coefficient of drag
03-11-08, 12:13 AM
#2
There is a thread that links to an article showing wind tunnel test results of an FD with and without the R1 wing. I have it bookmarked at home, but I'm travelling now. (The R1 wing adds drag, not downforce)
btw, that .25 sounds too low to me...
btw, that .25 sounds too low to me...
03-11-08, 02:21 AM
#3
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The official factory figures for U.S. spec cars are:
Standard body Cd .29
R model front air dam and rear wing Cd .31
Unless you are driving over 100 mph and really require the added stability, the aero appendages are more for show than go. In most circumstances the added appendages result in more drag and cost you a slight penalty in speed and gas mileage.
Standard body Cd .29
R model front air dam and rear wing Cd .31
Unless you are driving over 100 mph and really require the added stability, the aero appendages are more for show than go. In most circumstances the added appendages result in more drag and cost you a slight penalty in speed and gas mileage.
03-11-08, 04:59 AM
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From what I understand, the Coefficient of drag is basically how sleek the shape is. You also have to consider the size, or frontal area. That's where a FD would win over most cars for having lower total drag.
Use google if you want to know more, that's just what I've read before.
Use google if you want to know more, that's just what I've read before.
03-11-08, 05:28 AM
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03-11-08, 06:44 AM
#7
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frontal area as per mazda is 19.26 sq ft, 1.79 sq meters.
coefficients of drag are, as stated above... .31 R1 .29 non R1. that'd be 93-95 nose.
don't even ask what the Hummer noses w a front mount are Cd-wise.
hc
coefficients of drag are, as stated above... .31 R1 .29 non R1. that'd be 93-95 nose.
don't even ask what the Hummer noses w a front mount are Cd-wise.
hc
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03-11-08, 05:05 PM
#10
RHD Track Whore
As Caanon was saying...More important than the Cd, is the CdA (coef. drag multiplied by frontal area)
Cd=.29
A=19.26
CdA = 5.58 Ft^2
Compare that to these values and you really see how sleek and slippry the FD really is:
3.95 1996 GM EV1
5.10 1999 Honda Insight
5.71 1990 Honda CR-X Si
5.76 1968 Toyota 2000GT
5.80 1986 Toyota MR2
5.81 1989 Mitsubishi Eclipse GSX
5.88 1990 Nissan 240SX
5.92 1994 Porsche 911 Speedster
5.95 1990 Mazda RX7
6.00 1970 Lamborghini Miura
6.13 1993 Acura NSX
6.17 1995 Lamborghini Diablo
6.27 1986 Porsche 911 Carrera
6.27 1992 Chevrolet Corvette
6.35 1999 Lotus Elise
6.40 1990 Lotus Esprit
6.54 1991 Saturn Sports Coupe
6.57 1985 Chevrolet Corvette
6.77 1995 BMW M3
Cd=.29
A=19.26
CdA = 5.58 Ft^2
Compare that to these values and you really see how sleek and slippry the FD really is:
3.95 1996 GM EV1
5.10 1999 Honda Insight
5.71 1990 Honda CR-X Si
5.76 1968 Toyota 2000GT
5.80 1986 Toyota MR2
5.81 1989 Mitsubishi Eclipse GSX
5.88 1990 Nissan 240SX
5.92 1994 Porsche 911 Speedster
5.95 1990 Mazda RX7
6.00 1970 Lamborghini Miura
6.13 1993 Acura NSX
6.17 1995 Lamborghini Diablo
6.27 1986 Porsche 911 Carrera
6.27 1992 Chevrolet Corvette
6.35 1999 Lotus Elise
6.40 1990 Lotus Esprit
6.54 1991 Saturn Sports Coupe
6.57 1985 Chevrolet Corvette
6.77 1995 BMW M3
03-11-08, 05:39 PM
#12
I got the info here. Maybe I saw it wrong. http://www.rx7.net.nz/newrx7.htm
Dave
03-11-08, 08:51 PM
#15
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nice first post sip...
of course the bigger the composite (CD X frontal area) number the more drag.
think total aero drag isn't important? it is the factor that determines top speed and the miles per hour to solve for hp required is CUBED.
for instance...
FD stock approx top speed...
.29 X 19.26 X 159^3 mph/146,600= 153 fwhp plus 77 additional hp for the driveline losses= 230 total flywheel to run 159.
.29 X 19.26 X 200^3 mph/146,600 = 305 fwhp plus 93 additional driveline hp = 398 total flywheel hp to run 200 mph.
due to the speed being cubed, in this case it takes 73% more hp to go 25% faster.
want to go 240? that'd be 644 flywheel hp.
246 additional hp produces 40 more mph from 200 to 240.
the same 240 hp produced 159 mph!!
using sip's numbers it would take 780 flywheel whp to go 240 in the 95 M3.
finally, it is important to note that acceleration is created by having rwhp in excess of what it takes to drive your FD at a particular speed. the less drag you have the more acceleration.
hc
of course the bigger the composite (CD X frontal area) number the more drag.
think total aero drag isn't important? it is the factor that determines top speed and the miles per hour to solve for hp required is CUBED.
for instance...
FD stock approx top speed...
.29 X 19.26 X 159^3 mph/146,600= 153 fwhp plus 77 additional hp for the driveline losses= 230 total flywheel to run 159.
.29 X 19.26 X 200^3 mph/146,600 = 305 fwhp plus 93 additional driveline hp = 398 total flywheel hp to run 200 mph.
due to the speed being cubed, in this case it takes 73% more hp to go 25% faster.
want to go 240? that'd be 644 flywheel hp.
246 additional hp produces 40 more mph from 200 to 240.
the same 240 hp produced 159 mph!!
using sip's numbers it would take 780 flywheel whp to go 240 in the 95 M3.
finally, it is important to note that acceleration is created by having rwhp in excess of what it takes to drive your FD at a particular speed. the less drag you have the more acceleration.
hc
03-11-08, 09:01 PM
#16
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What about road loss, I don't think thats accurate.
Also a stock bodied (lowered) FC with 530 HP (probably FW) went 244MPH. By your calculations it should take more than 530HP to do that right?
I don't know what the FC's CD is but its got to be more than the FD.
http://www.mazdausa.com/MusaWeb/disp...itage04&bhcp=1
Also a stock bodied (lowered) FC with 530 HP (probably FW) went 244MPH. By your calculations it should take more than 530HP to do that right?
I don't know what the FC's CD is but its got to be more than the FD.
http://www.mazdausa.com/MusaWeb/disp...itage04&bhcp=1
nice first post sip...
of course the bigger the composite (CD X frontal area) number the more drag.
think total aero drag isn't important? it is the factor that determines top speed and the miles per hour to solve for hp required is CUBED.
for instance...
FD stock approx top speed...
.29 X 19.26 X 159^3 mph/146,600= 153 fwhp plus 77 additional hp for the driveline losses= 230 total flywheel to run 159.
.29 X 19.26 X 200^3 mph/146,600 = 305 fwhp plus 93 additional driveline hp = 398 total flywheel hp to run 200 mph.
due to the speed being cubed, in this case it takes 73% more hp to go 25% faster.
want to go 240? that'd be 644 flywheel hp.
246 additional hp produces 40 more mph from 200 to 240.
the same 240 hp produced 159 mph!!
using sip's numbers it would take 780 flywheel whp to go 240 in the 95 M3.
finally, it is important to note that acceleration is created by having rwhp in excess of what it takes to drive your FD at a particular speed. the less drag you have the more acceleration.
hc
of course the bigger the composite (CD X frontal area) number the more drag.
think total aero drag isn't important? it is the factor that determines top speed and the miles per hour to solve for hp required is CUBED.
for instance...
FD stock approx top speed...
.29 X 19.26 X 159^3 mph/146,600= 153 fwhp plus 77 additional hp for the driveline losses= 230 total flywheel to run 159.
.29 X 19.26 X 200^3 mph/146,600 = 305 fwhp plus 93 additional driveline hp = 398 total flywheel hp to run 200 mph.
due to the speed being cubed, in this case it takes 73% more hp to go 25% faster.
want to go 240? that'd be 644 flywheel hp.
246 additional hp produces 40 more mph from 200 to 240.
the same 240 hp produced 159 mph!!
using sip's numbers it would take 780 flywheel whp to go 240 in the 95 M3.
finally, it is important to note that acceleration is created by having rwhp in excess of what it takes to drive your FD at a particular speed. the less drag you have the more acceleration.
hc
03-11-08, 10:27 PM
#17
Racing Rotary Since 1983
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the formula comes from my well used "Tune To Win" /Carroll Smith and includes driveline deducts.
Kevin Draper built the two turbo setup for the RB FC and i am quite familiar w the motor. Kevin built the two turbos on my motor and i have worked w him for 6 years. the 530 number is (quite) conservative and is rear wheel. the boost number is off by a bunch. makes for good reading...
of course if you were to gross up the 530 to flywheel you end up w 623. close enough.
yes, you are certainly correct that the stock FC has more drag than the FD. i note the big mirrors are off the car and it is very low. i note they run skinny tires which helps a great deal. if they didn't have a full belly pan on the car, or depending on the rules, some sort of cleaning the underbody i would be surprised considering the highly sophisticated drivetrain.
all of which is off the fundamental point of my post.
aero is important. hp to go fast goes up w the CUBE of the MPH. the FD is one slippery stealthmobile
hc
Kevin Draper built the two turbo setup for the RB FC and i am quite familiar w the motor. Kevin built the two turbos on my motor and i have worked w him for 6 years. the 530 number is (quite) conservative and is rear wheel. the boost number is off by a bunch. makes for good reading...
of course if you were to gross up the 530 to flywheel you end up w 623. close enough.
yes, you are certainly correct that the stock FC has more drag than the FD. i note the big mirrors are off the car and it is very low. i note they run skinny tires which helps a great deal. if they didn't have a full belly pan on the car, or depending on the rules, some sort of cleaning the underbody i would be surprised considering the highly sophisticated drivetrain.
all of which is off the fundamental point of my post.
aero is important. hp to go fast goes up w the CUBE of the MPH. the FD is one slippery stealthmobile
hc
03-11-08, 11:33 PM
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What I notice is that a lot of current aero development is going on underneath the car with venturi tunnels and the like. Take a look at the Ferrari 430 Scuderia,
the 2005 Ford GT, or the new Corvette ZR1. There are no wild wings on these cars and they're all 200 mph vehicles. They're all stable at high speed and they do it with the most modest of lip / spoilers at the rear.
the 2005 Ford GT, or the new Corvette ZR1. There are no wild wings on these cars and they're all 200 mph vehicles. They're all stable at high speed and they do it with the most modest of lip / spoilers at the rear.
03-12-08, 03:16 AM
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That does make sense, for some reason I assumed the 530 was FW.
However the wikipedia article for CD lists the 1986 FC with AERO Package as having a CD of .29, also listing several other models at around .30, .31 etc.
Not sure how the aero package which adds a spoiler could have a lower CD than the car without a spoiler, but it would seem that the FC is also a very aerodynamic car, the frontal area is also about the same as the FD.
However the wikipedia article for CD lists the 1986 FC with AERO Package as having a CD of .29, also listing several other models at around .30, .31 etc.
Not sure how the aero package which adds a spoiler could have a lower CD than the car without a spoiler, but it would seem that the FC is also a very aerodynamic car, the frontal area is also about the same as the FD.
the formula comes from my well used "Tune To Win" /Carroll Smith and includes driveline deducts.
Kevin Draper built the two turbo setup for the RB FC and i am quite familiar w the motor. Kevin built the two turbos on my motor and i have worked w him for 6 years. the 530 number is (quite) conservative and is rear wheel. the boost number is off by a bunch. makes for good reading...
of course if you were to gross up the 530 to flywheel you end up w 623. close enough.
yes, you are certainly correct that the stock FC has more drag than the FD. i note the big mirrors are off the car and it is very low. i note they run skinny tires which helps a great deal. if they didn't have a full belly pan on the car, or depending on the rules, some sort of cleaning the underbody i would be surprised considering the highly sophisticated drivetrain.
all of which is off the fundamental point of my post.
aero is important. hp to go fast goes up w the CUBE of the MPH. the FD is one slippery stealthmobile
hc
Kevin Draper built the two turbo setup for the RB FC and i am quite familiar w the motor. Kevin built the two turbos on my motor and i have worked w him for 6 years. the 530 number is (quite) conservative and is rear wheel. the boost number is off by a bunch. makes for good reading...
of course if you were to gross up the 530 to flywheel you end up w 623. close enough.
yes, you are certainly correct that the stock FC has more drag than the FD. i note the big mirrors are off the car and it is very low. i note they run skinny tires which helps a great deal. if they didn't have a full belly pan on the car, or depending on the rules, some sort of cleaning the underbody i would be surprised considering the highly sophisticated drivetrain.
all of which is off the fundamental point of my post.
aero is important. hp to go fast goes up w the CUBE of the MPH. the FD is one slippery stealthmobile
hc
03-12-08, 10:03 AM
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Beat this!
Cd = 0.07 Nuna, World Solar Challenge winner 2001-2007
Formula 1 cars = 0.7 to 1.1 Cd
i wish I could find some reliable FD numbers EDIT: GOT IT! This is from a website dedicated to selecting a chassis for conversion to an electric car. They ended up choosing the MK1 MR2 because it is cheaper, fitment is no problem and parts are easy. The below cars were also chosen based on Curb Weight, the FD is hte heaviest of the bunch
Car CdA (m^2)
1993-1995 Mazda RX7 0.52
1989-1991 Honda CRX 0.53
1985-1989 Toyota MR2 0.535
1989-1994 Mitsubishi Eclipse 0.535
1990 Nissan 240SX 0.54
1990-1992 Mazda RX7 0.547
1993-1996 Mitsubishi Mirage Coupe 0.59
1992-1995 Honda Civic Hatchback 0.59
1989-1994 VW Corrado 0.59
1991-1996 Saturn SC1 0.603
1992-1992 Honda Prelude SI 0.61
1993-1997 Ford Probe 0.63
1984-1990 Pontiac Fiero 0.63
FD FTW!!!! Take off your rear spoiler and drop it even more! The regular spoilers on the FD don't create any downforce IMO, just drag.
Cd = 0.07 Nuna, World Solar Challenge winner 2001-2007
Formula 1 cars = 0.7 to 1.1 Cd
i wish I could find some reliable FD numbers EDIT: GOT IT! This is from a website dedicated to selecting a chassis for conversion to an electric car. They ended up choosing the MK1 MR2 because it is cheaper, fitment is no problem and parts are easy. The below cars were also chosen based on Curb Weight, the FD is hte heaviest of the bunch
Car CdA (m^2)
1993-1995 Mazda RX7 0.52
1989-1991 Honda CRX 0.53
1985-1989 Toyota MR2 0.535
1989-1994 Mitsubishi Eclipse 0.535
1990 Nissan 240SX 0.54
1990-1992 Mazda RX7 0.547
1993-1996 Mitsubishi Mirage Coupe 0.59
1992-1995 Honda Civic Hatchback 0.59
1989-1994 VW Corrado 0.59
1991-1996 Saturn SC1 0.603
1992-1992 Honda Prelude SI 0.61
1993-1997 Ford Probe 0.63
1984-1990 Pontiac Fiero 0.63
FD FTW!!!! Take off your rear spoiler and drop it even more! The regular spoilers on the FD don't create any downforce IMO, just drag.
Last edited by zenofspeed; 03-12-08 at 10:26 AM.
03-12-08, 10:48 AM
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The FD is not heavier then the fist gen eclipse, ford prob, mirage and some of the other cars on that list.
Beat this!
Cd = 0.07 Nuna, World Solar Challenge winner 2001-2007
Formula 1 cars = 0.7 to 1.1 Cd
i wish I could find some reliable FD numbers EDIT: GOT IT! This is from a website dedicated to selecting a chassis for conversion to an electric car. They ended up choosing the MK1 MR2 because it is cheaper, fitment is no problem and parts are easy. The below cars were also chosen based on Curb Weight, the FD is hte heaviest of the bunch
Car CdA (m^2)
1993-1995 Mazda RX7 0.52
1989-1991 Honda CRX 0.53
1985-1989 Toyota MR2 0.535
1989-1994 Mitsubishi Eclipse 0.535
1990 Nissan 240SX 0.54
1990-1992 Mazda RX7 0.547
1993-1996 Mitsubishi Mirage Coupe 0.59
1992-1995 Honda Civic Hatchback 0.59
1989-1994 VW Corrado 0.59
1991-1996 Saturn SC1 0.603
1992-1992 Honda Prelude SI 0.61
1993-1997 Ford Probe 0.63
1984-1990 Pontiac Fiero 0.63
FD FTW!!!! Take off your rear spoiler and drop it even more! The regular spoilers on the FD don't create any downforce IMO, just drag.
Cd = 0.07 Nuna, World Solar Challenge winner 2001-2007
Formula 1 cars = 0.7 to 1.1 Cd
i wish I could find some reliable FD numbers EDIT: GOT IT! This is from a website dedicated to selecting a chassis for conversion to an electric car. They ended up choosing the MK1 MR2 because it is cheaper, fitment is no problem and parts are easy. The below cars were also chosen based on Curb Weight, the FD is hte heaviest of the bunch
Car CdA (m^2)
1993-1995 Mazda RX7 0.52
1989-1991 Honda CRX 0.53
1985-1989 Toyota MR2 0.535
1989-1994 Mitsubishi Eclipse 0.535
1990 Nissan 240SX 0.54
1990-1992 Mazda RX7 0.547
1993-1996 Mitsubishi Mirage Coupe 0.59
1992-1995 Honda Civic Hatchback 0.59
1989-1994 VW Corrado 0.59
1991-1996 Saturn SC1 0.603
1992-1992 Honda Prelude SI 0.61
1993-1997 Ford Probe 0.63
1984-1990 Pontiac Fiero 0.63
FD FTW!!!! Take off your rear spoiler and drop it even more! The regular spoilers on the FD don't create any downforce IMO, just drag.
03-12-08, 10:58 AM
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Here are the dealer advertised curb weights. "Sometimes curb weight was given as a range, in that case I took something in the middle."
Car Curb Weight (Lbs)
1989-1991 Honda CRX 2100
1993-1996 Mitsubishi Mirage Coupe 2100
1992-1995 Honda Civic Hatchback 2100
1985-1989 Toyota MR2 2250
1991-1996 Saturn SC1 2300
1989-1994 Mitsubishi Eclipse 2550
1993-1997 Ford Probe 2690
1984-1990 Pontiac Fiero 2700
1990 Nissan 240SX 2700
1992-1992 Honda Prelude SI 2800
1990-1992 Mazda RX7 2800
1989-1994 VW Corrado 2800
1993-1995 Mazda RX7 2826
That is Incorrect.
And to back that up, here are the some curb weights from other sources (Wikipedia mostly):
Mirage 2017lb
Eclipse 2542lb
Probe 2696lb
FD 2826lb
Of course, removing the emissions stuff, stock twins and other junk, you can get a lighter FD. But all cars have weight saving opportunities.
Car Curb Weight (Lbs)
1989-1991 Honda CRX 2100
1993-1996 Mitsubishi Mirage Coupe 2100
1992-1995 Honda Civic Hatchback 2100
1985-1989 Toyota MR2 2250
1991-1996 Saturn SC1 2300
1989-1994 Mitsubishi Eclipse 2550
1993-1997 Ford Probe 2690
1984-1990 Pontiac Fiero 2700
1990 Nissan 240SX 2700
1992-1992 Honda Prelude SI 2800
1990-1992 Mazda RX7 2800
1989-1994 VW Corrado 2800
1993-1995 Mazda RX7 2826
And to back that up, here are the some curb weights from other sources (Wikipedia mostly):
Mirage 2017lb
Eclipse 2542lb
Probe 2696lb
FD 2826lb
Of course, removing the emissions stuff, stock twins and other junk, you can get a lighter FD. But all cars have weight saving opportunities.
Last edited by zenofspeed; 03-12-08 at 11:12 AM.
03-12-08, 11:14 AM
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Well then I am clearly wrong, and the FD is obviously a porker.
Here are the dealer advertised curb weights. "Sometimes curb weight was given as a range, in that case I took something in the middle."
Car Curb Weight (Lbs)
1989-1991 Honda CRX 2100
1993-1996 Mitsubishi Mirage Coupe 2100
1992-1995 Honda Civic Hatchback 2100
1985-1989 Toyota MR2 2250
1991-1996 Saturn SC1 2300
1989-1994 Mitsubishi Eclipse 2550
1993-1997 Ford Probe 2690
1984-1990 Pontiac Fiero 2700
1990 Nissan 240SX 2700
1992-1992 Honda Prelude SI 2800
1990-1992 Mazda RX7 2800
1989-1994 VW Corrado 2800
1993-1995 Mazda RX7 2826
That is Incorrect.
And to back that up, here are the some curb weights from other sources (Wikipedia mostly):
Mirage 2017lb
Eclipse 2542lb
Probe 2696lb
FD 2826lb
Of course, removing the emissions stuff, stock twins and other junk, you can get a lighter FD. But all cars have weight saving opportunities.
Car Curb Weight (Lbs)
1989-1991 Honda CRX 2100
1993-1996 Mitsubishi Mirage Coupe 2100
1992-1995 Honda Civic Hatchback 2100
1985-1989 Toyota MR2 2250
1991-1996 Saturn SC1 2300
1989-1994 Mitsubishi Eclipse 2550
1993-1997 Ford Probe 2690
1984-1990 Pontiac Fiero 2700
1990 Nissan 240SX 2700
1992-1992 Honda Prelude SI 2800
1990-1992 Mazda RX7 2800
1989-1994 VW Corrado 2800
1993-1995 Mazda RX7 2826
That is Incorrect.
And to back that up, here are the some curb weights from other sources (Wikipedia mostly):
Mirage 2017lb
Eclipse 2542lb
Probe 2696lb
FD 2826lb
Of course, removing the emissions stuff, stock twins and other junk, you can get a lighter FD. But all cars have weight saving opportunities.
03-12-08, 01:31 PM
#25
RHD Track Whore
nice first post sip...
of course the bigger the composite (CD X frontal area) number the more drag.
think total aero drag isn't important? it is the factor that determines top speed and the miles per hour to solve for hp required is CUBED.
for instance...
FD stock approx top speed...
.29 X 19.26 X 159^3 mph/146,600= 153 fwhp plus 77 additional hp for the driveline losses= 230 total flywheel to run 159.
.29 X 19.26 X 200^3 mph/146,600 = 305 fwhp plus 93 additional driveline hp = 398 total flywheel hp to run 200 mph.
due to the speed being cubed, in this case it takes 73% more hp to go 25% faster.
want to go 240? that'd be 644 flywheel hp.
246 additional hp produces 40 more mph from 200 to 240.
the same 240 hp produced 159 mph!!
using sip's numbers it would take 780 flywheel whp to go 240 in the 95 M3.
finally, it is important to note that acceleration is created by having rwhp in excess of what it takes to drive your FD at a particular speed. the less drag you have the more acceleration.
hc
of course the bigger the composite (CD X frontal area) number the more drag.
think total aero drag isn't important? it is the factor that determines top speed and the miles per hour to solve for hp required is CUBED.
for instance...
FD stock approx top speed...
.29 X 19.26 X 159^3 mph/146,600= 153 fwhp plus 77 additional hp for the driveline losses= 230 total flywheel to run 159.
.29 X 19.26 X 200^3 mph/146,600 = 305 fwhp plus 93 additional driveline hp = 398 total flywheel hp to run 200 mph.
due to the speed being cubed, in this case it takes 73% more hp to go 25% faster.
want to go 240? that'd be 644 flywheel hp.
246 additional hp produces 40 more mph from 200 to 240.
the same 240 hp produced 159 mph!!
using sip's numbers it would take 780 flywheel whp to go 240 in the 95 M3.
finally, it is important to note that acceleration is created by having rwhp in excess of what it takes to drive your FD at a particular speed. the less drag you have the more acceleration.
hc
Thanks, I try to contribute early on. Perhaps you will enjoy my 2nd post:
https://www.rx7club.com/showthread.p...=1#post7969592
*ends shameless self promotion
What parasitic losses does that formula comprise?
An additional thing to note is that at high speeds drag is sometimes given up in favour of downforce. No matter how sleek and powerful your car, you won't get anywhere without adequate traction and when lift=downforce you have a fatal problem.
http://www.youtube.com/watch?v=WLYIWY00X8M
http://www.youtube.com/watch?v=E0rzFdux3kY&NR=1
The right amount of downforce for a desired safe topspeed wilst minimizing CoD is a balancing act. One that Ferrari is perticularly good at (while making the car hot as well).
