Friday, August 22, 2014

Daystar Products New Hood Cowl for the Jeep JK Wrangler 2007- 2015

One of the biggest, and most challenging problems facing the Jeep JK owner is the amount of heat generated under the hood of the vehicle when it's offroad.  This is one of the reasons why the factory places the insulation barrier under the hood - to  to reduce noise and to protect your paint job from excessive heat. The problem is that is often the insulation itself isn't enough, and the paint bubbles up or cracks anyway.

There have been several different designs of hood cowls by other manufacturers, but in one way or another while they addressed the under hood heat problem - they also created other problems like weakening the structure of your Jeep's hood.  When Daystar took up the challenge of creating a hood cowl that removed this under hood heat, we also wanted to take up other challenges:
  • Most hood cowls and venting systems are fine when driving, but what about when you're doing a slow crawl over a rock face, revving the motor and only moving forward a couple of feet at a time? 
  • What about weight and paintability?  Do we want to install a large item such as a cowl that will be a bear to match the paint on your existing hood?  What about the cost? 
  • How easy is it going to be to install?  Will you have to go to the body shop, or will you be able to do it yourself?  

With our new Daystar Products Hood Cowl for the Jeep JK Wrangler we've solved all those problems and more.  The Hood Cowl reduces under hood temperatures,  keeps the structural integrity of the hood, is easy to install with templates provided for precise installation, keeps the under hood insulation from the factory,  is fully paintable, comes complete with all necessary parts, and is of course,  Made In The USA. 

The Hood Cowl is made from ABS plastic which is light, strong and holds paint well.  The design of the Cowl in conjunction with the vents is made to draw the heat away from the engine compartment even when the Jeep is standing still. 

The effectiveness of the Daystar JK Cowl and hood vents been tested. Throughout the development process the design and placement of the vents underwent severe scrutiny. To start we went to MOPAR and used their information on current hot spots under the JK hood, on JKs equipped with 3.8L and 3.6L engines.

We then went to the V8 conversion companies and added their data. This information was use to determine where and how large the vents needed to be and then located.

The next step was to determine how air flowed under, around and over the hood at idle, low and high
speed. This information would determine the location, shape and size of the vents, our goal from the onset of this project was to design a set of products that would work in concert to reduce under hood temperatures. The side and front center vents we placed in hot spots ( for low speed and stopped operation) so that excessive under hood could escape using simple thermodynamics, heat rises. The design of the front center vents need to be tackled from two directions: Under the hood they protrude into the airflow and "grab" the heat, above the hood they are shaped to redirect the air flow, thus creating a low pressure area that forces the high pressure air moving over the hood to create a vacuum that "pulls air from under the hood.

The front center vent and Cowl front opening were placed to eliminate a hot spot, but more importantly to remove air from directly behind the radiator. As air is introduced through the radiator at speed it builds up under the hood creating a high pressure area. This reduces the effectiveness of the radiator as incoming air "runs" into increasing resistance. the front vent and cowl are the first line of defense and get the air that comes off the fan, while the side vents allow the air that is moving around the motor to escape. An good example of the build up of pressure under the JK hood is how it flutters at higher speeds. [On a side note: the combination of our hood vents and Hood Wranglers will virtually eliminate the fluttering hood problem]

What does this all equate to? When designing the vents we focused on the extraction of heat under high and low speed conditions, something none of our competitors have done. Check it out:

For more information on our Hood Cowl and other Hood Accessories please visit: 

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