octane effects power and engine temp?
 

Hey guys/gals. I topped off my fuel tank last night, about half empty, with 87 octane with no ethanol. this morning I noticed less power. This evening I noticed even less power and the engine was not as snappy to rev and it was running warmer than usual. Oil looks clean, no condensates, coolant level is topped off and clean. I topped off the tank on my way home tonight, 91 octane, the highest I can get here, the engine ran at normal temp and the engine felt a little stronger but not as strong as I'm used to. Did I just get some bad gas? I was able to squeeze 3.4 gallons of 91 octane while topping off tonight.

Ethanol is lower total BTU content than gas by about 1/3, so any fuel containing a level of ethanol is going to be down on power and mileage.

will the engine run noticebly hotter too?

Why would you put 87 in???

Its all the station had that I stopped at. They were the last station in the region that wasn't putting 10% ethanol in the gas. But, I think I would be better with 91 and 10% ethanol?

I didn't notice, it must have happened recently, my wife said there is a new sticker that indicates 10% ethanol plus the inferior 87 octane. double whammy

my idle is rock solid

87 octane??? In a Porsche?? Ferdinand Porsche is rolling over in his grave.

This is slightly off topic, but may be of interest. Occasionally I have access to non-ethanol 93 octane fuel. I keep track of my mpg and maintenance using an app on my iphone. I find that with the non-ethanol I get about 1-2 mpg better highway mileage, and that it improves another 1-2 mpg in the warmer months. Here's the skinny:
Summer, non-ethanol, 26-28 mpg
Summer, ethanol, 25-27 mpg
Winter, non-ethanol, 24-26 mpg
Winter ethanol, 23-25 mpg
This data was collected since mid May 2013 over 23,000 miles in a 1999 911 C4. I had noticed similar trends earlier in my 2000 986S.

It could, but that could also be related to the overall quality of the gas as well.

I think it's directly on topic. Consumer reports observes a average 15% reduction in MPG with gasohol. :(

This must be a high elevation location. High altitude reduces octane requirement since the lower oxygen content richens the air/fuel ratio.

Brought to you by your Federal Nannies, along with less fuel stability, faster and higher levels of water contamination, and endless corrosion of expensive fuel system components......your tax dollars in action.

Money truly is the root of most evil!

I knew there was a reason I liked JFP. Fuggin Nannystate no doubt imposing stupid demands on it's people and over a hoax just adds insult to injury:barf:

What's it called?

The app is called Road Trip:
https://itunes.apple.com/us/app/road-trip-mpg-mileage-fuel/id298398207?mt=8

I think it's one of the best apps I've purchased.

improvement
 

I added octane booster to this tank till I get all the non 91 octane out. I also changed the oil. I discovered that my oil cap does not seal when it is tightened down. How come these engines have a vacuum at the oil fill tube instead of pressure?

The AOS also lowers the pressure in the sump to a vacuum around -5 inches of water so that the low tension piston rings can properly seal.................

running much better
 

Well, Changed the oil after 7k miles. still look pretty nice. discovered the loose oil cap and remedied that. added the octane booster and also topped off this morning with another 91 octane fuel. and she is running a lot stronger and temperature didn't climb much above 180 driving up in the mountains. I have a 160 degree thermostat. I was pretty nervous a couple of days ago with the acting up. low power, overheating. :)