The IS350 has 4 large plastic plates covering the entire engine. If you open the hood, all you see is plastic literally. Real purdy for people that don

 

well, I'm not familiar w/ the IS350 under the hood, but it appears from the pics that the intake hole is the same size in either case. And if it is the same size and there is nothing in front of it blocking the intake of air, then I'd say you're crazy. It appears that the plastic is there to keep intake noise down, and you have confirmed that by saying it seems louder - my guess is that the different sound you're hearing makes it seem like it is revving faster.

I guess I just don't see the logic in why you think it is getting more air into the intake w/ the plastic off.

Cooling is another factor and you may be right that the engine cools faster this way; however again I don't see how it's going to help your mileage or responsiveness (possibly less heatsoak would result in a cooler charge and thus slightly more power might be possible).

 

I think the OP's point is the intake hole itself might be the same size, but the plastic shrouding blocks most of the fresh air sources, so the intake is effectively smaller with the extra shrouding. Remove the shrouding, remove intake restriction.

Most car makers sacrifice a bit of power in the name of a quiet engine bay, especially in luxury or near-luxury models. I would not discount noticeable benefits, such as freer revving or better peformance and mileage with the removal of silencers and cosmetic coverings.

 

Personally, no offense, I think you are crazy. Looking at the pictures above, the mechanical engineer notices that the air flow may very well be WORSE without the shroud.

The shroud has a gentle curve arcing up into the air intake, while without the plastic, there is a more radical plane the air has to travel over, potentially causing air to be trapped.

All this is moot because I do not think there would be any noticeable difference between having the shroud and not having the shroud. The intake can only take in so much air and that variable has not changed in your two scenarios.

 

Buy an aftermarket less restrictive air filter.

 

Your engine bay is dirty - whoops, wrong forum.

 

Actually it was almost flawlessly clean for 8K miles. I took the plastic peice that fits on the very top of the engine and barely had to wipe of a little dust. I was amazed at how clean all the plastic on it keeps the engine in this car.

 

"Am I nuts?"

- Yes, you are!

I just love replaying to questions like that.

 

Based on the pictures without the shrud, you are directing some of the air downward towards the radiator. Unless you can extend the intake all the way to the grill, it's best to keep the shroud in place.

 

The shroud probably keeps pressure high and forces air into the intake. Without it, the intake is sucking air from the engine bay, which may be warmer as well.