I have hood louvers on my XD & they work best at 5-10mph in traffic from my results since having them for 9 months. Sitting at idle = you see heat waves flying out from them. Using an IR temp gun temp on hood vs louvers = warmer air is passing thru the louvers no doubt vs being trapped under the hood.

Transmission wise it's still got plenty of airflow around it & all LR's have HD Transmission coolers.

 

From what I've read/watched, placement of hood vent louvers can make a big difference in desired effects. Put them in the wrong place, and the effects can be the opposite of what you'd hoped for. There's quite a few videos on the subject out there. Back in the day, they pulled air for intakes from the high pressure area near the windshield, but you don't really want to put vent louvers there, or you risk creating higher engine temps at high speeds (high pressure ends up filling the engine bay, effectively slowing flow thru the radiator). They say it is also wise to consider what happens as the air flow changes angles and comes from someplace other than head on, which can also cause flow issues thru the radiator in certain conditions. Racers say the best place for hood vents with the desired effect of increased engine cooling seems to be just behind the radiator in front of the engine for head on flow, and to each side of there for crosswinds or turning at speed. Works out pretty well on the Disco's, as that area basically correlates to the front and front side edges of the hood hump.

 

I was thinking of wrapping the intake hose and MAF with exhaust wrap to minimize the heat but honestly I don’t know if that will help or not.

 

Somewhat concerningly, last summer when it was 118 degrees here in Oregon (aka the End of Days...) .. I took my D2 up to Mount Hood with some out of town guests. Hit traffic on I-84 on the way home and at one point I noticed that the Intake Air Temp reading on my Ultragauge was 190 degrees. That's crazy.

The D2 didn't overheat, but the temps on the UltraGauge of the engine coolant were in the 215 range, which was fine but causes me to be... stressed. I was concerned about the very very high intake temp reading.

 

Water / Methanol Injection

 

would be a lot more tempting if we could tune our motors easier/better than shipping the ecu to england...but I do like the idea. I believe the d2s would benefit from each intake runner getting an injector as I remember reading that our intake setups don't handle boost well due to the rear cylinders not getting the same amount of air (I could be way off base here but it made sense at the time reading up on supercharged rover motors in classics).

 

Mine are placed pretty much dead center over the exhaust manifolds (hottest part under the hood). My XD does fine during the summer months when cruising down the road with maybe 205F as the high. Idle and slow traffic = where temps climbed. The louvers have helped with slow moving traffic, and at idle out on the trail.

 

It was 13°F Monday morning, 31°F - with freezing rain and sleet yesterday...move to Michigan and you can experience these types of wonderful temps for six months out of the year. Solving your need/desire for cooler intake air temps. Other than that...l got nothing...lol.