Project Farm testing impacts of octane and ethanol content on power and mpgs...interesting!
- Thread starter TiGeo
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Top tier Reg with a bottle of Techron every 6-8 months, 30000 miles on car.
Regular? When was your last UOA?
What's your top MPG on trips? Ave MPG?
Try premium to see how much your MPG jumps.
Never had UOA done not smelling fuel in the oil nor does the level go up on the dipstick so assuming fuel dililation is not an issue. MPG 32-33 at 70-75 MPH, AWD with the 19' wheels, I have never tried premium fuel in it.
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We use Costco 98 octane ethanol free in everything.
*98 RON
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Yep, 98 RON. Used to use Shell 100 RON but no longer available.
I only had 1 car that was running right definitely got better mpg with premium. A VW new beetle 1.8t turbo. It would get around 25mpg with premium, with regular it would go as low as 14mpg. Everything else I ever bothered to test premium vs rug got the same or worse with premium.
octane rating should have no net increase in potential power output per unit of fuel, so the answer lies somewhere else if their was a mileage change.
since ethanol offers less potential energy per unit of weight than gasoline, it would seem to me that increasing the amount of ethanol in the fuel would lower fuel economy.
since ethanol offers less potential energy per unit of weight than gasoline, it would seem to me that increasing the amount of ethanol in the fuel would lower fuel economy.
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If the engine can advance the timing and take advantage of a higher compression ratio it will be more efficient. A higher octane rating allows more predictability when initiating the combustion at higher compression.
You’re thinking about Octane the wrong way: 5 myths about performance culture’s most misunderstood rating.
Octane is one of the most commonly discussed, highly marketed properties of performance fuels. Fuel manufacturers tout their high-octane products. Octane boosters promise added horsepower. And Hollywood promotes “high-octane” thrills for the next installment of their latest street racing...
www.etsracingfuels.com
dnewton3
Staff member
Agreed.If the engine can advance the timing and take advantage of a higher compression ratio it will be more efficient. A higher octane rating allows more predictability when initiating the combustion at higher compression.
You’re thinking about Octane the wrong way: 5 myths about performance culture’s most misunderstood rating.
Octane is one of the most commonly discussed, highly marketed properties of performance fuels. Fuel manufacturers tout their high-octane products. Octane boosters promise added horsepower. And Hollywood promotes “high-octane” thrills for the next installment of their latest street racing...
What people don't understand is the difference in concept between the BTU energy in the fuel vs. what the engine can do with higher RON rated fuels. Two topics which are often conflated in error.
The engine responding to changes in octane with adjustments to air/fuel ratio and spark timing is a matter of the ECU. Looking at just the fuel alone, octane has no impact on fuel economy nor power potential. For most cars on the road, the only thing higher octane will do is make the owner's wallet a little lighter. For those cars that do respond to higher octane, it's unlikely the improvement in fuel economy is enough to offset the cost of the premium fuel.
Where I am, regular E10 87 is $3.49/gal and premium E10 93 is $4.09/gal. (Regular ethanol-free 87 is $4.89/gal... phew!) Let's say a car gets 25 mpg on regular E10 87 and has a 12 gallon tank.
25 mpg x 12 gallons = 300 miles
12 gallons x $3.49/gal = $41.88 per tank or $0.14 per mile
On premium...
12 gallons x $4.09/gal = $49.08 per tank, a +17.2% increase in cost.
300 miles x 1.172 = 351.58 miles or 29.3 mpg over a 12 gallon tank to get the same $0.14 per mile
In order to just break even on the cost of the premium fuel, the car would have to improve fuel economy by +4.3 mpg which is -15% less fuel per mile. I don't see that happening. My wife's Mustang, which adjusts for the octane, has consistently shown a +1.5-2.0 mpg improvement on 93 over 87 along the same driving routes in similar weather conditions, well below the improvement needed to justify the higher cost. I would imagine +2 mpg is about the optimistic upper limit any vehicle would probably get from adjustments for premium fuel.
Where I am, regular E10 87 is $3.49/gal and premium E10 93 is $4.09/gal. (Regular ethanol-free 87 is $4.89/gal... phew!) Let's say a car gets 25 mpg on regular E10 87 and has a 12 gallon tank.
25 mpg x 12 gallons = 300 miles
12 gallons x $3.49/gal = $41.88 per tank or $0.14 per mile
On premium...
12 gallons x $4.09/gal = $49.08 per tank, a +17.2% increase in cost.
300 miles x 1.172 = 351.58 miles or 29.3 mpg over a 12 gallon tank to get the same $0.14 per mile
In order to just break even on the cost of the premium fuel, the car would have to improve fuel economy by +4.3 mpg which is -15% less fuel per mile. I don't see that happening. My wife's Mustang, which adjusts for the octane, has consistently shown a +1.5-2.0 mpg improvement on 93 over 87 along the same driving routes in similar weather conditions, well below the improvement needed to justify the higher cost. I would imagine +2 mpg is about the optimistic upper limit any vehicle would probably get from adjustments for premium fuel.
There it is.
A well programmed fuel map and super keen knock sensors with rapid fuel injection system can and does get better MPG with higher RON fuels.
Yes of course.
BUT with some engines like the CRV 1.5T the MPG on the hwy pushes almost near 40mpg vs say 34-35mpg on 88-89RON or so PLUS no fuel dilution with 92RON. That makes the premium worth it in my book.
like I said, its something else besides the octane rating. most gasoline engines have to run at Stoichio to meet emissions and mileage requirements, so exactly what the answer is and as to why, it probably boils down to tune and outlier unmeasurable stuff.. I don't think any of the tests quoted by Project Farm are detailed enough for any consistent answer.If the engine can advance the timing and take advantage of a higher compression ratio it will be more efficient. A higher octane rating allows more predictability when initiating the combustion at higher compression.
You’re thinking about Octane the wrong way: 5 myths about performance culture’s most misunderstood rating.
Octane is one of the most commonly discussed, highly marketed properties of performance fuels. Fuel manufacturers tout their high-octane products. Octane boosters promise added horsepower. And Hollywood promotes “high-octane” thrills for the next installment of their latest street racing...
Did you understand what I wrote and what others have noted? Yes it can be related to the octane rating if the engine can take advantage of being able to advance the ignition timing. Compression ratio is directly related to efficiency. The air/fuel ratio isn’t relevant here since it’s about extracting the most energy possible from the existing mixture. It’s not unmeasurable, you can watch the timing advance yourself if you’re so inclined.
But on the other hand there are a myriad of factors that influence fuel economy. As you mentioned the energy density of the fuel is also important. It’s one of the reasons why no one can accurately prognosticate about one specific variable, I once linked an article that showed that even at the same gas station the energy density varied about 4% and this was irrespective of winter/summer blends or other gross variables. Proper fuel economy testing in a laboratory always starts with standardized test fuel.
I think the commonality in these examples might be the compression ratio. On that Honda and my Mazda the CR is in the double digits. I definitely noticed a mpg increase by using premium gasoline.
Definitely has an impact and is factored in with a turbo effectively raising the static CR
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