Chevron is now 85 octane??

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I filled my car at the local Chevron today (Northern Nevada) and was surprised to see the 87 octane labels were now 85 octane labels. Not something I expected to see with a top tier gas. Is this becoming the norm?
 
Well, it's different by location what "regular" "midgrade" and "premium" mean, so it's the norm, but it isn't the new norm.
The difference has to do with elevation whether regular is typically 83 or 85 or 87 or something else entirely.
 
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We're at about 4,000 altitude. Around here regular gas has normally been 87 octane. Mid 89 and high octane 91. Now at this Chevron it's 85, 88 and 91. I'm going to look around and see what the other brands are doing.

I'll probably buy other brand now.
 
Originally Posted By: cb4017
We're at about 4,000 altitude. Around here regular gas has normally been 87 octane. Mid 89 and high octane 91. Now at this Chevron it's 85, 88 and 91. I'm going to look around and see what the other brands are doing.

I'll probably buy other brand now.


Why? Less dense air means less air being squeezed in the cylinders=less power and heat. Less heat means a lower octane requirement because ignition detonation is less. So lower elevation locations require more octane and higher elevations require less.
 
I've spent quite a bit of time travelling through Utah which mostly is above 4000 feet above sea level. Because the air is less dense, your effective compression ratio is lower than at sea level and therefore the need for higher octane is also reduced. Almost all the stations I've used (even in St. George at 2,800 feet) are 85, 87, and 91 octane respectively. And if by chance you find yourself driving to lower elevations with 85 octane in your tank, modern computer controlled vehicles will alter the ignition timing to prevent detonation (at a loss of overall efficiency and power). I understand this is normal in Colorado as well, but I wouldn't know for sure.

With a normally aspirated engine, I wouldn't be too concerned. I ran my old 2005 Silverado all around Utah, Northern Arizona, and up through Nevada and 85 had no noticeable effects. However now both of my vehicles are forced induction which would compensate for the lower air density at altitude. In that case I would run the "midgrade" 87 in those areas just like I run regular 87 in lower elevations.
 
7,000 feet here. mid-grade is 87. Oddly, my Ford says to use 87 octane regular and it doesn't say anything about it being OK to use less at altitude.

Just an oversight in the manual, I imagine.
 
Originally Posted By: dave1251
Why? Less dense air means less air being squeezed in the cylinders=less power and heat. Less heat means a lower octane requirement because ignition detonation is less. So lower elevation locations require more octane and higher elevations require less.


Many of today's cars are turbocharged or supercharged. Altitude plays no role in turbocharged automotive engine performance. The lower octane negatively affects boosted engines. In fact, some cars require 93 octane, with good reason.
 
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Originally Posted By: Cujet
Originally Posted By: dave1251
Why? Less dense air means less air being squeezed in the cylinders=less power and heat. Less heat means a lower octane requirement because ignition detonation is less. So lower elevation locations require more octane and higher elevations require less.


Many of today's cars are turbocharged or supercharged. Altitude plays no role in turbocharged automotive engine performance. The lower octane negatively affects boosted engines. In fact, some cars require 93 octane, with good reason.


In theory a forced induction engine would not lose power at altitude with the turbo/super charger compensating for the lower density. However in reality, in order to accomplish this the turbine would need to spin at a greater rpm to suck in enough air to compensate for the lower density. This will result in you needing to run higher engine rpm's to attain the power resulting in a greater lag before the power comes on. In addition, higher engine and turbine rpm's means increased engine temperatures above the designed efficiency range and increased temperatures means decreased power. Finally the CAC will not cool intake air as efficiently because the lower density air will not provide as much cooling at 6000 feet as it would at sea level.

So while they will see less power loss than a normally aspirated engine, they will still lose power.
 
The lowering of the octane is a recent change. The octane at this Chevron last time I got gas there was 87/89/91. I equate lower octane to lower quality and it irritates me to pay a top tier gas price for lower quality.
 
Originally Posted By: Cujet
Many of today's cars are turbocharged or supercharged. Altitude plays no role in turbocharged automotive engine performance. The lower octane negatively affects boosted engines. In fact, some cars require 93 octane, with good reason.

That may be quite true, but to the gas companies really care? They sell what they've traditionally sold in a locale, or sell what they're required to sell. Only one company here has a premium above 91, simply because the rest don't "have to" and it isn't customary.
 
Originally Posted By: cb4017
I equate lower octane to lower quality and it irritates me to pay a top tier gas price for lower quality.


You can do that, but it is wrong.
 
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Originally Posted By: Hollow
Originally Posted By: cb4017
I equate lower octane to lower quality and it irritates me to pay a top tier gas price for lower quality.


You can do that, but it is wrong.

I don't think so.
Lets say cb has been happily paying 2.00 for 87 octane regular. There is a 20 cent spread, so 89 is 2.20, and 91 premium is 2.40. Now, his local station brings in 85, 87, and 89. If the price isn't reduced accordingly, he is paying for a lower quality fuel, top tier or not. I agree, vote with your wallet, and buy elsewhere.
 
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Originally Posted By: BikeWhisperer
Originally Posted By: Cujet
Originally Posted By: dave1251
Why? Less dense air means less air being squeezed in the cylinders=less power and heat. Less heat means a lower octane requirement because ignition detonation is less. So lower elevation locations require more octane and higher elevations require less.


Many of today's cars are turbocharged or supercharged. Altitude plays no role in turbocharged automotive engine performance. The lower octane negatively affects boosted engines. In fact, some cars require 93 octane, with good reason.


In theory a forced induction engine would not lose power at altitude with the turbo/super charger compensating for the lower density. However in reality, in order to accomplish this the turbine would need to spin at a greater rpm to suck in enough air to compensate for the lower density. This will result in you needing to run higher engine rpm's to attain the power resulting in a greater lag before the power comes on. In addition, higher engine and turbine rpm's means increased engine temperatures above the designed efficiency range and increased temperatures means decreased power. Finally the CAC will not cool intake air as efficiently because the lower density air will not provide as much cooling at 6000 feet as it would at sea level.

So while they will see less power loss than a normally aspirated engine, they will still lose power.


I understand your point clearly, as we've performed hundreds of turbocharged dyno runs and operational tests in Colorado.

For automotive use, and at typical elevations, my point stands. The normally aspirated 3% per 1000 foot lapse rate is easily offset by the turbocharger. The bottom line is that the turbine has to do slightly more work. What many people fail to understand is that there is sufficient waste energy in the exhaust gasses to provide this slight increase in additional work.

This does not result in significant HP loss at any normal elevation with modern cars. In fact, most automotive engines will produce rated power to high altitudes. In fact, Ford clearly states that the 3.5L produces peak torque to altitudes well above 5000 feet. Owners notice no difference in performance to 11,000 feet. The only real difference is the turbocharger(s) RPM.

As for intercooler efficiency and effectiveness, as a general rule, higher elevations are cooler. Intake air temperature is affected by overall system efficiency. Once again, it's typical to see normal IAT's at altitude in Ford engines.

Back to the question at hand. High elevation locations often sell lower octane fuels. In modern turbocharged engines, this can result in loss of power. Using 85 octane in a Ford Ecoboost is not within the specifications and not a good idea.
 
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Originally Posted By: beanoil
Originally Posted By: Hollow
Originally Posted By: cb4017
I equate lower octane to lower quality and it irritates me to pay a top tier gas price for lower quality.


You can do that, but it is wrong.

I don't think so.
Lets say cb has been happily paying 2.00 for 87 octane regular. There is a 20 cent spread, so 89 is 2.20, and 91 premium is 2.40. Now, his local station brings in 85, 87, and 89. If the price isn't reduced accordingly, he is paying for a lower quality fuel, top tier or not. I agree, vote with your wallet, and buy elsewhere.


Nope, still wrong.

Octane =\= quality. You appear to be under the false premise that octane is a measure of quality of fuel, it is not.
 
Originally Posted By: Hollow
Octane =\= quality. You appear to be under the false premise that octane is a measure of quality of fuel, it is not.


Exactly, the energy content of the gasoline is not related to the octane rating.
 
Originally Posted By: beanoil
I don't think so.
Lets say cb has been happily paying 2.00 for 87 octane regular. There is a 20 cent spread, so 89 is 2.20, and 91 premium is 2.40. Now, his local station brings in 85, 87, and 89. If the price isn't reduced accordingly, he is paying for a lower quality fuel, top tier or not. I agree, vote with your wallet, and buy elsewhere.


He's getting the same energy with any of them.
 
Originally Posted By: BikeWhisperer
Originally Posted By: Cujet
Originally Posted By: dave1251
Why? Less dense air means less air being squeezed in the cylinders=less power and heat. Less heat means a lower octane requirement because ignition detonation is less. So lower elevation locations require more octane and higher elevations require less.


Many of today's cars are turbocharged or supercharged. Altitude plays no role in turbocharged automotive engine performance. The lower octane negatively affects boosted engines. In fact, some cars require 93 octane, with good reason.


In theory a forced induction engine would not lose power at altitude with the turbo/super charger compensating for the lower density. However in reality, in order to accomplish this the turbine would need to spin at a greater rpm to suck in enough air to compensate for the lower density. This will result in you needing to run higher engine rpm's to attain the power resulting in a greater lag before the power comes on. In addition, higher engine and turbine rpm's means increased engine temperatures above the designed efficiency range and increased temperatures means decreased power. Finally the CAC will not cool intake air as efficiently because the lower density air will not provide as much cooling at 6000 feet as it would at sea level.

So while they will see less power loss than a normally aspirated engine, they will still lose power.


Well, not entirely true. Many newer turbos are of the Variable Geometry variety, and therefore they generate the same boost at a particular RPM at any elevation. The Ecoboost turbos are VG for example. Boost is controlled by ECM and actuator.
 
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