2008-09 ACR top speed

[robiferretti]

Whats the fastest anyone has driven in one. Online saw a salt flats video which the car didn't manage to go over 173 mph. If I bring this car to the Silver State Classic, I want to make sure i'll be able to cruise around 200 mph on long straights. Curious as to how capable the car is stock with plenty of road.

 

[madninjaskillz]

too much downforce and not enough grip on the flats to hit 200 in a stock acr.

 

[PeterMJ]

Whats the fastest anyone has driven in one. Online saw a salt flats video which the car didn't manage to go over 173 mph. If I bring this car to the Silver State Classic, I want to make sure i'll be able to cruise around 200 mph on long straights. Curious as to how capable the car is stock with plenty of road.

ACR should have lower top end than the base hard top, viper top speed is drag limited and given the same power and higher Cd for ACR, the regular base should have higher top speed IN STRAIGHT line. The official figures are if I remember, 197 for the roadster and 201 for the coupe. ACR should be right around the roadster. Salt flats do not provide best traction, thus, lower top end.

 

[PeterMJ]

too much downforce and not enough grip on the flats to hit 200 in a stock acr.

Technically, there is no such animal as downforce, lift reduction instead. Lift reduction is created at expense of Cd, thus, ACR would have lower top end regardless but no as bad as on salt flats.

 

[PDCjonny]

You bought the wrong car for that type of race, the ACR stats have been published many times.
The 2010 is about 5-7 MPH faster in a straight line than the previous two years but neither will hit 185.
It wasn't designed for that.

 

[hou99gts]

184 mph top speed, drag limited. You'll need more power or less drag to reach 200 mph.

An aero coupe would be a better choice for the Silver State Classic, but you will need more power to achieve 200 mph.

 

[01sapphirebob]

About 175 is the fastest you would be able to go in an ACR unless you strip all the aero parts off the car.

 

[Allan]

175 would be very lucky on a good day with perfect conditions and thin air. That's the only time that my car is faster than a gen IV ACR,...top speed runs. All that aero stuff is like a parachute above 150. I thought I saw a top speed of 173 posted somewhere for the ACR. The 2010 may do a little more with the revised gearing.....thier wing is different as well. The ACR's advantage will be aparent on the high speed sweepers. Nothing is faster except an F1 car.

 

[Boxer12]

Look at some videos from Viper Cup and see what the boys do on the back straight at VIR ...of course, thats an ACRX but you can get more power from a modded ACR and put in the ACRX trans and a diff.

 

[Bobpantax]

The official top speed of the 2008 and 2009 ACR per Dodge and SRT is 177MPH. The 2010 ACR has different, more aero efficient, end plates on the wing and a different 5th gear ratio. Its top speed, per Dodge and SRT, is 184 MPH. The top speed of the Gen V with the aero kit, per the SRT engineers at VOI, is projected to be 191 MPH per computer model.

 

[robiferretti]

so with 600 rwhp and a 5th gear swap 190 is feasible?

 

[Bobpantax]

I do not know whether 600 RWHP would be enough to override the increasing downforce and resulting aero effect so that 6 MPH more is obtained.

 

[msp282]

i don't think mine (100% stock 2009 ACR) will accelerate once in 5th gear at 170ish.... whatever the top of 4th gear is seems to be top speed.....

at the Silver State don't you need to put a lot of safety stuff in the car once you get to the faster classes? I would think any car over about 150mph should require a full cage, fire suppression, etc...?

 

[BlknBlu]

Has anyone tested the integrity of the aero group to see where it's limits are. I know of a Front splitter ripping off a heavily modified ACR on a high speed run.

Bruce

 

[ACRucrazy]

The official top speed of the 2008 and 2009 ACR per Dodge and SRT is 177MPH.

That sounds about right, 176 was the number that was in my head.

 

[mjorgensen Woodhouse]

Has anyone tested the integrity of the aero group to see where it's limits are. I know of a Front splitter ripping off a heavily modified ACR on a high speed run.

Bruce

All the factory Aero parts have been designed, tuned and tested at max velocity of the stock cars, beyond that there is a margin of safety built in. That being said anyone can change angle of attack front or rear that can surpass the limits of the parts design. That is where knowledge and risk come into play, and a reason to steer clear of knock off products that are not as stringently tested.

 

[Paul Hawker]

All classes at Silver State Classic, (except unlimited) have maximum do not exceed speeds well south of 200 mph. These speeds are not needed to be competitive there, as the idea is to average your target speed, while staying within maximum/minimum allowable speeds.

No reason to drive 200 mph at that event unless in unlimited class.

As others have said, the ACR sacrifices top speed for high speed downforce. Your wings can exert over 1,000 lbs of downforce in the sweepers.

 

[PeterMJ]

All the factory Aero parts have been designed, tuned and tested at max velocity of the stock cars, beyond that there is a margin of safety built in. That being said anyone can change angle of attack front or rear that can surpass the limits of the parts design. That is where knowledge and risk come into play, and a reason to steer clear of knock off products that are not as stringently tested.

where are the results of these tests? Curious what Cd is for ACR. . Also, some aftermarket brands do test their stuff. BTW, a good knock off of factory front splitter should perform very much like the viper taxed part, as long as construction methods and materials are the same.

 

[ACRucrazy]

Not exactly what you are looking for but good info on the ACR pages 14-20.

http://www.prefix.com/1of1/VM2008Summer.pdf

 

[PeterMJ]

Do you think this is the reason why active aero exists? Cd for C6 vette base is 0.28 and the top speed, drag limited is 192. For ZR1, with wide body and ground effects, Cd is 0.35 and it takes another 200 hp to gain another 13 mph.

Base Viper coupe has Cd of 0.34 and top speed of 201, do the math to figure out how much hp it would take for ACR to break the 200 mph, assuming its aero would not fall off first.

All classes at Silver State Classic, (except unlimited) have maximum do not exceed speeds well south of 200 mph. These speeds are not needed to be competitive there, as the idea is to average your target speed, while staying within maximum/minimum allowable speeds.

No reason to drive 200 mph at that event unless in unlimited class.

As others have said, the ACR sacrifices top speed for high speed downforce. Your wings can exert over 1,000 lbs of downforce in the sweepers.

 

[robiferretti]

Ran Silver State Classic yesterday in 150 class. Tech speed 165 (max approved speed for class). Was driving 2009 Viper ACR (bone stock)

I hit 170 accidentally verified via GPS. That was in 5th gear without trying to push it I could have carried another 10 mph I am sure if I actually tried accelerating. Top speed wasn't the point though and I got DQ'd last time so I was trying to not get thrown out again.

Spent a lot of time at 160mph - 165mph Went through entire tank of gas and had gas light come on with 12 miles to go. Was hoping to come in with a 155mph average but had to try to manage fuel at the very end. Ended up learning some things about the car.

Doesn't hold speed in 6th gear (tried holding ~150-160 and just fell off in 6th) Had to race the whole time in 5th.

Clutch fluid boiled over and lost my clutch somewhere before the end of the race. Had to do a 5-6 shift to try to conserve gas and had ZERO clutch pedal. Not the most pleasant sounding 6-5 shift i've ever made but I needed the gear. Pulled into pits and couldn't grab any gear and needed to be pushed out of the way. 10 minutes later car was back to normal and clutch felt fine once fluid cooled back down.

Ran out of fuel. Full tank to conservative finish got me over the line. I ran out of gas 5 miles into the 7 mile drive to the gas station. Luckily I carried my momentum and rolled as slow as 5mph in neutral to the pump with the help of a slight downhill (and the laughter of my friends).

 

[SoCal Rebell]

At Willow Springs I hit about 155 on the front straight in 4th before I run out of track must brake a downshift for a 90 degree left, totally stock '08 Acr.

 

[MtnBiker]

Nice! That must have been thrilling!

I had similar clutch problem yesterday on track.

 

[TrackAire]

Ran Silver State Classic yesterday in 150 class. Tech speed 165 (max approved speed for class). Was driving 2009 Viper ACR (bone stock)

I hit 170 accidentally verified via GPS. That was in 5th gear without trying to push it I could have carried another 10 mph I am sure if I actually tried accelerating. Top speed wasn't the point though and I got DQ'd last time so I was trying to not get thrown out again.

Spent a lot of time at 160mph - 165mph Went through entire tank of gas and had gas light come on with 12 miles to go. Was hoping to come in with a 155mph average but had to try to manage fuel at the very end. Ended up learning some things about the car.

Doesn't hold speed in 6th gear (tried holding ~150-160 and just fell off in 6th) Had to race the whole time in 5th.

Clutch fluid boiled over and lost my clutch somewhere before the end of the race. Had to do a 5-6 shift to try to conserve gas and had ZERO clutch pedal. Not the most pleasant sounding 6-5 shift i've ever made but I needed the gear. Pulled into pits and couldn't grab any gear and needed to be pushed out of the way. 10 minutes later car was back to normal and clutch felt fine once fluid cooled back down.

Ran out of fuel. Full tank to conservative finish got me over the line. I ran out of gas 5 miles into the 7 mile drive to the gas station. Luckily I carried my momentum and rolled as slow as 5mph in neutral to the pump with the help of a slight downhill (and the laughter of my friends).

I wonder if the clutch fluid got hot from the stock manifolds giving off so much heat from what would be almost a near full dyno pull for a long time. I do know that some aftermarket headers had this issue. Did the clutch come back after the fluid cooled/bled the system?

Don't feel bad about running out of fuel....it has happened to a few people I know doing the SSC.

Congrats on the run, that is definitely a bucket list thing to do.

George

 

[Paul Hawker]

In my 96 Coupe I had good success in the 155 class running in 6th gear and a 3:55 rear end. I ran SVS headers and K&N filters.

Not all that much throttle response and needed to anticipate hills with additonal throttle or a down shift into 5th, but used less than 1/2 tank of fuel. Car just loafed along with the air conditioning on.

Stock rear gear will not pull 6th at those speeds, so you are forced to run high revs in 5th. Lots of heat and ***** gas.

 

[robiferretti]

clutch was fine when it cooled off in 10 minutes. Drove it back to Vegas without issue. Felt 100% normal.

 

[Viperless]

Motul RBF600 cured my clutch fluid boiling issues.