gasoline grades here...

[johngalt]

On the plus side, there is a gas station near me that sells ethanol free premium (91). However, it is about $.10 more expensive than the E10 premium. But the E10 premium is also only 91. Every place else I've been, the E10 premium is 93 and is the same price as the pure gas 91.

I'm curious as to why there is no 93 octane E10 in MN. Not that I much care since I can easily get pure gasoline.

Oh, and I can't buy beer in the grocery store either.

 

[LVSteve]

Local laws and/or supply chains can be frustrating. I'm not sure we have 93 octane in the valley at all, and ethanol free is only available in a very few places at a large price premium. Go to parts of the state with altitude like Tonopah and the gas doesn't go above 89 octane.

One thing that does frost me here is that I can buy beer and strippers on a Sunday but not cars. Really?

 

[bigwheelzip]

I'm curious as to why there is no 93 octane E10 in MN.

Can't vouch for the accuracy, but this purports to be a map of 93 Octane locations, with a bunch of markers in St. Paul MN.

93 Octane Gas Finder map

 

[johngalt]

Can't vouch for the accuracy, but this purports to be a map of 93 Octane locations, with a bunch of markers in St. Paul MN.

93 Octane Gas Finder map

I wonder if it is just the Holiday gas stations. That is where I've been going, I haven't seen 93 yet. I think Minneapolis is their headquarters.

 

[oneounceload]

Non ethanol here is almost $!/gallon more than regular unleaded

 

[muddocktor]

93 octane premium is pretty much the standard premium gas around Louisiana from what I've noticed. But around Midland TX I only saw 91 octane gas sold as premium gas. I don't know why that is except maybe their altitude is much higher and for some reason cars don't need the extra octane rating.

 

[TX-Dennis]

93 octane premium is pretty much the standard premium gas around Louisiana from what I've noticed. But around Midland TX I only saw 91 octane gas sold as premium gas. I don't know why that is except maybe their altitude is much higher and for some reason cars don't need the extra octane rating.

Exactly. Higher altitude means lower compression. Lower compression does not require as high an octane rating. That is changing somewhat, though with forced induction engines. There's still a difference in compression at higher altitudes, but it's much smaller.

The good news is that modern engine computers can adjust the vehicle to run well on whatever gasoline is available. That may result in slightly less power, but it won't damage the engine the way detonation (knock) can.

 

[LVSteve]

Exactly. Higher altitude means lower compression. Lower compression does not require as high an octane rating. That is changing somewhat, though with forced induction engines. There's still a difference in compression at higher altitudes, but it's much smaller.

The good news is that modern engine computers can adjust the vehicle to run well on whatever gasoline is available. That may result in slightly less power, but it won't damage the engine the way detonation (knock) can.

The amount of boost many turbo motors can run these days makes that questionable for the industry, IMHO. I suspect many have sufficient excess capacity to make themselves altitude insensitive. I darned sure the BMW diesel we own has. It stomps up and down the 4000' climbs between here and Victorville never shifting from 8th gear at 1800 rpm, traffic permitting.

 

[muddocktor]

Exactly. Higher altitude means lower compression. Lower compression does not require as high an octane rating. That is changing somewhat, though with forced induction engines. There's still a difference in compression at higher altitudes, but it's much smaller.

The good news is that modern engine computers can adjust the vehicle to run well on whatever gasoline is available. That may result in slightly less power, but it won't damage the engine the way detonation (knock) can.

Yeah, you get into turbocharging and that goes by the wayside a bit. Most turbos installed nowadays have enough excess capacity to still hit pressure limits even at altitude. Thank God for electronic knock detection so these higher stressed turbo engines don't self destruct from pre-ignition. I am kind of glad that my Colorado has a normally aspirated V6 instead of a turbo 4 like Ford put in the Rangers. I know that today's turbos are reliable, but if it does happen to go out I bet it's mucho expensive to change.

 

[Farmer17]

My 2018 Ram quadcab V6 will run on E85 but it will only get 14 mpg on the highway and on E10 gas it gets 20-21 mpg in the city and I drive with a heavy right foot. It doesn't get any better mileage when I use higher grades of fuel. My wifes Infinity SUV will only take premium which is 93 octane around here and it doesn't run too good on lower grades and I hate paying the higher price for premium gas but man that car is fast! Quarter mile under 14 seconds and 155 mph top end.

 

[Texas40]

Exactly. Higher altitude means lower compression. Lower compression does not require as high an octane rating. That is changing somewhat, though with forced induction engines. There's still a difference in compression at higher altitudes, but it's much smaller.



The good news is that modern engine computers can adjust the vehicle to run well on whatever gasoline is available. That may result in slightly less power, but it won't damage the engine the way detonation (knock) can.

Compression ratio is static regardless of altitude it is the air to fuel ratio that changes. As altitude increases air density decreases. Reducing the amount of air going into the engine. Which in turn decreases the engines power and increases the risk of preignition/lean condition.

Old days you had to compensate by adj/chg jets on the carb.Now the computer does it for you adj fuel/air ratio to get max power and avoid pre ignition and or lean condition.

Lean condition is what melts pistons in turbo and S/Cd motors.




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[stansdds]

I can't remember the last time I saw 93 octane gasoline in central Virginia. I remember back in the 1980's, when I still had my Gran Torino, 93 octane was replaced by 91 octane unleaded in the pumps around Richmond and that car would barely run on it.

 

[CAJUNLAWYER]

One thing that does frost me here is that I can buy beer and strippers on a Sunday but not cars. Really?

I can see buying beer but why in the world would you want to BUY a stripper ??????

 

[LVSteve]

Compression ratio is static regardless of altitude it is the air to fuel ratio that changes. As altitude increases air density decreases. Reducing the amount of air going into the engine. Which in turn decreases the engines power and increases the risk of preignition/lean condition.

Old days you had to compensate by adj/chg jets on the carb.Now the computer does it for you adj fuel/air ratio to get max power and avoid pre ignition and or lean condition.

Lean condition is what melts pistons in turbo and S/Cd motors.




Sent from my iPhone using Tapatalk

Compression ratio stays the same, true. But the combustion chamber pressures will remain the same with sufficient turbo boost. It all depends on whether the boost is relative to the local ambient pressure (relative boost, to coin a phrase) or is it absolute boost relative to sea level. Detonation is a function of the absolute pressure, IIRC.

 

[LVSteve]

I can see buying beer but why in the world would you want to BUY a stripper ??????

Do you prefer "rent"?

 

[johngalt]

Do you prefer "rent"?

I guess one just rents his beer too...