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Old 08-13-2010, 06:15 PM   #1 (permalink)
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aerobrick - '04 Dodge Dakota Quad Cab SXT
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blocking air flow in engine compartment

I am new to the idea of modding and have read several lists of stuff I could do to lower the CD of a vehicle. My question concerns blocking air flow with grill blocker and belly pans. The underside of my truck looks like a drag nightmare and I was thinking that I could make several sheet metal covers over the entire underside from front bumper to the rear bumper. Combined with grill block (not really sure what that is supposed to do) will make the underside very smooth. It can be attached with fasteners that allow removal for access easily, BUT is it bad to cover the underside of the engine .. and exhaust .. and block the radiator air flow. Since I can't block it completely due to wheel movement shocks etc, will their still be enough air flowing past the exhaust piping and muffler to keep it cool? And how much of the grill can I block. The electric fan will pull air from front of radiator into engine compartment from what ever open space so engine will still be cool.


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Old 08-14-2010, 10:59 PM   #2 (permalink)
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If you completely block your grill and underside of the vehicle it will become a zero emissions vehicle very soon because it will overheat and die.

It is not necessary to completely block the underside of the car to see gains. It would also be good to do it in stages so that you can monitor your engine temps under different loads and air temperature ranges.

Transmissions are very sensitive to increased heat. Even a small amount of added heat can shorten it's life.

I would steer completely away from covering any part of the exhaust. Done wrong you could trap enough heat to melt things like your interior carpet. I have seen it simply from a plugged cat on a car that didn't have an underbody pan. Heat dissapation is a huge concern in this case. The other thing you must consider is if you cover your exhaust it could cause C02 to build up and enter the cabin if it has a leak.

If you are going to do it be smart about it. If you do it wrong it could cause a fire, injury or damage to your vehicle.

If you really want better mileage get a small car. A truck will never be a high efficiency vehicle.

I installed a front and rear belly pan and have had very good results. In my case it had benefits beyond increased mileage. I have to watch my temp gauge carefully. Right now with the outside air temps near 100 I have had to remove the stock grill cover on the front of my car to ensure proper flow. Since the hot air has less area to exit my engine bay it is necessary to increase the positive pressure coming in.

Prepare to be flexible when you mod your car. The factory made sure that it would be durable and serviceable over a wide range of environments and driving styles. You are going to be optimizing it for fuel economy. There could be trade offs.


Last edited by EXPIOWA; 08-14-2010 at 11:06 PM..
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