Quote:
|
Gerry : Whether there is an advantage or difference in how the engine performs depends upon how you use the car. If you're light on the throttle and the engine doesn't normally see high loading, then there won't be much difference. If you take advantage of the engine's power, then there will be a difference. It comes down to how the knock sensor is managing the ignition timing curve. The blatant evidence would be born out of the datastream for the ignition advance. Lower ignition advance means less power and lower fuel economy. Higher advance gives you the opposite. It's a tough call and you can't apply a universal answer to every situation.
|
The G-Tech calculates power by measuring acceleration during a WOT acceleration run, so spark advance is certainly accounted for. I have a long straight section of road that is mostly flat and that seems to run perpendicular to the prevailing wind. Runs over the time that I have been testing with the G-Tech have resulted in power measurements within a 10 hp range. I have tried to maintain conditions as constant as possible, but temperature, humidity, barometric pressure and wind are all variables that will change developed power so the readings vary from day to day. My tests have shown no statistically significant change with fuel grade. There may be one, but it isn't very big.
Quote:
|
And it's hard to make the call with just one blended (some regular and some premium) tank of gas. I'd say try each for a month. This will give you higher resolution in your measurements and you can make a decision based upon the more abundant information.
|
I ran each grade of fuel for a minimum of 5 tankfuls, and driving essentially the same cycle revealed no change in overall fuel economy. The exception to this was the first tank of premium after a steady diet of regular, when mileage jumped by about 4 MPG. The second tank saw a return to my normal 24 MPG. My daily drive cycle is 6 miles of stop-and-go, 4 miles of normally high-speed country road, 5 miles of highway, and a mile of stop-and-go, then a reversed return home.