Jeep grill block
 

I took my inspiration from http://ecomodder.com/forum/showthread.php?t=1405 and picked up some pipe insulation from the home center.

The gaps in the Wrangler grill are 2 inches wide, so I got the largest insulation I could get. I got the firmer stuff, not the squishy stuff.

I cut it slightly longer than the opening and wedged it in. It seems to hold in there OK, standing still at least. But it was clear that it wouldn't stay, so I notched, actually just a slit, in the top and bottom and used that to hold to the upper and lower ends in place.

A few test runs yield them pretty stable, however in every attempt at speed one would get pushed into the space behind the grill. There must be just enough pressure build up ahead of them and once one gives, the rest are spared.

So, now I'm down to finding a way to keep them in. Short of hot melt glue tacks, I need to find a way to keep them from pushing through. I was thinking about lacing them together with monofilament line, but that won't do on the ends. Toothpicks may work, but may be unsightly, and won't be a long term solution.

I don't have good numbers with the SGII yet, check out the trip logs for any details. I've had to reinstall my spare and am getting ready for a road trip - it's a Jeep thing...

Anyway, here are a couple of pics to show my progress.

http://bp0.blogger.com/_Ay1mo0d8T0E/...s200/jeep1.jpg
http://bp1.blogger.com/_Ay1mo0d8T0E/...s200/jeep2.jpg

Perhaps you just need to leave one out and go from there.
Is there any one particular piece that seems to be the most prevalent at coming through?
That would be the one to leave out, common sense would say that is your point of stagnation.
If it is always a different one then just leave out the one in the middle.
Just a thought.
S.

No, it's not been the same one twice. It's pretty much just a friction fit, and once the radiator warms up, it may cause the material to soften. Leading me to some form of attachment, hot melt, monofilament, etc.

But, I was considering leaving out the center one, for aesthetic reasons.

I don't have enough data to indicate whether leaving one out is relevant or not; nor do I know how much impact it will have overall - can I get .5+ MPG out of it?

well, if they were more streamlined with the front, so that there's more air being directed around the Jeep instead of around the foam, you might yield better results. I gained actually about 1-3% out of it, which for me is about 1-3mpg's depending on the weather and wind conditions. Mine are clear plastic though, and I don't know where it came from, I just got it from my shop teacher, who had some extra laying around from our solar boxes.

I know I should use something else, but I was trying to prove the point first, cheaply. I intend to fab up some kind of flat block. But the foam was cheap and easy to work with.

I ended up skewering it with some bamboo skewers colored with a Sharpie. They held in great this morning.

I'm attending the Jamboree in Kentucky this weekend and wanted it in place for the trip down. $4 gas is a strong motivator!

Good luck awillard. I've always wondered that going with a grille block on the TJs would actually make it worse cause you have another flat surface moving through the air. With the grille open atleast there is a path for air to flow. Post up any results you get

Have fun at the Jamboree!

Yes, I wish I had more time to perform some test runs. I'd like to know if I'm wasting my time (and $) before I do 500 miles! The data for my daily commute don't reflect anything conclusive - crap traffic and poor light timing compromise any days' readings.

The fuel logs will reflect total highway effectiveness. Check back next week.

If you have room, put a 2 strips of wood in the back horizontally and screw them in from the front. You might be able to secure the wood strips to the grill from the back. ;)

remember that the Radiator is right behind it, and it IS another flat surface moving through the air. without the foam, you have turbulent air hitting the grille openings, then it's hitting and going through the wall-like radiator, which gets sucked by a fan (if there's a mechanical one) and pushed into the motor, which gets jumbled around. It's basically gonna be the same, but maybe direct more air around the jeep. without smoke or windtunnel testing I wouldn't know for sure :(

I haven't compiled the fuel data yet. I pushed a 20+ MPH headwind for almost 400+ miles - really ate into any savings. While in a protected area on flat road and not other traffic I was getting 22+ instantaneous MPG readings. I cannot attest to the block being the bonus or 60 MPH.

As a note, all 7 blocked shot the water temp to 230 and beyond, so a quick stop and I pulled the center block, then the temp returned to the 208-211 range which is more typical.

Eyeball estimate is about 20 MPG, but won't know until I enter the log data.

do TJ's have a mechanical fan? I know ZJ's do and... I've never seen the temp go over 190ish.

We do, the cooling system just sucks

you'd think that i'd be better on a TJ or YJ, but I've seriously never seen my temp go over 190, even while off-roading.

I know for those of us out here on the west coast, in stock form the cooling system is barely adequite. Simply turning on the AC would get things toasty. I think it has to do with the aero in the engine bay. Theres no air dam underneath the rad just a big exposed engine bay. There really isn't any directed air flow. On ZJ and WJs they do have a bigger (longer) rad than what we have in a TJ or a YJ and their bays are smaller and i believe have more sealed areas than in ours

I don't know about the later ZJ's, but I don't know how much more open the engine bay can get. Maybe on the later ZJ's and WJ's it's more sealed, but I've been under mine too many times. There's really not much there. Although you guys don't have much place for air to come in. We've got 2 grilles apposed to one, and the grille openings are wider. But you'd think that an open engine bay would be able to pull more air into the radiator. You're guys' aero much worse too, and the weight difference isn't much between the two. Maybe Jeep should have thought about the cooling system better? Just because the ZJ is larger doesn't mean it needs to be cooled more.

I wheeled all day in 4-Lo and the temp never went beyond 202. It could be a calibration issue with the SGII. Even on the way back to the lodge, the open road temp was normal, 197-202.

The grill block was removed for the day's activities.

a peek through the grille
 

A week ago,at the laundromat,a fella had a new '08 Jeep 4-door.All the leading edges were softened with small radius at the grille bulkkhead and windshield frame/A-pillar.I looked into the grille openings and noticed that Daimler had completely sealed the entire entry duct for the radiator.I wasn't allowed to look under the hood but it struck me that this Jeep would be a good candidate for a no-mechanical-fan/electric fan retrofit,if Jeep hadn't already done it.On the Pinto project,CAR and DRIVER picked up a full mpg when they removed the fixed fan.I've driven thousands of miles with no fan on the Dodge.The electric fan does just fine around town.That's not to say that it might not be an issue,stuck in grid-lock with the AC operating.Thats not an issue for me but might be for others.Your grille block will be most effective if the duct is air-tight,as errant air won't be spilling around the undercarriage and you'll have better ram-air to the heat exchanger.

No but you can can actually tow. I think 4.0 ZJs have a 5k limit? And all thats using the same running hardware as some TJs.

Pics of a TJs rad. I used my shoe as an informal scale. My boot is around 14" long, the rad I believe is 19.5" wide and ~24" tall
http://astralfoundry.com/linkgfx/IMG_0461.JPG

Engine bay. Not a whole lot of directed flow, the PS pump and the alt kinda block the view but if you look straight down its all open. The bay is the full length of the 4.0. The firewall starts at the bellhousing so its a good 3-4ft long and about 4 ft or so wide.
http://astralfoundry.com/linkgfx/IMG_0464.JPG

You know what I'd try, is find some nylon webbing and use that to lace the insulation to the grill. That might even look pretty decent when you are done. If that fails, I would cut a piece of coroplast to use as a backing. You could cut some slits in the plastic to lace the webbing through it.

What? tow weight or redline? cause it can both tow 5k pounds and go up to 5k without "redline" (it's actually yellow :D)

I'll take some pics of my bay tomorrow, but it's essentially the same thing. Open to the ground and I'm pretty sure that the bay is to the firewall. I'll measure the rad tomorrow too.

Towing. :p

Here's a thought...try blocking the upper part of the slots instead of the individual slots. Try halfway and move up or down accordingly. ;)