I'm trying to figure out if its worth the hassel and expense of adding 1 gallon of toluene or xylene to each tank of crappy 91octane calif gas I buy. Roughly, this brings me up to 93 octane.

I know that boosting the octane will retard the combustion of the gas and reduce knocks and pings, but can anyone tell me what kind of a horsepower or torque difference I should expect going from 91 to 93 octane?

 

probably not much difference, just a margin of safety there are people using 91oct running 20psi and no problems yet

 

I bet 5-10, or it it would at least feel like it.

 

Have you seen the dyno graphs of 91 and 93 octane fueled runs? Granted it's difference in tuning but octane levels do have a significant impact on power output.

 

word is that it will give you 10+ hp. i run 94, it really makes more torque down low, more hp up top, and the plateau at 5500 is gone.

 

yes I have, 93oct allows you to run a bit leaner....

 

can anyone point me in the direction of some dyno graphs of 91 vs 93 octane?

(subjectively, i sure like the 93 octane)

 

I felt a significant difference once I started mixing 100 octane and 91 to get a 93-94 mix. If anything, acceleration is smoother. I definitely runs better since all we get out here is 91. Most 76 stations here have 100 octane race fuel at 3.95 a gallon. Even though gas prices are rising, the race gas has held steady.

 

when I got my car Im sure they put a cheap *** gas in it , It ran like ****. I took it and drove easy for the whole tank, put amoco 93 and a new beast came to life
cant tell you hp #'s but in my case it was a big difference.

 

Sorry for slight off topic, but was wondering why certain parts of the country max out at 91 octane? Is it an emisions thing? Does lower octane burn cleaner? I would think its the opposite. Anyone have any clues?

 

We used to get 92 out here at one time. I know in the winter months, there is more of a certain additive (don't know offhand)due to bad air quality during winter months. During the winter months, there is usually an inversion in the atmosphere that acts like a lid and holds the polluted air close to the ground, at least here in the Vegas valley. You can visibly see the brown air (smog). And then I think April 1 we get a different mixture due to the warmer air, but still 91 octane.

We get screwed since we get 91 and the highest prices in the country. We are at about $2.25 per gal. for 91 right now, but at least we get 100 unleaded race fuel to mix if we choose.

 

I hate to bring it up, I don't want to hijack the thread or anything, but isn't there a 'good' additive for octane boost and a not-good additive - leaves red deposits on plugs, etc.? Just a quick info bit for this thread if you know, if you please - seems appropriate.

I'm lucky enough to get 93 octane here. The Shell 92 is actually 93 because they don't want to reblend a special 92 in our area, apparently (confirmed with Shell station owner). But, there IS this bottle of Outlaw Octane Boos sittin' in my garage, hmmmmmmm....

 

lots of stuff out there about octane boosters. Problem with those bottles of stuff you buy is that the "points" they talk about is like 0.1 units... You need to use a lot to go from 91-93 octane.

From what I can gather, toluene or xylene is very safe; its what the gas stations use to boost octane.

Pain in the *** to handle, and dangerous to store in quantity. Also, not cheap. I'm Paying around $7 per gallon for either.

 

I've posted this before, but I've been consistently raising the 93 pump here with Torco Accelerator to 97 or 98 octane, and more. Its a fuel accelerant not typical octane booster and is completely safe from deposit. 32 oz. can raises 20 gallons to 97 or up to 105. I put in about 2 oz. per gallon.

 

evo542, it seems like you haven't looked at any dyno results to back your claims.


dividedsky, the history of premium octane levels in California involves few things:

- 76's patented mass production of 92 octane gas
- increasing number of cars in California
- supply and demand of high octane gas

All this and more contributed to reduction of premium octane level to 91.