Ram Air VS. Upper grill block

[ECONORAM]

Originally Posted by oil pan 4

We should note that diesels normally see an increase in MPG with cold air intake.
Gas engines usually do not get the desired MPG boost.

That is my understanding now too. I think my two gas engine vehicles benefitted because the original intakes were too restrictive to begin with, so any change was an improvement...

@slowmover, I'd heard about a couple of those 747 intakes. Bet that was annoying...

What I've done for a combo of WAI and ram air is take a 4" dryer hose and strap it behind the radiator so it catches some of that airstream. I've placed it right at the point the upper radiator hose connects, and am getting about a 30* temp rise over ambient. I've not tried to check about the amount of MAP increase, but as those earlier have indicated it won't show up until you drop the hammer.

[Tesla]

Still interested in this and others experiences, mine being a turbodiesel achieved benefits in power, throttle response & economy. My setup is basically a plenum created between the bullbar (push bar) and the engine bay, sealed all around so the only inlet is front and lower centre of bar and only outlets are radiator and engine intake. At cruise I get 20-25mm suction in the airbox which used to be between 60-80mm before the mod, it was worth about 1mpg in the economy stakes. Coasting in neutral, engine at idle at 100km there is about 10mm positive pressure in airbox, I'd like to get to 0 suction at cruise on the flat and maybe 30mm pressure when neutral coasting.
I am currently looking at shrouding rear of radiator to control airflow there, so only as much air as required for cooling goes through leaving a higher pressure in the plenum for the intake. The mock up shroud I have works well with angled top and sides directing air to the lower half of engine bay to exit underneath and to front wheel wells. This is where I plan to mount a thermo fan for those specially hot occassions stuck in traffic, I am currently running no fan and when temps get up like above 35C I get just a little nervous watching the coolant temp gauge, note that the factory gauge has never gone above half, usually sits about 1/3. It was better when I had the back of radiator fully open, even when stationary, natural thermals seemed to keep temps lower even when stationary, anyway I digress.
One of the things I noticed with the manometer (home made) when doing testing is there is about a 10mm drop in pressure at front of vehicle when travelling in a line of traffic, at a good safe distance not tailgaiting vs open road with no one ahead for at least 100m so this confirms the idea of better economy travelling in a line of traffic rather than being up front.