Holes in Rear Bumper

[Sexc86]

Hey guys,

I have had much though about this topic. Mainly for EG / EK civics setting themselves up for drag racing. Cutting circular holes in the rear bumper to improve aerodynamics and have less wind resistance. However some say it by placeing holes it would produce greater turbulance and this creates more drag.

Wanted a few opinions on this. Possibly from people who have actually done it and seen positive results

Exhibit A. Yonas EGK24A



Thanks in advance

Regards Lyle

[DLO01]

I see the holes as an advantage over anything else. The rear bumper as it is acts as a parachute and a high pressure system will exist there (inside bumper) and low pressure (outside bumper). Its this DRAG that holds the car back. By putting holes there it will release the pressure or equalise it, inside and out.

Without the holes in the bumper, its like an aeroplanes wing. To gain lift it has high pressure underneath and low pressure above it to DRAG it up.

[EG5]

In my opinion it does help up abit but I never actually tested back to back on the same day @ WSID.

[90LAN]

or you can make a diffuser under the rear bar to similiar effect

[Zilli]

how about just removing the bumper all together...

[grumpy rooster]

or you can make a diffuser under the rear bar to similiar effect

This has been proven to make a difference of a couple of mph on an 11sec car. Especially when the factory fuel tank is removed. This leaves a cavern under the car where the air builds up.

[beeza]

Great topic!

Just put a thin sheet of metal under the whole car,front to back that can be reoved easily

[rk 86 wa]

has anyone actually done a CFD model to test this? You can easily find the theoretical gains if you can be bothered :P

[MWAKU]

yeah what happens if you remove the whole rear bar, that does make a difference? might aswell strip all the panels off your car when u drag

[bennjamin]

no point in a car that is above a certain trap speed/ET.....that is , that aerodynamics have little effect on performance / ET.

[Sexc86]

Of course.. but all small things add up to a bigger difference. Just not sure weather the holes will be a positive or a negative

[bennjamin]

Of course.. but all small things add up to a bigger difference. Just not sure weather the holes will be a positive or a negative

Interesting , im sure most serious drag racers have this or a similar anti-air-drag application in effect to net those 10ths. Im sure avoiding the standard rear bumper by cutting holes or removing all together / bypassing can only reap benefits.
No point on a +12 second car for example tho !