The Viper is truly a car built around its engine. In Part 4, we take Project Viper GTS to the dyno for a baseline power audit and see if our mighty 8.0L V10 is cranking out the factory claimed 450hp and 490lb-ft of torque. From there we add K&N replacement air filters and change out the disruptive corrugated plastic intake tubing for a set of ROE Racing polished aluminum smooth intake tubes to see if we can squeeze out a few more ponies.
This test is a little out of sequence since we went to the dyno prior to the Baseline Track Test in Part 3 but after we went through a few Maintenance items in Part 2 to get the ignition system and a few fluids up to snuff.
For the dyno work, we took Project Viper to our friends at Power by the Hour Performance in Boyton Beach, Florida. With a team consisting of Factory Ford certified technicians, fabricators, and tuners, PBTH is known for modifying Mustangs with everything from bolt-on supercharger kits to in-house developed turbo systems, suspension, brakes, fabrication, and dyno tuning. In addition to being a great bunch of talented guys, they also have the same 2,000-hp capable Dynojet 224xLC that we used on Project NSX, Project E36 M3 (silver), and Project E90 M3. This consistent dyno allows us to (relatively) accurately compare and overlay various project cars, which we will do later.
Our pristine 1997 Viper GTS has less than 8,000 miles on the clock and is completely stock other than the addition of High Performance AB “Quality” (Spark Plug) Wires, Gen-3 sized 18×10 and 19×13 Forgeline ZX3P wheels with Michelin Pilot Sport PS2 “C1” 275/35-18 and 345/30-19 tires, and a rear muffler delete.
These massive 345/30-19 rear tires have a 27.15” overall diameter, which is 1.24” and 0.92” larger than the factory (99-02) 335/30-18 tire and the original 335/35-17 tire respectively. The larger diameter changes our effective final drive ratio from 3.07 to 2.97 which increases our top speed in each gear, but hurts our acceleration by reducing the torque that is transmitted to the ground. It also puts us at 59mph in 1st gear at redline, just shy of eliminating the shift to 2nd gear which would have greatly improved our 0-60 acceleration time.
The stock Gen-2 Viper exhaust consists of 2.5” pipes with one catalytic converter and one resonator in each side sill, as well as a muffler at the rear of the car. The previous owner retained the stock cats and resonators but replaced the rear muffler with 3” straight pipes; a common modification that makes the car a little louder and more aggressive sounding.
With our car strapped to the rollers, we were ready to put down a baseline number. Only the bottom fan was used during all of the runs to blow air in to the radiator.
At 431.15hp and 468.02lb-ft of torque at the tires, we were surprised that our relatively stock 1997 Viper GTS produced numbers close to the factory rating at the crank! Before jumping to the conclusion that this is an optimistic dyno; bone stock 5.0L Coyote Mustang GTs consistently put down similar numbers on this dyno as they do on Roush Yates’ own Dynojet 224xLC that we used on Project E90 M3.While we have upgraded to high performance plug wires and removing the factory rear mufflers likely contributed to some power increase, our large rear wheels changed our effective gear ratio from 3.07 to 2.97 and lowered the peak thrust in 4th gear (1:1 ratio) from 1,246.24lbs of thrust to 1,205.65lbs, which may have lowered the power reading compared to if we used the smaller factory 17” wheels.
Having compiled over 100 dyno charts of Gen 1-5 Vipers, our car’s 431.15whp and 468.02lb-ft torque is one of the highest of any stock Gen 2 Vipers that we’ve seen, since they typically put down between 415-425whp on a Dynojet. Some cars dyno between 395-405whp, on lower reading dynos like Dyno Dynamics, which lines up perfectly with the car’s 450bhp factory rating and a commonly accepted 13% drivetrain loss. Due to the overwhelming amount of cars that make more than that, it’s likely that the Gen 2 Viper was under-rated from the factory and should be rated at 477hp (415whp/0.87). This drivetrain loss would put our relatively stock car at an impressive 496hp at the crank!
It’s somewhat of a hot topic for Gen-2 Viper owners, but the overwhelming belief that 1996-1999 motors make slightly more power than the 2000-2002 “creampuff” motors may be valid. With a 13 car sample size of bone stock Vipers or those only with intake work, 96-99 cars average 430whp while 00-02 cars average 411whp. Although there are a ton of variables from weather conditions and the dyno used, according to the data there is a noticeable trend of 96-99 cars being stronger
