2020 Shelby GT500 Mustang - 10.61@133 MPH - Press Drive Articles/Vids

2020 Shelby GT500 Mustang - 10.61@133 MPH - Press Drive Articles/Vids

2020_GT500_Press_Photos_035.jpg

Today is going to be a pretty busy one for those with a huger for 2020 GT500 news. Last week Ford held its first official Press Drive for it's latest Snake Car in Las Vegas. Those in attendance were sworn to secrecy until today. In this thread we're going to try to aggregate all the best articles and videos in one place for you to enjoy:















 
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16.5” rotor is a huge swept area. The rolling stock is crucially ~5-10lbs lighter per corner. The downforce may negatively effect braking of the acr at speeds above 100mph compared to the gt500 because the car is effectively heavier by hundreds of lbs with smaller 15.4” rotors to alleviate the stresses while working on woahing about 60lbs of additional unsprung outboard weight. Edit 57lbs*


Sorry man, but you are way off here. Downforce and mass are two completely different things. The downforce created by the ACR’s aero in no way hurts braking. It’s the exact opposite. Carrying 4100# of forward motion with 300# of downward force is way different carrying 3400# of forward motion with 1700# of downward force. Newton's Laws.

Example: F1 car (very light with lots of downforce, often exceeding the weight of the car). Simply taking your foot off of the gas pedal produces significant deceleration. The aero is serving as an air brake.

As for you unsprung weight comment....wheel weight is only a part. The CC front rotors on the ACR are less than 14# each, while the GT350 rotors (1" smaller that the 500) run 30# each.
 
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Sorry man, but you are way off here. Downforce and mass are two completely different things. The downforce created by the ACR’s aero in no way hurts braking. It’s the exact opposite. Newton’s law my friend.

Example: F1 car (very light with lots of downforce, often exceeding the weight of the car). Simply taking your foot off of the gas pedal produces significant deceleration. The aero is serving as an air brake.

As for you unsprung weight comment....wheel weight is only a part. The CC brakes on the ACR will be massively lighter that the rotors on the GT500. Call unsprung weight a wash between the two.

Another thing that would be fun to compare - if I cared to do the math - that I bet would be a wash is the rotational mass as well. If I remember correctly, moment of inertia is predominantly concerned with radius; the GT500 has lighter rims, but they're 20s, vs the ACR that has heavier rims but 19s. I bet the overall value is closer than we would think...
 
Please don't take this as an insult, rather an observation, but based on some of your comments I do think you have fundamental misunderstanding of how aer

I’m aware springs rates are matched to load. The gt350r might be stiffer than a gt350, but we both know the acr rides waaaaay more harshly because it runs very aggressive rates. That was entirely my point. It will be choppy on anything but a smooth surface like leguna. What are you trying to paint here? Where did I fail you with my words to give you this idea that spring rate somehow should get softer with higher downforce? At a loss for words, no offense.


Sorry man, but you are way off here. Downforce and mass are two completely different things. The downforce created by the ACR’s aero in no way hurts braking. It’s the exact opposite. Newton’s law my friend.

Example: F1 car (very light with lots of downforce, often exceeding the weight of the car). Simply taking your foot off of the gas pedal produces significant deceleration. The aero is serving as an air brake.

As for you unsprung weight comment....wheel weight is only a part. The CC brakes on the ACR will be massively lighter that the rotors on the GT500. Call unsprung weight a wash between the two.

The downforce aides deceleration absolutely. That’s partly why it’s there. The other part is to press the car into the ground while cornering so it’s less likely to brake tire adhesion with the road surface. It creates... wait for it... drag. It’s c/d is .54, and limits top speed to 175 as there is... wait for it... a resistance to accelerate. Most trucks have .45-.7 c/d’s too. They are a huge air brake as well without wings or aero pieces. A school bus is also a giant air brake, as is a motor home. Just being wing shaped doesn’t mean something will cause drag. Adjustability of aero pieces can actually cause... lift. Planes do this by the way. They have wings and actually fly.

Back to cars, take your F1 analogy.

F1 cars don’t run 235lbs of unsprung weight though. They run 15” wheels with fushy load absorbing tires because... there’s tons of aero force and a very small chassis to mitigate the forces against. The tire acts as an absorber as much as it acts as a road holder. It’s very goowey compound.

Imagine an f1 car with 235lbs of heavy unsprung rolling stock, it would be horribly slow. The tires would be gone in 3 laps.

I’m saying the downforce is detrimental to some braking dynamics on the acr because it is pushing those heavier wheels/tires down with additional load. The actual braking distance is not impaired, if anything its shortened. Now that the vehicle has been slowed, that extra 30% of unspurng weight the viper acr has motivated to woah now needs to experience a polarity shift of its centrifugal balance to either move left, right, or accelerate. That heavier rolling stock is now tasked with that tug which is transferred to the tires, and generally slows transitional balance, and wears tires. Overall it’s not beneficial to run such heavy wheels/tires. The viper acr would be much quicker and easier to control with carbon wheels. What is there not to get about that? An f1 car with all its aero would do far worse at braking and dynamic directional changes with heavier wheels as well. As a system, heavy downforce, stiff suspension and heavy wheels will lead to understeer on corner entry and a resistance to change direction. Although worded admittedly vaguely and open to critic, that’s my point. The downforce isn’t just magically bettering the acr’s braking. In a straight line sure but put total braking performance like transitioning to entering corners on decel or mid corner decel or off camber and the heavy wheels are further pushed to avoid turning in/understeer. There’s no 1 sentence way to easily state that effect but it’s whats implied by the idea that downforce isn’t the end all be all for braking. Braking isn’t just 60-0. Almost no car ever needs to perform a 60-0 straight line stop on a circuit unless it’s to avoid a wreck.

As for unsprung weight, compare the viper brakes and gt500 brakes, but keep in mind what is more so outboard and more so inboard. Yes the 16.5” rotor is heavier, but Not to the extent of 30lbs each vs the vipers. And let’s just stoke an ego fight and say they are.

Look at an ace wheel, tire and brake disc from a top down helicopter view and imagine where the weight exists.


(heavy wheel & tire|light disc)hubaxle

Now look at the gt500’s

(light wheel/tire|heavy disc)hubaxle

1. Notice the placement of weight.
2. Notice the span of the weight.
3. Keep in mind the vipers heaviest piece in all of this is a 10lbs heavier rear tire which is the outer most and tallest piece.
4. Even assuming the mustang is somehow running 30lbs heavier rotor in the form of 8-9lbs front and 7-8lbs rear, that is deep in the wheel, and centered on a hub. It’s also max 16.5” span again centered, and equally spread. The vipers rear tire is 3-4” tall, and a halo of additional weight, with a 15” span and 28” height.

Now play with those objects in your mind and see which one as a system is less or more prone to motivational distress or failure to perform as desired.

You can two athletes that weigh the exact same but one can easily run a 100m dash like an Olympian and the other can lift 500lbs on a bench press, one will be terrible at running and the other will barely lift 200lbs on a bench. That’s my point. Here. Even if the brakes negate the wheel advantage in terms of weight, where the weight is spread is far smarter on the gt500 for road feel, handling and general driver communication.

I guarantee a gt500 cftp car will be far slower with acr wheel/tire/brake (and accordingly optimized suspension recalibration) and likewise a viper acr will be dramatically faster with gt500 wheel/tire/brakes and accordingly recalibrated suspension tuning.

The viper does likely need a 355 rear to handle the load of a 1700lbs of downforce, so as a system that would become a hurdle to account for, so let’s say you take that into account and formulate a carbon wheel, and heavy rotor for the viper acr’s Dimensional needs and formulate a lighter 355 tire.

Michilines mustang gt500 specific tire is very light for its size at 29/30lbs.

This is too much shit to write. Why do you guys not pick stupid shit that will take hours to write and explain. It took me 2-3 times of trying to get back to this to break this down. Enjoy typos because I don’t have time to proof read right now.
 
I guarantee a gt500 cftp car will be far slower with acr wheel/tire/brake (and accordingly optimized suspension recalibration) and likewise a viper acr will be dramatically faster with gt500 wheel/tire/brakes and accordingly recalibrated suspension tuning.

Sorry man, your super long-winded posts have lots of errors in them. All of your examples aside.....your basic understanding of physics is lacking.

Don't have the time or effort to debate all of them. Keep writing these entertaining 5 page dissertations.

I guarantee a gt500 cftp car will be far slower with acr wheel/tire/brake (and accordingly optimized suspension recalibration) and likewise a viper acr will be dramatically faster with gt500 wheel/tire/brakes and accordingly recalibrated suspension tuning.

LOL....it's a guarantee!

I'm sold

You can't possibly make that summation with the information you have, and further proves that you tend to be a tad overzealous on things.
 
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Another thing that would be fun to compare - if I cared to do the math - that I bet would be a wash is the rotational mass as well. If I remember correctly, moment of inertia is predominantly concerned with radius; the GT500 has lighter rims, but they're 20s, vs the ACR that has heavier rims but 19s. I bet the overall value is closer than we would think...

Agreed....I bet it nets out very close, especially when you figure in the rotor weight differences. We won't know until someone weighs a set of 500 rotors, but I'd wager they run on the order of 20# heavier per rotor than the CC on the ACR. Following your point on MoI, not only are the 500 rotors MUCH heavier, they also have a larger radius.
 
I’m aware springs rates are matched to load. The gt350r might be stiffer than a gt350, but we both know the acr rides waaaaay more harshly because it runs very aggressive rates. That was entirely my point. It will be choppy on anything but a smooth surface like leguna. What are you trying to paint here? Where did I fail you with my words to give you this idea that spring rate somehow should get softer with higher downforce? At a loss for words, no offense.

The ACR also has 5X the downforce a GT350R has. To drive an aero car fast you actually have to drive it fast, where the aero is actually working. I'm going to use hyperbole for the sake of example, but a GT350R may be "smooth" at 80 mph where a viper is "choppy" but the viper going through that same corner again at 130 - 140 would be a much different story.
 
I like the discussion but the tech in the GT500 makes a difference like the magaride suspension and isn't static like the ACR.



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TT, I would highly recommend doing the Lucas oil race school, im not saying that as a dig at your theorys but you seem to have a real interest in it and its a great school that will go even farther in debth and you'd get some first hand experience in open wheel cars. A few of my friends have done it and its well worth the cash.
 
but I think the viper could really excel with mag shocks, and the gt500 would be so much more fun albeit slower with a stick.
The ACR would be a downgrade with mag shocks.
I like the discussion but the tech in the GT500 makes a difference like the magaride suspension and isn't static like the ACR.



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The static suspension is an advantage because it allows for more adjustability. The ACRs suspension is easy to set up too
 
The mag also has a fixed dampening range; it can dynamically adjust within that range, but you can't put a real race setup on the car because you'll exceed that range.

Mag ride is God's gift to the dual purpose car and is amazing technology, but the ACR is far from a dual purpose car lol, so why bother.
 
The mag also has a fixed dampening range; it can dynamically adjust within that range, but you can't put a real race setup on the car because you'll exceed that range.

Mag ride is God's gift to the dual purpose car and is amazing technology, but the ACR is far from a dual purpose car lol, so why bother.

Look to Ford's own no holds barred track focused GT MkII as a good example. They could have easily implemented a MR system in the car, but stuck with the highly adjustable "old" static setup. Why? Because they can better dial in the car for specific track applications, and have zero need to strike a balance between street and track use, which is the real benefit of dynamic suspension.

It's also interesting that they dumped the carbon fiber wheels on the street car in favor of aluminum. Hmmmm....Makes you wonder why.
 
The argument was never if a gt500 is always faster than a viper acr though. All in good spirit as this seems to be, the point is the viper acr doesn’t have as good of a wheel as the gt500 does.

Leave everything on the acr the same but put a carbon fiber wheel of the same dimensions on it and weighing something like 15-16lbs. Even if you keep the kumho’s which admittedly do have a very high load rating, or better yet if you get a lighter but equally strong tire on the car, the results would speak for them self.

That’s the guarantee @GTSpartan. It’s no stretch or the imagination. You quoted the beginning of that paragraph but read the part where I said keep the dimension. That’s important because the load has to be mitigated.

The rear of the acr with that aero weighs dynamically north of 3500lbs +/- at 175mph so the tires would blow if they were not strong enough so a lighter tire may not be feasible.

I do know the mkII gt has fixed shocks, and yes a fixed shock is superior on a smooth track.

I’ve pointed out before the acr will do best on a track like leguna, and it has to the tune of 1:28 which is race car territory. Sub 1:30 at Leguna is very fast.

But look at its times at grattan and vir. My point wasn’t that the acr is some piece of junk. I love the car, and want one. I’m saying great as it is, what holds it back at low speed is the heavy wheel tire package. At high speed it’s not accelerating very fast either. It’s awesome in its element of 60-125mph imo. Maybe it’s 53mph to 147mph but you get the idea.

The car needs to be as close to that 1.5g threshold as it can be since it’s trump card is pulling 1.5 g’s. Being manual and stiff as hell, it’s not going to impress on a low speed area because the heavy wheel/tire setup isn’t prone to turn in, the drivetrain will catch and bind depending on clutch inputs from the driver etc.

The gt500 cftp isn’t god’s gift to track days as delivered, and I’m not saying it will somehow beat acr’s all the time. My point is the reason the gt500 cftp is doing so well on many different types of venues and circuits is that it is setup with really good rolling stock, smart aero, and low centered weight. Look at its VIR times where it’s gone sub 2:43’s (viper ace went 2:40, Ford gt went 2:38 (and faster unofficially), 755hp zr1 went 2:37. That’s impressive for any car, let alone a 4080lbs mustang with 4 seats.

Look at its grattan times in the 1:22 range. That is where the viper has been. Let’s say the viper acr holds the record by .999 seconds, the fact a $90k 4080lbs mustang is lapping that close to a gutted viper with 1700lbs of downforce and 355mm rear tires is insane.

Again not shitting on the viper, just drawing the picture of where the gt500 cftp even at 4080lbs is making inroads on competing with a 3400lbs stripped viper on huge tires with 1700lbs or downforce that just happens to hold basically 20+ track records.

Hope no one thinks I’m trying to shit on them either, and I do want to go into a tech school to get some great real world time in. Just so busy with work/life
 
The ACR would be a downgrade with mag shocks.

The static suspension is an advantage because it allows for more adjustability. The ACRs suspension is easy to set up too
The ACR would be a downgrade with mag shocks.

The static suspension is an advantage because it allows for more adjustability. The ACRs suspension is easy to set up too

A mag shock setup to handle that size of load would be great. The small stuff on the shelf isn’t setup for that level of dampening but if engineered for the task ie start with something robust like a redesign of what was used on the h1 alpha weight wise but obviously fit and proportioned for a viper, the task at hand, and able to handle 3500+lbs of load. Current off the shelf mag ride stuff isn’t capable of handling those kinds of loads.

It was a hypothetical commentary. There also currently isn’t a carbon fiber wheel that I know of that fits the viper acr’s 355/30/19’s. Just bench racing stuff. Mag ride is great for a Goldilocks machine, but it’ll let down a racecar setup. It’s just not Stiff enough, and the magnetic properties while very quick are not lightning quick but the present load is so the car will always wonder unless it’s beautifully optimized.

My point was the viper is great but where it loses time in a lap is low speed choppy sections, and very high speed areas where it is well below 1.5g’s. This is why it’s laps at places like Grattan are great but not hold my beer amazing, same with its VIR lap where a zr1 will hit 180mph or whatever meanwhile the viper acr barely reaches 150mph. I’m sure the acr would be a bad choice for Le Mans, mean while a ford gt with only 630hp would probably be 10 seconds a lap faster. Just not what the acr is setup for. I gotta see what the acr runs at Sebring Seattle and how it was setup there. Honestly at Le Mans you’d probably do best to just take the rear wing and front splitter off an acr and loosen the suspension quite a bit, try to get 185-190 on the back straight.


Anyways all of this is bullshitting because who takes an acr to le mans.


The acr does awesome anytime it is as close to 1.5g’s as possible. It’s trump card is that it is mechanically setup to pull and sustain 1.5g’s.

The gt500cftp can hold 1.3g at high speed which is pretty damn impressive for a 4080lbs car. I’m actually surprised it’s doing so on 305/315 setup because if my math is right, it’s effectively holding 5304lbs of cornering weight at 170mph... that’s pretty insane load on relatively small tires. The viper by comparison and assuming my simple math is accurate is holding 5,100lbs. I just took the curb weights and multiplied them by 1.3 and 1.5. Lemme know who that’s actually done if your willing.

Static stuff is very tunable. 10 way adjustable shocks etc are great. I believe the vipers aero is also adjustable from 800lbs to 1700 as is the gt500cftp’s from 300 to 500lbs.
 
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Agreed....I bet it nets out very close, especially when you figure in the rotor weight differences. We won't know until someone weighs a set of 500 rotors, but I'd wager they run on the order of 20# heavier per rotor than the CC on the ACR. Following your point on MoI, not only are the 500 rotors MUCH heavier, they also have a larger radius.
On good I tell the stock front 16.5” rotors weight 50-52# each!
My ‘14 GT500 rotors are 15” and 32-33#.
-J
 
Wow a lot of figures I can not wait till it hits the track in the V8 cars racing in Aus. Then we will see the true 2020 do it thing
 

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