Sold on 89 Octane

[aeonixx1001]

Is that the Loves Truck Stop at Wildhorse?

I believe it is. Call em first...

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[2nd 392]

Back in the day 110 octane was also called Av gas, short for aviation gas. The octane rating does not correspond to more BTUs in the fuel. ie it’s not more explosive. It simply lets you run a higher compression ratio in your cylinder with more timing. Those do equate to more horsepower and more torque. The drawback is the way they get to 110 Octane. The only way I know to truly reach 110 is with the use of lead additive. If you put a gas with lead in a car with a catalytic converter, you will plug the converter. I would guess it would not be compatible with other components in a modern vehicle either.

And highly unlikely the computer could advance the timing enough to make Avgas cost effective even if it was no lead…. The 115-145 they filled the flathead 6 flight line van with when they fueled the aircraft didn’t hurt it. (but may have improved it’s 0-15 mph number)

 

[bcupton]

Ethanol will eventually ruin any engine. (IMHO). I agree on 89 octane and even better if you can buy non-ethanol corn gas! I get between 1-2 more mpg when I use non-corn gas.

 

[aeonixx1001]

So, they seem to bust the octane myth, yet before they do one pull, they admit they would use at least 91 in a real car because of real world issues.

The 91 pull showed a percentage point better torque, which is what we use going up hills, leaving a light.

I'm not surprised timing did not change.

They admitted the engine ran leaner with the 91, which is exactly how you improve mileage.

Previous poster noted our computer is always running into and out of lean and changing mixture based on knock. That also helps MPG and something I don't think engine masters did, they manually adjusted parameters.

BTW, I am not sold on using higher octane, just trying it out.

It just makes sense, Higher octane = more energy and you can say to the wheels. So it is more efficient, but then cost becomes a factor.....

 

[YBABRAT]

So, they seem to bust the octane myth, yet before they do one pull, they admit they would use at least 91 in a real car because of real world issues.

The 91 pull showed a percentage point better torque, which is what we use going up hills, leaving a light.

I'm not surprised timing did not change.

They admitted the engine ran leaner with the 91, which is exactly how you improve mileage.

Previous poster noted our computer is always running into and out of lean and changing mixture based on knock. That also helps MPG and something I don't think engine masters did, they manually adjusted parameters.

BTW, I am not sold on using higher octane, just trying it out.

The meat of their findings is detonation. Many don't know if it is happening when ECU detunes what it can to minimize knock. Removing knock will keep performance in line. E85 or oxygenated fuel may be too low for 11.3:1 compression. Our engines are not specified for e85. It is almost impossible to find here where I live. As long as I keep seeing the results with 89 or better, I will never go back to 87.

 

[F4Flyer]

I just use top tier 91 from places like Shell and Exxon. One vehicle calls for it so I just use that in all three. Never had any issues but I used to use 87 till a couple of years ago. I live at 6,000 ft and we go to 10,000 ft almost every weekend from May-Sep. In my head, the vehicles run better with 91 so I continue. 91 also always has good detergents.

 

[azjl#3]

And highly unlikely the computer could advance the timing enough to make Avgas cost effective even if it was no lead…. The 115-145 they filled the flathead 6 flight line van with when they fueled the aircraft didn’t hurt it. (but may have improved it’s 0-15 mph number)

i think engine masters did a good job showing timing is unaffected by octane, however, mixture ratio is and does effect mpg.

Anyone familiar with specs, timing etc for the Maserati 3.6?

 

[2nd 392]

i think engine masters did a good job showing timing is unaffected by octane, however, mixture ratio is and does effect mpg.

Anyone familiar with specs, timing etc for the Maserati 3.6?

Surprising, the knock sensors don’t adjust the timing ? Old muscle car guy who twisted distributors doesn’t get why not to use the longer burn of higher octane for increased power/efficiency. Even early computers like my 95 V10 PU, it went from ~12 mpg down to ~8 mpg with the new reformulated “clean” gas. A good $5K (90’s $) of performance upgrades including a tune with more advance and back to ~11/12 mpg with a good power gain. Premium required but for a good mpg gain with a good power gain due to being more efficient is well worth the extra cost of premium.

 

[watchluvr4ever1116]

It just makes sense, Higher octane = more energy and you can say to the wheels. So it is more efficient, but then cost becomes a factor.....

Higher premium octane contains the same energy as lower regular octane.

 

[morrisl29]

And highly unlikely the computer could advance the timing enough to make Avgas cost effective even if it was no lead…. The 115-145 they filled the flathead 6 flight line van with when they fueled the aircraft didn’t hurt it. (but may have improved it’s 0-15 mph number)

Advance that timing to 200 degrees BTDC and hang on. LOL!

 

[WI_Sarge]

is it harmful to the engine to switch back and forth between octanes?

 

[morrisl29]

is it harmful to the engine to switch back and forth between octanes?

As long as you don't go below the factory recommended Octane it's all good.

 

[m3reno]

I was getting a slight knock with 87 octane and by switching to 89 no more knock. It happens more in the summer months vs the winter. Usually on take-off's is when the knock occurs, on the high way it seems fine.

 

[2nd 392]

I was getting a slight knock with 87 octane and by switching to 89 no more knock. It happens more in the summer months vs the winter. Usually on take-off's is when the knock occurs, on the high way it seems fine.

The fast burn time of low octane creates more detonation than the slower burning higher octane. Hot air, even hot expanded fuel has a detrimental effect. This is why intercoolers and cold fuel cans exist.
IE- the gen 5 Whipple SC Mustang produced ~700HP, the new gen 6 for 24 with more efficient screws and a larger inverted intercooler produces ~800 HP. on the same engine.

 

[SaintNick]

Interesting. In higher elevations than even yours, I found I'm lucky to get 1/2 MPG bump running 87 no ethanol. Compared to 85 octane with ethanol blend. In multiple studies from multiple vendors.

I "feel" like the no ethanol gas is better qualitatively, and I feel better using it or blending half/half, but my MPG numbers have never been there, in any season. 3.6.

So I got around 13-14 in Dallas with much more stop and go. In Utah, the worst I have done is 17 and up to 22 with 3.6 e-torque.

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