What type of HP/Toque loss could I expect if I tuned for 87 from 91 (or 93) octane, if the blends are equal ethanol etc.?? Is it really worth it to run the higher octane on a (mostly) street vehicle??

 

I would be more concerned with detonation with the lower octane fuel and breaking a piston and tearing up a motor. It will take a lot of $0.10 cheaper gas to pay for another short-block... I've seen four LS7 vettes come through here in the past year that ran lower grade fuel and killed a piston that ended up breaking the sleeve. Just food for thought.

Jon

 

If you are trying to make power and start milling heads, running cams for high DCR yes this will hurt you. This can also limit your mod options. If you tune for 87 you will have to cut some timing back to make it work on a stock motor. To be honest your better off just sticking with 93 or whatever you can get ahold of and mod with the intent to keep some mileage in mind while modding. You can raise compression, install a cam with boltons and get good mpg with a 6 speed and stock gearing if you keep your foot out of it.

 

My full intention was to time it properly and that is what I was wondering...how much HP/Torque do you really lose when reducing that. Our premium is $.30 a gallon more up here so that was a notable factor while considering this for a regular driver. I have not had a chance to test the MPG's but they should be decent (I hope) with 3.42's, 28" tire and .67 OD trans.