Got my RCF late October and curious to know if you removed the cover under the hood vent and:

1. Do you cover it before you wash it?
2. Where does the water go if you drive in the rain?
3. Is the AC vent still blowing warm air with it open?
   

Appreciate the feedback!

 

No, I just wash it the way it is from factory. I do see steam rising from the hood vent once I am finished washing and drive out. It is supposed to handle rain water so nothing needs to be done. I believe the water that makes it through the extractor vent, drains through the bottom.

 

https://www.clublexus.com/forums/rc-f-2015-present/819217-hood-scoop-costmetic-or-functional.html

 

Removed the cover shortly after getting the car and left it off so that I have a functional vent. Even after going through a car wash, engine bay is dry. It drains in front of the engine. Just give the bay a wipe down from time to time. I got this pic last winter that shows a bit how air is flowing over the hood:



Very obvious there's a lot of air coming out of the vent at speed. Leaving that cover in place just makes it cosmetic vs functional.

 

I took my mine off right after I got my car. I wash my car weekly and the drive it daily. I never had any issues with water getting into the engine bay. I've checked several times even after hard downpours of rain and it was dry. You can really see the heat coming out of the engine bay when the car is fully warmed up. I would remove it to get the functionality from it.

 

I took mine off and never put it back on. You can see the heat pouring out the vent when parked. I also took the plastic engine cover off.

I wash mine and try not to spray down the vent but take no real precautions. When I am drying the car I pop the hood and wipe the air intake tube of the little bit of water that is on it.

 

I didn't like the opening left when completely removing the cover. It looks unfinished to me. So I just cut the section out of it. I might look on eBay again and play around with cutting another opening cut out. But definitely heat is extracted and i park the car you can see the heat pouring out of the vent.. so i can assume the same if not more is happening at speed.




-Nigel

 

How did you guys take it off? Did you just pry off the plastic rivets?

 

^^^^Maybe you can see better here what nigel821 did:

 

I just took off the plastic rivets, pretty easy but they're easy to lose in the engine bay so put a hand under them when removing.

 

What’s the benefit of doing this exactly? More downforce up front?

 

Used for engine cooling especially while doing hot laps

 

cooling, and helps evacuate air from the engine bay reducing drag. It's a functional aero part of the car, as long as it's opened up.

 

I personally wouldn't remove that cover. My thought process is other than the obvious fact you will be introducing a big gaping outlet for more dirt and dust to get into your engine bay;

• I would believe Lexus engineers ran some pretty extensive computer simulations (perhaps even some wind tunnel tests) and found this cover design the most efficient in reducing drag co-efficient. Removing the cover I would imagine creates a great deal of turbulence underneath the hood as huge volume of air will be coming in over the hood through the gaping hole now created and into and underneath the hood.
• Secondly the small hole in the factory design of the cover will actually extract hot air from the engine at greater efficiency as it creates a Venturi effect (a jet effect, acceleration induced by a chock/constriction due to a pressure delta) accelerating the hot air out with greater speeds combined with less obstruction from denser air trying to come in from the top. Kind of like a squirt gun.

Taking out the cover I seriously believe will create inefficiencies by inducing more drag and turbulence and definitely in speed of heat extraction. The goal is not to introduce colder air into the engine but efficient heat extraction without impacting drag coefficient. It's still a functional vent with the cover on and a highly effective one at that.

 

That thought process is flawed. Air does not enter the opening, it escapes up and out. The leading edge being slightly sunk creates a low pressure area that helps "suck" air from the engine bay. That tiny hole is just a water drain nothing more, there's no fancy venturi anything happening with the cover in place. There's a large volume of air going into the engine bay via the grill, and it needs somewhere to go. The cover blocks air from escaping the engine bay, which is what the vent is designed for. Removing the cover is the only way to make that a functional aero vent.

The simpler answer is that Lexus put the cover there in case new owners of a $70-80k car were worried about dust in the engine bay. I can say that after 2 years of no cover, and daily driving, my engine bay isn't dirtier. Just wipe it down from time to time.