Nice Holes in your hood.

[BigAl]

I don't have a picture but my buddy cut (2) 3"x10" holes in his cherokee hood and used aluminum sofit louvers from LOWES. Total cost was ~$4. They don't really look that bad

[Shovel]

A local Cherokee owner who lived down the street from me before I moved... (his name's Purple.. for anyone who might know him) - just cut a pair of triangular holes in his hood and lined the edges with loom edging. It actually looked OK! and they were about 1/2 way down the hood, so likely not caught in the high pressure windshield zone.

The fact that OEM's have used vented hoods (5.9L grand cherokee, 1980's turbo chrysler sedans, triumph cars.. etc) lends credibility to their function.

[PhulesAU]

Geez, you'd think I was adding a snorkle for a ride to wal-mart. I understand the wind tunnel testing and why (sorta) nascar does what they do. " circles are boring" BUT who did the testing at 3 - 5 mph??? That is where this will do the most good. waiting in line on a trail or on ramp just doesn't fit the testing model as described.

[ntsqd]

I don't think any of us doubted that. It is the higher speed operation that we're concerned with. I am anyway.


Who wants to be in exactly the same place that they started from every 1.5 minutes anyway?

[robert j. yates]

Some Jeeps will run hot no matter what you do. Mine has run in the 220* plus range ever since it was new on the freeway at 65mph with the ac on. I've had my Jeep since March of 98 (brought it new) and have dealt with the following.....

Custom 2 row aluminum radiator = no workie
Separate circuit transmission cooler = no workie
Lowering the winch = no workie
Hi flow water pump = no workie
Hood vents = no workie
Ceramic coated header = no workie
New engine = no workie...the Jeep still runs at 220* plus

Now with all of that said....I do see a noticable flow of hot air out of my Genrite hood vents...particularly in crawling situations. Having done all kinds of investigation on this...it seems I have only a 10* temperature drop across the radiator to which I ascribe the culprit as the ac condensor which runs at 325* My rig is lifted both in suspension and body and this problem was there when it was stock so the lift is irrelevent. While I can appreciate the fact that there is science behind cooling systems and airflow....Jeeps are bricks and have a rather smallish engine bay. They build up heat no matter what once we start driving them harder and load them up with additional weight....figuring out ways to vent it is not a bad thing.

[ntsqd]

Late models are designed to run hotter than older vehicles. One year Corvette, that I know of, was programed to turn on the radiator fans at 235*f!

While it is designed in and every single dimension, component, or program sub-routine is expecting that temp, you can affect it with a different value T-stat. Though I'm not sure I'd worry about the high number if it holds steady at that temp regardless of operation.

[robert j. yates]

A modern engine can easily run at 300* if the head gaskets and so forth were able to withstand that level of operating temperature so the high number itself does not bother me per se, its the indicated lack of reserve.

The ECU on the TJ will dictate when it thinks things are to hot and sweep the guages. Having the guage sit in the middle of or to the right of the "0" on the guage, halves the indicated level of reserve which IMO, is not good. Yes they are designed to run hotter for emissions purposes and particularly so given that the 4.0 does not use EGR. Hot though is what the factory indicates as normal or 210. If my Jeep ran up to 210 and stayed there, I would be more comfortable.

A friend of mine has actually done some rather significant testing of underhood heat build-up on TJ's ( he runs an Avenger Supercharger) and subsequent results that could be expected from venting. For some reason, I cannot access his archive at the moment but once I do, I will post the link. I performed my hood vent placement as a result of his recommendations.

[Bayou Boy]

Just an FYI. A lot of vehicles actually have what are called "idiot guages". These gauges don't actually sweep as the conditions change. Say we are talking about a temp gauge. If the water temp is between 180* and 235* (random numbers that I pulled out of thin air) the guage will read dead center. any higher and it immediately goes to hot.

Manufacturers started doing this because idiot drivers would bring their cars in when the gauge went just a little above the center thinking there was something wrong. These "idiot Gauges" kept people from coming in when their car was running just fine.

So while you may think that all of the things you are doing to try and make your Jeep run cooler aren't working, they actually might be and you just don't know it because your stock gauge isn't capable of telling you.

[robert j. yates]

I know all about so-called idiot guages. I run a Scanguage to get around all of that.

Edit:......I have also done some significant testing with mechanical guages so I *know* exactly, the nature of my running hot problem. My *idiot* guage is actually quite accurate based on my results.

[toyrunner95]

did you look into the AEV conversions hood? its super expensive, you may have to sell a kidney but it might be worth it.

https://secure.aev-conversions.com/s...ode=40303001AA