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2015 Challenger SRT Hellcat M6
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Discussion Starter · #1 ·
Shortly after I bought my 2015 HC, a buddy of mine asked about the stated and actual horsepower (BHP and RWHP). I gave him the factory numbers and mentioned that actual HP would probably be less, as has been my experience with other Challenger models. Today he sent me a link to an article published in late 2014 by Torque News. The numbers are surprising.
 

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Challenger SRT Redeye
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There are HP to wheel numbers north of 650 hp.
 

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2017 Dodge Challenger Hellcat
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my 2017 put down 622whp and 582 ft/lbs on a dyno jet, dyno guy pulled up another hellcat for comparison stock to stock and that hellcat put down 652whp I dont remember the torque
 

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Challenger SRT Hellcat
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I’ve read here that the M6 puts down a little more power than the A8 but I don’t recall why that would be. Drivetrain loss maybe?
 

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2020 Challenger Hellcat Redeye NB
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403 Posts
I’ve read here that the M6 puts down a little more power than the A8 but I don’t recall why that would be. Drivetrain loss maybe?
Manual trans drive train loss is always lower than automatics... it's gotten significantly closer the last 10 years or so due to the advancements in automatic transmissions.
 

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2020 Challenger Hellcat
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810 Posts
Also keep in mind that dyno testing is absolutely terrible at giving actual horsepower numbers. It's all simulated based on input parameters, then on variables like atmosphere, test equipment latency, temparatures, etc.

Dyno tests are best used for only measuring a before and after result on the same vehicle (preferably under identical conditions). Identical tests, from one to the next still vary up to 20hp in many cases. As repeated pulls are made, the power goes down (at least on non air to water intercooled vehicles) as IAT and charged air temperature increases. This is why I tend to thumb my nose at CAI and throttle body manufacturers who claim that dynos show a 10% gain in power according to dyno results. Having experience with this, I know that if you heat soak a car by running it 5x through the dyno, replace the CAI or TB, then dyno it once to show a 10% gain over the previous last pull is really just a 0% or negative gain. That, or running the modified car with a lesser load is another common trick.

I'm ranting, but what I'm trying to get at is that dyno testing and using the HP output as a marker for actual performance = impossible. It can show trends and make historical comparisons, but one thing a dyno cannot do is give you an accurate readout as to your final actual horsepower. But, people try and do it anyway.
 

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2017 Challenger SRT Hellcat
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Also keep in mind that dyno testing is absolutely terrible at giving actual horsepower numbers. It's all simulated based on input parameters, then on variables like atmosphere, test equipment latency, temparatures, etc.

Dyno tests are best used for only measuring a before and after result on the same vehicle (preferably under identical conditions). Identical tests, from one to the next still vary up to 20hp in many cases. As repeated pulls are made, the power goes down (at least on non air to water intercooled vehicles) as IAT and charged air temperature increases. This is why I tend to thumb my nose at CAI and throttle body manufacturers who claim that dynos show a 10% gain in power according to dyno results. Having experience with this, I know that if you heat soak a car by running it 5x through the dyno, replace the CAI or TB, then dyno it once to show a 10% gain over the previous last pull is really just a 0% or negative gain. That, or running the modified car with a lesser load is another common trick.

I'm ranting, but what I'm trying to get at is that dyno testing and using the HP output as a marker for actual performance = impossible. It can show trends and make historical comparisons, but one thing a dyno cannot do is give you an accurate readout as to your final actual horsepower. But, people try and do it anyway.
100%. But, as to the original post, these motors do seem to be underrated.
 

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DRIVESRT.COM
Challenger SRT Hellcat
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As I understand the SAE ( Society of Automotive Engineers) horsepower testing for new cars, each manufacturer must bring 6 engines for the rating. All 6 are tested on a certified engine dynamometer, with all accessories attached and a full amount of the recommended engine oil. The engine with the lowest horsepower is then given the official rating for all of the manufacturer's cars. The 797 rating on the Redeye was the softest of all 6 engines tested. BTW, they had to use 91 octane because that is only what is available in many locations.

I'm guessing that most Redeyes have more like 805-815, especially after looking at the article mentioned above. And I agree with Xylander, most chassis dynamometers are unreliable. Some are even adjusted to give phony numbers to enhance the tuner's reputation.
 

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Challenger SRT Redeye
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I have an official paid for copy of the SAE certification on the 2019MY 6.2 HO Engine in the Redeye. I don’t know about six submitted, but it “softly” achieved 812 HP at 6400 RPM and 719 ft-lb at 4800 RPM. Then FCA rated it at 797/707. It does not specify the fuel used, but if that was 91 octane, that means it was probably not working to its full potential either.
 

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Exactly. And I'll bet it's another 5-7 hp on 93 octane. Soft engine meaning a little down or light or low on HP. But I'm guessing you knew that.
 

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Charger SRT Hellcat
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Then there's the thin mountain air AND 91 octane. Do we still lose 3% per 1000' increase in altitude?
 
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