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I know this topic has been all over this forum but I am really torn over what I should do about my Predator.

Here is my situation:

I own a 2009 Dodge Challenger R/T 5.7L Auto and just purchased the Predator for it. I have installed a few new modifications: Mopar CAI, MBRP Cat Back Exhaust, BT Catch Can. I currently use 87 Octane in my Challenger. I am looking for an answer to a question I have. I'm not sure if a custom tune is right for my vehicle or not. I want to stay away from paying a lot of money at the gas pump for 93 Octane every fill up. I would like to stay with 87 Octane or even 89 Octane. I am trying to get the most out of my vehicle and use my challenger as a daily driver. What would you recommend me do? Use one of the pre-installed predator tunes or custom tune?

Thank you in advance for your time helping me out.:)
 

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You can probably get a custom tune that will accommodate 87 octane, but you'l lose performance. Your best bet if you're trying to save money at the pump is to get an 89 octane tune. You won't see much, if any, performance gain, but you will see a slight increase in driveability and improved shifting. Go to Diablosport's section on this forum and send them a PM with your question.
 

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When I first installed my Predator I ran it on the 89 CAI stock tune and definitely noticed a difference over stock and after a month or so changed up to the 93 CAI stock tune. At first it seemed the 89 had a better low end and the 93 had a better top end but not so sure. Now with the colder weather and engine fully broke in it really pulls good all the way. But the car ran great with the stock 89 tune so I would go with it and save some money.
 

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According to the Predator tune page, you can use 89 octane instead of the 91 octane, but you have to detune the timing which of course reduces performance and kind of defeats the purpose of adding a tune to the car. I got a predator for my car thinking i could use the 91 octane tune and use the mid grade gas, then afterwards realized that our mid grade in Florida is only 89 octane. The car runs fine with the 91 canned tune using 89 octane, but i don't run full throttle with it either, its a daily driver and rarely see's the pedal mashed to the floor. Here is the comments regarding the 89 octane gas. to my knowledge the predator comes with a 91 octane tune, a 91 CAI tune, and a 93 octane tune. I'm not aware of an 89 octane tune in it.

17) Running 89 or 100 Octane Fuel
Since the introduction of this tool, many have asked if they can run 89 octane fuel with a Predator tune. The answer is Yes and No! If you are going to install a Canned Tune shipped with the Predator, you Must run at least 91 octane and NO you cannot run 89 octane fuel. Diablosport has authorized using Modify Tune on the Perf 91 or Perf 91 CAI tune, by retarding timing 2 degrees in all six WOT Spark settings to run 89 octane fuels, so in this case, YES you can once timing is retarded 2 degrees as listed. Make sure you log some WOT passes and play them back to insure no LT Retard appeared. Similarly, if you are at the race track and can purchase 100 Octane Low Lead, you can Advance the timing of the 91 octane tune by 4 degrees, maybe 5 with data logging to check for knock.
Diablosport Predator

The car runs a bit peppier than it did when running 87 octane regular, and it will break the tires loose on launch which it pretty much wouldn't do before unless you brake torqued it. I figure if i plan on doing any performance driving with it, i'll mix in some 93 premium with the 89 octane i run in it now, or put some 93 in for the next fillup then load the 93 CAI tune in it.
 

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Warlock you are correct, momentary lapse of cranial rectal inversion. It was the 91 CAI with 89 gas. You don't see a whole lot of 91 in my area, it is 87,89 and 93 most places. But it did run fine on the 89 and did notice any detonation at full throttle
 

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Warlock you are correct, momentary lapse of cranial rectal inversion. It was the 91 CAI with 89 gas. You don't see a whole lot of 91 in my area, it is 87,89 and 93 most places. But it did run fine on the 89 and did notice any detonation at full throttle
You wont notice any detonation at full throttle, because the Knock sensors will be going NUTS pulling tons of timing to keep your teeny little ring lands from cracking. You will be down on power from what it would make on premium fuel though.

I have to question the idea of buying a performance car, then a performance tuner, then trying to run cheap gas with it???

To safely run low grade fuel in these cars, you'd likely have to pull timing from the stock setting, which will cause a loss of power....no getting around it.
 

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I only used the 91 perf tune as a starting point, even though i do have a drop in k&n filter. With mine the stock tune said regular 87 gas was fine, i understand the 6spd's need 91 or higher, but the car ran fine with the stock tune at 87. I was only using the next level tune to see how it ran and see if there was a difference that you could tell, and in some ways there was. I'm sure running premium would probably make a difference, but i'm not planning on removing mds, nor will it see any track time in the near future, running 13s isn't enough to get me to drive to gainesville raceway over 60 miles away. If it was able to push into the 12s i might, but that is a ways off at this point. I'm fairly satisfied with a mid 13 car for daily use. Its as fast as the old charger was on crappy rubber or as the stealth used to be stock. The cars too new to consider modding it significantly to worry about 12s.

As for a performance car and cheap gas, mid grade gas isn't cheap gas, and the hemi isn't supercharged, or turbocharged, and was designed to run on regular which is one reason why i got an auto instead of the 6spd. I run premium in my supercharged cars, but there is no point in running premium if the car doesn't need it to run properly. My supercharged cobra with a handheld tuner worked fine with 93 octane, as does my turbo stealth running double the factory boost levels.

It may be advisable to run premium with any tune with the predator, i just wish diablo had tunes designed for the fuels that we have available, running 93 premium doesn't make sense to me going to the office and back 5 days a week at 70mph and only part throttle. The tuner is a tool, where i can add a higher level tune on the weekend when i want to run a tank of premium, then i can back it off with the stock tune if i have to during the week. I'd just like a happy medium i can use all the time without swapping tunes out.
 

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If your looking for performance, running premium will be by far the best fuel to go with.

Here is a quick break down of cost and mileage of different fuel octane.

Lets say you drive a high amount of miles, like 14,000 miles a year.
Lets also say your Challenger gets only 18mpg average.
That is 777 gallons of fuel per year.

777 gallons x 3.08 (Ohio average for 87 octane) = $2393 a year
VS
777 gallons x 3.41 (Ohio average for 93 octane) = $2649

A cost difference of $256 a year
/ 12 months
= $21 per month extra for a much better driving performance car. (based in Ohio fuel cost averages, 18MPG average and 14,000 miles a year.)

Sure, I wouldn't run premium in a 95 Honda as the gains are just not as evident as it would be in the Challenger.

Tim C
 

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MrBaseball, I pretty well have the same set up as you. The car runs like a bat outta hell with the Diablo 91 CAI tune. You really don't need to get a custom tune IMO unless you start playing around with the airflow (headers, 85mm TB etc).
 

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Discussion Starter #11
Thank you all for your valuable information. I think I need to just suck it up and go ahead and treat my hemi with higher quality fuel. I'm debating to use 93 or 91 still. I've heard mix reviews as which is better with the tuner.
 
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