93 octane gas

brodude2002 · Jul 22, 2005

i know the manual says to only use 87, but will using 93 hurt the engine?

kevins05v-6 · Jul 22, 2005

wont hurt it but i dont think it will help it, unless you get it tuned for 93 octane

fazm83 · Jul 22, 2005

I think MM&FF tested the GT and gained 2.5hp using 91 over 87 without a tune.

kevins05v-6 · Jul 22, 2005

is 2.5hp worth the extra cost of gas though?

Zodiac · Jul 22, 2005

Testing showed a 5hp increase in power using 93 over 87 octane gas.

brodude2002 · Jul 22, 2005

93 is 20 cents more per gallon than 87, so if i were completely empty and had to fill all 16 gallons, that 20 cents x 16 is $3.20 more. not to mention from experience, 93 ocatnce is more efficient, and i usually get better mpg count using 93.

fazm83 · Jul 22, 2005

Yes it also gets metter gas mileage, like 2-3mpg. But over 16 gallons, thats a max of 48 more miles, which if you are gettin decent gas mileage in your car, might be worth it, but if you are gettin 16mpg, and with 93 you are getting 17mpg. its not worth the extra dough. Here 91 is $0.20 more, 93 you have to mix 100 with 91 (obviously not half and half)

Zodiac · Jul 22, 2005

I love living in georgia.. 93 is the common top line octane in gas stations. So easy to find, andusually only around 20 cents more. The lowest octane my cars ever had was $5.00 worth of 91 octane when they were out of 93 and I had been driving on empty for two days already. Even after only that little gas, I could tell the difference. The car just didnt feel as peppy or to pull as hard as it usually did.

kevins05v-6 · Jul 23, 2005

i am going to have to try the higher octane for a tank or two..

MSP · Jul 23, 2005

Very interesting thread! I tested this out before, and my car actually seemed to pull less with the higher octane... Anyone know why that may happen? Perhaps mine was more inclined to follow the 87 only rule?

brodude2002 · Jul 23, 2005

how much of the lower octane did u have left in ur tank when u filled it with the higher octane gas? i filled my tank with 93 when my tank was completely empty,to get the full effect.

Jenns01TA · Jul 23, 2005

MSP said:
Very interesting thread! I tested this out before, and my car actually seemed to pull less with the higher octane... Anyone know why that may happen? Perhaps mine was more inclined to follow the 87 only rule?

My meager understading of this process is somthing like this:

The octane rating of gasoline tells us how much the fuel can be compressed before it spontaneously ignites. When gas ignites by compression rather than because of the spark from the spark plug, it causes knocking or early detonation in the engine and subsequent loss of HP. Lower-octane gas, like 87-octane gasoline, can handle the least amount of compression before igniting.

The compression ratio of the engine determines the octane rating of the gas we use in the car. One way to increase the horsepower of an engine of a given displacement is to increase its compression ratio. Higher compression ratio engines require higher-octane fuel. The advantage of a high compression ratio is that it gives the engine a higher horsepower rating for a given engine weight. The differences in compression ratios on 05 Stangs are relatively small, but the room for the process (our Bore and Stroke specifications are large). Those with the V-8 can handle a change in octane better than the V-6 due to the size of the compression area.

Compression Ratio V-6 9.7:1 9.8:1
Bore and Stroke (in.) V-8 3.95 x 3.32 3.6 X 3.6

Higher compression ratios produce more power, up to a point. The more you compress the air/fuel mixture, however, the more likely it is to spontaneously burst into flame (before the spark plug ignites it). Higher-octane gasoline prevents this sort of early combustion. The higher the compression ratio the higher the octane gasoline needed for proper combustion. However, the other 3 aspects of the reciprocation need to follow the laws of engineering and phyics to perform optimumly.

Given the modulation of the Stang, changes in intake/combustion/compression/exhaust will cause an issue with the proper cycle of reciprocating internal combustion.

So, in a hand basket there is the dissertation on combustion relative to octane ratios in the engine. (God I am such a frekin’ nerd!)

Jenn

Jenns01TA · Jul 24, 2005

NOONE WANTS TO ADD ANYTHING ELSE? I feel like a thread killer.

fazm83 · Jul 24, 2005

Thread killer? Maybe all that greek made sense to him and he was extremely enlightened

Jenns01TA · Jul 24, 2005

Okay. It just seems like....... Jenn Posts = Thread stop. I am noticing a pattern and I don't want to seem like a know-it-all thread killer...

Thanks Faz

Jenn

Zodiac · Jul 24, 2005

No worries Jenn, I still blame you

brodude2002 · Jul 24, 2005

jenn- what does all that u posted mean?

Jenns01TA · Jul 24, 2005

brodude2002 said:
jenn- what does all that u posted mean?

In regards to compression and the use of higher octane.

Okay, I made up a quick little illustration to help all the visualization learners. I made the notations of pretty much what I was trying to say. A picture is worth a thousand words. >> Add too high octane without changing when the spark plug makes the explosion in the piston chamber and you set up a potential for early detonation and loss of HP. The car is designed for 87, stick to it unless you plan on a chip to tell the computer when to fire the spark plug (timing based on the compression stroke of the piston in the cylinder.) or one of the other items noted. There are a few more options, but, I think I have already gone way too far.

BTW - GTs can compensate a little better since they are using a different CAM set-up that can change within a set of variables sort of like VTEC, but there is not a separate exhaust CAM.

Here is my lame illustration.

Does this help?

Jenns01TA · Jul 24, 2005

Zodiac said:
No worries Jenn, I still blame you

Most do Sweetie.. Most Do!

BTW.. are you a sixer or an eighter?

~J~

afixer · Jul 24, 2005

Jenns05Stang said:
Most do Sweetie.. Most Do!

BTW.. are you a sixer or an eighter?

~J~

just where are you going with this.

93 octane gas

New Member

New Member

New Member

New Member

New Member

New Member

New Member

New Member

New Member

MSP

New Member

Active Member

Active Member

New Member

Active Member

New Member

New Member

Active Member

Active Member

The Informant

Similar threads

Privacy & Transparency

Privacy & Transparency