Bully Dog

jrod332 · June 18, 2009

Im wondering if anyone has had any luck with the bully dog power tuner for gas. I have one and did a basic tune. I have yet to tune it for a higher octane. Im hesitant to spend the money on the higher octane if that setting isnt going to get me that much more MPGs. would it make a difference setting it for the highest setting and still use 87? I have read a lot of mixed signals about different tuners on this forum. To much to search through.

96chevy7.4L · June 18, 2009

The premium octance tune might get you 1 or 2 mgs but you will notice a difference in power. You don't want to put the premium tune it an run 87 gas as there is a good chance the engine will detonate which is not good. Also some of the programmers recommend going to to a cooler thermostat if using the premium tune I don't know if bully dog recommends this or not. Hope this helps.

AgDoctor · June 19, 2009

i dont know anyone with one, but i can tell you that an 87 octane fuel with a 93 tune would be bad, but these NBS trucks alter timing after a certain amount of detonation occurs---I have heard, not sure. better off selling the Dog and getting another tuner, or Tune.

Perry · June 19, 2009

Running 87 octane with a 93 octane tune shouldn't hurt the engine.

I can't speak for the new Silverado's as I've only tuned an '02 Silverado, but the PCM holds 2 seperate tunes, one for 87 octane and one for 93 octane. The PCM is suppose to use readings from various sensors to detect the current octane of fuel being used and switch to the appropriate tune to match the fuel octane. If you were to program your truck with the 93 octane tune and then fill up with 87 octane fuel, the PCM should sense that and revert to the 87 octane tune stored in the PCM.

pineland is correct, the PCM will try to alter timing if it senses to much detonation by reverting back to the 87 octane tune. But if there is to much detonation with the 87 octane tune then damage can occur.

As for the cooler thermostat, that is an option the tuner can change in the PCM. If the tuner or Bully Dog recommends a cooler thermostat, then most likely they have changed that option in their program and set it to work with a different thermostat than the factory one.