Hood louvers and hood scoops

[FellowTraveler]

Body style and type of vehicle aside Fender vents are used in various ways.

1) Fender vents at top and at trailing edge of fender and vented directly into engine bay/bonnet evacuate air always lip or not, however lip @ leading edge of opening is preferred method .

2) Fender vents at trailing edge of fender frt/rear of vehicle and vented directly from wheel well are for reducing pressure in wheel wells and help the cooling of brake components.

3) Fender vent at leading edge of fender and ducted to brakes cools brakes and complements wheel well vent if installed.

4) Fender vent at leading edge of fender ducted into intake or cabin.

Other uses are sure to come into play and not written in stone.

[corax]

As has already been said, vents will do better in the low pressure area near the front of the hood (i.e. between the radiator and front of engine). Here's a great 3 part article that I found a little while back, well worth the read before you start cutting your hood

AutoSpeed: Undertrays, Spoilers & Bonnet Vents, Part 1
AutoSpeed: Undertrays, Spoilers & Bonnet Vents, Part 2
AutoSpeed: Undertrays, Spoilers & Bonnet Vents, Part 3

FWIW, wish I would have read that article before I installed my Ford T-Bird vents - 6 inches forward would have made a world of difference as measured by my Magnehelic gauge

[brian90744]

heres mine on the ford ranger (black hood), yes louvers release engine heat.

I'm seriously considering installing hood louvers on my Montero. I'm also considering and pondering the effects of installing a hood scoop.

I understand the functionality of add louvers, they let heat out, at pretty much any vehicle speed. But my primary concern with a hood scoop is that it may disrupt the proper flow pattern for pulling air through the radiator at highway speeds. Sure, it will force (cooler) air into the engine bay, but I'm worried that the pressure would be to great, limiting the efficiency of the radiator and fan.
And for the record, I'm less concerned about looks than functionality.

Thoughts on this subject?

[LaOutbackTrail]

As has already been said, vents will do better in the low pressure area near the front of the hood (i.e. between the radiator and front of engine). Here's a great 3 part article that I found a little while back, well worth the read before you start cutting your hood

AutoSpeed: Undertrays, Spoilers & Bonnet Vents, Part 1
AutoSpeed: Undertrays, Spoilers & Bonnet Vents, Part 2
AutoSpeed: Undertrays, Spoilers & Bonnet Vents, Part 3

FWIW, wish I would have read that article before I installed my Ford T-Bird vents - 6 inches forward would have made a world of difference as measured by my Magnehelic gauge

Here's an excerpt from the first article:

Bonnet entrance vents – eg to an intercooler – are located and shaped to build-up a positive pressure on one side of the heat exchanger. For example, this Impreza WRX uses a very large forward-facing scoop to cause increased air pressure on the top surface of the intercooler. If at the same time there is a lower pressure on the other side of the ‘cooler, air flows through it. However, this in turn directs more airflow into the underbonnet space, creating an even greater need for a lot of exit flow capability.
So if you’ve added a bonnet scoop to pick up air – or you have enlarged the standard scoop – it’s quite possible that there’s a pressure build-up under the bonnet which is dropping the efficiency of your radiator, intercooler, oil cooler and/or air-conditioning condenser.
Get rid of that pressure build-up and all of the above will work better...

Then a few lines down suggests using a magnahelic gauge. I have about 10 of them at work that we don't use any more... I do forsee commandeering them for this project.

[FellowTraveler]

Manufacturers install engine bay covers under vehicle for a reason case in point my 1999 GMC Suburban had a large composite cover attached at lower part of front suspension/engine cross-member and extending up and forward to the radiator support what this did was prevent high pressure air from entering engine bay just after radiator shroud this prevented flow issues through radiator, what happened in my case was that I installed an aftercooler in area where the cover was then installed a spoiler to force air through aftercooler this stalled the airflow through the radiator, bad move.

Again, pay close attention to air flow into engine bay specially through hood vents because when vents are placed too far past radiator they become air intakes at speed period.........................if that air coming into your engine bay is too great it can and will stall flow through your radiator.

Autospeed articles read them!

[Ray_G]

Pretty happy with the vents from here: http://www.hoodlouvers.com/products.html#productshood

Don't have scientific #'s but do have a constant eye on the temp gauge (it's a Land Rover V8...comes with the territory) and have watched both the standard hood I kept and the vented one as it relates to the stock gauge. Will have a SGII hooked up soon and can keep a closer eye on it. Primarily done for low speed heat escape vice on road cooling (which is adequate in stock form).
r-
Ray
IMG_0226.JPG

[grandpa]

LaOutbackTrail, any updates on the hood louvers on the Montero? I'm thinking about this also.

[LaOutbackTrail]

Its not the highest on the priority list, now that its coming Winter time and we're just now starting to use the truck. I thought about getting the Pajero hood scoop as there are reinforcements under the hood (even bolt holes) minus the hole in the hood. Problem with the Pajero scoop is that there's really no point to it, since its not positioned optimally for anything other than the intercooler on diesel engines.

Another issue I ran into is that the underside of the hood is asymmetrical. It will be difficult to place the louvers without cutting away at any of the supports.

It's on the list right after finishing the fabrication of my cargo barrier, drawers, ARB fridge slide out, fixing the heater, sliders, skids, camping table, etc etc etc.

[grandpa]

I understand about the "list". Mine is growing. I'm going to research this for maybe a summer project.

[XJINTX]

Scott you've probably seen mine but I like the cooling performance I get with mine. I also like the fact (warm fuzzy) they have the bottom deflectors to move water away from engine.