Aerodynamic Balance of a 944
01-16-2009, 06:37 PM
#31
Nordschleife Master
CD numbers (see the fourth table down):
http://www.mayfco.com/dragcd~1.htm
http://www.mayfco.com/dragcd~1.htm
01-16-2009, 06:44 PM
#32
Drifting
Thread Starter
Thanks for the support Pat. I think I will incorporate some sort of splitter into the final design. I might just have it stick out about an inch or so to start, and be adjustable. I think attempting to flatten out the bottom of the car could have positive effects as well, if done properly.
I realize it's sort of a ridiculous task sacrificing drag for potential downforce on an underpowered car, but it's interesting to me nonetheless and I think it's fun trying to improve on a design. I also think it's quite satisfying to make something in your garage that's an original part.
I am concerned with mechanical grip as well, but most of the parts and improvements related to mechanical grip cost a lot more than homemade aerodynamic "improvements." If a cheap improvement, such as a gurney flap, will have a positive effect at, lets say, over 80mph, then why not do it?
Just my point of view.
I realize it's sort of a ridiculous task sacrificing drag for potential downforce on an underpowered car, but it's interesting to me nonetheless and I think it's fun trying to improve on a design. I also think it's quite satisfying to make something in your garage that's an original part.
I am concerned with mechanical grip as well, but most of the parts and improvements related to mechanical grip cost a lot more than homemade aerodynamic "improvements." If a cheap improvement, such as a gurney flap, will have a positive effect at, lets say, over 80mph, then why not do it?
Just my point of view.
01-16-2009, 07:48 PM
#33
Race Director
Ritz,
Keep in mind that aero bolt-ons are designed to work in tandem with a good mechanical system, not replace one. Not that you are trying to do that, but you get the idea...it takes both parts to make a difference.
Good Luck, and if you need anything PM me.
Keep in mind that aero bolt-ons are designed to work in tandem with a good mechanical system, not replace one. Not that you are trying to do that, but you get the idea...it takes both parts to make a difference.
Good Luck, and if you need anything PM me.
01-16-2009, 08:55 PM
#35
Race Director
But.....
01-16-2009, 11:03 PM
#36
Addict
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You need to be more concerned with mechanical grip and balance than with aero balance. At the speeds you will be doing at DE, the aero part will be negligible. You have precious few hp to expend trying to gain downforce. You're better off trying to eliminate drag instead of increasing it.
Drive it like the low horsepower aerodynamic rock it is.
It can teach you much
01-16-2009, 11:19 PM
#37
Race Director
03-23-2009, 10:31 AM
#39
Nordschleife Master
Ritz,
See pic below, I did go with a 4" splitter this year. This has really planted the front end at speed, something that was a serious problem for me in the past. For example, T9 at Road Atlanta where the front end seemed to hop from the lift. With the splitter the front end is now planted in that corner. However, as mentioned, this has somewhat upset my rear balance at speed where it is a bit loose. Thinking about either a Gurney flap or rear wing. In the meantime, I'm going to soften the my rear bar and see if it helps any.
See pic below, I did go with a 4" splitter this year. This has really planted the front end at speed, something that was a serious problem for me in the past. For example, T9 at Road Atlanta where the front end seemed to hop from the lift. With the splitter the front end is now planted in that corner. However, as mentioned, this has somewhat upset my rear balance at speed where it is a bit loose. Thinking about either a Gurney flap or rear wing. In the meantime, I'm going to soften the my rear bar and see if it helps any.
03-23-2009, 11:22 AM
#40
Race Car
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Ran a DE at VIR-South this weekend with stock aero and the belly pan in place. Car felt fine, but didn't have enough power in 4th to accelerate up the hill at the end of the straight! It would get just about to 110 and then just stay at that speed.
DC Auto has a big stack of belly pans. Some of them are kind of beat up but I got one that was "mint" and it is already mostly destroyed so just go ahead and order a couple.
DC Auto has a big stack of belly pans. Some of them are kind of beat up but I got one that was "mint" and it is already mostly destroyed so just go ahead and order a couple.
03-23-2009, 11:26 AM
#41
Nordschleife Master
My car does have the belly pan on it. As you can see from the pic below, the splitter extends to just beyond the front edge of the pan.
03-23-2009, 11:35 AM
#42
Three Wheelin'
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I'm going to go with a 968 rear spoiler and I got an AIR front piece for free, so I'm going to run that too, if I can repair it well enough. I would however love to get a CPR V1.
I've been looking into the effect of Vortex Generators for 944's and I'm wondering this:
What if a set of VG's were placed on the trailing edge of the cabin, just before the hatch glass, to help retain the laminate barrier over the back of the car, thus reducing lift and drag on the rear. I think this would do two things. First, it would reduce the pocket of turbulent air behind the car that's causing drag, through retaining that laminate barrier (making the footprint of the back of the car smaller). Second, it would increace the rear spoiler's effectiveness, by bringing the airflow closer to the surface of the vehicle.
It's possible, that a set of VG's and a factory duckbill would be all an NA needs. And a set of VG's and a 968 spoiler would be all a 951 would need... Just thinking.
I've been looking into the effect of Vortex Generators for 944's and I'm wondering this:
What if a set of VG's were placed on the trailing edge of the cabin, just before the hatch glass, to help retain the laminate barrier over the back of the car, thus reducing lift and drag on the rear. I think this would do two things. First, it would reduce the pocket of turbulent air behind the car that's causing drag, through retaining that laminate barrier (making the footprint of the back of the car smaller). Second, it would increace the rear spoiler's effectiveness, by bringing the airflow closer to the surface of the vehicle.
It's possible, that a set of VG's and a factory duckbill would be all an NA needs. And a set of VG's and a 968 spoiler would be all a 951 would need... Just thinking.
03-23-2009, 12:00 PM
#43
Drifting
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03-23-2009, 12:45 PM
#45
Rainman
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i think in past discussions we found that the rear valence on a 951 had no downforce effect, but rather served to smooth airflow under the back of the car. the air under the car previously would travel along the underbody and then it would bump into the spare tire bin and inside of the rear bumper which would cause some drag, the valence prevents the air from doing this and in addition hides the ugly muffler lol.
however, installing just the valence probably wont have much effect, youd need the whole 951 underbody package to get similar results.