Actually there is a lot to be said for that level of consistency. For one, your mpg calculations are always consistent if its the same fuel, and if you calculate mpg by fill-up receipts its always best to use the same station if possible.
Mainly what the engine is capable of doing with it.... true.
But energy potential being the same is incorrect.
The energy potential is determined in the test engines that dictate the octane a particular fuel can display on the pump.
So by definition, the higher octane fuels have higher energy potentials (and potential to knock if taking MON mainly into account).
The AKI Octane value display on US/Canadian pumps is an average of RON and MON (R+M/2).
To get AKI, test engines are used which have extremely variable compression ratios (for the RON value) and variable ignition timing (for the MON value).
Simplifying the subject somewhat, the higher the Octane the higher the activation energy (or energy extracted from the ignition).
^^^ quoted for truth.For simplicity sake, Ill compare E85 and gasoline. While the activation energy of E85 is much higher, the potential energy in a gallon of E85 is much lower. A gallon of gasoline has a potential energy of 114,500 BTU, whereas E85 has a potential energy of 81,800 BTU.
No kidding, "mind tricks" and placebo effect mostly. Although some are reporting reduced mileage. The main significant and measurable impact will be on wallet for owners of CX-5 engineered to be run on regular gas.
I tried the 91 in mine for about 1500 miles and switched back to 87 and noticed no drop in performance and if anything the mpg reading ticked up .1 so no more 91 for me.
Thanks for the report ta240, good to hear feedback based on actual driving for 1500 miles (versus speculation, butt dynos, people staring at the mpg meter real-time, etc.).
Conclusion: Most significant impact was the extra $10 in petty cash you paid for gas during that 1500 miles.
Is it the info button (if I remember correctly) on right side of steering wheel (up/down arrow) to select avg speed, avg gas mileage, range, etc.
ouch, that bold text was for me I think. I'll admit, I earned that. Funny thing is that I was getting bad mileage with the 93 octane until the last 1/4 tank when I had a chance to hyper-mile it a bit and pulled off 29.5mpg for the tankful. So I ruined my own experiment (bang)
insideline said:We also spoke to Mazda engineer Masuhiro Mora, who told us that although the American CX-5 is tuned to run right as rain on 87 octane, there's likely to be at least a modest performance benefit to filling it up with 91 when we eventually test it. "With 91, you should have slightly better torque in theory," he said.
"We also spoke to Mazda engineer Masuhiro Mora, who told us that although the American CX-5 is tuned to run right as rain on 87 octane, there's likely to be at least a modest performance benefit to filling it up with 91 when we eventually test it. "With 91, you should have slightly better torque in theory," he said."
That essentially says nothing, an experiment that never happened, words such as "likely" "modest" and "slightly better torque in theory" is the best he could do. And many months later, no followup, no test.
I'm going to believe engineers at Mazda that actually finished the job and specified regular gasoline in the Mazda CX-5 owners manual. I will be running 87, until Mr Mora gets off duff and proves his empty guess.
To each his own. You are correct that there are no controlled scientific tests from which to base a decision. We are left with speculation; Speculation of a Mazda Engineer vs speculation of random forum posters. I choose the former. If his is an "empty guess" then what does that make everyone else's? In the end I choose to spend the (minimal) extra money, as is my prerogative, because I believe there is benefit.
it sure would be nice for mazda or an aftermarket tuner to release somthing that would allow us to program the engine for 14:1 as I understand is possible with the skyactiv engine. i'd be willing to pay a little extra for 91 octane for a little extra performance and efficiency.