well i recently looked under my hood and had a bit of a brain teaser to solve... where the hell is the air coming from?!

i mean... i saw the intake for the engine but nowhere for the air to come from! then i realized that its probably the three dainty vents in this picture


so my question is... why not just get rid of that plastic cover? then the air flowing in should look something more like this


wouldnt that be much less restrictive and allow more air to flow into the engine? or do i have this all backward and the air is restricted for a reason

 

possibly... that why mine are out!!

 

ok heres my problem. its a lexus so b4 i touch it i need to be bloody well sure that i'm not going to break it so just reassure me that taking them out hasn't caused any problems

 

If you look at the inside of the hood you can see a piece of rubber weather stripping that isolates the engine bay's hot air from being pulled in from the intake. You can also see it as the dirt line on the front cover in the pics.

Also I think it helps keep the hot air rising from the radiator out of the intake path.

When I was at the dragstip earlier in the year, I removed all the covers except for this one based on the statments above.

My two cents

 

Those covers were placed there for a reason. Maybe since they knew our engines are ugly, or maybe it does serve some functional purpose.

Be as it may, I would find it hard to believe that Lexus would leave in something that would restrict the flow of air coming into the engine.

 

ooooooooh good observation! actualy tho that was something that i didnt notice. well i have a counter theory......well... hmmmm. if the heat radiating off the engine is hot then is stoped by the rubber barrier... the rubber barrier would stop hot air from getting from the engine to the intake but not heat in general because ultimately air isnt traveling towards the intake from the engine (unless you are in reverse i suppose) so all it is doing is acting as a resistor for the heat. so lets say an imaginary value of air entered the intake with the piece of plastic and an imaginary amount of heat entered with the rubber barrier. you are cruseing along at 50km/h and their are 20 "airs" entering the intake and 10 "heats" entering. so then you decide to pull over and remove that plastic thing and as a result you have 40 "airs" and 15 "heats" (because lets face it.. that rubber thing is probably not doing a hell of alot.) but because the air is traveling toward the intake and their is nothing stopping the outside air from reaching the engine anymore in this path, then at a certain speed, the colder air outside will push the hot air inside away from the intake but only at a higher velocity. SO... when you are stopped their should be no major or minor increase or decrease in power because your engine will be at idle anyways and the engine will inevitably heat the air because it is so close to the air box with little air flowing through it at no velocity but at a higher velocity their should be more air reaching the engine and possibly less heat reaching the intake

 

You guys are scaring me. I really hope you're just kidding here.

 

well actualy you make a good point but as far as i can tell... they are just their to clean up the appearance

 

I heard its to cut down the engine noise.. i could be wrong though. Either way just leave it on, it makes it look better and if anything it would make such a minimal difference that you wont even notice any power gains

 

i removed all the covers except the front one as well.

The hood is already the best cosmetic cover to the ugly engine, why putting extra pieces of plastic to capture heat.

and i "feel" the car sounds better without the covers, and the car lighter by 0.5lbs

 

I drive with no engine covers at the track and I'm currently running without them as I'm too lazy to put them back on while testing out different exhaust configs. Those clips that hold it down are weak and the more you pop them in and out the more they need to be replaced. Not to mention the engine covers add an unwanted 7lbs to the car.

 

OK so i took them off and went down side streets for 10 mins then about 10 on the highway. the only noticeable difference would be the sound. the engine sounds louder and a bit meaner (which might b good lol) and you can hear the road more clearly, such as just the weals rolling along the pavement or going over a pebble or the wind on the highway etc... so if lexus put thows in to dampen sound then they did a pretty good job. other than that their was no noticeable power increase at any point other than gear 2 at around 3000rpm which is odd but kinda good because i never was too fond of gear 2 below 4000rpm but it seemed to have a slight increase in power this point. other than that, every other gear... well i haven't really tested 6 because i didnt want to go too far over the speed limit... well the other gears seemed the same so ultimately i think that sticking with the covers is the wiser decision unless you are prone to tinkering with what ever and need to constantly remove the things.

 

I would be happy to bet my car no human on earth will be able to notice any power difference with the covers on or off.

Any difference you notice is entirely in your head and likely a result of the car being louder.

This is why people with hot-air short ram intakes think their car is "faster" with them on when it measurably is not.

 

I pulled the plastic side covers off as well; it is more aggressive looking when hood is open and easier to clean the parts.

But before I did that I called Lexus to find out what's the purpose of the plastic side covers. Technician said it really doesnt serve any purpose (doesn't even reduce engine noise that much). They all think its just part of the engine design...to have cleaner look.

 

the only sensible reply in this thread.