Good afternoon everyone. I have two questions for you all here they are:
1. My cousin owns a 2016 Jeep Grand Cherokee SRT8 he recently had two aftermarket parts installed exterior wise that being a tailgate wing and roof spoiler add on and wanted me to ask you all if the wing and roof spoiler together are doing anything with downforce.
2. 2014 Jeep Grand Cherokee Laredo with the V6 cheers to over 190,800 miles. Code P0420 but no symptoms such as loss of performance or gas mileage. Last year I used intake cleaner to clear some of the carbon buildup out last year of November which temporarily killed the code before it came back two months later. Should I worry about it? It drives fine there's no lack of acceleration nor top speed and has great gas mileage. The O2 Sensors and cats aren't clogged. Edit: I've used high quality fuel treatments like Gumout and few others but didn't seem to kill the code either.
one question per post please, per Scotty's insistence. It's right in our forum rules on the front page so please read them.
My bad
if the wing and roof spoiler together are doing anything with downforce.
absolutely nothing. Is your Cherokee sliding off the road a lot?
It isnt
it's either cosmetic or there to reduce drag/improve fuel economy.
Thumbs up
It's just for style.
I think they do perform a small function, similar to spoilers on an airplane wing.
"... modify the transition in shape between the roof and the rear and the trunk and the rear, act to minimize the turbulence at the rear of the vehicle."
https://web.archive.org/web/20111030170649/http://www.cardata.com/spoiler_fuel_economy.htm
You'll see them on pretty much all SUV's with steep rear hatches .
The flow of air becomes turbulent, and a low-pressure zone is created, increasing drag and instability. Adding a rear spoiler could be considered to make the air "see" a longer, gentler slope from the roof to the spoiler, which helps to delay flow separation ... This may reduce drag in certain instances."
https://en.wikipedia.org/wiki/Spoiler_(car)#Passenger_vehicles
So , they might be helping you save 0.2 mpg or something.
It's an aftermarket part, though. If they actually made them even a tiny bit more fuel-efficient, I would think they'd be engineered like that from the factory. You know, they obsess over even the tiniest bit of improvement in gas mileage.
boundary layer for a box traveling at 80 MPH is around 0.3". It might be possible. I would think that going slower would mean a much more exaggerated form of a spoiler. I calculated that using an old calculator from aerospaceweb.org, I'm surprised it still exists, it hasn't been updated since 2007.
I will say I do notice a bit of improved fuel economy
My cousin owns a 2016 Jeep Grand Cherokee SRT8 he recently had two aftermarket parts installed exterior wise that being a tailgate wing and roof spoiler add on and wanted me to ask you all if the wing and roof spoiler together are doing anything with downforce.
It's there to make the car feel like it's more aggressive. It does absolutely nothing, otherwise. You need to be going at very high speeds in order to generate any significant downforce, and it must be aerodynamically designed for it. Formula 1 racecars race with top speeds of 200+ MPH. The wing on those cars is very wide, with a large camber, like an airplane, but in reverse. Those wings are only around 6" wide, and they contain almost no true aerodynamic qualities; you're not going at speeds high enough to generate downforce. You're only going 80 MPH. Formula 1 cars drive at 200 MPH and they still have a huge surface area to generate the downforce. It's just for style.
