I own a 2005 S with manual tranny. My question is this: is it safe to add a high quality octane booster to my gas for better performance? I already run premium Shell gasoline but I keep seeing these claims of X amount of HP gains in performance motors.
I hope to have installed a smaller supercharger pulley. But that won't be for a while yet. I am also running an OEM air intake system.
Anyone have any thoughts on this subject?
Thanks.

 

Save your money, it won't really do anything for you. Run 93 or higher and you should be fine.

 

Here's a general octane booster question that I don't need to start a thread for.

I have access to 94 Octane 99.9% of the time. On the rare occasion that I go on a long road trip, I might not. I'm getting a tune in 2 weeks. Would it be safe to tune for the 94 I regularly use and keep some octane booster in the boot for the rare occasion that I may be stuck with 91? If so, how much of these octane boosters is needed to bump a full 50L tank up from 91 to 94? Does anyone know?

 

We only get 91 down here in Arizona. I only use a booster during the summer when you can get some knocking.

 

waste of money you dont need it. 91 is fine if your stock i use 93 because its all we got around here and the cheapest compared to 91 or anything higher at all the gas stations. (i buy costco gas )

unless your getting tuned for anything higher than (93-104) you dont need it. and you better have a good reason to waste your money for running such i octane gas; like rediculesly high boost.

octane does not add HP it only resists knocking.

 

An ounce of an effective octane booster should raise your octane rating by 2-1/2 numbers. That is, if you start with 86- octane gasoline, one ounce of booster to a gallon will take it to 88-1/2 octane. One word of caution. Octane boosters decrease in effectiveness as their quantity increases. Just because one ounce gives you 2-1/2 numbers more, ten ounces will not give you 25 numbers. Here's a good scale of just about how decent octane boosters will work:
One ounce/per gallon ¼ 2-1/2 numbers increase
Two ounces/gallon ¼ 4-1/2 numbers increase
Three ounces/gallon ¼ 6 to 6 1/2 numbers increase
Four ounces/gallon ¼ 7 to 7 1/2 numbers increase
A good rule of thumb is that anything over three ounces per gallon is wasted. Some crazies dump in a whole can of booster, thinking they're going to get radical gains. Actually, they'll get a decrease in performance, as excessive ratios can cause the volatiles in the gas to deteriorate and excessive aromatics can make the engine run "heavy," or rich.

 

Thanks for the info! Maybe I'll just stick with 91 for simplicity's sake.

 

Here in calif. we can only get 91 octane. My car does have a slight ping and the only booster I have found to work in eliminating it is Lucas oil products octane booster.

 

IMO get the tune with the lowest common fuel you plan to use...so maybe 92-93, then when you can get 94 great!!
getting a tune for 94..then having it disappear might result in issues.....
some folks are temped to get a tune on racing fuel....so they car brag about dyno numbers.....kinda defeats the purpose of optimizing the car for running in one regular state IMO.
Mine was tuned on 93...and when I got a tank of 90 ( in the middle of nowhere up in maine one day), it does not run as well..less power...can't say it pings or anything, but I can feel it.
If you read the instructions on octane boost...you need it BY THE GALLON, not by the 16 oz container......to get a usable increase in high-test fuel.
in lower octane fuel, (87) not so much.......

 

Don't waste your money on those power drinks for your fuel. A tuner here in Socal recommends shell 91 octane as best of what we have here in California.