Tuning, 87 octane vs 91 octane

[Twisted]

I am going to have my car dyno tuned tomorrow. I originally needed to bring it in for a gear recalibration, but decided to go with a custom program too. Bone stock car. Is the 91 octane tune worth the price of the gas or should I just stick with a 87 octane tune. Is there much difference other than timing advance?

 

[Gearbanger 101]

could be worth a few horsepower if your car is primarily stock.....could be worth a heck of a lot more if you're running a blower or nitrous car. What are your mods?

 

[csledd]

how about 93 octane!!

I was running 87 but went to 93 when I got my tune. The higher the fuel grade the more timing they can seem to pull. And the price difference is minimal, I think I pay $2-4 extra dollars when I fill up.

 

[FEARED]

how about 93 octane!!

I noticed he lives in Lake Orion and I believe the octane is determined by elevation. 91 is the highest available at most stations in phoenix which has a 1100ft elevation. Lake Orion is around 900-1000 so if this is true he'll have a hard time finding anything above 91.

edit: It could be the higher the less octane needed. Not too sure about this but I know I cant get 93.

Just checked the elevation of Paducah and its around 400-500. Would support the theory i guess.

 

[Give Me TP]

I am going to have my car dyno tuned tomorrow. I originally needed to bring it in for a gear recalibration, but decided to go with a custom program too. Bone stock car. Is the 91 octane tune worth the price of the gas or should I just stick with a 87 octane tune. Is there much difference other than timing advance?

It's would not be worthwhile in my opinion to get a 87 octane dyno tune, because the only adjustments usually made are for auto shift points/pressure. Do a baseline session with the your factory tune and then do another with the 91 octane tune if you can, and adjust the 91 octane tune for best performance. Timing advance and A/F ratio is adjusted.

 

[Gearbanger 101]

how about 93 octane!!

I was running 87 but went to 93 when I got my tune. The higher the fuel grade the more timing they can seem to pull.

I think you meant to say "add", since pulling timing is to "retard" it.

 

[hognutz]

You can run more timing advace without detonation on higher octane.

Most like worth about 10hp.

you have to decide if that hp is worth filling up with premium fuel.

you should not go back to 87 if you car is tuned to 91 or 93.

 

[Twisted]

Tuning got pushed back to tomorrow. Does the higher octane allow more time across the whole rpm range or just at higher piston speeds/higher rpm

 

[hognutz]

ocatane increases the flash point of the fuel. it is a constant.

 

[Twisted]

Right, as octane goes up,the resistance to detonation increases or flashpoint. Is this resistance needed more at higher rpms? Nevermind, I answered my own question. Your timing isn't constant across the whole rpm band.