Hood louvers and hood scoops

[LaOutbackTrail]

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?

 

[AFSOC]

The pressure difference caused by louvers has no effect on ability to flow air through the radiator as long as your fan shroud is in tact.

 

[TangoBlue]

The pressure difference caused by louvers has no effect on ability to flow air through the radiator as long as your fan shroud is in tact.

What he said.

 

[LaOutbackTrail]

Roger that.

 

[G_fresh]

LaOutbackTrail, make sure you post what and how you do this project. I have been thinking the same thing with my 80 Series...

Any links to something similar?

 

[frgtwn]

Water Crossings?

I've always wondered if scoops or louvers affect the engine bay in a deep water crossing. A quick thought would be that one cannot build up air pressure by pressing against the area with a bow wave.

Any thoughts?


Dale

 

[squareaffair]

I doubt yours or any montaro could travel at a high enough speed for a hood scoop to affect engine bay pressure, scoops work best if they feed an intake directly into a closed air box, not just the engine bay

 

[FellowTraveler]

Fender vents work better IMHO

After much research I decided to go w/fender vents to evacuate hot under hood heat on my suburban. My concern came from converting to EVANS waterless coolant which pulls lots of heat from my diesel but my aluminum radiator w/2rows of 1" tubes could not dissipate the extra heat in the coolant fast enough at speed for my liking. All operating speeds below say 55 mph were not the issue it was when I when drive faster the heat would build up and engine temps would climb not critical but border line.

Having a WARN classic bumper it has the diesel intake air-dam to radiator option so I increased its size too for dissipating the extra heat at speed. Next I opened both fenders to vent heat and now have temps under control.

All 1990's burbs, pickups and cab chassis have inner fender cutouts venting through outer door frame by opening outer fender in same area hot air has an easy path out of engine bay.

Even at idle the air escaping from vent is HOT!

Vents in hood function differently depending where they are placed, just behind radiator it will vent only at any speed, vent placed in any area further back will act as an air intake at speed whether or not facing forward, backward or side ways, beware of information to the contrary, fender vents placed high and as far back as practical on fender are best suited for venting hot air from under hood/bonnet at all speeds regardless of body design.

As for scoops an air box would eliminate any negative effects by forcing all air whether rammed or cowl into a closed area "the air box".

 

[LaOutbackTrail]

I've always wondered if scoops or louvers affect the engine bay in a deep water crossing. A quick thought would be that one cannot build up air pressure by pressing against the area with a bow wave.
Any thoughts?
Dale

Howdy Dale, its been a while!

I'm not so much concerned about the bow wave point you make as there is considerable mass at the front of the engine which displaces water. And we all know that an engine bay is not sealed from below, thus allowing a significant amount of water/mud/dust to splash up into and all over the engine bay components. I'm not convinced that any water allowed in by louvers would be detrimental.

I doubt yours or any montaro could travel at a high enough speed for a hood scoop to affect engine bay pressure, scoops work best if they feed an intake directly into a closed air box, not just the engine bay

There are three primary possible functions of a hood scoop. Ram air-- forced induction into the air box- slight supercharger effect at high speeds, directed air onto an intercooler, and engine bay cooling. And are you sure there isn't any pressure difference between 10 and 60mph? Think of it this, when you roll down your windows on the hwy, there is considerably more wind noise and air turbulance in the cab at 60 than at 10. My assumption would be there is that potential under the hood too. But I do not have any firm knowledge or experience from race cars or the like where optimal air flow and aerodynamics is key, especially in an often limited space.

 

[FellowTraveler]

Here are images of my ugly fender vents and the scribe marks for cutout of area for reverse air intake scoop directly over air box I'll make a gasket assembly to seal hood scoop to top of air box.

 

[warrpath4x4]

my XJ had heat issues even after a bigger radiator and other things, i believe in function over form so i found some cheap soffet vents for a house at home depot for about $3 each. dropped my engine temps by 10 degrees at all speeds and idle, these have a mesh screen built in to keep leaves out, i just used a hole saw and put some holes in under them instead of cutting the whole piece out.

 

[LaOutbackTrail]

I went out to the truck last night to ponder the louver idea. The hood will not be an issue, but going through the fender won't be possible on my montero. Too much crap bolted to the inner fenders and between the inner and outer fenders.

I'm considering using one of these options:
http://www.quadratec.com/products/12124_034X_PG.htm
http://www.quadratec.com/products/12124_035X_PG.htm

 

[etbadger]

We added hood and cheek louvers to let hot air out of our engine compartment, especially at lower speeds. The results are significant, and, while coupled with increased size in transmission cooler, also reduced our measured engine coolant, oil, and exhaust gas temperatures under similar conditions.

The hood louvers do allow some rain/snow and leaves to enter the engine compartment, though we placed them such that the water coming in does not drip on much affected by water. In fall I toss a tarp over the hood if we are parked under deciduous trees. When parked and idling after a hot drive the heat pumps out of the louvers, and seems to reduce the amount of heat that comes through the firewall/doghouse into our cabin.

I did place the hood louvers as far to the sides as possible given our hood construction, and have verified by yarn tufts while driving that air is exiting rather than entering at speed. Further toward the hood/windshield junction in the middle is usually considered a high-pressure area and might push air into the engine compartment, adding back-pressure to the radiators and reducing effectiveness.

Little write-up I did at our web-log soon after installing: www.badgertrek.com/sportsmobile/vehicle.shtml#Louvers

-e

 

[LaOutbackTrail]

Thanks for the info and pic. I can't tell though, are the louver openings facing forward or back?

 

[etbadger]

Thanks for the info and pic. I can't tell though, are the louver openings facing forward or back?

Our hood louvers angle to the rear to exclude water when we are driving in rain; this does allow rain in when parked, however the louvers are about 1/16" thick and rain that lands on the hood away from the louvers just runs around them. It is quite possible to put a plastic tray under the louvers to route incoming water away, but has not proved necessary where we live. The cheek vent louvers angle down.

-e