1986 GT: Will computer know premium fuel?

ragtop71

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I have been using regular fuel for years with no problem. If I change to 93 octane, will the computer know enough to advance my timing to take advantage of the 93 octane? Thanks.
 
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Daggar

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No it will not. Your wasting money by trying to advance the timing yourself too. Lower octane gas burns hotter and faster than higher octane gas. If your car performs well with regular gas and doesn't ping then you're doing very well. You can start advancing your timing until you do get pinging then back it off 2 degrees and you'll be perfect. Running higher ocatane gas for the sole purpose of advancing your timing is worthless. You will acutally end up with a net loss of HP instead of a gain.
 

HISSIN50

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Wow, what a time to be deciding to voluntarily use premium - be glad you dont have to! That stuff is wiping me out.
 

Funanin

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haha, god this place is turning into such a rice forum... "does the computer do it for me" muhahaahahah

check/reset your timing before you change your level of octane in your fuel.
 

v8only

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Jul 3, 2003
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Daggar said:
No it will not. Your wasting money by trying to advance the timing yourself too. Lower octane gas burns hotter and faster than higher octane gas. If your car performs well with regular gas and doesn't ping then you're doing very well. You can start advancing your timing until you do get pinging then back it off 2 degrees and you'll be perfect. Running higher ocatane gas for the sole purpose of advancing your timing is worthless. You will acutally end up with a net loss of HP instead of a gain.

great advice. so you think advancing the timing as much as possible on 87 octane, and that's that eh? no 89?
 

HISSIN50

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There can be power to be had from higher octane and more timing but it takes a good bit of octane to get there. If talking pump gas, I dont see the benefit (given an octane spread of 5 points or so from regular to premium).
 

Daggar

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v8only said:
great advice. so you think advancing the timing as much as possible on 87 octane, and that's that eh? no 89?
Ummmm... no, but how detailed into this discussion would you like to get? What I posted is above is very generalized and over simplified. It's more a matter of finding the right octane pump gas/blend for a given engine combination then advancing timing enough to make full use of that blend/octane. Let's also not forget that each time you fill your tank (even from the same gas station) that the blend is likely to be different based upon age, source, time of season, etc. Fuels obtained from completely different stations will likely differ even more. It's a "green grass grows all around" topic. If Vehicle X generally runs best on 87 octane fuel then it's in your best interest to advance timing to a reliable level to make full use of that fuel. If vehicle X has a tendancy to run best on 89 then the same would apply. Running 14* of timing on 87 octane gas does mean that you will gain even more power by running 18* and 93 octane. Climbing the octane hill doesn't work like that and you will eventually hit a threshold where the dividens will have you working backwards and actually loosing power.

I don't mind explaining the whys but this is definitely a well involved topic that will make one's head hurt (unless you're a chemist, which I am not :D ).
 

DMAN302

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I am interested to see if in fact I can run a touch more timing now that the temps are no longer in the 180's everyday. I run premium and 14 deg's...but I'm averaging just over a tank every 6 weeks :notnice: and with that kind of usage the extra 15$ doesn't hurt as much. I should note both my wifes and my daily drivers NEVER even get to look at the premium pumps.
 

Daggar

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DMAN302 said:
I am interested to see if in fact I can run a touch more timing now that the temps are no longer in the 180's everyday. I run premium and 14 deg's...but I'm averaging just over a tank every 6 weeks :notnice: and with that kind of usage the extra 15$ doesn't hurt as much. I should note both my wifes and my daily drivers NEVER even get to look at the premium pumps.
You really should consider having one of your wives stick with 87 and the other with 89. It will decrease the chances that they run into one another at the pump! :p
 
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