Mopar Controller with 98 or 100 Octane?

[Boxer12]

Anybody tried running higher octane with the Mopar controller on Gen 4? How long did it take for the computer to adjust to the new gas? Did you notice any power increase?

 

[mjorgensen Woodhouse]

We have run 100 octane on the dyno and got a lower number than the 93. IMHO too much octane is like retarding timing and loosing power. The PCM is tuned to optimize the 93, any more is retarding the flame front (timing).

 

[Boxer12]

We have run 100 octane on the dyno and got a lower number than the 93. IMHO too much octane is like retarding timing and loosing power. The PCM is tuned to optimize the 93, any more is retarding the flame front (timing).

good to know, thanks Mark. Let me know if you try 95 or 98. Jim

 

[plumcrazy]

unless its tuned for the higher octane or actually needed, its a total waste and like mark said could very well likely HURT performance

 

[vincy]

I thought the Mopar controller was designed for race fuel but able to run on 93 octane.

It seems to me it takes a long time for the computer to adjust to any changes.

 

[Boxer12]

Its not clear to me from reading The Grailkeeper's post if the PCM is able to adjust to higher octane, but it seems implied that it is tuned for a range of 93 down to 90. I think Mark helped with the tuning, I just wonder about anything above 93. I will have to mix gas in Utah next month, and am a little concerned about it, and was hoping I could just add some 98 or 100 in with some 90 (max octane at pump in UT) without having to be too precise. So, to get 93 from 90 and 100, I am going to have to do some math. About 1 gal of 100 to about 3 gals of 90, right?

 

[plumcrazy]

id get a hold of tom and see what he says.

 

[utahviper]

91 Octane is the rating for premium. You might not have to worry about the octane rating in Utah. The mopar ecu is designed for 93 but that is at sea level, as you increase altitude your overall compression decreases. Thus you should be able to run 91 octane at high altitude without any detonation. My 08 has never had any detonation issues but I do not have a mopar performance ecu. This has been my experience with all vipers. I can run more timing with less octane at high altitude. If I go to sea level I run higher octane from the pump and everything is fine.

Are you going to MillerMotorsports Park?

 

[mjorgensen Woodhouse]

The MAX octane that will be affective is 93... The Mopar PCM will also run on 91 and 92 though if it has to. If you plan on going to the track or hard driving in high temps shoot for the 93 if you can get it. People do mix fuels, but they do not always effectively mix and you could end up getting bursts of good and bad at the wrong times so don't count on this as a fix. Some have had great luck with octane boosters that are designed for mixing though and I'm one of them. Not all are created equal though so do your research and don't use them in every tank as there is no real data points about the possible affects of prolonged usage in the Viper motor. FWIW.

 

[Boxer12]

Thanks for clarifying that Mark. Miller Motorsports Park is exactly where I am going, for NASA Nationals. Needless to say, I need max performance. I think if you mix gas in the can it should be ok, but maybe I will just buy a few more containers and haul 55 gal of 93 gas to the track (9 racing sessions plus 2 practice) to be safe.

 

[Viper X]

This is second hand and perhaps Dan Cragin will chime in, but according to what Dan has told me, our cars with the Mopar controller (mine has Belangers and a K & N) run very well at up to 95 octane on his dyno (his shop is close to sea level) and actually prefers 95 and 94 to 93 octane.

I've been doing what most of us here in Kalifornia do, mix 100 with 91 (best we can get) and try for about a 50 / 50 mix. Car runs strong at the track - no issues.

Good luck,

Dan