Jeep Cherokee Aeromods

[FastPlastic]

I've been inspired by all the posts I've been reading in the aerodynamics forum, So last week I started working on aero modding my Jeep. I decided to start with something simple, the front grill block. I'm only doing a partial block because here in Iowa it can get up to 110 degrees over the summer. I think I'm only going to fill five of the seven slots, and make two more for winter so I can do a full block.

So far i've got three done and put in.

[Red]

Cool

[ankit]

Nice, and the best part is that they are stealthy. Now, did you use saran wrap or some kind of plexy glass/plastic?

[FastPlastic]

Originally Posted by ankit

Nice, and the best part is that they are stealthy. Now, did you use saran wrap or some kind of plexy glass/plastic?

It's plexi from a broken picture frame I had laying around. Couple of min on the scroll saw a little sand paper and some foam tape and bam. You have yourself a grill block.

[Daox]

Nice and clean.

[FastPlastic]

So for the past 5 or 6 days now it's been raining. So I haven't been able to work on the Jeep. Instead I started looking over photos I took last week to get ideas for what to do next. I've decided the next project is going to address the para shoot they call a rear bumper.

The fuel tank hangs really low on the Jeeps, So do I need to wrap around the tank some with the tray or can I just butt it up against the rear of the tank?

I'm guessing either way would be an improvement from the para shoot I have back there already. Just looking for input.

[adrive7]

If you have the material, I would go with option "B". Try to make the transition from gas tank to panel to bumper as smooth as possible. Although, really at this point the flow is already ridiculously turbulent, so a bump won't matter too much.

[Nerys]

Be careful with grill blocking. Cherokee's run VERY hot normally. Less cooling is NOT a good thing.

There is a few ways you can start to improve both off road performance AND aerodynamics :-) Skid Plates

Yeah love skid plates anyway the Front skid plate would start up an underpan belly quite nicely with some added bonuses. Its metal good protection of your belts and namely the alternator which is prone to failure from water and mudd entering it directly. The skid plate stops the majority of this (have not killed an alt since installing it went through 4 of them prior to that. :-)

this will give you a good start on cleaning up the aerodynamics of the underpan. I know thats where I am going to start once I get my baby going again (damned things running like crap. We think its the fuel pump (it does have nearly half a million miles on it and sat for the last 5+ years :-)

[adam728]

Originally Posted by adrive7

If you have the material, I would go with option "B". Try to make the transition from gas tank to panel to bumper as smooth as possible. Although, really at this point the flow is already ridiculously turbulent, so a bump won't matter too much.

I'm agreeing with this guy. I'd start up front to realize gains. I doubt the rear bumper is catching much air underneath, as flow is in no way laminar and shooting up in there. The axles will be destroying airflow long before it reaches that point.

[DifferentPointofView]

Sweet Block I did something similar with clear plastic, but plexi works good too.

Is it just me or does the ZJ have the only good cooling system? I've never seen the needle get to the 210 degree mark. It usually hangs around between 180-190.

One thing that gets annoying is when you take it to autozone or something to get something and the guys ask why theres plastic over your grille. Then you say to heat the engine faster (less time in open loop) and create less drag. Then they ask whether or not you need a new thermostat and if yours is faulty OH!:

Maybe try using plexy over the headlight slots, they seem to be mini-parachutes Removed the roof racks yet? (if there is any)

[SuperTrooper]

My next move would be an attempt at extending (lowering) the front air dam. Push the air around the sides instead of under. I googled by butt off trying to find an aftermarket air dam for the Cherokee and got nowhere. Years ago J.C.Whiteny used to sell universal front spoilers, but no longer.

An alternative would be to lower the whole vehicle.

[FastPlastic]

Originally Posted by DifferentPointofView

Sweet Block I did something similar with clear plastic, but plexi works good too.

Is it just me or does the ZJ have the only good cooling system? I've never seen the needle get to the 210 degree mark. It usually hangs around between 180-190.

One thing that gets annoying is when you take it to autozone or something to get something and the guys ask why theres plastic over your grille. Then you say to heat the engine faster (less time in open loop) and create less drag. Then they ask whether or not you need a new thermostat and if yours is faulty OH!:

Maybe try using plexy over the headlight slots, they seem to be mini-parachutes Removed the roof racks yet? (if there is any)

So far with just the three blocks the temp has been rock solid at 190. Can't say I've heard the electric fan kick in either.

Covering the headlight slots isn't a bad idea. Just not sure how I would do it and make it look nice. I'm all about stealthy aero mods.

It does have the small stock roof rack. Which I have thought about taking off. But I don't really have a place to put it when it's off. I'd like to keep it for when I sell it eventually. If I leave it on is there an optimal location for the cross beams? Is there a low pressure zone towards the middle because of the flat roof?

[TheDon]

I like the plexi glass idea. It would pop into my grill with no mods to the grill chrome. Where to buy a good sheet of it? I presume its of thin kind

[adrive7]

Originally Posted by FastPlastic

It does have the small stock roof rack. Which I have thought about taking off. But I don't really have a place to put it when it's off. I'd like to keep it for when I sell it eventually. If I leave it on is there an optimal location for the cross beams? Is there a low pressure zone towards the middle because of the flat roof?

If you don't want to take it off, you could cover it with plastic to smooth out the airflow over it.

[jeremy128]

I wonder how much a kammback would help?

[Daox]

Just a general note, but its usually best to start with the front of the vehicle and work your way back aerodynamically. On such a dirty underside, the air is probably already sped up quite a bit at that point which will negate the benefit of this mod. It is a good mod non-the-less, but just an FYI.

[SuperTrooper]

Originally Posted by FastPlastic

So far with just the three blocks the temp has been rock solid at 190. Can't say I've heard the electric fan kick in either.

Covering the headlight slots isn't a bad idea. Just not sure how I would do it and make it look nice. I'm all about stealthy aero mods.

It does have the small stock roof rack. Which I have thought about taking off. But I don't really have a place to put it when it's off. I'd like to keep it for when I sell it eventually. If I leave it on is there an optimal location for the cross beams? Is there a low pressure zone towards the middle because of the flat roof?

Can you remove just the cross beams?

Are the fender flares easily removable? Those babies stick out like big air scoops. The early Cherokees didn't have them.

[DifferentPointofView]

Can you remove just the cross beams?

If it's anything like the ZJ, then yes, you can remove the cross beams and leave the long ones (what are they called again?) on there. but that requires removing the whole rack, in which once you've done this, you might as well leave it all off.

I have mine in my brothers bedroom I've got a thread on doing some of this stuff, but the problem is it's all for zj's.

I know that the ZJ has a small lip that pushes air down towards the pavement. don't know how far it pushes it.

The problem with putting an air dam on one of these is there is no longer an approach angle, and you end up scraping up everything with it.

With lowering it, I don't know where you'd get a lowering kit for a Jeep, or what Jeep owner would have the heart to lower it. But if you can find a lowering kit, for the price of the springs/shocks etc. you might as well find and buy a geo or beater civic to roll around in. There'd be better returns anyway.

A belly pan wouldn't be such a bad Idea, I've thought about it a few times, it'd keep stuff from getting as badly gouged on a big rock, and I finally found a nearby (17 miles) sign shop I could buy coroplast from. Might just give it a try

[FastPlastic]

Originally Posted by TheDon

I like the plexi glass idea. It would pop into my grill with no mods to the grill chrome. Where to buy a good sheet of it? I presume its of thin kind

I just used a piece from a broken picture frame. So it is pretty thin, which makes it easy to curve around bends. If you want to be lazy you could just pick up a picture frame from Wal-mart $10. Otherwise if you have a local hobby store (Hobby Lobby around here). I've seen the same size sheet for about $6. Another reason I choose to do it this way, be it harder because you have 5-7 slots to fill. I can always pop one or two out if I start having heat problems.

[DifferentPointofView]

Do you have other pics of the XJ? I'd like to see what we're working with here.