Top end Bonneville straight line speed poll

[hemigeno]

I thought of that, but it seems more likely the "theoretical" numbers are the projected horsepower and top speed numbers.  I know the engineers back then were pretty sharp, but I'd be surprised if they could calculate drag numbers very precisely simply from looking at the scant Daytona advertisements floating around at the time.  The way it looks to me, they tested a car in the Dearborn tunnel at 120mph and projected the balance of the numbers from those results... but that's just conjecture on my part.

[Ghoste]

The Creative back door theory is interesting.  Enough money to a night shift employee and things happen.  Dearborn had a lot spies watching that car out at Chelsea too though didn't they?  Could they have derived an accurate shape from that?

[JB400]

I'm pretty sure Ford could have gotten their hand on a Dodge charger easy, and just by looking at photos put a nose and a wing on it.  It'd give them a pretty good baseline even if they didn't have the actual car.  I'm going to assume that Chrysler had a  Torino and a Cyclone to do comparison tests on as well.   

[Ghoste]

But getting their hands on a Talladega or Spoiler II before they even shipped any wouldn't be so easy.  And certainly Ford would have had a 500 around that they could mock up.  Interesting, more so than their findings even.

[hemigeno]

And certainly Ford would have had a 500 around that they could mock up...

... with pre-production '70 Charger fenders & hood, not to mention a novel-concept nosecone/valance, and rear wing?  Maybe I'm too much of a conspiracy theorist, but I like their chances of quickly obtaining reliable drag data from a borrowed street Daytona (perhaps they only took measurements rather than testing the whole car??) moreso than being able to interpolate these same components from spy photos.

Granted, the chin spoiler for the wind tunnel tests would still have to be modeled after what they expected the oval track configuration to be rather than what is found on the street versions, so their reconnaisance work at Chelsea would have played a big role in that area for sure.  Even the race chin spoiler's shape and location was in a complete state of flux for Chrysler about that time - and it had a fairly significant impact on downforce/drag numbers as did the wing's profile (inverted Clark "Y" airfoil and the angle of the horizontal wing section).

[ae8i]

Whichever car that has George Wallace as the race engineer.

[Ghoste]

So we need to get the Ford aero guys in on this and find out who did this?

[odcics2]

The Ford numbers would be wind tunnel, so straight line, not lap.
Supposedly, DC-93 ran a best lap of 203 at Chelsea in the July 1969 test runs.   (NOT 243 or any other outrageous numbers!    )
I don't know of an actual document that states that, though...

Perhaps, this is why the Ford numbers have "203" listed on the header??     

   

   

[Aero426]

 The way it looks to me, they tested a car in the Dearborn tunnel at 120mph and projected the balance of the numbers from those results... but that's just conjecture on my part.

That is what they did.  Take the Ford memo numbers with a grain of salt.  For example, the King Cobra tested well in the tunnel, yet was inferior to the Talladega on the race track.   The Daytona that Ford tested was a street car, not a car in race trim.

Chrysler did have their hands on a street Talladega for examination in the Woodward Garage shop in Detroit.  No tunnel tests were made as Chrysler would have had to take the car to Lockheed in Georgia and drop it in through the roof.

[Ghoste]

So Doug, what are thoughts as to Ford having this data before the car was available?

[Aero426]

So Doug, what are thoughts as to Ford having this data before the car was available?

The ship list as we know, is when cars were sent to respective dealers.   But those dates may not take into account cars used for internal or public relations purposes, or exactly WHEN they were completed.  A good example is the Dale Reeker car, built very early and shipped last.    These internal use cars could be ones not included on the list.  Or they may be on the list, and "shipped" when their use as PR car was complete.    I have no idea how Ford got their hands on the car.     It is plausible to assume that it was a press car.    

I have not gone back to look at magazine articles to see when they were issued, and then to work backward a few months to account for lead times of the day.  

[odcics2]

Or a Ford guy was tipped off that they were in the process of being built at Creative.  It was no secret that the car was coming out or was going to be "mass" produced. 

Before the cars were lined up in the back lot, completed, there must have been a few that were being worked on inside at a "slow build" pace to get the bugs out of the process.  And the blueprints were already around...     

IMO - Ford had a 500 and built a cone based on the info they could come up with, either from the Reeker car or a mole at Creative.   

[Aero426]

Or a Ford guy was tipped off that they were in the process of being built at Creative.  It was no secret that the car was coming out or was going to be "mass" produced. 

Before the cars were lined up in the back lot, completed, there must have been a few that were being worked on inside at a "slow build" pace to get the bugs out of the process.  And the blueprints were already around...     

IMO - Ford had a 500 and built a cone based on the info they could come up with, either from the Reeker car or a mole at Creative.   

Yep.

[Ghoste]

I wonder if any of the behind the scenes stories will ever come out?  Somehow I don't think they will.

[elacruze]

As hinted a couple times above, traction is the issue at bonneville. Horsepower is never in short supply, and the Mopar wings have the most potential downforce so most able to find traction.
If the real question is which has the highest theoretical top speed, that's addressed by the wind tunnel info posted above.

[learical1]

Running under SCTA-BNI rules at Bonneville in 1970 in the Production class the contest is just between 2 cars, Superbird-Daytona. For the simple reason that one had to race with an engine design that was available in the car raced. For example Superbirds and Daytonas could have a Hemi or a wedge; 440, 426, 413, 400, 383, 361, 350 or even a destroked b-block, or stroked Hemi, B, or RB. Can't run a 340 in those cars in Production Class.

This means that a Mercury would get a 351 family motor and a Talledaga would get a 428 family motor. That is why there aren't any records by Ford bodies in the SCTA-BNI Bonneville record books in the Production class.

Weight is not your enemy at Bonneville. Aero, traction, and horsepower are. Fill any of the 3 cars with lead weight and their traction is about the same.

NASCAR back in the day at the flats, 429 Mercury, 426 Superbird or 426 Daytona.

NASCAR 1969 or 1970 body today, either of the 426 cars, strictly because of engine development.

Just my opinion.

Redbird, so would the 427 tunnelport be legal in a Talladega in Production class? the 428 and the 427 are both FE blocks...

Elacruze, as Redbird stated above (and he has driven a SuperBird at Bonneville), traction is part of the equation, but so are aerodynamics and horsepower.  Yes, you can 'dial in' more traction without adding weight on a Daytona because of the wing, but to get more traction, you increase the downward angle of the wing to increase downforce, but that also increases drag.  Weight isn't nearly the problem at Bonneville like it is at the big ovals, so you add ballast to increase your traction.  If traction was that critical, all wheel driven cars at Bonneville would run big fat tires.  Instead, as long as you aren't planning on turning at speed, you see skinny tires at the salt flats; less friction to overcome.  Also, in 1969-1970, the Boss 429 had a serious horsepower advantage over the Hemi.  That's why I believe the Spoiler II might do pretty well at Bonneville.

[tan top]

 not wanting to vere too far off track ,  what was  the rear tire height  of the daytonas/ superbirds run at  Bonneville &  on the nascar tracks 

[Ghoste]

Was the Boss 9 a "serious" horsepower advantage over the Hemi?

[learical1]

Was the Boss 9 a "serious" horsepower advantage over the Hemi?

25-30 HP.  Ford had the Holley Dominator before Ma Mopar did.  That alone may have made the HP difference.

[Ghoste]

They had commissioned Holley to build that carb did they not?

[learical1]

They had commissioned Holley to build that carb did they not?

Yepper.

[Redbird]

Bruce,

I don't have a current rule book where I am right now. But I have one from a couple of years ago. FWIW I don't think the definition of engine swap had ever changed in the rule book. I'll quote a couple year old rule book.

" An engine swap is the replacement of the original engine with one of a design, which was not available as a factory option for the particular car in question. The main factors used in determining design differences are cylinder head bolt pattern, intake manifold bolt pattern, and bell housing bolt pattern. Bore and stroke is not considered. Examples: a Chevrolet 350 engine in a 1955 Chevrolet is not a swap, but a 396 in a 1955 Chevrolet is."

I don't know enough about Tunnel Port parts to offer an opinion.

If one moves up from a Production Class to a Gas Coupe, or Altered one can swap engines. But then it is not a production car, plus one can do other things to the car on those classes.

Horsepower meaning money is a challenge for a lot of folks at Bonneville. There are a lot of past middle aged baby boomers at Bonneville today with wheelbarrows of money, there are also a lot of people there using just their milk money.

The salt is as hard as asphalt when it has been dried by the summer wind and sun. It is also slippery, think driving a muscle car on ice and snow with 60 series tires, not too smart.

Bonneville tires can take a lot of air pressure, I used 65 psi. Rolling resistence goes down at those numbers.

Bonneville tires have a small contact patch, more pressure on the ground per square inch of contact area. A tire round in section, I was told by a Goodyear engineer back in the day, tends to be the safest. An example is the section shape of an airplane tire, round.

Galen

[odcics2]

not wanting to vere too far off track ,  what was  the rear tire height  of the daytonas/ superbirds run at  Bonneville &  on the nascar tracks 

Same as the front!  (couldn't resist)

Seriously, I've seen the tires differ in height and width and all were marked the same size.  27 - 28" would be a ballpark, though.

[tan top]

not wanting to vere too far off track ,  what was  the rear tire height  of the daytonas/ superbirds run at  Bonneville &  on the nascar tracks  

Same as the front!  (couldn't resist)

Seriously, I've seen the tires differ in height and width and all were marked the same size.  27 - 28" would be a ballpark, though.

  same as front  !!      


oh right ,  thats interesting 

[bigfastjohn]

As a person who has run 299 mph on salt while losing 1000 rpm to wheelspin I can assure you that traction is a major issue on salt.Also the bigger the frontal area to be pushed through the air(a thin liquid)no matter how pointed it is then the greater the chance of the tires slipping. Ballast is the normal way to stop this but I guess it could be accomplished  with  wing downforce.