The Hellcat has amazing consistency in acceleration.

Discussion in 'SRT Hellcat Performance' started by Driver72, Aug 4, 2015.

  1. Driver72

    Driver72 Gold Member

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    I know many on here are so worried all the time about IAT Temps, IC Temps, Oil Temps, etc etc and thinking that plays a major part in performance with those temps being a bit higher hurting the performance in this car.

    Well, I've said before and have also read before that with the Hellcat, unless all those things are REALLY REALLY HOT, it doesn't really matter as the car performs the same.
    I noticed this at the drag strip when I went, my best time was the 3rd of 3 passes when the car was really the warmest, even though I did give it some cool down time.
    I read other people running at a drag strip almost back to back runs for 5-6 runs and their best times were the later runs.

    I've commented on this when many many people were stating that dyno numbers seemed to be lower without sufficient cool down times between runs. I've noted that I don't think it's that, I think it's the lack of proper air for these engines on a dyno. You just don't get them.

    Well last night, I did my baseline stock intake runs for the Hellcat.
    Did various speeds, various gears.

    And you know what? At first I would stop the car and wait 3-5 minutes between passes.
    And I got the same time as I did the first runs.

    So then I decided I would do some basically back to back runs.
    I have my dedicated starting point, I'd do a run, then turn around. Drive softly for about a mile then turn back and go back to my starting point.
    Same times again.
    And ironically, after 40 miles over 1.5 hours of "testing" on nearly every single test, I'd get almost exactly the same result on the last test as I did on the first, no matter if I turned the car off and let it sit for 5-10 minutes or just drove regularly for 1 mile as I returned back to my starting point and did this over and over again.

    On a couple of my runs, my best times came later, when the car had done the most runs.
    To give you an idea, my first two runs I did last night I got a time of 6.9 seconds from 30-100 mph starting in 3rd gear, with 3-5 minutes of cool down between those two runs.
    I decided after all the various runs I did before I went back home, and just moments after doing other runs, I wanted to do a 30-100 mph 3rd gear start run one more time. Got 6.8 seconds.
    So the very last test when the engine was arguably the hottest, after running non stop for over 1/2 hour and doing 6-8 rolling acceleration runs, was .1 second better than the very first two tests that night when the engine was the "coolest".

    Here's what I learned, and have suspected myself based on my limited drag strip time in THIS car (have dragged race dozens of my other cars), and also having seen other publications post how the HC did equal or better times as it's engine and such got a bit warmer:
    Once the coolant temp, oil temps, get up to their "normal" operating temps, as long as you keep moving and give it even just a 1/2-1 mile of cruising, the temps stabilize. They heat up a bit immediately after the run, but takes little time for them to drop back to normal.
    Same with the IAT temps.
    Same with Intercooler temps.
    This car really does have amazing cooling abilities.
     
    Last edited: Aug 4, 2015
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  2. Hemibuck

    Hemibuck Gold Member

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    Interesting. I notice that even when it's hot out with the AC on that the car is still amazing!
     
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  3. Paladin06

    Paladin06 Have Guns Will Travel Staff Member Hellcat Car Club Gold Supporting Member

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    It's the only car I've ever owned that does not take a power dump with the AC full on. Hell I street race things like SS Camaro's and walk them with the AC on. :D
     
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  4. DGatzby

    DGatzby Gold Member Hellcat Car Club HCC Charter Member Midwest Regional Pres.

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    Yes, the car is the only one I have owned/driven that is still fun and a pleasure to drive in a hot steamy day. Performance is notably down, but plenty of punch remains. On those days and they have been few, I have sat back turned the seat vents on, chilled and listened to my SD music. Great car.
     
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  5. Hemibuck

    Hemibuck Gold Member

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    I swear the car runs cooler with the AC on. I was out tearing it up and noticed the temp getting up. It was hot and smoky out from all the fires so I closed her up and threw on the AC and the temp was lower! Amazing car. They don't get the credit they deserve.
     
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  6. Driver72

    Driver72 Gold Member

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    I have about 165 miles on the AFE CAI now.

    I am going to hopefully add at least the 45-50 more tomorrow before doing the full battery of acceleration tests compared to my stock intake times.

    But a little teaser here:
    On my way back from my recent 65 mile drive, I went to the testing road I use.
    Did one of the runs, and equalled my BEST time on the stock intake, which was .1 second better than the first two runs on the stock intake.
    But this was after 65 miles of straight driving, both highway and city. AND, with a DA that was 500 feet higher.
    I then turned around and did another one of the tests (different from the one I just did), and got .2 seconds faster than any of the 3 times I got with the stock intake doing that same acceleration test.
    And again, this was with a DA of 1935 feet compared to the DA of 1450 feet I had stock.

    I did 4 different acceleration tests with stock intake, did each of them 3 times (so a total of 12 rolling run acceleration tests).
    The times were all very consistent, usually exactly the same times even in back to back runs.

    So as it stands, even without the full 200-250 miles AFE recommends on the intake, it has equalled or bettered the stock intake times even with worse conditions. May just be an anomaly, or the AFE CAI may actually be working and doing something.
    Stay tuned for the full 12 runs with the AFE intake compared to the stock, once I get another 50-100 miles on the AFE, and hopefully can get a DA that's closer to the stock's 1450 feet too for best case comparison results.
     
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  7. Hemibuck

    Hemibuck Gold Member

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    Well you will be one of the few with any good results from this intake.
     
  8. Driver72

    Driver72 Gold Member

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    Because I believe I am the only person who is actually road testing it, not putting it in a lab on dyno rollers with questionably insufficient fans for needed air flow as my determining factor for owning or keeping it. I said I'd never base my decision on whether I was going to keep the AFE CAI based on one persons dyno (lab test) results, even though I thoroughly appreciate and respect that DAK did those dyno tests. They were very informative and does call into question how AFE got their 37 hp gain from the intake while on a dyno. Others SHOULD be able to replicate that, or at least get close. But unless they know exactly how AFE did their tests and got the 37 rwhp, it's hard to say why DAK's didn't do better. Clearly AFE thought he would or should as they paid for the re-dyno after at least 200 miles of adaptation.
    Nonetheless, I even encouraged people to wait the additional week or so for my road tests before returning their AFE intake, but apparently one single dyno test was enough for people to send it back.

    I know I have had a few distractors who think my testing isn't "valid" and one 23 year old kid who posted "LMAO" because I use gps based testing gear to get actual road test results (he apparently didn't/doesn't know that's what every single automotive magazine, journal, or website that tests cars do, and I use the same equipment).

    Not saying my final tests will prove that it's doing better than stock, but in my little teaser test it did equal or better the stock times already with a DA of 500 feet higher, so that's a plus. If it gets better times on average, or better times period in 3 of the 4 different tests that will be pretty conclusive for me. But again, if it doesn't get better on average or only marginally better on 1 or 2 of the tests, I myself probably won't keep the AFE intake either.
     
    Last edited: Aug 5, 2015
  9. Hemibuck

    Hemibuck Gold Member

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    There are quite a few that are road testing them. But for $450-550 it better give me a seat of the pants difference. For $400 more I can get a new flashed ECU that will give the seat of the pants increase we are looking for and then some. But I hope you get what you paid for.
     
  10. Driver72

    Driver72 Gold Member

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    Who has road tested them already, with timing gear, on either the road or even a track?
    As far as I know I have seen nobody else post results on the road, or even mentioned they are doing it.
    And going to a track isn't the best for comparison either, as launches affect times drastically, so unless they can consistently launch with similar 60 foot times each and every time, the 1/4 mile results won't be the most accurate factor. Even so, I was going to go to the drag strip tonight with it, but it got "rained out" even though it was just a passing rain shower that stopped 1 hour before the gates even opened and 2 hours before racing was to begin, the sky was clear after that. Oh well.

    As for "seat of the pants difference"
    You do realize that 37 hp on a 707 hp car is only 5%. That's really hard to feel by the seat of your pants.
    That would be similar to 10 hp on a 200 hp car. You aren't going to get a "seat of the pants difference" in feel from 10 hp on a 200 hp car either.
    And that's IF you are truly getting the full 37 hp they claimed. If the intake is giving the car even 20 hp at WOT, that surely wouldn't be much to feel, and even in my acceleration test would at most yield .1-.2 seconds improvements.

    If you could get repeatable 60 foot time launches (say 1.8 to 1.85) in the 1/4 mile that 20-37 hp MIGHT improve your time by .1 to .15 seconds and 1 mph faster traps. But again, you'd need the same or similar DA too, the track would have to be prepped the same each time too, as difference in prep means differences in traction and friction, which affect ET's and speeds.

    Anybody who was thinking they'd get a noticeable butt dyno difference, on just an intake on a 707 hp 4,500 lbs car, even if it truly did make 37 hp, I think is fooling themselves a bit. But I also think getting a full 37 hp out of just an intake is a bit of a stretch. I'd be happy with 20 hp. So again, if my road tests show on average I'm getting better times on the AFE CAI than I did on the stock intake on 12 runs of 4 different acceleration tests, to me, it would be clear that it is giving more power.
    Will soon find out.
     
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  11. rayzazoo

    rayzazoo DRIVESRT.COM Gold Supporting Member

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    Btw, a 0.1-0.3 sec 1/4mi race gain is at least 1 1/2 to 4 Challenger lengths quicker in the 1/4mi to put things in perspective.
     
    Last edited: Aug 5, 2015
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  12. Driver72

    Driver72 Gold Member

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    Old conventional wisdom has always been that .1 second in the 1/4 equals 1 full car length.
    Of course that varies from car to car and from power level to power level.
    Faster cars will cover more ground in less time so that old conventional wisdom is good for a baseline.
    So yes, you are correct, .1-.3 seconds is 1.5-4 car lengths in the 1/4 mile, all else being equal.
     
  13. Hemibuck

    Hemibuck Gold Member

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    You know that this really makes some sense. I have been in the world of NA motors with decent HP for so long that I needed to wrap my head around what I am really driving. 707 HP is an insane amount of HP and your right 37 is not a big increase in the overall scheme of things. But either way I'm not dropping $550 for "better sound" and maybe some improvement. The fasted HC Charger in the world is using the stock airbox. If the price drops I might be in but when you pop the hood and they see the intake they are going to ask what that gave you as far as HP goes and then your left to say "ummmm not sure but it sounds and looks cool". I just need some proven increases in performance before I go all in.
     
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  14. Driver72

    Driver72 Gold Member

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    Me too and that's why I'm road testing it, to actually see if there is some proven increase in performance.
    I don't want to waste my $445 on the intake if I don't get measurable results.
    If it shows the gains and people say, "what kind of hp does it give you" I will probably say, "Company claims around 37 hp, a couple dyno tests have shown little to no gain, but I did a bunch of acceleration tests, and based on that, I'd estimate a gain of roughly X amount." If I see .1-.2 second improvements I'll probably say 15-20 hp fill in that X amount with 15-20 hp.
    Again if I don't see at least .1 second improvement on basically every test, I'll probably be sending it back too. Ironically I've already seen .2 second gain on one of the tests (just did it 1 time though, I like to do each test at least 3 times to see if it varies or is consistent and accurate each time) over the stock intake test, but it's an acceleration test you'd never really do (8th gear WOT pull) so that is really the least important test for me.
    Looks like I'll be able to do the AFE tests tonight, or no later than tomorrow as looks like the weather may cooperate.
    I'll have 250 miles on the AFE filter by then (have 220 now and about to go out again for another little blast around.)
     
  15. rayzazoo

    rayzazoo DRIVESRT.COM Gold Supporting Member

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    Hehe, I actually got my results from doing the math calculations for Challenger. Surprisingly, I had no clue that there was a general rule of thumb, however, it's good that the math is supporting the theory.
     
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