I think everyone's always interested in dyno results and time slips, so I just thought I would share the timeline of my car's modifications and the results over time. I've got a 2016 R/T with the 345 ci (5.7L) currently running with the 392 cam, 392 intake with active runners, Hellcat airbox, JBA short tube headers, and a Corsa Xtreme catback.
I never did a true stock dyno pull so unfortunately we won't have an absolute baseline. Reports vary a bit, having surveyed a lot of threads I think 318 whp is reasonably typical for the R/T's.
At the time of my first dyno pull in Attachment 1, the only modifications I had which could conceivably add power were the hellcat airbox, catback exhaust, and I was running the Diablosport canned 91 octane tune. There was no tuning performed with the first dyno, it was only a baseline, which yielded 330 whp and 362 torque. So if 318 whp is an accurate stock value, then we can attribute +12 whp to the catback and canned tune, and potentially a bit more if the car would have been tuned from the dyno.
Some time later I had the 392 intake and short tube headers on the car, and this time I got dyno tuned. This days results are given in Attachment 2, but we have some details that need to be discussed to fully understand them. In the attachment the red curve is the before and blue curve after. The headers provided significantly improved torque and power throughout most of the band, just falling off at the higher RPM's like one would expect. I drive in the low-mid RPM range, so that's primarily why I forewent the long tubes in favor of short. We would have expected the 392 intake to have improved the peak horsepower at the high RPM range, and the fact that it didn't and that we don't see any kind of inflection point at the 4800 RPM runner switch point is a dead giveaway as to what happened. Later that night I used my trusty borescope to verify that my runners weren't switching. The runners were in long mode, so the intake was probably not too different than the stock intake's long runners, and that explains why we have next to no change at the high end. I eventually determined that the solenoid was bad and replaced it, so we'll have active runners by the time we get on the last dyno session.
Now here we are in the present. I just got the 392 cam installed a couple of weeks ago and had it tuned, so this final tune will be for the 392 cam and the functional 392 intake. on top of everything else. At the end of the day, 382 torques and 376 horsepower! Not the 391 horsepower seen in this youtube video (
), but in my research it looks like 376 horsepower is perhaps a more typical result for our cars with the same modifications.
At the dragstrip my quarter mile pass is 13.7087 sec and 101.63 MPH at 6010 ft density altitude in Attachment 4. Obviously your results may be better at lower altitudes, but this density altitude is pretty typical for my elevation and I'm confident that if I get a good day where its even a little bit lower that I'll get into the 13.6's. I also feel like I probably have room to improve in the 60 ft, so I could get a little bit better on that front as well. Other than that, since I can't afford forced induction this is probably close to as good as I'm going to get at my elevation.
Since then I went ahead and ported my intake manifold and bought a larger throttle body to match just to check those last two things off the list. I'm not sure its worth the money to dyno tune again just for those two things, what do you all think?
![Preston Dyno Baseline 2020-03-09.png]()
![Dyno 2020-07-30.jpg]()
![2021-03-25 Dyno Results.jpg]()
![Best timeslip 2021-03-27.jpg]()
![Engine bay 2021-04.jpg]()
I never did a true stock dyno pull so unfortunately we won't have an absolute baseline. Reports vary a bit, having surveyed a lot of threads I think 318 whp is reasonably typical for the R/T's.
At the time of my first dyno pull in Attachment 1, the only modifications I had which could conceivably add power were the hellcat airbox, catback exhaust, and I was running the Diablosport canned 91 octane tune. There was no tuning performed with the first dyno, it was only a baseline, which yielded 330 whp and 362 torque. So if 318 whp is an accurate stock value, then we can attribute +12 whp to the catback and canned tune, and potentially a bit more if the car would have been tuned from the dyno.
Some time later I had the 392 intake and short tube headers on the car, and this time I got dyno tuned. This days results are given in Attachment 2, but we have some details that need to be discussed to fully understand them. In the attachment the red curve is the before and blue curve after. The headers provided significantly improved torque and power throughout most of the band, just falling off at the higher RPM's like one would expect. I drive in the low-mid RPM range, so that's primarily why I forewent the long tubes in favor of short. We would have expected the 392 intake to have improved the peak horsepower at the high RPM range, and the fact that it didn't and that we don't see any kind of inflection point at the 4800 RPM runner switch point is a dead giveaway as to what happened. Later that night I used my trusty borescope to verify that my runners weren't switching. The runners were in long mode, so the intake was probably not too different than the stock intake's long runners, and that explains why we have next to no change at the high end. I eventually determined that the solenoid was bad and replaced it, so we'll have active runners by the time we get on the last dyno session.
Now here we are in the present. I just got the 392 cam installed a couple of weeks ago and had it tuned, so this final tune will be for the 392 cam and the functional 392 intake. on top of everything else. At the end of the day, 382 torques and 376 horsepower! Not the 391 horsepower seen in this youtube video (
At the dragstrip my quarter mile pass is 13.7087 sec and 101.63 MPH at 6010 ft density altitude in Attachment 4. Obviously your results may be better at lower altitudes, but this density altitude is pretty typical for my elevation and I'm confident that if I get a good day where its even a little bit lower that I'll get into the 13.6's. I also feel like I probably have room to improve in the 60 ft, so I could get a little bit better on that front as well. Other than that, since I can't afford forced induction this is probably close to as good as I'm going to get at my elevation.
Since then I went ahead and ported my intake manifold and bought a larger throttle body to match just to check those last two things off the list. I'm not sure its worth the money to dyno tune again just for those two things, what do you all think?
