This kind of has to do with emissions. Anyways when I was at the emissions place the guy told me that lower octane is better because it burns cleaner. Now I have been reading articles and it seems like octane rating has nothing to do with how clean it will burn. Anyone care to shed some light on these statements ?

Also will denatured alcohol up the octane rating of gas if added ?

 

basically the higher the octane the more complex the molecules are, therefore it is harder to completely burn them. the only reason you need higher octane fuel would be if your motor will detonate with the lower octane fuel. in addition, the car will make the post power with the lowest octane fuel that wont cause detonation. i would throw some 87 and go through emissions.

 

Lower octane = faster burn

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nvmyb20hatch &raquo;</TD></TR><TR><TD CLASS="quote">basically the higher the octane the more complex the molecules are, therefore it is harder to completely burn them. the only reason you need higher octane fuel would be if your motor will detonate with the lower octane fuel. in addition, the car will make the post power with the lowest octane fuel that wont cause detonation. i would throw some 87 and go through emissions. </TD></TR></TABLE>

Ok, but here is what is throwing me off.

If you add denatured alcohol to your fuel it will burn a lot cleaner, and if denatured alcohol raises octane why does it burn so clean, is it because of the molecules in it ?

Basically I'm hearing to add denatured alcohol to fuel to pass emissions but I'm also hearing that lower octane is better. Its kind of a contradiction. Unless octane rating does not really play a big role in emissions and how clean the gas burns.

So should I really not worry about the octane when it comes to emissions ?


Modified by 90blackcrx at 7:39 PM 12/14/2004

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nvmyb20hatch &raquo;</TD></TR><TR><TD CLASS="quote">. in addition, the car will make the post power with the lowest octane fuel that wont cause detonation. </TD></TR></TABLE>

can anyone confirm this statement??? I have NEVER heard that before from anyone.

 

Ok so what would result in a cleaner burning fuel ? Or does it even matter ?

93 octane gas with denatured alcohol
87 octane gas with denatured alcohol

Also why does denatured alcohol mixed with gas burn cleaner, is it because you boosting the octane or is it just because denatured alcohol burns cleaner ?


Modified by 90blackcrx at 8:18 PM 12/14/2004

 

I always thought that the higher the octane the cleaner and more efficient it burns!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hybrid_vtec &raquo;</TD></TR><TR><TD CLASS="quote">I always thought that the higher the octane the cleaner and more efficient it burns!</TD></TR></TABLE>

See same here, but I can't find a definite answer. Anyone ???

 

Yes, LOWER the octane without detonation = most power

less octane = simpler composition = easier to burn more complete

Sometimes extra timing will make more power and offset loss of higher octane gas, therefore in this case you will make more power with higher octane, but only because of more advanced timing and the fact that engine "likes" the extra timing advance...

 

Higher octane the more resistant to knock it is. Thats why most race motors run race gas , if they ran 87 octane they could run no timing advance and wouldnt make near as much power

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by NAPIER &raquo;</TD></TR><TR><TD CLASS="quote">Higher octane the more resistant to knock it is. Thats why most race motors run race gas , if they ran 87 octane they could run no timing advance and wouldnt make near as much power</TD></TR></TABLE>

Yes ok, but does higher octane burn cleaner ? Also is there anything such as to much octane ?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 90blackcrx &raquo;</TD></TR><TR><TD CLASS="quote">

Yes ok, but does higher octane burn cleaner ? Also is there anything such as to much octane ? </TD></TR></TABLE>


The real question is which burns more efficiently?

Yes there is such a thing as running too high of an octane.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hybrid_vtec &raquo;</TD></TR><TR><TD CLASS="quote">
Yes there is such a thing as running too high of an octane.</TD></TR></TABLE>

Yeah I figured that, but what would that be ? 110 maybe ?

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hybrid_vtec &raquo;</TD></TR><TR><TD CLASS="quote">
The real question is which burns more efficiently?
</TD></TR></TABLE>

See people might take efficiently as 2 different things, 1 could burn more and 1 could burn less but cleaner. I just want some people that know a few things to shed some light on this because I'm hearing a lot of different things.

 

The octane number of a gasoline is NOT a measure of it's hotness or coolness in the burning process, and it is NOT a measure of how 'powerful' it is. The octane number is simply a measure of how good the gasoline resistance of detonation. This is a huge misconception. Higher octane fuels are better at controlling the decomposition into auto-ignition compounds than lower octane fuels. Many people think they can run higher octane fuel at leaner temps. well they are simply wrong.

Obviously the afr and charge density are some big factors affecting the burn rate. as mentioned before the higher charge density will burn faster because of the function of gas pressures and gas temps. chamber size, spark plug location and other factors will also affect burn right, but we wont really be concerned with that for now. Slower burn time reduces pumping efficiency, thats why you want to use the lowest octane that will not detonate. The pure fact of higher octane does not make the fuel burn slower, its actually the chemical composition, many people do not know this either.


Thank mase for the great info

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by NAPIER &raquo;</TD></TR><TR><TD CLASS="quote">The octane number of a gasoline is NOT a measure of it's hotness or coolness in the burning process, and it is NOT a measure of how 'powerful' it is. The octane number is simply a measure of how good the gasoline resistance of detonation. This is a huge misconception. Higher octane fuels are better at controlling the decomposition into auto-ignition compounds than lower octane fuels. Many people think they can run higher octane fuel at leaner temps. well they are simply wrong.

Thank mase for the great info</TD></TR></TABLE>

I already knew that, maybe it helped someone else out reading this thread but the whole point of this thread was.

Hybrid I'm gonna use your example because its basically what I'm trying to say

Does higher octane burn more efficiently and does higher octane burn cleaner ?

I really wanted to know what to put in the car before emissions but it really does not matter since I'll be adding denatured alcohol which is just gonna boost the octane up. But if I can put 87 octane in compared to 93 and then add the denatured alcohol, 87 octane is still gonna be lower in the long run by 6 points.