V
aerodynamics?
- Thread starter the bruce
- Start date
thx bruce ... thread jack time ... you know how you were talking about adjusting the brake system thru vagcom. so would that make the brakes more sensitive if you choose the 02 setting? or would it just make it that the car wont freak out when you break hard? ...
Braking hard is often common with 'jumping' fast onto the brake. Remember
a racetrack and you try to brake as late as possible.
In this situation ESP 'thinks' you need an emergency stop and you just may
not be able to kick the brake pedal hard enough (while in truth you try to
brake sensitive to avoid ABS). Result: the system releases full pressure on
it's own, ABS will work hard, deceleration is below optimum and the driver
feels like being a passenger. This is bad. And it's even worse on setting '01'.
:frown:
On setting '02' you can jump on the brake quickly without any negative effect.
It's almost like a conventional brake system.
OK. We are officially off topic now, but this is interesting. Is there a thread on this? If I understand the gist: ESP off and VDCS to 02 for the ABS. Is this correct?
sorry, got the threads mixed up ...
Both will produce an effect. The larger the better (more front DF).
From the view of DF and drag it would be best to keep this as long as possible under the car.
Ideally it is a part of a full flat underbottom and ends up with a diffusor.
But keep in mind gear box cooling. The OEM undertray 1K0 825 237 P includes two NACA ducts
on the driver side for this.
http://www.golfmkv.com/forums/showthread.php?t=162853&page=3
From the view of DF and drag it would be best to keep this as long as possible under the car.
Ideally it is a part of a full flat underbottom and ends up with a diffusor.
But keep in mind gear box cooling. The OEM undertray 1K0 825 237 P includes two NACA ducts
on the driver side for this.
http://www.golfmkv.com/forums/showthread.php?t=162853&page=3
Some more pressure measurements from a mkV R32:
Values are in inches of water at 60, 70, and 80 mph taken from a Dwyer Magnehelic gauge.
Underbody bracket hanging 2.5 from ground: 2.0, 2.5, 3.5
Top of front license plate (static pressure): 0.9, 1.2, 1.8
Top of front license plate (total pressure): 1.9, 2.5, 3.5
Engine bay (passenger side): 0.8, 1.2, 1.7
Rain tray (near center): 1.0, 1.8, 2.0
All measures are static (tube opening 90° to airflow) except the one measured from the top of the front license plate (total) where the tube opening was directed into the airflow (thanks Anile).
Interpreting these values, a couple of things strike me. First, there is very little pressure gradient across the front of the car (license plate static) and the engine bay. The pressure differential is greater when total pressure is taken into account. This latter differential (1.1, 1.3, 1.8) probably more accurately reflects the pressure loss across the radiator.
Second, the rain tray area at the base of the windshield is higher pressure than the engine compartment. This would suggest that removing the seal that isolates the engine bay from the rain tray (or replacing it with low profile trim as per mod shack) would modestly increase engine bay pressures and reduce airflow through the radiator. This result is contrary to what many hope to achieve by breaking that seal. Food for thought...
Third, the underbody pressure seems suspiciously high. This may have something to do with the way I bent the bracket. The bottom portion is bent at 90° into the wind to simulate a collection duct (my eventual goal). Even though the tube opening is pointing at the ground, this simple bend might be inflating that value.
I want to get a few more measurements and then I'm done. Enjoy.
Values are in inches of water at 60, 70, and 80 mph taken from a Dwyer Magnehelic gauge.
Underbody bracket hanging 2.5 from ground: 2.0, 2.5, 3.5
Top of front license plate (static pressure): 0.9, 1.2, 1.8
Top of front license plate (total pressure): 1.9, 2.5, 3.5
Engine bay (passenger side): 0.8, 1.2, 1.7
Rain tray (near center): 1.0, 1.8, 2.0
All measures are static (tube opening 90° to airflow) except the one measured from the top of the front license plate (total) where the tube opening was directed into the airflow (thanks Anile).
Interpreting these values, a couple of things strike me. First, there is very little pressure gradient across the front of the car (license plate static) and the engine bay. The pressure differential is greater when total pressure is taken into account. This latter differential (1.1, 1.3, 1.8) probably more accurately reflects the pressure loss across the radiator.
Second, the rain tray area at the base of the windshield is higher pressure than the engine compartment. This would suggest that removing the seal that isolates the engine bay from the rain tray (or replacing it with low profile trim as per mod shack) would modestly increase engine bay pressures and reduce airflow through the radiator. This result is contrary to what many hope to achieve by breaking that seal. Food for thought...
Third, the underbody pressure seems suspiciously high. This may have something to do with the way I bent the bracket. The bottom portion is bent at 90° into the wind to simulate a collection duct (my eventual goal). Even though the tube opening is pointing at the ground, this simple bend might be inflating that value.
I want to get a few more measurements and then I'm done. Enjoy.
so theres also a negative side to having a splitter ...
Sure. I'll move the tubes tomorrow to new places and take another run. Any other requests?
Bruce, I'll take a measurement on the outboard portion of the rain tray if you want to verify.
Maybe a couple of spots along the hood. I'm curious about whether some of these after market hoods with vents are actually functional.
I need to put a tube near the spindle hub as well.
I think I also have my IR probe mounted and aimed properly. Once done with the pressure measurements, I want to move on to rotor/caliper temp measurements.
I would do the polar bear mod before I removed the rear engine bay seal.