[dippert]

in an attempt to help keep my powertrain cool, i installed a TMD functional hood scoop. I don't have any pics from the install itself, but it's extremely straight forward. I bought the scoop from TenaciousTJ back in April

Here are some pics:

IMAG0066 by mike.dippert, on Flickr


IMAG0065 by mike.dippert, on Flickr


IMAG0064 by mike.dippert, on Flickr

my next step is to use some louvers as a means of evacuating the hot air, I'll probably put them on the lower section of the hood (to the side of the scoop), about even with the back of the scoop. The scoop comes with 2 more pieces you can use to direct the air to the top of the stock airbox horn, but as you see i don't have the stock airbox so i'm not using those pieces. It has a little hump at the mouth of it to help keep debris and maybe water out. I still need to seal around the edges, what type of silicon is safe for automotive paint? I remember somebody saying the typical household stuff eats auto paint.

My LJ originally came with that huge mat pinned to the hood, I'm not sure what it was for (probably sound deadening), but I think i'm going to spray on some lizard skin to replace it.

 

[KaiserJeep]

I know it's not obvious, but that hood scoop would work better if it was turned around, with the opening facing the windshield, and in the high pressure area in front of and at the bottom center of the windshield. That's why the cowl vent is located where it is. That's also where NASCAR racers duct high pressure air into their fuel injection (from the windshield wiper slots). Your basic choice is between a scoop that LOOKS like it would work and does not, or a scoop that looks wrong but works good.

If you want to learn more about the topic of functional scoops on TJ hoods, try reading this article:

http://www.oman4x4.com/hoodvents.htm

....at least, do so before cutting holes in your hood. This guy did actual air pressure testing and published the results.

 

[dippert]

I know it's not obvious, but that hood scoop would work better if it was turned around, with the opening facing the windshield, and in the high pressure area in front of and at the bottom center of the windshield. That's why the cowl vent is located where it is. That's also where NASCAR racers duct high pressure air into their fuel injection (from the windshield wiper slots). Your basic choice is between a scoop that LOOKS like it would work and does not, or a scoop that looks wrong but works good.

If you want to learn more about the topic of functional scoops on TJ hoods, try reading this article:

http://www.oman4x4.com/hoodvents.htm

....at least, do so before cutting holes in your hood. This guy did actual air pressure testing and published the results.

Pressure and velocity are inversely related in a fluid substance. Pressure in a fluid is created by resistance. Low pressure may just mean the air is flowing smoother over the hood. When you are relying on vents to evacuate the air from under the hood (high pressure), it makes sense to seek out the low pressure zones. For my application air velocity is more important b/c I'm trying to force air into the scoop, which creates a high pressure pocket inside the scoop. Assuming the pressure in the scoop is greater than under the hood, the air will flow into the engine bay, but trying to compete with the grille might be a challenge. An air velocity meter would be the best instrument to use for this, but I'm not worried about it. I'd like to see the readings from the senors mentioned, I'm curious about the pressure difference at the rear of the hood vs the base of the windshield.

The reason those NASCAR induction methods are effective is b/c the engine is trying to create a negative pressure in the intake ducting. When an opening is placed at a high pressure point, the air naturally flows toward the source of the low pressure, as I'm sure you know. The front of the car, or the leading edge of the hood, has the highest pressure. But putting an opening or scoop up there would mean running the ducting to a more crowded part of the engine bay. Also, the aero disturbance caused by a non-smooth surface would increase drag enough to piss off the aerodynamacists. If the MCAI was totally sealed off all the way to the cowl vent it might give even better results. I believe it is benefiting solely from a temp decrease, and the increased pressure at the scoop just compensates for a dual filter system. But I digress...

 

[TenaciousTJ]

Looks great on your Jeep and glad you could put it to good use!