DesmaisonLCM wrote:

> i'm having a track day this 2nd Oct and i wonder if i could improve perfs of
> my Alfa 75 2.0 TS using some 'octane booster' mixed with the fuel .

Your engine is constructed for at specific octane setting. Lets
assume your engine is build for running on 97 RON, that means that
the compression ratio and the camshaft profiles gives a dynamic
compression ratio that matches 97 RON petrol perfectly. Lets say
you go cheap and fill the car with 95 octane. Since 95 burns
faster than 97, the engine management needs to retard the ignition
in order to avoid that the mixture burns too soon and press down
on the piston before the piston reached the top (knocking).
Retarding the ignition means that the car loses power and are less
fuel efficient.

Lets say you use octane booster and run the car on 100 octane. The
engine management goes to it's default 97 RON setting, and since
the engine doesn't knock, it keeps the ignition at the optimum
point for 97. All in all you gain nothing by boosting above 97
octane.

If you want extra power, you need to start with physically
improving the engine. If you shave something of the top, modify
cams, valves and so on, you end up with more power, but also a car
that no longer runs perfect on 97 octane. Boosting the octane is
then a really good idea.

In short, the compression ratio, the ignition timing and the
octane has to match each other..

--
Hygge..
Thomas

<http://www.carftp.com> - a library of car videos.