105 Octane - Is it Worth it ?

Just wondering what other's think. It's available right near me - used to use it on my Audi TT 225 chipped - never really felt any difference.

Waste of money unless you have modified your car to take advantage of it.

Noothing special - CAI and Fabspeed exhaust are the only engine mods - thought of a chip but not convinced it will make a noticeable difference in a NA '99. In a Turbo, it makes a huge difference.

There are a lot of posts from the past that would probably convince you to not spend the money on the 105 Octane.

Randy, Wouldn't make any difference on a NA car... Would just help a turbo car run higher boost, cooler... Jack

Probably won't, but sometimes like the thought

You could run higher compression with the higher octane and make more power. However, with your current mod's you'd be thowing away money on the expensive stuff IMHO. Even if you chipped it the chip would need to be tuned to take advantage of the extra octane.

Yeah no reason at all to use 105 octane. Remember- higher octane doesn't mean it burns better or with more explosive power. All higher octane does is allow the fuel/air mixture to be compressed higher without premature detonation (knocking as it's known). The only way to raise compression is with a turbo or supercharger, or basically an engine rebuild that increases the stroke.

To get more power from 105 you would have to be able to advance timing. Here in California you can only get 91 (except for a few stations with race gas, 100). Since the car is optimized for 93 octane (says so right in my manual) the computer is alway pulling timing (retarding). So I gues you can say that thanks to the state of california my Porsche is RETARDED. I have on occasion mixed a little 100 with 91 to get the octane up to ~93-94. The car will idle a little smoother and pull a little smoother, but I doubt you could measure a power difference on a dyno. When I used to drive my S2000 with a 11.5:1 compression ratio, it made a bigger difference when I upped the octane.

I also mix 100 with 91 and do feel the difference during idle and the car feels stronger. I think the improvement is from bringing it up from 91 to 93 but anything over that is probably a waste. Retarding the motor is basically de-tuning it so using 93 over 91 has to improve performance (you would think). I definatley feel the difference putting 6 gallons of 100 with each tank fill.

For years, I have been mixing a blend of 4 gallons of 100 with 12 of 91 in my 996, and have to say that there is a positive difference. The car is much smoother, pulls better, and gets better gas mileage. There is no sense if filling up solely on 100 race gas, but as a blend with premium it will make a difference.

I just went out this morning and picked up 5 gallons of Toluene from a paint store to mix for my 930. I haven't tried this, but did a bunch of research which showed how the Tolluene would enhance the octane rating when mixed in one gallon increments to a 16 gallon tank. I was getting just the slightest bit of detonation...so the indy told me to put in the Toluene...just enough to raise the octane rating a point or two. I managed to find it for $35 for a five gallon can. Sure works out cheaper than those 16 ounce cans of "Octane Booster" they're sellng for $8-10 at Kragens. According to the research, 16 ouces of Booster only raises your octane rating from 91 to 91.2...so the advertising is misleading.

Make sure the tolluene doesn't destroy your O2 sensor.

If the ECU changes the ignition timing (which I am pretty sure it does), sure it should help with power if it can advance the timing. 11.3:1 compression is not low, pretty high actually. A waste of money, maybe, depending on how you look at the hp/dollar. We need someone to dyno to see for sure bit I think it would be worth a few ponies.

You don't mix the toluene in large quantities...like I said, a gallon at a time. There's a complete write up on it at: http://www.elektro.com/~audi/audi/toluene.html . This is what prompted me to go buy it. But if you decide to do this...be prepared to be run thru the mill....toluene is restricted due to the misuse of it by the glue and gas sniffing idiots. I had to show all sorts of ID...and then the store manager walked out and looked at my car before he was satisfied this was a bonafide purchase. Toluene is also very volatile and flammable. I plan to transfer if from the 5 gallon can to one gallon containers so that I don't spill or slop it on the car's paint.

Where do you guys buy 100 octane in SoCal?