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I've been getting a lot of repeat questions lately, some weird questions and some completely absurd ones, so I figured we should clear the air on Hellcat tuning. Our in-house or email tuning package that we use is centered around Diablosport's CMR software. AJ and Myself have worked together on the Hellcat tuning for the past 8 months and we've achieved some really remarkable Hellcat achievements to date (the 3 quickest Hellcats in the world in the 1/4 mile, we're featured on the March cover of Hot Rod Magazine, Hellcat X, etc.). We continue to push these cars more and more every day and we're the first to admits that the tuning will always be a work in progress, as it should be.

I get asked a lot what transmissions we tune. We tune Auto's and yes, we tune 6-Speeds, too. Some very powerful 6-Speeds I might add.

Here's the link to our email tuning package: HHP/HEMITUNER 2015+ Hellcat Tuning Package

We sell and tune for exhausts, intakes, ATI lower pulley's, Metco upper pulley's, Injector upgrades, and so on. We tune for pump gas (91 or 93) and race gas. The only thing we really haven't been pushing or offering is E85 tuning since we're not in FL or TX where it's popular - eventually we'll offer it. You get one pump gas and one race gas email tuning package. Down the road if you make additional modifications to your Hellcat, most retuning packages only run $150.00.

Enough about our package, here are the basic talking points of tuning:

1. What is the best tuning software: There will never be a true answer to this, there's so many different ways to judge software. The best software is usually tuner dependent (i.e. an LS tuner who uses a popular GM tuning software will do better with that software than he will with Diablo). For the top HEMI tuners, we all use Diablosport as our main tuning software and . Both AJ and myself have and use HP Tuners and SCT (among others) and they are good software suites but my personal opinion is that Diablo's CMR software gives me more tuning capability to do what I have to do, it's a ton more customer friendly so email tuning and datalogging is the easiest, and we can do multiple tunes for customers and you can have unlimited tunes loaded on your handheld. But, that's opinion. If you have to assign a "best tuning software" title, I would assign it based off what's on the fastest Hellcats. The fastest overall Hellcat is actually completely email tuned, I've never seen the car.

2. Remember that horsepower numbers from a dyno don't mean a thing. Every dyno is different and dyno numbers can be manipulated. Different dyno makes respond differently. And even on the same dyno, numbers can be inconsistent, especially this time of year. I tuned Eric (Faster Cat) Friday night with 93 octane on the dyno and with the same tune his Auto Challenger with the ATI pulley made 3 different sets of numbers. I made over 800rwhp with an Auto on 13.5 psi, it's on the internet so it must be true, right?



This was on 93 octane, and no tuning changes were made. Pull 2 was my standard winter tuning, my dyno room was 61 degrees and slightly chilly. I opened the dyno bay doors to let in the cold air for pull 3 and then turned on my dyno load cell for pull 4. Don't focus on dyno numbers, they don't mean that much at the end of the day. Also, this leads to a good point on transmissions...

3. Manual transmission cars should always put out a dyno number about 6% to 7% higher than automatic transmissions. I've had them baseline up around 680rwhp where the auto's are normally around 640rwhp. You can't compare the two.

4. What gear your dyno pulls are made in will affect your dyno numbers. Manual trans should be dyno'd in 4th gear. The Automatic transmissions should be dyno'd in the highest gear to 6th gear as possible. 6th gear is the 1:1 ratio gear. Due to it reaching super high speeds I have to dyno auto Hellcat's with stock rear 2.62 gears in 5th gear and only use 6th gear when the rear gear has been swapped to 3.09's. I think most tuners do the same. If your Hellcat gets dyno'd in 4th gear it will read considerably less power.

5. Max Boost: 15psi is the maximum safe boost limit on these motors for pump gas. As you go over 15psi you have to start pulling timing out at a fast pace so it's not worth the risk of trying to run anything more than either an ATI pulley or a Metco 2.85 upper.

6. Race gas is not cheating, it's the intelligent choice. Especially if you are racing your car at the track. For you guys that are modding your cats, pushing a car to it's limits on pump gas could have terrible consequences. Pump gas is not forgiving and tuners who push cars to their absolute limit on pump gas usually end up tearing that motor up sooner or later. I tell customers who are racing to pick a race gas and we'll do a tune up on it and I will get aggressive on that fuel since it makes a little bit more power and adds protection to the engine at the same time.

7. Nitrous without tuning is extremely dangerous for multiple reasons.
A. The Hellcat runs a self-correcting wideband O2 sensor for engine management at full throttle air/fuel.
B. When you spray a wet nitrous kit it is adding fuel in order to richen up the air/fuel ratio.
C. On the Hellcat, at full throttle the car runs a fuel pressure of 80psi thank to the variable fuel pump setup.
D. The excess fuel you're adding with the nitrous kit is being removed from the injectors by the computer.
What does that all mean? It means it's now lean, possibly dangerously lean, and you're left hoping that the blower that is designed to pump a compressed gas evenly distributes the liquid fuel to all cylinders. The best solution is to get tuning so that the fuel curve can be fixed and the timing can be safely adjusted.

As far as tuning goes, I hope this clears up a bunch of questions, especially from you guys that are new to the game. Both AJ and I will keep an eye on this thread and reply as quickly as we can to your questions. We're both two of the busiest guys in the HEMI market so just give us a little bit of time but we'll do our best to answer any questions posted about our tuning.

Joshua, HHP
 

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Many thanks Joshua for taking the time out to post this.
Very helpful.
Do you think I am still safe running a 2.85 upper pulley with Shell Vpower Nitro 99 octane which I believe equates to your 93/94 unleaded.
 

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Thanks for the info Josh, i know i have been one of the people sending you a couple emails :p Appreciated the help tuning my PCP Challenger with the Edelbrock, looking forward to your help with my Hellcat now as well.
 

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Thanks for the info guys. Question are you guys able to tune boost by gear? for who may not know what that is its the ability to select the amount of boost for each gear.
 

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Discussion Starter #6
Thanks for the info guys. Question are you guys able to tune boost by gear? for who may not know what that is its the ability to select the amount of boost for each gear.
To my knowledge there's no capability of tuning boost for each individual gear. Maximum boost is mechanically controlled by supercharger pulleys. On the performance tuning we cannot adjust boost levels, only trigger the boost bypass valve in a particular gear to dump all boost out. Boost bypass valves are either open or closed, open and she makes 500 hp, closed and she makes max boost and max power.
 

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I need to talk to you and AJ for a few new idea's I have, LOL
TC
 

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I think it's important for guys looking for a tune to know that HHP/hemituner tunes are the only tunes that have been validated at the track and not just a one hit wonder, this is very important because Linda and I went thru all the " well that didn't work like I thought it would " days at the track testing, dyno numbers do not relate to performance at the track, that will need to be figured out, HHP has done the work and will continue make improvement that all HHP customer will receive.
TC
 

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Discussion Starter #9
Do you think I am still safe running a 2.85 upper pulley with Shell Vpower Nitro 99 octane which I believe equates to your 93/94 unleaded.
Definitely and the datalogs will confirm all of this once we get started.
 

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Have Guns Will Travel
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Thanks for the information. I have great confidence in your work. You provided the tune for my 08 SRT8 back in the day and I've no complaints. I think I'm in.
 

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Question regarding below quote"

"Max Boost: 15psi is the maximum safe boost limit on these motors for pump gas. As you go over 15psi you have to start pulling timing out at a fast pace so it's not worth the risk of trying to run anything more than either an ATI pulley or a Metco 2.85 upper."

If I read this right, you are saying "daily driver-occasional track" should use either ATI pulley or 2.85 upper and not both. If only upper is 2.75 acceptable or pushing too much. All this on 93 octane.

Great write-up, by the way.
 

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I think it's important for guys looking for a tune to know that HHP/hemituner tunes are the only tunes that have been validated at the track and not just a one hit wonder, this is very important because Linda and I went thru all the " well that didn't work like I thought it would " days at the track testing, dyno numbers do not relate to performance at the track, that will need to be figured out, HHP has done the work and will continue make improvement that all HHP customer will receive.
TC
I don't mean to disrespect any accomplishment made by you or HHP,but I have a problem with your statement above.
My car has been 9.93 @ 139 at South Georgia Sports Park and was backed up with a 9.98 on the same day.This setup was done late in the year so we have not been to the track since.We also just won the heavyweight sponsored class on both Saturday and Sunday at the Ocala 1/2 mile event where we ran 169 mph.All of this was done on factory wheels and rear gear.I know that you and everyone that you have worked with have worked hard for your success,I commend you for that but others are working toward and reaching goals as well.I can promise you that my car and many others will not prove to be one hit wonders.
I won't hijack the thread with my tuning shop's details,they can be found in the racing section under the Florida half mile thread,page 2.

Good luck to everyone trying to make their car as fast as they want it to be, I appreciate all of the tuners and vendors who support these cars!
 

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Georgia, your too quiet so you slip under the radar,LOL Your in a place that I call limbo because 9.90-10.00 there is a lot that starts to happen in the tuning, this is your season coming up shortly I hope to see you post up that you have gone faster.
TC
 

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Dang I wish you guys were closer to me. Do you recommend any shops in Michigan that can do the mechanical upgrades and then install your tuning?
 

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Discussion Starter #18
2.75 acceptable or pushing too much.... on 93 octane.
It's right over the edge for a pump gas setup and we have to start pulling timing out it so I would say that it probably won't make any additional power over the 2.85 until race gas is applied and the lost timing can be added back in. It will also unnecessarily create more heat and there is a chance that you may end up crossing the line where the injectors are maxed out and you will then need to upgrade them as well.

I don't mean to disrespect any accomplishment made by you or HHP,but I have a problem with your statement above. My car has been 9.93 @ 139 at South Georgia Sports Park and was backed up with a 9.98 on the same day.... I won't hijack the thread with my tuning shop's details,they can be found in the racing section under the Florida half mile thread,page 2.
That's contradicting, lol. But no matter what, congrats! You're one of the few 9 second Hellcats and that alone is a huge accomplishment. The whole point of this thread is not to put down any other tuner but to educate others on the tuning we do and why certain things are not done.

Do you recommend any shops in Michigan that can do the mechanical upgrades and then install your tuning?
PM me with where in MI you are. There's a good number of shops up there.
 

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Joshua thank you for your efforts and reporting facts. Can I ask what you would feel would be my best way to combat my high elevation losses. I live at 3500-4000 ft above sea level. I have had tuning before on another FI platform and really enjoyed getting rid of throttle lag etc. We only have 91 up here. Please feel free to answer here and pm me prices for products needed as I have a great shop here with a Dyno.
Thanks in advance
 

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It's right over the edge for a pump gas setup and we have to start pulling timing out it so I would say that it probably won't make any additional power over the 2.85 until race gas is applied and the lost timing can be added back in. It will also unnecessarily create more heat and there is a chance that you may end up crossing the line where the injectors are maxed out and you will then need to upgrade them as well.
What if I added a long tube headers along with an aftermarket catback which both of them will reduce the boost 1-1.5psi, also a bwoody heat exchanger to lower the iat and a set of an id1000 injectors to prevent the injectors from maxing out!

I know it's a long list, but wouldn't that make the 2.75 pulley make more power than the 2.85 without pulling timing out?
 
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