Effect of grill block and exhaust manifold heat shield on air intake system
 

I'm planning to make a grill block for my car but I've got concerns about it blocking the airflow into the engine. The factory plastic intake is behind the factory grill and by blocking it, it would seem that I'm allowing less air into the engine.

In theory, would this make the engine run leaner by decreasing the fuel consumption? Would this also force the engine to take in hotter air inside the engine bay, resulting in less fuel consumption?

What if I also removed the exhaust manifold heat shield while the grill block is on? Would that heat up the air around the engine compartment and intake, thus acting sort of like a warm-air intake (thus decreasing fuel consumption)?

Thanks.

Fuel is metered based on how much air is consumed, so it won't run leaner. If it's restricted too much, you could end up wasting energy trying to suck the air in. You don't make it sound like the grille block will be close enough to the intake for that to happen.

It will probably increase intake air temperature, which helps for some people and has no effect for others.

I can't offer a guess about the heat shield.

unless you have a full bellypan, you won't restrict the air coming in. my grill is completely covered and I have a fairly large air dam along with a WAI which I achieved by making a heat shield (car didn't come with one) and taking the air from INSIDE the heat shield which has pushed my temps to almost 180 degrees which has helped my efficiency. take a look at my gaslog.

I will say that this doesn't work for everyone but it did work for me. if you have a scangauge you can monitor your incoming air temp. depending on how your car regulates the fuel, it will or won't help. I am not sure what the situation is where it doesn't help as it helped for me. I do have a pic of my grill block and intake in my garage also of my airdam which I didn't see too much from as far as gains. I am just too lazy to take it off. plus it gets me a lot of questions and attention.

Take a good look in the vicinity of the exhaust manifold before you remove the heat shield. Sometimes there are sensitive components close to the exhaust which can't tolerate the heat. On my car the alternator is right next to the exhaust manifold. I've heard plenty of stories from others who own the same car that I have. They tend to blow alternators and develop leaks in the power steering pump soon after removing the heat shield.

that's a really good point about the heat sheild's proximity to other components...I'll take a look at that. Thanks!

I went all out, and made a ram air setup, heat-wrapped my headers, put a fine mesh over my grills, and made a coroplast belly pan.
If it would help, I can put up pictures.

here is mine I left the coroplast white to emphasize my point of there is no need for 14 feet of parachute on the front of my car. I run right at the temp the thermostat opens and the car rolls much further. I also run a hot air intake and it works my temps run between 140f and 160f but I had it fall off once costing me 10mpg
https://www.fuelly.com/attachments/fo...271813d705.jpg

Convert the roof rack into a vortex generator!

we had snow not too long back and as I drove my wake looked like a perfect cone I think at this point I need to concentrate on making it cut the air better at the front and not worry so much about the back

my mileage literally went up from a all time max of 33mpg highway to 46mpg highway, with 50psi in tires, drafting at about 80 ft on semi's, and a HAI+heat shield. View my gaslog for more info or pics. Heck, I just got 38mpg highway w/ winter fuel and intake temps only reaching 85*F

edit: not to mention my engine is so loose I'm burning 2 quarts of oil every 300 miles driven.