Some info on AV and Race relative octane levels.
AV-GAS... 100LL is rated "100" on a special Aviation octane rating... and the 100 relates to a "lean mixture rating"
NOT AT ALL similar to motor fuel (road) ratings.
The "LL" relating to Low-Lead (low tetraethyl lead content, not to exceed .56grams/liter.... much lower than typical 110 race fuel)![Face Icon Small Cool :face-icon-small-coo :face-icon-small-coo](https://www.snowest.com/forum/images/smilies/old/face-icon-small-cool.gif)
100LL has a MOTOR OCTANE NUMBER (MON) of approximately 103. This will give a more accurate comparison for an "apples to apple" snapshot of this fuel compared to other motor fuels.
By comparison.
Sunoco 110 has a MON of approx 105. With a lead content of approx 4.0grams/Liter.
There are many different characteristics of the fuel, eg Reid Vapor pressure, specific gravity, evap temps etc.... Octane IS important, but only a small snapshot of the whole picture....But for this conversation in this thread... not really necessary since we have all had great reports of all of these fuels for use in our sleds over the years.... no need for an argument of these points for this discussion IMO.
Although I hate to use etanol pump fuel for mixing (for my own reasons), in my area... and many others, it is the only option... (and, yes, there are some that are blessed with non-eth in certain areas
)
Using 100 as the octane number of AV-GAS, 110 for typical race fuel and 91 as your octane number of Premium pump full will NOT give you an accurate idea of the octane rating of mixture.
To Calculate fuel ocatane in a mix of two different fuels... you must first make sure that you are using the SAME OCTANE rating.... MON is a good place to start.
100LL MON = 103 MON (approx)
91 'Premium' Pump fuel with 10% ethanol = 88 MON (approx)
110 Race fuel typical = 105 MON (approx)
Those would be much better numbers to use with the following formula to determine your mixed octane number relative to the BASELINE of typical 91 pump fuel. Note that Non-Ethanol "Pump-91" fuel will have a slightly lower MON of approx 87 MON due to the increased octane of the added Ethanol.
( [ % Fuel A ] x [ Octane of Fuel A ] ) + ( [ % Fuel B ] x [ Octane of Fuel B ] ) = Octane of Mixture
For example... a 50/50 mix of typical 100LL to 91(10% eth) 'pump'.... would give you approximately 95 MON in your end mix.
[Lower than the 103 MON of the AV-GAS and higher than the 87MON of the 'premium' pump fuel.]
Also, as a side note... the word "PREMIUM" fuel has ZERO to do with the QUALITY of the fuel within a brand.... It is just a industry name that refers mostly to the Octane number of the fuel.
It is easy to LOSE performance...both in overall max power & throttle response ('torquieness' and throttle 'character') by using too HIGH of an octane.
Pump gas will, for our intents and purposes in mountain sledding, have better throttle character for our uses than 100LL... and that is not simply related to Octane ratings.
This is the reason I'm an advocate of MIXING pump fuel to 100LL to get the right blend for your uses....
Since MOST turbos sold today are lower boost (sub 8 lbs psig, on sleds used above, say... 5K feet.... you are losing performance using straight 100LL in a given sled... and mixing 100LL with Pump fuel will optimize your smile factor and get the most out of what you paid dearly for (sled and kit... and time off work !!)
You need to do your research...a little trial and error...or talk to people with the SAME sled/kit as you have... and, find the mix for you for the elevation and boost levels you are riding... To enjoy what you have !
Hope this helps.
My 2¢
.
AV-GAS... 100LL is rated "100" on a special Aviation octane rating... and the 100 relates to a "lean mixture rating"
NOT AT ALL similar to motor fuel (road) ratings.
The "LL" relating to Low-Lead (low tetraethyl lead content, not to exceed .56grams/liter.... much lower than typical 110 race fuel)
![Face Icon Small Cool :face-icon-small-coo :face-icon-small-coo](https://www.snowest.com/forum/images/smilies/old/face-icon-small-cool.gif)
100LL has a MOTOR OCTANE NUMBER (MON) of approximately 103. This will give a more accurate comparison for an "apples to apple" snapshot of this fuel compared to other motor fuels.
By comparison.
Sunoco 110 has a MON of approx 105. With a lead content of approx 4.0grams/Liter.
There are many different characteristics of the fuel, eg Reid Vapor pressure, specific gravity, evap temps etc.... Octane IS important, but only a small snapshot of the whole picture....But for this conversation in this thread... not really necessary since we have all had great reports of all of these fuels for use in our sleds over the years.... no need for an argument of these points for this discussion IMO.
Although I hate to use etanol pump fuel for mixing (for my own reasons), in my area... and many others, it is the only option... (and, yes, there are some that are blessed with non-eth in certain areas
![Face Icon Small Tongue :face-icon-small-ton :face-icon-small-ton](https://www.snowest.com/forum/images/smilies/old/face-icon-small-tongue.gif)
Using 100 as the octane number of AV-GAS, 110 for typical race fuel and 91 as your octane number of Premium pump full will NOT give you an accurate idea of the octane rating of mixture.
To Calculate fuel ocatane in a mix of two different fuels... you must first make sure that you are using the SAME OCTANE rating.... MON is a good place to start.
100LL MON = 103 MON (approx)
91 'Premium' Pump fuel with 10% ethanol = 88 MON (approx)
110 Race fuel typical = 105 MON (approx)
Those would be much better numbers to use with the following formula to determine your mixed octane number relative to the BASELINE of typical 91 pump fuel. Note that Non-Ethanol "Pump-91" fuel will have a slightly lower MON of approx 87 MON due to the increased octane of the added Ethanol.
( [ % Fuel A ] x [ Octane of Fuel A ] ) + ( [ % Fuel B ] x [ Octane of Fuel B ] ) = Octane of Mixture
For example... a 50/50 mix of typical 100LL to 91(10% eth) 'pump'.... would give you approximately 95 MON in your end mix.
[Lower than the 103 MON of the AV-GAS and higher than the 87MON of the 'premium' pump fuel.]
Also, as a side note... the word "PREMIUM" fuel has ZERO to do with the QUALITY of the fuel within a brand.... It is just a industry name that refers mostly to the Octane number of the fuel.
It is easy to LOSE performance...both in overall max power & throttle response ('torquieness' and throttle 'character') by using too HIGH of an octane.
Pump gas will, for our intents and purposes in mountain sledding, have better throttle character for our uses than 100LL... and that is not simply related to Octane ratings.
This is the reason I'm an advocate of MIXING pump fuel to 100LL to get the right blend for your uses....
Since MOST turbos sold today are lower boost (sub 8 lbs psig, on sleds used above, say... 5K feet.... you are losing performance using straight 100LL in a given sled... and mixing 100LL with Pump fuel will optimize your smile factor and get the most out of what you paid dearly for (sled and kit... and time off work !!)
You need to do your research...a little trial and error...or talk to people with the SAME sled/kit as you have... and, find the mix for you for the elevation and boost levels you are riding... To enjoy what you have !
Hope this helps.
My 2¢
.