Jeep grill block - Page 2 - Fuel Economy, Hypermiling, EcoModding News and Forum

DifferentPointofView · 05-01-2008, 10:28 PM

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

Red · 05-02-2008, 01:39 AM

Quote:

Originally Posted by DifferentPointofView

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

DifferentPointofView · 05-02-2008, 07:27 PM

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.

Red · 05-02-2008, 10:05 PM

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

DifferentPointofView · 05-03-2008, 12:13 AM

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.

awillard69 · 05-03-2008, 08:13 AM

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.

aerohead · 05-03-2008, 02:33 PM

Quote:

Originally Posted by DifferentPointofView

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.

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.

Red · 05-03-2008, 09:14 PM

Quote:

Originally Posted by DifferentPointofView

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.

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

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.

brick · 05-03-2008, 09:32 PM

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.

DifferentPointofView · 05-04-2008, 01:36 AM

Quote:

I think 4.0 ZJs have a 5k limit?

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

)

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.