Easy Aero
Our front bumper is an aftermarket part made by Stillen with a built-in larger than stock air dam.  This part made a fine functional aero addition.  We added a splitter to it.  One trick to make a splitter more effective is to block off any nonessential holes in the front fascia where air can leak past it.  Air leaks bleed off stagnation pressure and you lose downforce.  We built carbon fiber block off points to block off any nonessential cosmetic vents in the front fascia that air could get into.  We also sealed the joint between the splitter and the fascia.  These measures can easily make the splitter 50% more effective and reduce drag as well.  Just sealing between the splitter and the fascia can improve effectiveness 25%!  Every bit of air entering the nose is smoothly diverted to the radiator. None of the flow is allowed to slam into the core support.
On the Stillen bumper, this is a huge Fast and the Furious faux scoop that just let tons of air blast to nowhere doing nothing but create drag. Now the big leak is filled and the air is diverted smoothly around and where the air backs up against the front of the car it makes downforce instead of leaking to blast into the core support!
Air hitting the scoop on the other side of the bumper is rammed into a cold air box that feeds the engine higher pressure cold air. This is good for more than a few hp at speed. The scalloped sides of the vent are closed down to prevent air spillover, increasing the vents effectiveness.  Excessive air that the engine does not suck in can still stagnate and make downforce.
More detail on the airbox entrance fake scoop block off.
All air entering the front of the car has to pass through the radiator or the engine oil cooler. Baffle plates and ductwork guide all the air through these heat exchangers with as little turbulence as possible. No air is wasted or leaks. This greatly improves the function of the radiator and oil cooler, reduces drag and increases downforce. We should block off the grill as we now know that the lower inlet is enough to keep the engine cool, this would reduce drag.


  1. You mentioned “racket mounted pins that slide into holes on the support bracket mounted on the frame. ” Any chance you have a part number or example link to go off of? Thanks!

  2. Ive got A Z32 Race/Street setup. Still using the factory locations for the intercoolers (using US spec bumper). Would it be best to have the air exit out the bottom if front of each wheel or put vents in the wheel wells? Currently I am only using the factory exit out the bottom ( the version without the factory NACA duct).

    Rear Diffusers in the back are challenging due to the dual exhaust. At this time I am not interested in a side exhaust. How much would it reduce in performance if you ” poke” the exhaust through or would I be better off making a smaller one that just goes between both exhaust pipes?

    Last thought. It’s regarding air flow in the Engine bay. Currently I don’t have any holes in the hood, however I was thinking of taking off the molding that seals the hood near the windshield/wiper area. It would leave a 1″ gap along the entire width of the hood where the air could exit. I am unsure if that would help or hurt.

    1. I would vent in the wheel well or better out the sides in front of the wheels. It is better to blow the exhaust over the top of the diffuser rather than in it. Removing the molding at the rear of the windshield is a bad idea, the base of the windshield is a big high-pressure zone, the flow would back into the engine compartment, the opposite of what you want.

      1. By your comment of the high pressure zone in front of the windshield, would that also mean lifting the hood to vent hot air is a bad idea/ineffective?

        1. Yes, looks cool, works bad. Look at static pressure contour from CFD on Google image search. Pretty obvious, it’s a bad spot to vent. You want to vent in LP zones, gurney flaps, and gills, can prevent flow reversion.

  3. Those strakes on the diffuser are flow conditioners, not VG. The point of them is to reduce spanwise flow. They were heavily used on early swept wing aircraft.

    Also, the point of producing a vortex, is to have an effect on a surface downstream, pointless to put VG on the rear, unless that vortex is directly making down force (which is unlikely, but not necessarily inconceivable.)

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