Have you ever tried the octane boosters? How do they add performance to your car? How much did you pay for it?

 

Don't waste your money. Unless your ECU is "tuned" for higher octane, using will do more harm than good.

 

Thanks baseballfanz!!

 

i dont see how you could harm, by having higher octane, it would just be a waste without a tune

 

Correctamundo. I see guys talk about "I just put premium in my car that recommends 87 octane and my car is faster!" and its just stupid. Higher octane just slows the fuel burning rate, which works good with high compression or boosted engines.

 

I have a 08 CTT and the mannual calls out using minimum octane 93, but the highest available octane in all Calif gas satations is 91. So what can you do ?

 

Only 91 in Cali? Our Premiums are 93 here in NYC

 

Our Premiums in the UK is 99 - Shell Optimax...

 

How much is it a liter there these days?

 

Around $2.10 per litre...

 

Old thread revival... but correct me if I'm wrong, wouldn't the computer advance the timing and adjust for the higher octane, hence more power?

 

Yes, you are correct. It will. I used stp octane booster, clear bottle, golden color. Aside from running much smoother and a very very slight increase mpg, no real difference.

However, I filled up on some 91 octane ethanol free gas in NM on a trip and the difference in power, smoothness, and mpg was substancial.

 

I don't quite understand.. The Cayenne calls for 91 octane and premium around me is 93, so what do you normally run if the 91 made your car run smoother and get better mpg?

 

The 91 was ethanol free but good luck finding any. You can do a search on puregas.org

 

Search if you have any Sunoco stations near your place. They sell unleaded 100 octane at the pump. You wouldn't believe the huge difference it makes with a correct tune.

You can also do your own race gas with injecting methanol or methanol/water mix.

The best thing you could get from a station performance wise would be E85 or E90 but your car would need to be tuned and modified to run on Ethanol.