542668

[mannydantyla]

^^^ thanks!

New idea: indentation of the fender right behind the front wheel, and air curtains (not to be confused with skirts!) for the front wheels! The indentation is easy; the air skirts will have to be fabricated along with a new front bumper (maybe one day far into the future). Ecomodding is an amazon thing. So many activities! So many enhancements to be made! Can you tell I'm excited!



(source: http://ecomodder.com/forum/showthrea...s10-35043.html )

An extreme version of the fender indentation:


And here's how air skirts work to reduce turbolant air around the front tires: http://ecomodder.com/forum/showthrea...tml#post496612

I feel like a BIG improvement that can be made with my jeep, with the huge openings for the tires, is at the front wheels. BMW agrees, they say on their official blog that 30% of the drag is at the wheels. http://www.bmwblog.com/2014/02/26/bm...n-engineering/ (the article is really really good btw)



Also, notice the articulation of both front and rear wheels, I need every inch of the wheel well when offroading:




Lastly, here's a nice visualization of my jeep's aero:



Note the blue pressure zone under the rudder.

(lol ok ok I stoll that joke from here: https://robrobinette.com/S2000Aerodynamics.htm )

[freebeard]

ToyotaGT One TM1

The relief you show requires major surgery, extend the wheelbase or re-hinge [suicide] the door. Less radical is the Honda Insight and others with a rolled lip.

I think a good start for an air curtain would be a splitter under the front bumper with upturned wingtips, like modern air liners. It needs to be a converging duct that exits at the outer edge of the tire.