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Anyone ever find a drag coefficient for our cars?


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Mostly curious, but I've never seen one.

 

To add to the question, what is the top speed verifed by GPS that anyone has seen in a 71-73 fastback?

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"I love my Hookers!" and "Get some Strange" probably have a different connotation to non automotive enthusiasts!

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No I havent either, but i know a 70-J code Torino was the first factory car to break 12 seconds with out any Mod's,and is listed as the second fastest factory car of the era behind the 427 Cobra.

"I never try anything, I just do it" :angel: [/size][/font]

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Mostly curious, but I've never seen one.

 

To add to the question, what is the top speed verifed by GPS that anyone has seen in a 71-73 fastback?

 

This site estimates it at 0.5 which is not great. Can't vouch for accuracy.

 

http://www.automobile-catalog.com/make/ford_usa/mustang_1gen/mustang_1gen_mach_i/1971.html

73 conv. 460, D0VE large valve heads, Performer RPM manifold, Voodoo 227/233 cam, Holley 950 HP carb, C6 trans, 3.25 trak-loc.

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Great sight. Thanks

2rr7aiv.png

 

Just cruising along minding our own business when BAM!!! The LAWS show up.

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Mostly curious, but I've never seen one.

 

To add to the question, what is the top speed verifed by GPS that anyone has seen in a 71-73 fastback?

 

This site estimates it at 0.5 which is not great. Can't vouch for accuracy.

 

http://www.automobile-catalog.com/make/ford_usa/mustang_1gen/mustang_1gen_mach_i/1971.html

Where is the boss ? hehe...1971 Boss 351 jumped from a standing start to 60 mph in 5.7 seconds and ran the quarter-mile in 13.6 seconds. In a Motor Trend test from 1971...Stock it beat the big block 429's...Plus im not sure where they figured out the top speeds..But thats all relevant too who orderd it with what rear end gears ...lol...They need to show..This car with this gear..ran this fast."Or should" seems like they just doing a little math and no research....lol...351 4v with a 275 is going to have a better top speed than some one with a 3.25 like mine...Btw..Mine all stock as a rock would run 130 mph before i ran out of rpm's..With original factory carb and manifiold.

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Mostly curious, but I've never seen one.

 

To add to the question, what is the top speed verifed by GPS that anyone has seen in a 71-73 fastback?

 

Found this in my favorites

Http://429mustangcougarinfo.50megs.com/performance_data.htm

"I never try anything, I just do it" :angel: [/size][/font]

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LOL. My Jeep Cherokee is nick named 'the flying brick'. Only a parachute would make the drag coefficient worse.

'Mike'

73 Convertible - 351C/4V CC heads/4bolt/forged flat tops/comp 270/rhodes/mallory unilite/tri-power/hookers/glasspacks/c6/3.50 limited slip/Gear Vendors/Global West sub frames, strut rods and shelby style traction bars/ Rear sway bar/tilt steering (not original)

 

Pics of modifications included in: [button=http://www.7173mustangs.com/thread-1973-convertible--3335]My Garage[/button]

 

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LOL. My Jeep Cherokee is nick named 'the flying brick'. Only a parachute would make the drag coefficient worse.

 

 

I owned a 78 Jeep cherokee 360-2V,holly carb, dana 44's. was one of the best sounding stock engines i ever heard. broke the frame in a few places on a logging road,then the tow out by my friends F-250 finished her off.:(

"I never try anything, I just do it" :angel: [/size][/font]

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Before I became a member of the '71-'73 movement back in Aug 2010, I was getting ready to finally put a '78 Wagoneer's AMC 360 into my '80 CJ-7, along with an '82 Wagoneer's TC-727.

 

Let's just say I got distracted, since the 360's still on the engine stand. :D

Eric

mach1sig2.gif

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When I was in college, I found a book in the library that discussed traction and hydroplaning. Part of the research testing was done with a 71-73 Fastback--can't remember what year specifically. But pictures in the book showed the car at speed from a "human perspective" as well as from the "road's perspective". The human perspective photo is how I knew it was a Mustang and it was labeled as "130 mile per hour test pass" or something to that effect. Next to it, was a picture of the tire contact patch over a piece of glass of the car passing at 130mph. Couldn't tell you the name of the book anymore or how I stumbled onto it--especially since I studied "Business" in college.

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1931 Ford Model A Station Wagon
1969 Mach 1 - 351C, TKO-600, 4WDB, R&P, A/C, Shaker, Fold Down, etc.
1972 Mach 1 - 351C, FMX, PDB, PS, A/C, Fold Down, Console
1996 Mustang Cobra Convertible - 10psi Procharger, 436rwhp

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Neat memory there!

 

Aerodynamics not withstanding, I have the gear ratio and power band peaking just about right for a top speed of better than 150 mph. But without a legal place to run a top speed test, I've been too timid to break 135. It was still pulling hard, but the front end was heading toward being a bit on the spooky side.

http://www.7173mustangs.com/gallery/1_01_07_15_8_53_18.png

 

"I love my Hookers!" and "Get some Strange" probably have a different connotation to non automotive enthusiasts!

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Back in my younger days there was a long stretch of highway 80 i could open up my 72 Mach , at 145 mph it smooth sailing

2zdx09d.png

Yea,Tho i cruise through the valley of the shadow of rice,I will fear no Turbo,For Torque art with me.Thy rods and crankshaft,they comfort me. :D Robert [button=http://www.7173mustangs.com/forum-garage?filterxt_uid=357]Visit My Garage[/button]

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  • 3 years later...

Ummm, this is slightly incriminating, but worth mentioning. Regardless of what the drag coefficient of a '71-73 Mustang actually is, I logged 172 mph on a local road somewhere in southern Arizona. I was not alone either, my friend and I were both tuning our 4R70W transmissions, particularly the overdrive gear and lockup behavior in 4th gear. I was actually shocked! There was plenty more gear and power left to go, but that was as far as I pushed it in order to tune my lockup converter scheduling in 4th gear.

 

I was particularly surprised that I was able to out-accelerate my friend's Falcon with a turbocharged 302, similar weight. Speeds were recorded using an onboard Garmin GPS unit since tuning requires better accuracy than my stock speedo.

 

As one of my co-workers has said before, it's possible to make absolutely anything fly, regardless of how bad the aero is on it (I work at an aircraft design and development firm).

1971 Mustang fastback: 10.3:1 C90E 408W hydroller - CDAN4 EEC-V w/EDIS8, girdled, lowered and caged

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MuscleCar Review "25 Fastest Fords" article

 

Specials;

'65 Shelby 427 12.20 / 118 (slicks

'70 Boss 429 12.30 / 112 (slicks

 

"stocks":

 

1) '62 Shelby Cobra 260.......12,90 @ 114..........4 spd.

2) '66 Shelby Cobra 427.......13,20 @ 110..........4 spd.

3) '68 Cougar XR7 GTE 428...13,23 @ 103,39.....C6

4) '69 Boss 429....................13,27 @ 107..........4 spd.

5) '70 Torino Cobra 429 scj...13,30 @ 106..........4 spd.

6) '71 Torino Cobra 429 scj...13,30 @ 106..........4 spd.

7) '71 Mach 1 429 cj............13,40 @ 105...........C6

8 ) '63 Marauder S-55 427....13,40 @ 105,7........4 spd.

9) '70 Boss 302....................13,43 @ 103,22.......4 spd.

10) '68 Mustang 428..............13,56 @ 105,62......4 spd.

11) '63 Galaxie 500 2dht 427..13.60 @ 107..........4 spd.

12) '69 Mach 1 428................13,69 @ 103,4........C6

13) '70 Mach 1 428................13,80 @ 103...........4 spd.

14) '71 Boss 351...................13,80 @ 104...........4 spd.

15) '65 Shelby AC Cobra 427..13,80 @ 106..........4 spd.

16) '64 Shelby AC Cobra 289..13.80 @ 112..........4 spd.

17) '69 Shelby GT500 428.......13,87 @ 104,52.....4 spd.

18 ) '69 Cougar ht 428cj.........13,93 @ 102,38.....4 spd.

19) '69 Cyclone 428cj.............13,94 @ 100,89......C6

20) '69 Fairlane Cobra 428......13,96 @ 101..........C6

21) '64 Galaxie 500 2dht 427...13,96 @ 106,80.....4 spd.

22) '70 Cyclone Spoiler 429scj..13,97 @ 100........4 spd.

23) '66 Comet Cyclone 390......13,98 @ 103,8......C6

24) '65 Mustang ht GT 289.......14,00 @ 100.........4 spd.


PS. I've got the drag cofficiency somewhere in my files. Was used & determined by some drag team back the good ole day. I'll try to find it.

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"stocks":

1) '62 Shelby Cobra 260.......12,90 @ 114..........4 spd.

 

Or, so they say :s

Dad's 260 Tiger only mustered, IIRC, a 16.4-ish @ somewhere in the mid-80 range back in the early '80's. Close ratio toploader (way too tall 1st gear for launching), a whopping 150 advertised HP and near zero traction didn't help... wound up the springs and wheelhopped BAD if it actually did get any (needed Traction Masters). With it's current (ahem, installed in the early '90's) Dunlop "big" rubber on it, it won't spin tire. Period.

A 15.99 woulda been cool that day.

 

I'll have to dig up that Keystone Raceway time card. It's probably still in the console.

 

Car was so stock at that time, probably still had its original antifreeze :)

And that I can vouch for.

 

Good stuff, all. Neat topic. I imagine that the vertical taillamp panel on our '72-73's added more drag than any other component.

Wonder if someone like Dark Horse Racing or any Bonneville racers has any info to view? Would be interesting to see, just for fun.

Pete - MotoArts Decals and Signs

'71 Sportsroof 351C-4V/4-speed - FINALLY under construction - no, wait, on hold again...

'90 Mustang 7-Up 5.0 ragtop, rolling beater - SOLD

'66 Sunbeam Tiger Mk.IA, survivor

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Jeff,

When I went back to the local Tech College to take the upholstery class the teacher in the automotive repair was into Bonneville racing. His car was a Mustang II not one of our Mach 1's. He was a member of the 200 mph club and his engine was like 235 ci. He held the record for the CI class he was in. He was running a GM engine that was made up of donated parts from racing friends in NASCAR.

With the correct added equipment I would think a 71 - 73 could go over 200 easily with a strong engine and correct gears. Don't forget they run special tires for high speed they have very little tread to make them not go crazy with the thick tread walking you see on street tires. The street tires tend to throw the tread off at high speed.

He is the guy that really proved to me that the NASA scoop design works. He had friends that work at Ford in Atlanta at the wind tunnel. They gave him the shape to use to incorporate a NASA scoop into his Mustang II. The hood he was running had one of the tall scoops like the Pro Mod guys run. So he went to Bonneville and took both hoods. He made some passes with his old hood and it was doing just fine. He runs a programmable fuel injection not a carb. He took the Pro Mod hood off and put the NASA hood with the scoop flat on the hood similar to the 71 - 73 and made another pass and melted the pistons out of the engine it got so much more air. So the NASA hood design does pull more air in than the tall hoods if done correctly. Don't know if ours is correct or not but you could tell with some sensors and high speed runs.

I don't want to read an article about someone crashing in Tenn. after hitting a possum.

There were high speed trials just south of Charlotte in Laurinburg, N.C.. They ran over 200 mph there but I think it got closed down in 2012. It was a WWII air force base. You might do some checking with ECTA the East Coast Timing Association on where you run safe, they ran the events there. The company I worked for had a division there called Scotland Mfg. made heavy truck oil filter cases, deep draw.

Your tires and wheels have to be approved to run in any of the trials here or Bonneville. I help build a streamline for Bonneville. You have to do several low speed runs on the short track to show the car is safe. Slow is over 100 and gradually work your way up. You cannot just go and take off down the main course. I have personally never gone over 170 and that was in Nov. at the Charlotte track it felt slow. They told me it always does until you hit the wall. When I started to pick up my speed they pulled me into the pits and did a tire check before I made it to 170. Just getting the feel of the car when time was up.

David

When a man is in the woods and talks and no women are there is he still wrong??:P

David

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  • 1 month later...

Regarding the aerodynamics, the shallow angled rear window/deck coming smoothly off the roof and the flat rear panel are absolutely the best parts of the car. The worst is almost certainly the massive amount of grille/intake above & below the front bumper. Also the underside of most cars is usually bad for drag as its so untidy, so lowering the front or having a deep spoiler is always good because you are keeping too much air from getting under there.

 

I plan on blocking up the lower intake on mine with some aluminium sheet. Painted black it should be pretty much invisible in there. Also I have a grand plan to lower the front edge of my cheapo aftermarket fibreglass spoiler a little more, probably with say a 2" deep lip of aluminium then fair this back to the lowest point of the valance or even (preferably) back to the rad support. A lot of cardboard templates required!

 

I think Finmach got confused between aerodynamic drag & drag racing...that's excusable in his case!

 

I'd love to have the nerve to run my car over 150mph but it hasn't got the gearing, I think 125-130 will be about it and also I don't have tyres that I can trust at the moment.

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We, my wife Amy and I race standing mile land speed time trials under the East Coast timing Assc. ECTA. She drives, We currently hold 5 records in several classes. Top speed last year was 180.577 in our '91 camaro CD .34. Anyone wanting to run over 135 on "street" tires let me know so as I can get some life insurance on you, not a smart thing to do. The ECTA did run at Maxton, NC but lost the lease and the surface was falling apart. We currently run at the air port in Wilmington, OH. 2miles of like new concrete. They have a class for those who want to just make some runs without trying to break records. It is called Time Only, TO. Registration has just opened for the first race of this year. Butt loads of fun. Look up the ECTA for info. Rules are tight but it's for your safety. BTW .5ish CD is about right.

Live, Laugh, love

ECTA, Ohio mile Landspeed record holder

C/GALT-136.36, AA/FALT 159.38 mph, New B/GALT Record 180.577mph- speed is the need !

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If I hadn't done the 4R70W, I would've most certainly done a Tremec 3550 or TKO manual transmission. The overdrive gear is one of the best mods you can make to your old Mustang. Just need to make sure that your transmission selection can handle the power and torque!

 

The sheetmetal blocking sounds like a very good plan. I'd be interested in seeing what you come up with. I recently taught myself how to design parts in Solidworks, which has made cutting metal on the waterjet infinitely simpler.

1971 Mustang fastback: 10.3:1 C90E 408W hydroller - CDAN4 EEC-V w/EDIS8, girdled, lowered and caged

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  • 2 years later...

About 1979, I became the owner of a 1971 Mach-1 -- or, more accurately, what was left of a 1971 Mach-1. The kid who first owned it went through 7 engines and 4 transmissions, and an assortment of driveshafts, and I know at least the gearing in the rear axle wasn't original. I don't have any elapsed time claims from anyone who knew that guy or the car when it was in the original owner's hands, but several people told me he was making "well over 500 horsepower" and that the car would do "between 125 and 130" in the (standing-start) 1/4-mile.

 

My parents sacrificed hugely for me: the shell cost $300; that was my Christmas and my birthday present. I worked and saved, and my parents "matched" (and I believe probably over-matched) my contributions towards getting the car into a driveable condition; Dad did most of the labor while I watched and learned. The front brakes were drum units from a 1972 Maverick that was wicked quick for a 302-2V; it had been dad's mom's car, until it was smashed by a railroad locomotive. Word to the wise: a little drop of water may seem like nothing in the gas tank, but it will kill your engine at the most inopportune time.

 

I frankly don't know how the kid got fuel for the car: in those days, we didn't have SEFI and "ignition modules" were the closest thing we had to computer controls; the octane requirements had to be ridiculously high. I know he had access to drums of VP, and in those days you could get both 100/130 and 115/145 aviation gasoline at a nearby airport, but none of those options seemed reliable for a "street car" that guzzled the go-juice. Some suggested he was associated with the organized crime that ran the state in those days; whether that was true, I don't know, but I was (perhaps curiously) invisible to the police whenever I was in that car.

 

At some point, I learned from the kid's dad (who seemed astonished that I was actually driving the car) and from a few policemen that the car had been traveling at "more than 165 mph" when the driver lost control and the car had been sliced -- basically into two pieces -- by a telephone pole that passed through the car behind the front seats. I don't know how the kid survived that sort of crash, and the idea that the car had been repaired following that sort of catastrophic damage seemed incredible, but in the latter part of the mid-1980s, I decided to disassemble the car and rebuild it the way I really wanted it.

 

In the rear of the car was a shipping label very similar to the ones we used in air freight, and associated documentation basically indicating the back half of the car's unibody had been shipped to a local Ford dealer and a body shop; it didn't seem to me that it was a complete paper trail, but it certainly corroborated to me the claim the car had been split apart. The gears in the 9-inch rear provided a 2.75:1 reduction through an open differential; I think the axles were of the 28-spline variety -- which seems quite weak for the sort of power the previous owner had been sending to the ground.

 

So. In a SAE standard atmosphere, each cubic foot of air weighs 0.00256 pounds. If we assume the product of the aerodynamic drag coefficient and the car's frontal area (CdA) is 12.8903125 square feet, overcoming the aero drag at 165 mph requires 395.3 horsepower. Practical variations in air density will slightly change that number. When tuned well, the original Boss 351 engine (several of which had been the basis for the car's successive engines) could easily supply that much power while using the OE cast iron exhaust manifolds, without resort to exotic fuel or aftermarket hardware.

 

That leaves rolling resistance and post-(flywheel/flexplate) driveline losses, including slippage. Realistically, this is going to require roughly 499 lbs-ft of torque at 5800 rpm, assuming total net slippage of 4.37 percent. That seems easy enough, until you do the BMEP math: 213.934 psi, if the OE bore and stroke are retained; with a 0.060 overbore, the required BMEP drops to 207.658 psi. In the first few years of the 1970s, getting those BMEP levels from a gasoline-fueled, naturally-aspirated V8 was the automotive equivalent of landing a man on the Moon and safely returning him to earth in 1969.

 

However, it's too easy to simply claim "BS" and walk away: at least 4 of the engines the kid had run in the car had been strokers, and it's unclear whether any of the engines had been sleeved to allow 4.080-inch (popular in NHRA Pro Stock Clevelands) or larger bores. 366, 377, 393 and 408 combos were fairly popular in those days; a 408 would have delivered the power with a BMEP of 184.416 psi -- which is well within the realm of credibility.

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That's a long way to say no.

http://www.7173mustangs.com/gallery/1_01_07_15_8_53_18.png

 

"I love my Hookers!" and "Get some Strange" probably have a different connotation to non automotive enthusiasts!

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There's a book, IIRC "Mustang Muscle Cars", that's a compliation of Mustang reviews of magazines of that day. There's a review of the 71 that shows a drag coefficient in the specs area. I have a copy, just not sure where I put it.

 

 

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Lets guess. I say .34.

 

Sent from my SAMSUNG-SM-G930A using Tapatalk

20160929_171923_edit2_small.jpg

 

1971 M-Code Mach 1 w/Ram Air, 408 stroker, 285/291 0.558" roller cam, Blue Thunder intake, TKO600, Hooker headers with electric cut-offs, FiTech EFI w/ RobBMC PowerSurge pump

Strange center section with Truetrac, 3.5 gear and 31 spline axles, 4-wheel disc brakes

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I'd bet it is closer to .44

http://www.7173mustangs.com/gallery/1_01_07_15_8_53_18.png

 

"I love my Hookers!" and "Get some Strange" probably have a different connotation to non automotive enthusiasts!

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