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Has anyone had experience adding chemicals like Toluene, Xylene or Acetone to petrol to raise the octane rating. I am trying to determine if they are worth the cost and what side effects they have. Lots of Google stories etc but better to get knowledge from those that have done it.

Back in the late 1990's we ran street stock and used to play with 'Benzine' (which is a paint thinner) we used to run fairly wild timing in the old 202 and it did seem to save from pinging especially on a hot day.

PS : Fuel additives didn't have a rule back then, they where outlawed soon after we started using them

Same here, back in the 90's I played with Toluene with great success. Was actually injecting it into a plenum at one stage.

I do believe benzine is one of the components of fuel used as anti knock additive as standard.

benzine is well know carcinogen so be careful playing with it.

you could use naphthalene, its a double benzine molecule and works well as anti knock additive.

moth balls and crystals used to be made of it.

A reason for not playing around with it anymore is that fuels from the pump are so much better now, remember back then we could only buy super and unleaded, we now have premium in different levels and even better E85, etc..

yeah I guess it depends on the class of racing, I know some street stocker blokes here were trying to run E85 for increased compression but they are not allowed to use anything other than 98 octane petrol!

but yeah if you have no rules dictating what you can run then E85 is certainly the pick of the bunch for higher compression and street legal!

Thanks for the input. I have done as much research as I can and most do say Toluene. I do know that BP Optimax is around 17% (info from BP) so adding another 10% should take to over the 100 octane which is specified for the car with other benefits for a turbo engine. I am a little concerned with reading I have made that mention soot buildup but I think I will give it a go. At this stage I don't want to try E85 (but would love to) because the car is not registered and the only option is a days tuning on the dyno to get it right. Toluene is quiet cheap at under $80 for 20 litres and with only another 10% it should do a few race days.

toulene is nasty shit dont breath it in ive used it for thinning one brand of spraypaint that required it and i spent a week sick in bed its NASTY shit ide avoid the shit LOL.youll also get looked at buying it due to it being used to make methamphetamine LOL

if you want to test that stuff out just use shell fuel it's full of it the other brands are clean!

it also melts everything known to man LOL