Fuel tyes (RON & additives)

1/ Is someone able to explain to us what the RON number is, what the benifits of different RONs are and how to find out what brand of fuel are what RON ?

2/ Should one use unleaded, LRP or the real 4-star?

3/ Also additives, are there differnt types/brands/specs ?

4/ My fuel tank has a BIG filler, must be more than 2 inches (5 cm0 in dia.

I have an early 1986 GTA turbo (air-cooled) and am interested to understand this Fuel business for best perormance and good engine wear protection/life.

Thanks in advance, Simon

Really you want to be running super unleaded, at the highest RON rating. RON is the octane rating of the fuel, basically telling you how easily the fuel will preignite with ignition and heat. A low octane fuel will burn very easily, but andvances in ignition and heat (or boost) can make it ignite prematurely, causing detonation. This is why on a GTA, with the quite high compression and high temperature charge from the turbo you should run as high as possible. Race cars normally run race fuels at over 105 octane, so they can run really agressive ingnition timing and compression ratios. On contrast, the A610 which runs a low 7.6:1 compression is given to do 250bhp on only 95 octane, from Renault. If you increase the boost though, you should also increase the octane rating.