acr downforce

[canadian viper]

any one know what is the downforce of a reg acr? we know the extreme aero is 2000 lbs.

[AZTVR]

any one know what is the downforce of a reg acr? we know the extreme aero is 2000 lbs.

Interesting question.
I can't find that 2000 pound number from SRT; but, here is what I did find from SRT.

The following link talking about the extreme aero version states, "SRT engineers have experienced nearly 1 ton (approximately 1,800 lbs.) of downforce at top speed of 177 mph"
It also states, "the Extreme Aero package delivers more than three times the downforce produced by the Viper TA (Time Attack) 2.0 package"
http://www.drivesrt.com/news/2015/05/new-2016-dodge-viper-acr-fastest-street-legal-viper-track-car-ever.html

That puts the TA 2.0 at less than 1800/3= 600 pounds

The following link, talking about the regular ACR states, "The Viper ACR features a carbon-fiber front splitter with kick-up diffusers and detachable extension, front dive planes and a dual-element rear wing. These measures combine to produce more than 2 1/2 times the downforce of the TA 2.0 version."
http://www.drivesrt.com/news/2015/06/dialed-in-downforce-taking-viper-acr-aerodynamics-to-the-extreme.html

That makes the regular ACR's downforce be 600*2.5 = 1500 lbs.

Those calculations are based on ignoring the qualifier phrases of "more than" in the press releases which actually mean that the downforce numbers are approximate.

[99RT10]

For reference, the 08-10 ACR had what lbs of downforce? I want to say it was 1000 at 150 mph?

[AZTVR]

For reference, the 08-10 ACR had what lbs of downforce? I want to say it was 1000 at 150 mph?

I just saw that in an article on allpar.com as 1200 lbs @ 150mph for a 2008 ACR. FWIW.

[ACRucrazy]

http://i150.photobucket.com/albums/s99/ACRucrazy/000%20Misc%20Viper/Wing_zpsuuvrs7iy.jpg

[docwviper]

Interesting question.
I can't find that 2000 pound number from SRT; but, here is what I did find from SRT.

The following link talking about the extreme aero version states, "SRT engineers have experienced nearly 1 ton (approximately 1,800 lbs.) of downforce at top speed of 177 mph"
It also states, "the Extreme Aero package delivers more than three times the downforce produced by the Viper TA (Time Attack) 2.0 package"
http://www.drivesrt.com/news/2015/05/new-2016-dodge-viper-acr-fastest-street-legal-viper-track-car-ever.html

That puts the TA 2.0 at less than 1800/3= 600 pounds

The following link, talking about the regular ACR states, "The Viper ACR features a carbon-fiber front splitter with kick-up diffusers and detachable extension, front dive planes and a dual-element rear wing. These measures combine to produce more than 2 1/2 times the downforce of the TA 2.0 version."
http://www.drivesrt.com/news/2015/06/dialed-in-downforce-taking-viper-acr-aerodynamics-to-the-extreme.html

That makes the regular ACR's downforce be 600*2.5 = 1500 lbs.

Those calculations are based on ignoring the qualifier phrases of "more than" in the press releases which actually mean that the downforce numbers are approximate.

The 2000 lbs quote comes for the ACR release video with Kuniskis. I believe he said it produced nearly 2,000 lbs or 2,000 lbs.

[docwviper]

The link above also states that the rear carbon diffuse is carbon fiber? I haven't seen that in photos. It looks plastic?

Also, it says the interior is different in that it has "lower instrument panel and door armrest panels". Anybody else know about this?

[Courtney @ViperExchange]

The link above also states that the rear carbon diffuse is carbon fiber? I haven't seen that in photos. It looks plastic?

After getting my hands on the Extreme, I can confirm these ARE indeed Carbon Fiber. We have the media car from FCA for the track event at COTA this coming weekend, expect more details when I can go through the Viper!

[docwviper]

What about the "lower instrument panel and armrest panels"?

[Rapidrezults]

What about the "lower instrument panel and armrest panels"?

I think they are referencing the flag pattern on the armrest panel in the picture below. I guess they have it on the lower instrument panel as well.

http://i296.photobucket.com/albums/mm163/rapidrezults/20-2016-dodge-viper-acr-fd-1_zpsfefnjea1.jpg

[SADVIPER]

I remember the whooping number of 2,000 during the release video commentary! This beast main weapon is the aero I reckon.

[docwviper]

I remember the whooping number of 2,000 during the release video commentary! This beast main weapon is the aero I reckon.

Hilarious I reckon as well ;) A play on words in the video because I think he says nearly 2,000.

[mjorgensen]

Hilarious I reckon as well ;) A play on words in the video because I think he says nearly 2,000.

With all the Arrow Stage II packages we are doing on the ACR's and ACR Extremes there will be plenty of cars seeing 2000+ I bet ;-)

[Vprbite]

That's a lot of smush.

I would assume a novice driver will be all over the place until he learns speed helps you turn. (I include myself on that list.)

[Rapidrezults]

That's a lot of smush.

I would assume a novice driver will be all over the place until he learns speed helps you turn. (I include myself on that list.)

I would assume the same, but from what a lot of the press drivers and reviewers said, the extreme car was so easy to drive they were amazed. I think some of them even mentioned that it was more predictable at the limit than the GTS/TA's they had tested. I think they really got this car right in terms of the aero tuning.

[docwviper]

http://i150.photobucket.com/albums/s99/ACRucrazy/000%20Misc%20Viper/Wing_zpsuuvrs7iy.jpg

Where did you get this? I've never had an adjustable suspension like this so figuring out what is 6 and 5 should be interesting. Also, wondering how ride height be adjusted? Can this be done without taking the wheels off? I heard on the new ACR we can adjust the suspension compression and rebound without taking off the wheels.

[mjorgensen]

Where did you get this? I've never had an adjustable suspension like this so figuring out what is 6 and 5 should be interesting. Also, wondering how ride height be adjusted? Can this be done without taking the wheels off? I heard on the new ACR we can adjust the suspension compression and rebound without taking off the wheels.

On the Gen4 ACR all the suspension settings start at full "stiff" which is considered the "0" position.

[rw99]

On the Gen4 ACR all the suspension settings start at full "stiff" which is considered the "0" position.

...and full "stiff" is the max righty-tighty :D

[rw99]

http://i150.photobucket.com/albums/s99/ACRucrazy/000%20Misc%20Viper/Wing_zpsuuvrs7iy.jpg

Mild hijack: if you add the additional pair of front canards from the ACR-X to an '09 ACR with stock H2 rear wing (and modest ride height), which rear wing hole position should be used to maintain the same front/rear downforce balance?

[XSnake]

Mild hijack: if you add the additional pair of front canards from the ACR-X to an '09 ACR with stock H2 rear wing (and modest ride height), which rear wing hole position should be used to maintain the same front/rear downforce balance?

The only time I use position 2 is at Daytona. Everything else is 3 and 4. I have the notes from when Matt B and Kuno from SRT used my car for testing and all notes mention 3 & 4.

[XSnake]

I heard on the new ACR we can adjust the suspension compression and rebound without taking off the wheels.

You can adjust comp/rebound while leaving the wheels on......if it's up in the air on a lift. lol. Just finished doing that actually. New Extreme cars will be able to adjust by reaching through the hood extractors once they are removed. Non extreme cars should be able to do it once the hood is up.

[rw99]

The only time I use position 2 is at Daytona. Everything else is 3 and 4. I have the notes from when Matt B and Kuno from SRT used the my car for testing and all notes mention 3 & 4.

Great info, thanks!

[docwviper]

You can adjust comp/rebound while leaving the wheels on......if it's up in the air on a lift. lol. Just finished doing that actually. New Extreme cars will be able to adjust by reaching through the hood extractors once they are removed. Non extreme cars should be able to do it once the hood is up.

Nice can't wait.

[Shooter]

Approx 600 lbs more then the Gen IV ACR @ 177 mph on the stock wing settings. Pretty big difference. I bet the new one will corner like it's on rails. Gonna be even more hurt feelings for the other makes when these Gen V ACR's hit the track.

[ACRucrazy]

Where did you get this? I've never had an adjustable suspension like this so figuring out what is 6 and 5 should be interesting. Also, wondering how ride height be adjusted? Can this be done without taking the wheels off? I heard on the new ACR we can adjust the suspension compression and rebound without taking off the wheels.

Viper Magazine summer 2008.
Also found here:
http://news.kwautomotive.com/pictures/news_2359/PR_The_ACR_Viper_on_Track.pdf


Mild hijack: if you add the additional pair of front canards from the ACR-X to an '09 ACR with stock H2 rear wing (and modest ride height), which rear wing hole position should be used to maintain the same front/rear downforce balance?

AFIAK the ACR-X front canards add ~100 pounds of additional downforce @ 150 mph if that helps.

[ViperSmith]

Approx 600 lbs more then the Gen IV ACR @ 177 mph on the stock wing settings. Pretty big difference. I bet the new one will corner like it's on rails. Gonna be even more hurt feelings for the other makes when these Gen V ACR's hit the track.

C7Z sells more and gets better MPG so the ACR is irrelevant

/s

[Clutch2014]

C7Z sells more and gets better MPG so the ACR is irrelevant

/s

Not if Dodge throws some good marketing behind it. I would love to see a series of BMW The Hire-style short films featuring the Viper, as well as commercials that drive home just how good a car it is.

Bonus points if they get Joe Carnahan to direct some promo stuff. Ticker might just be my absolute favorite of those films.

[fuggles]

On the Gen4 ACR all the suspension settings start at full "stiff" which is considered the "0" position.

I'm treading on thin ice here contradicting the man who sold these. However, I believe the gen4 acr came with the factory recommended street setting which is front 13/18 & rear 13/17 (c/r). Mine still had the factory stickers with the warning about adjusting. I didn't count but it was many clicks to 0.

[rw99]

I'm treading on thin ice here contradicting the man who sold these. However, I believe the gen4 acr came with the factory recommended street setting which is front 13/18 & rear 13/17 (c/r). Mine still had the factory stickers with the warning about adjusting. I didn't count but it was many clicks to 0.
Not a contradiction at all, Kent. Mark's referring to where we start the count, not the settings from the factory. Wherever the car's set, dial each to full stiff zero... and then count up.

[XSnake]

I'm treading on thin ice here contradicting the man who sold these. However, I believe the gen4 acr came with the factory recommended street setting which is front 13/18 & rear 13/17 (c/r). Mine still had the factory stickers with the warning about adjusting. I didn't count but it was many clicks to 0.
Mark is saying that all adjustments and settings are made from full stiff. Not that the cars come from the factory set at full stiff. If you want to get to setting 10 and your max is 18 then you would go all the way up to 0 (full stiff) and then go back 8.

[fuggles]

I see I have reading comprehension issues. I must be old. lol

[RedTanRT/10]

The only time I use position 2 is at Daytona. Everything else is 3 and 4. I have the notes from when Matt B and Kuno from SRT used my car for testing and all notes mention 3 & 4.


XSnake, thanks! That makes sense as your adding more front downforce




AFIAK the ACR-X front canards add ~100 pounds of additional downforce @ 150 mph if that helps.

ACRucrazy, thanks I thought they added 100 lbs, and as always thanks for the chart.

Remember reading that taking off the 6 hood vents (X-style) adds another 50 lbs.

Look like in H3 plus, ACR-X second canards and removing the hood vents should get a G4 to about 1,600 lbs @180mph vs. G5 1,800 at 177 mph

[lmcgrew79]

Spreadsheet I made on Gen4/5 Aero Numbers.

http://i119.photobucket.com/albums/o141/lmcgrew79/Viper%20Downforce%20Compare_zpszlqn2urc.jpg

[Bruce H.]

C7Z sells more and gets better MPG so the ACR is irrelevant

/s

Not sure many are being purchased by the faster track rats these days with all the over-heating issues they're having, and a buddy with one that ran Road America with me last week used considerably more fuel each session than I did in the T/A.

[Darius]

Spreadsheet I made on Gen4/5 Aero Numbers.

http://i119.photobucket.com/albums/o141/lmcgrew79/Viper%20Downforce%20Compare_zpszlqn2urc.jpg

I remember hearing a long time ago that a f1 car could theoretically drive upside down at 200mph or less. I wonder how fast a ACR would have to go to make 3400lbs of downforce. That would make for a awesome video :)

[lmcgrew79]

I remember hearing a long time ago that a f1 car could theoretically drive upside down at 200mph or less. I wonder how fast a ACR would have to go to make 3400lbs of downforce. That would make for a awesome video :)

At 3400 lbs 231 MPH:)

[Bruce]

At 3400 lbs 231 MPH:)

So how much power will it take to run 231 MPH? Someone had better build this engine and we'll have the first ever production car that can run upside down.

[Darius]

So how much power will it take to run 231 MPH? Someone had better build this engine and we'll have the first ever production car that can run upside down.

I'm sure a full build with twin 91's will do it lol, and balls to match.

[Snakebit10]

So how much power will it take to run 231 MPH? Someone had better build this engine and we'll have the first ever production car that can run upside down.

One of the mile Vipers that did 240-ish mph was making around 1300+ to the wheels if my memory is correct. And it didn't have anywhere near the G5 down force. So I'm guessing the rwhp will have to be exponentially much more than 1300rwhp to get the G5 ACR extreme to 231mph, well at least within the mile. Who will volunteer to drive such a Viper upside down? :)

[Dman]

So how much power will it take to run 231 MPH? Someone had better build this engine and we'll have the first ever production car that can run upside down.

A Saturn V rocket strapped to it, should so the trick.

[Stealth78]

So how much power will it take to run 231 MPH? Someone had better build this engine and we'll have the first ever production car that can run upside down.

I think oiling is going to be an issue! :t0135:

[Stealth78]

Spreadsheet I made on Gen4/5 Aero Numbers.

http://i119.photobucket.com/albums/o141/lmcgrew79/Viper%20Downforce%20Compare_zpszlqn2urc.jpg

I have to be honest, what catches my attention is the lack of downforce on the base model when comparing Gen4 to Gen5.

[XSnake]

So how much power will it take to run 231 MPH? Someone had better build this engine and we'll have the first ever production car that can run upside down.

I believe the S7 could run upside down theoretically

[TrackAire]

I would love SRT to clarify this "down force" number. I'm calling bullshit that the car can actually have 1845 lbs of weight pushing down on it plus a 200 lb driver....that's 2045 lbs of weight on the chassis (or 5 fat girlfriends in my world).

I don't recall the spring rates of the ACR Extreme Package, but I'd think with over one ton of weight added to the car it would be on the bumps stops at 170 mph on a glass smooth surface....hit the smallest bump and you'll skate off the road.

Now I can see the 1845 lb number as the summation of the reduction of lift plus the added down force the aero package can provide at different speeds. IDK, maybe I'm wrong and the springs can hold up eight 250 lbs guys sitting on the car and not bottoming out at speed.

Nice job on the down force chart, pretty eye opening on what the different models can generate at different speeds.

[lmcgrew79]

Yeah i actually calculated the difference according to the springs rates. On a base gen5 200/500 it would theoretically take 1400 lbs to compress all the springs off the car 1 inch. On the Acr 600/1300 it would take 3800 lbs, the difference in the downforce is 1961 at 180. The difference in weight is 2400 to compress the springs. Now where everything goes out the door is because the geometric angle of the mounting points etc etc, changes all of that. But in theory the ACR would drop as the same as a base if you added 431 lbs to the car or two passengers, and that is only at top speed.

[TrackAire]

Hmmm, I didn't even think of the leverage points of the A-arms and the angle of the springs....yikes, too much math for me, lol.

So 2000 lbs of down force and 3300 lbs of car weight is way over 5000 lbs at 170 mph.....luckily the new Kuhmo ACR tires have a combined max weight capacity of over 6000 lbs :)

[laz]

Per FCA US Media Website:

ACR
1101 @ 150
1533 @ 177

Extreme Aero
1200+ @ 150
1700+ @ 177

[fuggles]

According to Viper Magazine the spring rates are 600/1300. So 2k lbs would be ~3/4 in drop. Not much.

What I don't understand is how they mount the wing on the hatch lid and not damage something?

[SSGNRDZ_28]

Just for fun on an open wheel car you might have 5500 lbs of downforce [+/-] ; 2800 / 1500 [+/-] lbs springs equating to ~1800 / 800 [+/-] wheel rates on a track like as Laguna Seca with ride height around 1.3/2.3". Spring rates might range anywhere from 500-4000 lbs depending on setup. The car might weigh 1900 lbs.

[lmcgrew79]

Hmmm, I didn't even think of the leverage points of the A-arms and the angle of the springs....yikes, too much math for me, lol.

So 2000 lbs of down force and 3300 lbs of car weight is way over 5000 lbs at 170 mph.....luckily the new Kuhmo ACR tires have a combined max weight capacity of over 6000 lbs :)

Yes its way to difficult.


According to Viper Magazine the spring rates are 600/1300. So 2k lbs would be ~3/4 in drop. Not much.

What I don't understand is how they mount the wing on the hatch lid and not damage something?

Those rates are per corner 600 600 1300 1300.

[ACR Steve]

The key will be can you drive the car past what your brain says mechanical stick will be. To drive an Aero car really fast you usually exceed your brain is telling you.

[VENOM V]

Spreadsheet I made on Gen4/5 Aero Numbers.

http://i119.photobucket.com/albums/o141/lmcgrew79/Viper%20Downforce%20Compare_zpszlqn2urc.jpg

Fantastic, thanks for doing that! Great comparo.


I have to be honest, what catches my attention is the lack of downforce on the base model when comparing Gen4 to Gen5.

I agree, and I experienced it first-hand. I think they made the base model super slippery and low drag in order to hit the 206 MPH, but at the expense of high speed stability. Before I put the TA carbon aero front and rear on my GTS, the car was kind of scary at the limit on high speed sweepers. Also turn 1 at Laguna Seca- when you're wide open and cresting the hill, the ass end was light enough that it would dance a little. The aero transformed the car, much more stable and easy to drive with confidence.

Having also owned and tracked a car with a big wing, it is a tremendous advantage over a spoiler. I cannot wait to track the ACR.

[TrackAire]

According to Viper Magazine the spring rates are 600/1300. So 2k lbs would be ~3/4 in drop. Not much.

What I don't understand is how they mount the wing on the hatch lid and not damage something?

That is kind of my point, there is no way that rear deck like can handle a physical force of 1000 plus pounds of downward energy. I am amazed that the Gen 4 lid can handle the ACR wing to begin with and from my experience, the Gen 5 deck lid feels very light and flexible when in the open position. All that energy on two fairly small mounting points has got me wondering how it can survive (obviously it does and has survived well at least on the Gen 4).

Interesting topics, wish SRT would chime in and clarify how much actual energy is physically pushing on the car down at a given speed.

[VENOM V]

That is kind of my point, there is no way that rear deck like can handle a physical force of 1000 plus pounds of downward energy. I am amazed that the Gen 4 lid can handle the ACR wing to begin with and from my experience, the Gen 5 deck lid feels very light and flexible when in the open position. All that energy on two fairly small mounting points has got me wondering how it can survive (obviously it does and has survived well at least on the Gen 4).

Interesting topics, wish SRT would chime in and clarify how much actual energy is physically pushing on the car down at a given speed.

I had to re-inforce my Camaro's decklid for that reason- the wing was flexing the crap out of it, losing downforce and risking damage to the trunk. I'm sure the SRT engineers have that issue resolved, a wind tunnel test would have sorted that out during development.

[ViperSmith]

On the VCA site when they did a tour of Prefix it had pictures of the reenforced trunk for handling the downforce.

[VENOM V]

On the VCA site when they did a tour of Prefix it had pictures of the reenforced trunk for handling the downforce.

Sweet. I figured they'd have that base covered :drive:

[flyingskibiker]

What I don't understand is how they mount the wing on the hatch lid and not damage something?

My thoughts exactly. And I'm pretty sure I saw a kind of flexing wiggle in the hatch when it was opened in one of the press day videos!