Chevron gasoline

[Dave Head]

As usual - stay within the realm of the vehicle you know. Audi V8s run 
better with the highest octane available - there's plenty of data on 
this right within Audifans... Better mileage and loads more power. Its a 
high compression engine. It is designed for higher octane in europe and 
then detuned in the ECU for US gas. You put higher octane and it runs 
better - far better. On the US timing map. Read the toulene threads. If 
I run 91 - which my engine is spec'ed for, I get ok performance. If I up 
to 93, its better. I dump a gallon or 2 of toulene in there, and its 
approaching yeeha! We've had 4 V8s in this family for 5 years and 
130,000 miles - what's your experience? Ask Keith, Scott or Ingo...

You run with a higher octane level, and you've also just increased your 
margin to knock when conditions are not optimal - hot weather, carbon 
buildup, track conditions. Plus, when you get pushed into a lower map - 
you're stuck there until you turn off the car and restart it.

They sell diesel at stations too. You pull up to a pump the has 106 
octane and big stickers that say 'leaded fuel' - its not a whole lot 
different.

If you drive like your grandma, you'll be fine with the octane you're 
spec'ed for. If you drive and have fun, put the best gas in it you can.

Brett Dikeman wrote:

>
> On Apr 27, 2005, at 3:21 PM, Dave Head wrote:
>
>> Any car with a knock sensor and a turbo will benefit from a higher  
>> octane rating.
>> Most cars with knock sensors will benefit from a higher octane rating.
>
>
> The ECU is programmed with timing and boost tables designed for a  
> specific octane minimum octane; it won't take advantage of a higher  
> octane just by throwing it in the tank.  Running a higher octane than  
> what is recommended will in fact hurt performance because overall  
> efficiency drops; higher octanes burn more slowly, so that detonation  
> doesn't occur.
>
> Knock control is designed purely for TEMPORARY running on inferior  
> gas or with engine problems (severe deposit buildup, for example).   
> It doesn't magically see "oh, the owner filled me up with 94, when  
> all I need is 89...well, let's advance the timing a whole bunch,  
> whoopeee!"
>
>> Try running race gas in a V8 - it loves it!
>
>
> Then you have internal engine problems- like the wrong plugs, or a  
> lot of carbon buildup...or your gas station is shorting you on octane  
> levels.  Check with a scan tool to make sure the ECU isn't retarding  
> ignition more than it should be.
>
> Quite a bit of race gas is also leaded, which is a sure fire way to  
> destroy the cat and O2 sensor in very short order.
>
> Brett
>