Your engine bay has allot of flow release mechanisims for air in the engine bay, from the curved firewall leading to the undertray, to the frame ports… your creating a problem that doesn’t exist. The only reason you’d want to control flow is if you needed cold air inlet for the CAI. And ANY lift you’d experience is not going to occour in normal, ( or above), hwy speeds, so unless your running the back straight at Mosport with 350+ hp under the bonnet… you needn’t worry. if you REALLY want to control flow in the Engine bay find as much info and tech specs/design layouts from the last 5 years of DTM, thats pretty much the ultimate in saloon aero below the belt line.
actualy there is hardly any vacume from under the car because cold and hot air REALY hate eachother.
in effect this would not cause the car to lift of the ground, because the lines of the car push it down at high speeds. so you want as smooth of air flow as you can get to let the air compress and move untouched. there for pulling the car down more.
if your that worryed about cooling put in 4 electric fans, 2 on the front blowing air onto the motor and 2 on the back of the rad sucking air in and blowing in on the motor.
even still none of this matters THAT much unless your going 300kph+
NACA ducts are a NASA developed inlet designed to be the least air flow intrusive way to collect air from the smallest possible ‘surface’ opening. You can see them most often on 40-50’s aircraft. Constant volume is actually a reversed looking version of the NACA duct, so don’t get confused.
No idea what thats about, air temp does not matter beyond say, heating your cabin. All modern cars have a pseudo ‘airfoil shape’ as such cars naturally have ‘lift’. The fact that a std car weighs in at what it does, keeps it mostly on the ground. ( Some super/hyper cars DO need wings to keep the damn things planted though ). As you smooth the underside of the car you DO gain flow eff. however you also increase the lift by increasing air speed, this lowers the air pressure under the car even more… ( airfoil theory again) the more pressure differential between the upper and lower surfaces the more lift in creates. A rear diffuser, front air dam, trim plates, rear wing, spoilers are all effective ways to keep a vehicle planted. but again, 99.9% of all daily drivers do NOT need to worry about lift… ever.
Ducting… that is the key to any GOOD heat exchange system, I did a V mount for an S13 awhile back, he found that he had to tape off the std. pig nose front opening by as much as 50% because it was doing TOO good a job of cooling at hwy speeds by dropping the temps down below optimum operating temps…
yeah i know what your saying, never the less theres a million different little things you can do to increase or decrease drag and cooling but im saying some small things have drastic effects.
to a degree its like blowing across a straw. plug one end and blow aross the other and not much happens the airs not effected that much but un plug one end and the air will want to go up the straw as well as go down it and you have fighting or equiliseing (sp?) pressures. you have a million things that come into facors some im major ways others not some much, vents are good in indea. huge ricer holes in the hood. bad
That hood you roughed up looks alot like the hood I made for some events this year.
Just out of curiousity anybody know or tried putting ducting behind dtrl grills leading to a fmic? Good idea or not worth it idea?
How/why would you do that? The bend required to get it back around infront of the FMIC would hardly be worth it I would think… My IC piping bends right infront of the grilles and my FMIC sits in front of the hole in the bumper where it should. Methinks that’s probably about as good/effective as you’re going to get.
If you’re gonna be ducting anything from the grilles it would/should be brake ducts…
ok so do u guys think i should give up on the duct directing air flow in?
and possibly just stick 2 vents on either side. I see the vents being the least possible to be harmful to the over all ballance.
If anything i’ll just leave it till i get a wind tunnel
We think a like? 
Yeah thats my next project, still trying to find some write ups on this