The 2015 Dodge Challenger SRT Hellcat has 707 horsepower and 650lb-ft of torque in stock form, making it the most powerful American production car by a comfortable margin when it first debuted. Since then, the Dodge Charger SRT Hellcat has since matched those power figures so there are two Dodge products atop the list of the most powerful American production cars ever. The 2015 Chevrolet Camaro Z06 is the closest competitor to the Hellcat Challenger, but with “only” 650 horsepower and 650lb-ft of torque, the new super-Vette falls short.
Even without real competition from other factory-stock cars, Dodge Challenger Hellcat owners are likely to run into more powerful cars which have been modified and it comes as no surprise that owners are looking to squeeze more power out of this beast. It does come as a surprise that we haven’t seen more shops working to make big power from the Hellcat Challenger, but the folks from Forza Tuning and Performance are the first I’ve seen who are publically making a run for 1,000 horsepower with the supercharged Hemi.
Forza Builds, Dynos the Hellcat
The folks at Forza Tuning and Performance have put together a handful of short videos showing their progress with the 2015 Dodge Challenger SRT Hellcat, including a look at the dyno runs and the dyno sheets.
The first video below shows the Hellcat Challenger being worked out in stock form, at which point it made 654 rear wheel horsepower and 609lb-ft of rear wheel torque. That video ends by teasing the Stage 1 package, which includes new spark plugs, a cooler thermostat, Amsoil 0W-40 Signature Series oil and a Forza in-house custom tune.
The second video begins by showing us the Hellcat Challenger dyno run with the Forza Stage 1 kit, which results in 691 rear wheel horsepower and 632lb-ft of rear wheel torque. Next, this second video adds an ATI 10% overdrive lower pulley, which adds 1-2 pounds of boost and lifts power levels to 733 horsepower and 674lb-ft of torque.
In the third video from Forza Tuning and Performance, the Hellcat Challenger has been fitted with ARH headers and cat deletes before heading back onto the rollers. The headers added more power and torque, with the output climbing to 746 rear wheel horsepower and 693lb-ft of rear wheel torque.
The third video ends by showing the Hellcat Hemi with the top end pulled apart, promising development of the Hellcat stage 4 and 5 kits – with the ultimate goal being 1,000 horsepower.
Checking Forza’s Numbers
There are a few key points with these videos that my Hellcat-hating readers will be quick to point out. First and foremost, the stock Hellcat Challenger dyno run resulting in 654 rear wheel horsepower is much higher than other dyno numbers I’ve seen – from both private owners and media outlets. Most of the Hellcat Challengers I’ve seen tested on the dyno make in the 625-635hp range, so this dyno is probably a bit on the high side.
Next, the math listed in their video descriptions are likely to get major criticism from the Hellcat haters. Under one video, they state that 654 rear wheel horsepower leads to 817 horsepower at the crank. This has to have been calculated by assuming an incredibly high drivetrain loss rate of 25% and while we all know that the Hellcat Hemi is underrated, it isn’t underrated by 110hp. They used that same 25% ratio when calculating the crank horsepower with their various stage kits, so I would call their numbers a little higher than they really are.
Forza used 25%, but 15% is a far more reasonable number for calculating power numbers. For instance, if the Hellcat Challenger made 654 rear wheel horsepower and had a 15% drivetrain loss ratio, the engine would actually be making around 750 horsepower. This number still seems high, but it is in a far more reasonable ballpark.
If we take the 15% drivetrain loss number and apply that to the Forza stage kits, Stage 1 is making just under 800 horsepower while Stage 2 is making almost 850 horsepower. Finally, the Stage 3 kit is making just under 860 horsepower – really with nothing more than headers, cat deletes, a crankshaft pulley and a good tune.
We will continue to follow the progress of Forza Tuning and Performance as they work towards getting their Hellcat Challenger to the 1,000hp mark. In the meantime, enjoy the videos below of the Forza Hellcat on the dyno.