Lol... I mounted HID lights behind the grill of my FJ. It did effect the light output but not much. See its really just a math problem...
Rigid rates the 20" at 7900 Lumens and the 40" at 15800 lumens. That means that the 20" puts out exactly 1/2 the light as the 40" (weird I know). But anyways: for the grill to make the 20" as dim as the 40" it would have to block half of the light. If you look at your grill, you will notice that the cross sectional surface area of the solid parts of the grill is much much less than the open parts ( This makes sense as Ford wants as much airflow as possible for cooling). If the grill was 50% soild and 50% open then it would dim the 40" down to about the level of the 20". For the 40" to be dimmer than the 20" the grill would have to be MORE solid than open. I think its easy to see that isn't the case.
My guess is you lose about 10-20% of the brightness of lights put behind the grill. If you really care, (which I don't), you could actualy measure and work the geometry of the grille and get a true cross sectional percentage.
Don't you guys hate Engineers? lol
Rigid rates the 20" at 7900 Lumens and the 40" at 15800 lumens. That means that the 20" puts out exactly 1/2 the light as the 40" (weird I know). But anyways: for the grill to make the 20" as dim as the 40" it would have to block half of the light. If you look at your grill, you will notice that the cross sectional surface area of the solid parts of the grill is much much less than the open parts ( This makes sense as Ford wants as much airflow as possible for cooling). If the grill was 50% soild and 50% open then it would dim the 40" down to about the level of the 20". For the 40" to be dimmer than the 20" the grill would have to be MORE solid than open. I think its easy to see that isn't the case.
My guess is you lose about 10-20% of the brightness of lights put behind the grill. If you really care, (which I don't), you could actualy measure and work the geometry of the grille and get a true cross sectional percentage.
Don't you guys hate Engineers? lol