91 octane up to 93 or 95, race fuel mix or…?

[pk2]

Hello,

Need to boost our local So. Cal. 91 octane fuel to a min of 93 for my supercharger to work in a healthy way (like not blow up). Straight 100 I think would be an expensive over kill. Could I just create a ratio of 100 with 91 to come up with 93 or so?

Done a little division (probably wrong), it seams as though a couple of gallons of race fuel with 10 gallons so of 91 would do or it. (If my principle is right, what would the equation look like?)

As an alternative, are any “Octane boosters” worth a ____? None that I’ve seen make any numerical claims and though they claim to clean injectors, I’ve heard they gum them up. Thoughts?

PK

Edited October 23, 2007 by pk2

[greerj1]

25% 100 octane + 75% 91 octane = 93.25

.25(100)=25 + .75(91)=68.25

25 + 68.25 = 93.25

Roughly 3@91:1@100

This is true if the octane content is linear with the volume.

I believe it is.

James Greer

[4agdtym]

I asked a weapon's engineer (and Porsche owner) this question and got an answer indicating the relationship was not linear.

I once put 2 gallons of 102 mixed the rest of the way with 91. My unscientific observation was a slight improvment in mpg and a slight decrease in operating temp. I haven't done it again. I paid $7.50 for each gallon of the 102. Not a good trade off.

I would be interested in other options for improving octane if it provided a worthwhile and realistic performance increase.

[pk2]

I asked a weapon's engineer (and Porsche owner) this question and got an answer indicating the relationship was not linear.

I once put 2 gallons of 102 mixed the rest of the way with 91. My unscientific observation was a slight improvment in mpg and a slight decrease in operating temp. I haven't done it again. I paid $7.50 for each gallon of the 102. Not a good trade off.

I would be interested in other options for improving octane if it provided a worthwhile and realistic performance increase.

It’s always been my understanding that unless your using forced induction, using fuel with an octane above recommended will get you nowhere. Lower octane and the ECU will make amends to a point.

Porsche says 93, mine runs fine with 91 (no detonation or anything) 93 would be better and a must when it’s super charged.

Regards, PK

[pk2]

25% 100 octane + 75% 91 octane = 93.25

.25(100)=25 + .75(91)=68.25

25 + 68.25 = 93.25

Roughly 3@91:1@100

This is true if the octane content is linear with the volume.

I believe it is.

James Greer

Thanks, I found out that there are conversion charts put out my fuel suppliers (including 76). There’s a couple posted in responses to a post of mine on PPBB with these tables. At first blush, my guess was right. 10 (91 oct.) to around 2 (100 oct.) will get you about 93 octane.

There’s a product cal Octanium or something like that, that someone has some dyno number for. Apparently actually does something, takes about a bucks worth a gallon.

Thanks for the equation though.

PK