Comparison Test: Evil Twins
Evil Twins: Dodge Viper SRT10 vs. SRT10 ACR
The ACR edges out the stock SRT10 in every category in our standard road test.
By Patrick Hong • Photos by Brian Blades, Guy Spangenberg, and John Lamm
LAP TIMES:
SRT10 ACR: 1:29.33 sec
SRT10: 1:32.19 sec
It is arguable how street-friendly the Dodge Viper SRT10 is in standard form. Beneath the brawny bodywork is a thunderous 600-bhp, 8.4-liter V-10 paired with a sturdy Tremec 6-speed manual transmission. Riding on a firmer suspension setup than the average sports car, the Viper can easily put the power down — and overwhelm its generous Michelin Pilot Sport tires if you're heavy-footed. With a quick 3.4-sec. 0–60-mph acceleration time, a dizzying 1.01g skidpad grip level and a 70.2-mph average slalom speed, the SRT10 blurs the line between a road car and a track car.
Still, for hard-core Viper enthusiasts who follow the motto "Race on Sunday, sell on Monday" literally, and want to spend most of their time on the track, Dodge has the perfect solution in the SRT10 American Club Racer (ACR). The ACR is equipped with the same V-10 engine and 6-speed manual transmission found in the stock Viper. The two also share the same basic interior fitment. However, that is where the similarities end.
The ACR has extensive aerodynamic improvements consisting of a carbon-fiber front splitter, fixed front dive planes and an adjustable rear wing, modifications that generate 10 times the downforce of a standard Viper. At 150 mph, the ACR experiences about 1200 lb. of downforce, distributed approximately 45 percent to the front and 55 percent to the rear.
To translate the ACR's substantial downforce into usable grip, Dodge engineers installed KW coil-over racing shocks that are adjustable for damping and ride height without removing the wheels. A new front anti-roll bar increases roll stiffness, and StopTech slotted brake rotors team with stock SRT10 Brembo calipers to slow the car. Lightweight forged aluminum Sidewinder wheels are used for lower unsprung weight. Michelin Pilot Sport Cups, barely street-legal tires with a low 80 treadwear rating, provide the ACR with excellent traction on the track.
With these focused modifications, the ACR edges out the stock SRT10 in every category in our standard road test. While acceleration runs showed only minor improvement, it is in braking and handling exercises where the racy Viper shines. Braking from 80 mph is shorter by 11 feet, steady-state lateral grip has improved by 0.11g, and improved transient dynamics through the slalom bump up the average speed by 3.2 mph.
The improvements are amplified further when Steve Millen takes both cars onto the big track at Willow Springs. With a lap time advantage of almost 3 seconds, the ACR is clearly the faster twin. Millen points out that "as with all Vipers, you must be the boss of the car, and the harder you run it, the better it is. And while the power and the gearing of the two cars feel the same, the ACR has way more grip and stability, thanks to its aerodynamics and dialed-in damping control."
Through every corner, the ACR carries more speed than the stock SRT10. Through the long right-hander of Turn 2, the ACR confidently grips the track and behaves consistently neutral with no surprises. This allows Millen to pick up the throttle earlier. There is almost a 10-mph advantage here. Down the hill through Turn 5 and over a slight crest through Turn 6, Millen barely breathes the throttle because of the ACR's tremendous grip and confidence- inspiring stability. In Turn 9, Millen comments that the stock Viper "has quite a bit of commotion over the bumps and undulations on the track." In contrast, the ACR "has less jiggle in the steering wheel because it drives smoother and you don't have to adjust as much. After the apex coming onto the straight, it feels neutral. And as soon as you get on the throttle, it just drives off, while drifting off the exit."
Overall, Millen says the ACR "works like a race car. It is balanced and well-planted through fast corners. The steering has terrific feedback. Once you get it turned, you know exactly where it is and where it is going to go and what it is going to do." Referring to the SRT10, Millen notes that you have to adjust the steering more and it takes longer to find the car's limit. Through fast corners "you are modulating the throttle more to make sure you know the rear is gonna come with you."
On the street, the stock Viper makes no pretensions of being a grand tourer. Of course, there are a few comfort amenities such as leather trim, power windows and locks, air conditioning, even a radio with a CD player. But the rumble from the V-10, the noise from the tires and the bumpy ride from the firm suspension will probably drown out any high-fidelity music or spoil a relaxing cruise. The seating position is a bit awkward for folks who are height-challenged and need to find the best compromise between reaching the pedals and not sitting too close to the steering wheel. Feature Editor Mike Monticello comments: "As a road car, the Viper suffers. The suspension is jouncy over bumps, and the footwell will roast your feet if you get stuck in traffic."
If the stock Viper is hard to handle on the road, then the ACR notches up the impracticality rating at least 10 times. It doesn't help that our ACR is a durability test car from Dodge. It has a racing seat installed for testing (production versions will have standard SRT10 seats) and a welded-in rollcage for track exercises. And there is some rear jitter under hard braking — Dodge tells us that the pads are due for replacement after extended testing just a few days before. The car is rough-riding and noisy. And it rides low enough that you have to inch your way up any driveway because of the front splitter. Fortunately, its front section can be removed for easier everyday driveability.
With the ACR, you gain a lot more performance on the track for a premium of only about $5600 (as tested). What you lose is questionable. It all depends on your tolerance for the already noisy and firm-riding character of the standard SRT10. For those who seek a Viper purely because of its track prowess, go for the ACR, because what you gain in sheer speed more than outweighs the price you pay for the road-going impracticality.
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