Anyone have wind tunnel pictures ?
02-08-2010, 04:40 AM
#16
Three Wheelin'
*bump*
keen to see these scans!
keen to see these scans!
02-08-2010, 07:37 AM
#17
Instructor
Roger that. While we are talking about spoilers, how do these rules differ from other less worthy cars with spoilers? Such as a Dodge neon or even Mistibishi Eclipse, you might see how they have small spoilers on and i have always said its just for looks.
Eventually..upwards of like 60 plus, does it start making a difference? It definetly wouldn't surprise me for other cars since they are not Porsches...they do not have the sporty curvature of one where the air basically flows over the spoiler, exactly like Van said. If you have a Porsche chances are your raising up your spoiler to the roof if you want to get any affect from it aerodynamics wise.
Then we get to the M3 lips right on the edge of the trunk, which are found on the generation before the current one. What you guys think?
Eventually..upwards of like 60 plus, does it start making a difference? It definetly wouldn't surprise me for other cars since they are not Porsches...they do not have the sporty curvature of one where the air basically flows over the spoiler, exactly like Van said. If you have a Porsche chances are your raising up your spoiler to the roof if you want to get any affect from it aerodynamics wise.
Then we get to the M3 lips right on the edge of the trunk, which are found on the generation before the current one. What you guys think?
02-08-2010, 08:54 AM
#19
Former Vendor
From this thread on 924board:
And from another somewhat related thread:
I'll repeat that last phrase for emphasis:
Our lowly Porsche 924 Turbo has the best figure of ALL of the cars on the list, matched only by the Citroën GSA X3
The factory spoiler definitely makes a difference...
Originally Posted by ideola
Not a toofah or a Porsche, but I dug this link out of the "Posts Rescued From the Old Board" section. It is an article by Wayne D. Guinn excerpted from his book Camaro: Untold Secrets (Hot Rod Library, Inc, 2001; ISBN: 187877218X, 9781878772183). I found the discussion of "plows" and "tails" to be pretty interesting. Sort of the point made is that without extensive testing capability, it's a real trial and error deal to get the balance correct based on the speeds and cornering characteristics you need to address.
CAMARO SPOILER EQUIPMENT
Notable quote:
If one were to employ the DIY aero testing methods discussed frequently at AutoSpeed with the above intervals, it might be possible to come up with some meaningful data for the toofah...
CAMARO SPOILER EQUIPMENT
Notable quote:
Parameters measured were lift and downforce. The two most important aerodynamic factors that affect traction and handling at speed. Speed intervals of at 65, 85, and 115 mph were chosen as a practical range of test points for analysis and comparison. The 65 mph mark representing a typical highway speed, 85 as the intermediate passing or top crusing speed, and 115 as an average race speed on medium and short road race courses.
Originally Posted by ideola
For the first time, I have found somewhat reputable coefficient of drag figures for our cars.
published in Fluid Mechanics (1995)
by Robert Alan Granger
(note the Road & Track citation)
Same numbers repeated in a later work, but not cited:
published in Advanced engineering fluid mechanics (2005)
by K. Muralidhar & Gautam Biswas
What's absolutely fascinating to me is that our lowly Porsche 924 Turbo has the best figure of ALL of the cars on the list, matched only by the Citroën GSA X3! 8)
published in Fluid Mechanics (1995)
by Robert Alan Granger
(note the Road & Track citation)
Same numbers repeated in a later work, but not cited:
published in Advanced engineering fluid mechanics (2005)
by K. Muralidhar & Gautam Biswas
What's absolutely fascinating to me is that our lowly Porsche 924 Turbo has the best figure of ALL of the cars on the list, matched only by the Citroën GSA X3! 8)
Our lowly Porsche 924 Turbo has the best figure of ALL of the cars on the list, matched only by the Citroën GSA X3
The factory spoiler definitely makes a difference...
02-08-2010, 09:48 PM
#20
6th Gear
Join Date: May 2005
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Well, when you're looking at figures from the early 80's those figures don't look too bad...
But then you realize that cars even just a few years later made significant decreases in Cd.
http://en.wikipedia.org/wiki/Automob...ag_coefficient
For example, a Scion xB has less drag (as well as about 100 other cars)
Unfortunately, Cd numbers do not tell the whole story, as drag and downforce are very closely related. The key is how to create a lot of downforce, without increasing the drag significantly which is no small chore.
But then you realize that cars even just a few years later made significant decreases in Cd.
http://en.wikipedia.org/wiki/Automob...ag_coefficient
For example, a Scion xB has less drag (as well as about 100 other cars)
Unfortunately, Cd numbers do not tell the whole story, as drag and downforce are very closely related. The key is how to create a lot of downforce, without increasing the drag significantly which is no small chore.
02-08-2010, 11:31 PM
#23
Nordschleife Master
Everyone should read this: http://autospeed.com/A_108656/cms/article.html
It's part 1 of a 5 part article on DIY aero testing.
Enjoy!
It's part 1 of a 5 part article on DIY aero testing.
Enjoy!
02-08-2010, 11:39 PM
#24
02-09-2010, 02:19 AM
#25
Drifting
Join Date: Sep 2008
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ritzblitz: if that's your car, only one phrase of warning, 911 gt1 flipping.
as much as you want a flat bottom, there's still air getting under the car, it needs a place to go, too much air creates lift, the enemy. using technology used on the 917, tunnels work best, for a 944 a little lip spoiler to hold the front down at higher speeds, any air under the car can be directed towards the torque tube tunnel, which if done right the exhaust can dump into there also. this allows for a flat bottom and a suction effect on the car.
of course with all this, redo the springs, obviously if you have 600lb springs and 200lbs of suction/down force, the car isn't going to squat down.
for spoilers in the rear, as high up in the air...anyone else remember Chapperal race cars from the 70's? that's the reason you see the gt3 rsr's with such high spoilers, spoilers want as much clean air hitting them to make them work the best. a good spoiler for a 944 that allows better than stock while still looking good, a 968 turbo spoiler, with the adjustable center peice.
BMW's lip spoilers(as well as c6 corvettes) work extremely well for weekend warrior duties.
the enemy of the Porsche with CD, front engined cars were tall engines, and boxy, and the mid/rear engined still had large front ends. CD for a 1994 968 and a 1994 911 C2 were the same.
also active aerodynamics have come along way, the 911 aero spoiler going up at 75(as with the cayman/boxtser). if anyone remember the 1991-1996 3000gt VR4, it had active aero that was extremely effective. so much so that at 120mph, any lift at the front end or rear were canceled out by the two spoilers. it's a very cool car to see in the wind tunnel.
as much as you want a flat bottom, there's still air getting under the car, it needs a place to go, too much air creates lift, the enemy. using technology used on the 917, tunnels work best, for a 944 a little lip spoiler to hold the front down at higher speeds, any air under the car can be directed towards the torque tube tunnel, which if done right the exhaust can dump into there also. this allows for a flat bottom and a suction effect on the car.
of course with all this, redo the springs, obviously if you have 600lb springs and 200lbs of suction/down force, the car isn't going to squat down.
for spoilers in the rear, as high up in the air...anyone else remember Chapperal race cars from the 70's? that's the reason you see the gt3 rsr's with such high spoilers, spoilers want as much clean air hitting them to make them work the best. a good spoiler for a 944 that allows better than stock while still looking good, a 968 turbo spoiler, with the adjustable center peice.
BMW's lip spoilers(as well as c6 corvettes) work extremely well for weekend warrior duties.
the enemy of the Porsche with CD, front engined cars were tall engines, and boxy, and the mid/rear engined still had large front ends. CD for a 1994 968 and a 1994 911 C2 were the same.
also active aerodynamics have come along way, the 911 aero spoiler going up at 75(as with the cayman/boxtser). if anyone remember the 1991-1996 3000gt VR4, it had active aero that was extremely effective. so much so that at 120mph, any lift at the front end or rear were canceled out by the two spoilers. it's a very cool car to see in the wind tunnel.
02-09-2010, 04:03 AM
#26
If its showing up in the device manager properly (ie no yellow exclamation points) try using google picassa to do the scan. I've had good luck with it when the OEM software failed to work on vista/7 for customers pc's.
02-10-2010, 03:47 AM
#27
Rennlist Member
02-10-2010, 03:48 AM
#28
Rennlist Member
Everyone should read this: http://autospeed.com/A_108656/cms/article.html
It's part 1 of a 5 part article on DIY aero testing.
Enjoy!
It's part 1 of a 5 part article on DIY aero testing.
Enjoy!
02-10-2010, 02:53 PM
#29
Three Wheelin'
Join Date: Jan 2010
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If enough guys are serious, a full day wind tunnel can be rented (with an experienced wind tunnel operator) for $6-$9K. No small coin mind you, but for 50+ guys, it is not such a big deal. I was part of a group of Datsun 240-280 guys that did this two years ago, and we learned an incredible amount about the airflow around 1st gen Z cars. Several parts suppliers offered free aero parts (wings/airdams) to test, and a group of a dozen guys with 4 cars worked all day trying different configurations, as well as baseline stock runs. All info learned was shared with the group who paid for it all. I have been using this info to improve, and at a minimum not do anything to the car that may increase drag/reduce downforce.
If you're serious about drag/downforce, then it may be an excellent opportunity.
Just a thought.
Scott.
If you're serious about drag/downforce, then it may be an excellent opportunity.
Just a thought.
Scott.
02-11-2010, 11:23 PM
#30
In response to the undertray idea, does anyone have a technical solution to attach the panels to the underside of the car?
I'm imagining a short threaded tube that is itself bolted to the underside of the car?
The greatest source of drag is the surface under the car and turbulence through the wheels/arches, so this is the place to start.
Coincidentally this is also a key area to generate downforce via "ground effect"... in simple terms creating low air pressure under the car...
I read an excellent article in racecar engineering about undertrays and diveplane/splitters - I reckon a thin grp undertray would be worth the weight for a track 944 if it's shaped right.
I'm imagining a short threaded tube that is itself bolted to the underside of the car?
The greatest source of drag is the surface under the car and turbulence through the wheels/arches, so this is the place to start.
Coincidentally this is also a key area to generate downforce via "ground effect"... in simple terms creating low air pressure under the car...
I read an excellent article in racecar engineering about undertrays and diveplane/splitters - I reckon a thin grp undertray would be worth the weight for a track 944 if it's shaped right.