Why does everyone think E85 is 105 octane
Thread Starter
New Member
Joined: 01-15-16
Posts: 46
Likes: 0
From: Wentzville, MO
Why does everyone think E85 is 105 octane
Almost every post where people talk about E85, they seem to think the octane rating is 105 comparing it to 93 octane gas using (R+M)/2.
There is no source I could find that stated an (R+M)/2 of 105?
It is 95-97 depending on winter-summer blends, and even lower if its the new 51% winter blend in some regions.
The octane rating of e85 is good, but its not that good. The reason e85 is so good is because of its cooling properties which aren't represented very well in the octane rating.
The Enthalpy of Vaporization per unit mass at room temp of Ethanol is 2.6 times that of gasoline, this means it basically takes 2.6 times as much energy(mostly heat) from the air to vaporize liquid ethanol to a vapor versus gasoline. That's how ethanol is so good at combating internal cylinder temperatures and hot intake air to reduce knock. This is also why in colder weather it is harder for high blends of ethanol to start. The fuel has difficulty vaporizing so that it can burn.
There is no source I could find that stated an (R+M)/2 of 105?
It is 95-97 depending on winter-summer blends, and even lower if its the new 51% winter blend in some regions.
The octane rating of e85 is good, but its not that good. The reason e85 is so good is because of its cooling properties which aren't represented very well in the octane rating.
The Enthalpy of Vaporization per unit mass at room temp of Ethanol is 2.6 times that of gasoline, this means it basically takes 2.6 times as much energy(mostly heat) from the air to vaporize liquid ethanol to a vapor versus gasoline. That's how ethanol is so good at combating internal cylinder temperatures and hot intake air to reduce knock. This is also why in colder weather it is harder for high blends of ethanol to start. The fuel has difficulty vaporizing so that it can burn.
Last edited by xRedrumisBack; May 16, 2016 at 09:50 PM. Reason: corrected ethanol to e85
New Member
Joined: 07-18-14
Posts: 82
Likes: 2
From: ohio
Thread Starter
New Member
Joined: 01-15-16
Posts: 46
Likes: 0
From: Wentzville, MO
Who gives a flying what the calculation is, when you running a 105 octane gas variant you get to the same timing as running e85.
And honestly I have yet to see any actual tests of e85, just forum posts.
And honestly I have yet to see any actual tests of e85, just forum posts.
Thread Starter
New Member
Joined: 01-15-16
Posts: 46
Likes: 0
From: Wentzville, MO
Just thought I'd give some insight into why it performs as well as higher octane gasoline. Just interesting to know why instead of just saying is better
It's cooling effects are well known and why people run it, you see no significant increase in timing after about e50 on port injection and around e60 on direct injector. Only reason people run straight e85 is for cooling or laziness at the pump since most states and stations don't have ethanol mixing pumps
Thread Starter
New Member
Joined: 01-15-16
Posts: 46
Likes: 0
From: Wentzville, MO
It's cooling effects are well known and why people run it, you see no significant increase in timing after about e50 on port injection and around e60 on direct injector. Only reason people run straight e85 is for cooling or laziness at the pump since most states and stations don't have ethanol mixing pumps
It started raining so I still need to try adding some more. Also might add a little more E as well
Joined: 12-30-07
Posts: 14,079
Likes: 197
From: NEPA
Platinum Member
Platinum Member
Joined: 04-12-09
Posts: 4,869
Likes: 16
From: Connecticut
$7/gal?!?! I'm coming to where ever you are to get fuel then! Cam2, or anything comparable, is right around $12/gal out my way.. lol
As far as the octane ratings go. Although I'm clearly not a chemist, nor do I care to have the equipment or no how to test and compare octane ratings in fuel, I can at least share this much.
A few years ago I did a pretty in depth test,comparing an array of fuels and concentrations of the fuels. I'm not going to write an entire paper on the matter atm so, long and short of it....
Unleaded and oxygenated Cam2 (100 octane, 105ron 95mon) produced less hp and could not take as much timing as even e47-e50 blends of ethanol. The most noticeable power drop off was in torque and seat of the pants driving. Granted, there are far more potent versions of race fuel than 260GT out there, but they're also not very emissions friendly, or wallet friendly for that matter. For me, unless you go for the "big boy" juice and are going for serious power, it's just not worth spending the money on actual race fuel.
On a side note.... There's nothing like the smell of running race fuel though!! lol
As far as the octane ratings go. Although I'm clearly not a chemist, nor do I care to have the equipment or no how to test and compare octane ratings in fuel, I can at least share this much.
A few years ago I did a pretty in depth test,comparing an array of fuels and concentrations of the fuels. I'm not going to write an entire paper on the matter atm so, long and short of it....
Unleaded and oxygenated Cam2 (100 octane, 105ron 95mon) produced less hp and could not take as much timing as even e47-e50 blends of ethanol. The most noticeable power drop off was in torque and seat of the pants driving. Granted, there are far more potent versions of race fuel than 260GT out there, but they're also not very emissions friendly, or wallet friendly for that matter. For me, unless you go for the "big boy" juice and are going for serious power, it's just not worth spending the money on actual race fuel.
On a side note.... There's nothing like the smell of running race fuel though!! lol
Joined: 12-30-07
Posts: 14,079
Likes: 197
From: NEPA
$7/gal?!?! I'm coming to where ever you are to get fuel then! Cam2, or anything comparable, is right around $12/gal out my way.. lol
As far as the octane ratings go. Although I'm clearly not a chemist, nor do I care to have the equipment or no how to test and compare octane ratings in fuel, I can at least share this much.
A few years ago I did a pretty in depth test,comparing an array of fuels and concentrations of the fuels. I'm not going to write an entire paper on the matter atm so, long and short of it....
Unleaded and oxygenated Cam2 (100 octane, 105ron 95mon) produced less hp and could not take as much timing as even e47-e50 blends of ethanol. The most noticeable power drop off was in torque and seat of the pants driving. Granted, there are far more potent versions of race fuel than 260GT out there, but they're also not very emissions friendly, or wallet friendly for that matter. For me, unless you go for the "big boy" juice and are going for serious power, it's just not worth spending the money on actual race fuel.
On a side note.... There's nothing like the smell of running race fuel though!! lol
As far as the octane ratings go. Although I'm clearly not a chemist, nor do I care to have the equipment or no how to test and compare octane ratings in fuel, I can at least share this much.
A few years ago I did a pretty in depth test,comparing an array of fuels and concentrations of the fuels. I'm not going to write an entire paper on the matter atm so, long and short of it....
Unleaded and oxygenated Cam2 (100 octane, 105ron 95mon) produced less hp and could not take as much timing as even e47-e50 blends of ethanol. The most noticeable power drop off was in torque and seat of the pants driving. Granted, there are far more potent versions of race fuel than 260GT out there, but they're also not very emissions friendly, or wallet friendly for that matter. For me, unless you go for the "big boy" juice and are going for serious power, it's just not worth spending the money on actual race fuel.
On a side note.... There's nothing like the smell of running race fuel though!! lol
VP109 is my new poison
Much better than just regular old CAM2 and similar price out by me.
$7/gal?!?! I'm coming to where ever you are to get fuel then! Cam2, or anything comparable, is right around $12/gal out my way.. lol
As far as the octane ratings go. Although I'm clearly not a chemist, nor do I care to have the equipment or no how to test and compare octane ratings in fuel, I can at least share this much.
A few years ago I did a pretty in depth test,comparing an array of fuels and concentrations of the fuels. I'm not going to write an entire paper on the matter atm so, long and short of it....
Unleaded and oxygenated Cam2 (100 octane, 105ron 95mon) produced less hp and could not take as much timing as even e47-e50 blends of ethanol. The most noticeable power drop off was in torque and seat of the pants driving. Granted, there are far more potent versions of race fuel than 260GT out there, but they're also not very emissions friendly, or wallet friendly for that matter. For me, unless you go for the "big boy" juice and are going for serious power, it's just not worth spending the money on actual race fuel.
On a side note.... There's nothing like the smell of running race fuel though!! lol
As far as the octane ratings go. Although I'm clearly not a chemist, nor do I care to have the equipment or no how to test and compare octane ratings in fuel, I can at least share this much.
A few years ago I did a pretty in depth test,comparing an array of fuels and concentrations of the fuels. I'm not going to write an entire paper on the matter atm so, long and short of it....
Unleaded and oxygenated Cam2 (100 octane, 105ron 95mon) produced less hp and could not take as much timing as even e47-e50 blends of ethanol. The most noticeable power drop off was in torque and seat of the pants driving. Granted, there are far more potent versions of race fuel than 260GT out there, but they're also not very emissions friendly, or wallet friendly for that matter. For me, unless you go for the "big boy" juice and are going for serious power, it's just not worth spending the money on actual race fuel.
On a side note.... There's nothing like the smell of running race fuel though!! lol
Thread
Thread Starter
Forum
Replies
Last Post
Foximus
Parts
15
Jul 9, 2016 01:46 PM
Doug's Cobalt SS SC
Problems/Service/Maintenance
5
Jun 17, 2016 01:23 PM
Viperoni
Drivetrain
5
May 10, 2016 01:11 PM
