Top end Bonneville straight line speed poll

[learical1]

Everybody knows that one of the big advantages to the 'Bird and Daytona was the wing.  It added stability to the cars on the high banks at Daytona and Talledega, allowing faster lap times.  However, in a straight line, the drag created by the wing and its supports probably slowed the Mopars down slightly.  So, at Bonneville, which of the aero cars would give the highest top speed?   I gave you a choice of engines on the FoMoCo products, because while the tunnel-port 427 may not have had the 'off the corner' torque of the Boss 429, they were very similar in overall horsepower.  I also gave everybody a chance by including the SuperBird and Talladega, when most schools of thought lead us to believe that the Daytona was superior to the 'Bird and the Spoiler II was superior to the Talladega in a straight line. Please give your reasoning.  

[learical1]

I chose the Spoiler II with the Boss 429.  This car often sat on the pole at the big tracks.  I'm not sure if the Boss 429 is really superior to the 427 tunnel-port in top end performance, but I believe it has more potential, so I went with the Boss '9.  However, if I was building a Spoiler II for Bonneville, I'd go with the tunnelport just because it's an easier fit.

[41husk]

I voted for the Daytona, first to break 200MPH, and I like them best

[Ghoste]

I voted Daytona because I think its package is slightly better than the Plymouth and I think the Fords had about hit their max on the big ovals.  I think had they gone much faster they too would have been looking for extra downforce at the back.

[Indygenerallee]

OOOooh That's a tough one....... Daytona with a elephant of course!!! 

[tan top]

Daytona  , but superbird is the next closest  , had almost as good aero as the daytona , but not quite

[learical1]

Just a reminder:  downforce keeps you 'glued' to the track.  Up to a certain point, the more downforce you have, the less you have to slow down for the corners.   Too much downforce = increased drag = slower speeds.  Not enough downforce = no traction in turns = slower lap speeds.  But I'm talking straight line, ultimate top end 'Bonneville' kind of speeds, not lap times.  I changed the thread title to make things a bit clearer.  I also allowed for vote changes, in case you change your mind.
BTW, I'm waiting for Doug S (aero426) to chime in.  I'd like his take on this.

[learical1]

And I'd really like C5HM's opinion, too!

[Ghoste]

I'll stay with my answer for now.  My reasoning for it being that while agreeing on the downforce and drag, remember the wing on the Mopars adjusted so you could set it for the right amount of downforce.  The shape of the Ford at speed was going to eventually create lift in my opinion which would be worse for straight line.  Now your question taken literally, as set up for NASCAR makes it a different thing.  I'm taking your question to mean NASCAR ready but running on the salt with minor tweaking to set a record for straight line top speed, NOT which car is faster in a straight line if you drove it right from Talladega to a salt flat with no changes.

[hemigeno]

A couple of dumb question here:

Aren't most of the participants' top speeds significantly limited by their vehicle's traction?  Seems like you're going to need a certain amount of downforce to keep the rear wheels planted even while going in a straight line - meaning a properly balanced package of nose and wing on a Daytona probably still gives it an edge.

Also... didn't the #71 Daytona (the actual car now owned by Tim W.) and Bobby Isaac set new speed records at Bonneville after the '70 season was completed?  If I'm not mistaken, don't some of those records still stand?  I'd be interested to know if the Ford/Mercury aero offerings were sent to the Flats back then also.  From what I remember from talking with the (now late) Harry Lee Hyde Jr., the #71 still had more speed to show -- but exhaust leaks and time kept them from doing more.  They broke the exhaust after a spin during one of Bobby's runs.

I haven't really heard Bonneville stories from any blue oval teams, although they may have done a whole lot and have maybe even broken some of the K&K team's records too.  

[odcics2]

If you go by the HP of the engines and the drag numbers in the real world, I bet it would be close between the 426 Daytona and the 429 Mecrury.

Keep in mind the wing is adjustable for downforce - just enough tilt to keep the tires on the ground...
The Merc would need the rear spoiler tweaked to maximum performance. (note: not lowest drag, nor max. downforce, but a combination)

It's a fact that a wing produces less drag for the same downforce as a rear spoiler.

429 had an edge on top end HP, since it was a newer design.   Daytona has lower drag - per aero tests run by Ford!! (and can be seen on the DSAC web site)  

Glotzbach ran 199.466 to grab the pole for the first Talladega race in the #88.  LeeRoy Yarborough was a close second.  Neither car competed due to the tire boycott.

 
This is a good question!  

 

[learical1]

Now your question taken literally, as set up for NASCAR makes it a different thing.  I'm taking your question to mean NASCAR ready but running on the salt with minor tweaking to set a record for straight line top speed, NOT which car is faster in a straight line if you drove it right from Talladega to a salt flat with no changes.

Yeah, I could have worded it better.  I just didn't want anyone to think I meant stock street cars.  A 351 W Spoiler II isn't going to cut it.  I should have said something to the effect that you take 6 early 1970 NASCAR Aero cars (with side glass),  set them up to go in a straight line (no worries about turns), and let them loose at Bonneville.  Which car will have the highest 'flying mile' speed?

[odcics2]

A couple of dumb question here:

Aren't most of the participants' top speeds significantly limited by their vehicle's traction?  Seems like you're going to need a certain amount of downforce to keep the rear wheels planted even while going in a straight line - meaning a properly balanced package of nose and wing on a Daytona probably still gives it an edge.

Also... didn't the #71 Daytona (the actual car now owned by Tim W.) and Bobby Isaac set new speed records at Bonneville after the '70 season was completed?  If I'm not mistaken, don't some of those records still stand?  I'd be interested to know if the Ford/Mercury aero offerings were sent to the Flats back then also.  From what I remember from talking with the (now late) Harry Lee Hyde Jr., the #71 still had more speed to show -- but exhaust leaks and time kept them from doing more.  They broke the exhaust after a spin during one of Bobby's runs.

I haven't really heard Bonneville stories from any blue oval teams, although they may have done a whole lot and have maybe even broken some of the K&K team's records too.  

The car used at Bonneville was not NASCAR legal.  It was a USAC sanctioned run.  

[hemigeno]

The car used at Bonneville was not NASCAR legal.  It was a USAC sanctioned run.  

I understand that completely... the #71 in salt flats trim had no driprails and other non-NASCAR modifications.  No one said anything (initially) about NASCAR rules applying though, I thought...  

[learical1]

A couple of dumb question here:...

Also... didn't the #71 Daytona (the actual car now owned by Tim W.) and Bobby Isaac set new speed records at Bonneville after the '70 season was completed?  If I'm not mistaken, don't some of those records still stand?  I'd be interested to know if the Ford/Mercury aero offerings were sent to the Flats back then also.  From what I remember from talking with the (now late) Harry Lee Hyde Jr., the #71 still had more speed to show -- but exhaust leaks and time kept them from doing more.  They broke the exhaust after a spin during one of Bobby's runs.

IIRC, what hampered Bobby and Harry more than anything else in 1971 was poor salt conditions.  Ideally for endurance runs at Bonneville, you want a 10 mile circle to run on.  That is almost like running in a straight line, the curve is so gradual.  Well, the salt was too wet in places to allow a true circle that year, and Bobby had to run a 10 mile flat OVAL, and he drove it like a dirt track, letting the back end slide out.  That does slow you down a bit. 

And, if you move all your ballast weight to the rear of a Spoiler II, you'd probably have more than enough traction for 210 + MPH.

[Ghoste]

As speeds increase though the blunter nos of the Mercury is going to come into play more and more.

[odcics2]

Now your question taken literally, as set up for NASCAR makes it a different thing.  I'm taking your question to mean NASCAR ready but running on the salt with minor tweaking to set a record for straight line top speed, NOT which car is faster in a straight line if you drove it right from Talladega to a salt flat with no changes.

Yeah, I could have worded it better.  I just didn't want anyone to think I meant stock street cars.  A 351 W Spoiler II isn't going to cut it.  I should have said something to the effect that you take 6 early 1970 NASCAR Aero cars (with side glass),  set them up to go in a straight line (no worries about turns), and let them loose at Bonneville.  Which car will have the highest 'flying mile' speed?

Hemigeno  - He added the "NASCAR" AFTER your comment and prior to mine!    

[Redbird]

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. A back in the day time puts Lindsley's Plymouth or the #71 car pretty much equal in top speed, Lindsley's car being a lot more stock-especially the front spoiler.

Today with the mega dollar motors in a SCTA-BNI rule car, the 426 cars win, because the rules are the same; in a Production class you have to run a "family" motor. Engine development is a lot better for the 426. Bring your wallet.

Stepping up in classes where a motor swap is allowed, back in the day the 2 hemi cars or a 429 Mercury. Engine development+aero for the 3 cars I think would be about equal at that time.

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.

The rules are why it would be very hard for the tribute #71 car to get a record. Front end modified makes it a Competition Coupe. Not even close to a Production, Altered, or Gas coupe classification.  Record for CC is about 250 MPH in A class motor. Modified quarters would make it ineligible for the Competition Coupe class and a time only car. Mostly to say a very cool car.

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.

[Aero426]

The Spoiler II was a bullet on the ovals.   I don't think one has ever been run on the salt.     But I bet it would run very well. 

[odcics2]

Here is the Ford wind tunnel info from the DSAC website.  Larry Rathgeb has stated the hemi in the Engineering Daytona put out 575 hp during the 200 run.  These figures from Ford support that. 

[Ghoste]

Is that top speed an average lap speed or straightaway?

[tan top]

interesting thread  

Is that top speed an average lap speed or straightaway?

thats what i've always wondered !! with that chart  , think  could be lap speed , caculated by time !!
not straight line speed ,  pure speculation now   , but if you had a arrow straight strip of black top ,  10 miles long !! no power / speed  robbing   banking   etc etc wonder what the top end for all the cars would be , even the C500

what it comes down to as we all know  , is  can the motor make enough power  to pull  X amount of rpm  ie 6500 or 6600 6800  (((((  think ( not sure ) at the time that was the max safe limit sustained RPM for a Hemi ))))))   , with   2.94  or 2.76  rear gears  + tire hight ,  in high gear , ( fourth )  if the motor  not making enough power to turn that RPM in a given body style , & there is no more power in the motor  ,   make  the car cut through the wind better !

wonder what would of happened ir the Areo cars could have run with  twin four barrels

[Ghoste]

I've wondered because did they not obtain higher lap speeds at Chelsea's much larger than average oval?

[hemigeno]

I've studied the doc that Greg/odcics2 posted before, but something just jumped out at me...

How-in-da-heck did Ford get their hands on a Daytona to use in their wind tunnel on August 3, 1969, when the only one shipped up to that point was maxwellwedge's car (414619) that went to the Toronto Car Show?  The next one didn't leave Creative Industries of its own accord until 8/16/69.  Did one leave Creative's back lot late one night and get returned before the next morning?  

[Ghoste]

Maybe that one is the theoretical data test?

[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.

[Ghoste]

Is the wing versus adding ballast not a moot point here though?  If we are talking about top speed as set up for NASCAR then the Ford aero cars could run no more ballast than they do on a high bank.  Or do I need to go back re-read because this has already been covered? 

[Redbird]

For a Production based car using SCTA-BNI rules, one of the main challenges is the amount of air going under the car and the lift it provides. Under the rules, all that is allowed in the front is whatever front bumper or spoiler the manufacturer sold. Even with the big lump-o-iron in front, air lifts the car at speed.

A 1982 Pontiac Firebird had an optional aero front that works great.

A NASCAR car solves the same problem because one can run Harry Hyde's best front spoiler, like the original #71 KK car did.

[learical1]

If we are talking about top speed as set up for NASCAR then the Ford aero cars could run no more ballast than they do on a high bank.  Or do I need to go back re-read because this has already been covered? 

For the oval tracks, ballast was added low,between the front and rear wheels.  I believe the rules call for a minimum weight, not a maximum weight.  Theoretically, you could add as much ballast as you need.  Extra weight kills acceleration, not top end.

[Ghoste]

Perhaps true of the amount of weight we are discussing but I'd disagree if you meant that as an absolute.

[JB400]

There's a maximum and a minimum weight limit.

[Sbird69]

There is absolutely no disadvantage from the wings and actually the additional ass end weight is a benefit. Another example would be that we fill the regular gas tank to water (at 9lbs per gallon it works great) to provide additional rear tire 'bite' on the slippery salt as you attempt to gain traction and get up to speed before the timing lights. The wings are adjustable and can be matched to your actual car attitude to provide a neutral force. Tha ADVANTAGE is the end supports of our wings and the lateral force which prevents the rear end from going sideways.   Roof rails must be fabricated,installed, and are mandatory on most of the production style vehicles run on the salt as the SCTA wants the over-car air stabalized. Drag coifficient number of the areo cars are available and should then be matched with the actual 'frontal area' number of each car.  The Daytona is tops of the areo's with the Bird and the Fords a toss up. If you search old archives you'll find comments from our Boston area local boy that won the Daytona 500 in 1970, Pete Hamilton, that on that February day 42 years ago he remembers throwing Petty's #2 car into the turns at dangerously excessive speeds and that the ass end stayed on the track like it was glued to the ground. God bless the Salt and that a place such as that even exists for us to play on. I do every August at Speed Week.
Sbird69

[odcics2]

There's a maximum and a minimum weight limit.

Checking the 1970 Nascar rule book, I found that there was a 3,900 lb. minimum weight only.   They did not specify a max. weight.  But more weight would slow a car coming off the corner...   And add to tire and brake wear.   

[Ghoste]

It would be kind of strange to specify a maximum weight in almost any motorsport wouldn't it?

[odcics2]

It would be kind of strange to specify a maximum weight in almost any motorsport wouldn't it?

Tractor pulls maybe?? 

[Ghoste]

Oh, yeah maybe.  Never thought of that one.

[held1823]

a max weight at bonneville makes perfect sense. traction is the issue, so any extra weight could be overcome with horsepower. 

it would be kind of humerous to pop a trunk lid, only to find a row of tractor weights hanging inside.

[odcics2]

a max weight at bonneville makes perfect sense. traction is the issue, so any extra weight could be overcome with horsepower. 

Or better aerodynamics!!! 

[Ghoste]

All hail the Charger Daytona. 

[JB400]

All hail the Charger Daytona.  

[odcics2]

All hail the Charger Daytona.  

Especially the race cars with the drooped front ends!!