Open elements and mileage?

[TurboTony]

Has anyone noticed a signifigant difference by running any sort of open element filter as opposed to the factory airbox?

The reason I ask is awhile ago I removed just the lid of my 98 air cleaner and tried it for a few tanks that way. I "may" have noticed a slight increase in power, very hard to say though. Likely just me actually hearing the turbo made me think that. I did notice a slight decrease in milage.

My truck usually gets 640ish km to a tank, around 85 liters of fuel. With the filter open it droped to the high 500's.

I reinstalled the lid and the mileage is back up.

Anyone have any thoughts?

Tony

[damork]

Not real sure here, but opening the lid on the air filter my let the engine get more hot air from the engine compartment leading to lower economy. I think the cooler air coming from the fender well area would be better than engine compartment air.

[Scooby]

I am running the open style element sold by SS Diesel. My mileage increased when I installed the filter. I was driving the truck daily at that time, and I believe I gained 1 mpg after installing the filter. It definately makes the boost come up quicker.

[jspringator]

I ran mine without the lid on all winter, but put it back on for summer towing. I think I read a post here from someone who recorded higher EGT's while towing with an open design. I need to conduct an experiment!