BRZ/FRS AeroKits by WingsofWar

[Dimman]

Originally Posted by WingsofWar

Basically this...they(or he actually) said the cars basic shape is too slippery for a performance car. Wondering if people will be ok if they bump up the power levels over 300-400hp and start to feel like the car is too light in the rear. Need to harness that wind power to stay planted.

So he really meant it needs more downforce. That is not the same thing as more drag. Silly engineer.

[serialk11r]

Have a massive diffuser sticking out the back, closest point to the ground be behind the CoG. Maybe add a wing. Problem solved

What production cars come with significant downforce in the rear? Not many...

[Dimman]

Downforce problem: Solved.




On a serious note, WoW would you be willing to do a little design/testing on hood vents anyways? You may not be doing hoods now, but later, who knows, right? Plus having something functional that fits in the design of the kit would be nice.

[serialk11r]

Only thing about that is the hood is rumored to be aluminum right? So replacing the hood isn't going to be a particularly cost effective thing to do as it wouldn't really cut weight. The way engine bays are (aerodynamically dirty as hell, best to avoid flowing too much air in there), I have some trouble seeing the value in a hood replacement that doesn't have much other benefit.

[WingsofWar]

Originally Posted by Dimman

So he really meant it needs more downforce. That is not the same thing as more drag. Silly engineer.

yeah...not really sure why he said drag instead of downforce.

maybe he was talking about the shape of the body..instead of adding downforce via attachments like wings and diffusers, maybe changing the basic shape of the car for more downforce? I dunno

Either way, id like my kit to produce more downforce from the shape rather than add wings and diffusers. Otherwise no point in producing a body kit for the performance oriented guys.

I guess im willing to do some Hood sketches for you guys while im at it. but im not interested in making a replacement hood..especially if its already light weight aluminum.

[Dimman]

Originally Posted by serialk11r

Only thing about that is the hood is rumored to be aluminum right? So replacing the hood isn't going to be a particularly cost effective thing to do as it wouldn't really cut weight. The way engine bays are (aerodynamically dirty as hell, best to avoid flowing too much air in there), I have some trouble seeing the value in a hood replacement that doesn't have much other benefit.

Forgot about the aluminum hood. D'oh.

As for aero-wise, engine bays are huge high-pressure zones which pushes up against the hood. A sealed bottom will help reduce that, but might as well vent that pressure to the natural low-pressure areas on the top of it, too. Plus the flow-through can increase rad efficiency.

But I guess it will be kind of hard to justify ditching an aluminum hood, that already jacked the price up, for a slightly lighter, also expensive carbon one with slightly (significantly would be nice) better aero...

Edit:

WoW, how about some templates so we can hack up our hoods ourselves? (I'm not sure if I'm kinding.)

[serialk11r]

If the bottom is sealed, then the pressure vents out the end part of the hood and wherever else they put holes no? Anyways, reducing the radiator opening would cut some of the airflow through the engine bay. I doubt radiator efficiency is a big deal, if you're not turbocharging. One thing that could be done is adding a shroud ahead of the radiator to allow a gradual pressure decrease with less turbulence, just like jet engine intakes.

But I think it's important to understand that the rear of the car is where aerodynamics is the most important...the natural body shape of a car produces lift at the back, and creates a pretty bad wake. At the front of the car, you can improve stuff slightly but it doesn't do very much better. The engine bay is probably the easiest place to find improvement, however you'd have to look at the specific car to know how you can change things. I hear some cars vent radiator air out through the wheel wells, some vent to the windshield or something, it's complicated. Basically if you want to increase downforce in the front you'd want to have venting upward instead of to the side. Encouraging air that hits the bumper area to flow up rather than under the car or to the sides (this is dependent on a lot of factors though) is probably going to produce some downforce too.

[JDM-dono]

Ok, getting back onto topic on the roof channel.

IMO, the channel on the roof acts in a similar way to vortex generators, hear me out.

By observing the roof channel, we can see that it gradually widens out (as illustrated in my very basic paint drawing below). So in essence it acts as a diffuser. If we consider the boundary layer growth, the boundary layer itself will only grow to be a few centimeters even at speed. This means that the depth of the channel will contain most if not all of the boundary layer. So as this boundary layer travels along the roof in this diffuser channel, it slows down and its pressure increases (basics of how a diffuser works). The energy of the boundary layer gains more energy in this channel and is able to remain attached further down the rear of the car.

As boundary layer remains attached for longer, we have cleaner air for the wing. Boundary layer separation is also delayed which in turn reduces turbulence at the rear of the car and drag.

[serialk11r]

Er what's the shape at the front? You only showed a picture of the rear.
Also, you're ignoring the air that is flowing around the tunnel...which is definitely going to be affected.
I don't know whether what you are saying about the air going through the tunnel is right and whether it delays flow separation, but it is not doing the same thing as vortex generators. This "diffuser" mechanism recovers the energy from the air, while vortex generators are adding energy to the air so that it will follow the surface more closely.

[WingsofWar]

yeah that roof channel is not the same as vortex generators...like serialk11r said..it actually recovers air rather than generate energy. Normally a roof will see plenty of low pressure after coming off the windshield and as it moves towards the rear it detaches and causes lift.

but i think some key things about that roof is...
yes it does keep the boundary layer longer
yes it air velocity increases at the channel
Yes air is attached longer and can be feed closer to the rear

but i think more importantly, is that air is "focused" and predictable

[McAndrewsR]

Very nice work! I would definitely consider a kit after seeing what you have come up with so far. If I would comment on something, I would agree with what someone else posted.. The front lip doesn't look "nimble" enough.

However, anything remotely close to the GT300 and I'm sold.

[Camouflage]

Definetly looks very interesting.
But not "extreme" enough in my opinion.

[Dimman]

Originally Posted by serialk11r

If the bottom is sealed, then the pressure vents out the end part of the hood and wherever else they put holes no? Anyways, reducing the radiator opening would cut some of the airflow through the engine bay. I doubt radiator efficiency is a big deal, if you're not turbocharging. One thing that could be done is adding a shroud ahead of the radiator to allow a gradual pressure decrease with less turbulence, just like jet engine intakes.

But I think it's important to understand that the rear of the car is where aerodynamics is the most important...the natural body shape of a car produces lift at the back, and creates a pretty bad wake. At the front of the car, you can improve stuff slightly but it doesn't do very much better. The engine bay is probably the easiest place to find improvement, however you'd have to look at the specific car to know how you can change things. I hear some cars vent radiator air out through the wheel wells, some vent to the windshield or something, it's complicated. Basically if you want to increase downforce in the front you'd want to have venting upward instead of to the side. Encouraging air that hits the bumper area to flow up rather than under the car or to the sides (this is dependent on a lot of factors though) is probably going to produce some downforce too.

Rear of the hood is a high-pressure zone because of the windshield. Look at old muscle cars with cowl-induction. They placed the intake at the back of the hood facing the windshield so the carb could pick up the more pressurized air.

Natural low pressure area is the curve of the hood/fenders where it starts to flatten out, or droop down in some cases. It can also be enhanced a bit with a gurney-type flat flap just in front of the venting.

[mastawyrm]

As someone who has never bought or even considered aftermarket bodykits let me just say that these look very not ricer. I certainly wouldn't shake my head at these if I saw it on the street :P