hotdat Posted June 16, 2008 Report Posted June 16, 2008 I have done a bit of a search but still need a bit of help. I am purchasing a noss head, i live in Australia and our pump fuel highest octaine rating is 98, I live 96 meters above sea level.I am fitting a 64.5 piston and the engine is a stock port. I wish to advance the timing as well. What size domes can I use? And how much timing can I run while running on the 98? Assuming that the American and Australian fuel ratings are the same. Please correct me if I am wrong. Quote
HammerShee99 Posted June 16, 2008 Report Posted June 16, 2008 (edited) Australian octane ratings are different than American octane ratings... Australia uses research octane number for their rating (as does most of the rest of the world) whereas the US uses the average between motor octane number and research octane number, so you guys have higher octane ratings than we do. Seeing as you're close to sea level, I think you'd still be able to run pump gas with 21cc domes, but you'd be cutting it pretty close to the cutoff point between being able to run straight premium gas and having to mix 50/50 premium and race fuel. You should be safe running +4 timing. Edited June 16, 2008 by HammerShee99 Quote
hotdat Posted June 16, 2008 Author Report Posted June 16, 2008 Thanks, that has saved me a lot of trouble. Another thing is, there are 3 main types of unleaded fuel in Australia, we have our plain old unleaded (91ron), premium unleaded (95ron) and most of the big company's have there own name for there high end fuels,, like Shell have one called V-power and B.P has one called Ultimate, these are (98ron) and from what I know Shell has a fuel that has only been available for about 6 months and only in major city's called Optimax Extreme and it has 5% ethanol and an octane rating of (100ron). It's not available anywhere near where I live and I have heard its not good anyway so I will be running it on (98ron). Is the 98 higher than your premium seeing? As we have premium rated at (95ron). Quote
HammerShee99 Posted June 16, 2008 Report Posted June 16, 2008 Thanks, that has saved me a lot of trouble. Another thing is, there are 3 main types of unleaded fuel in Australia, we have our plain old unleaded (91ron), premium unleaded (95ron) and most of the big company's have there own name for there high end fuels,, like Shell have one called V-power and B.P has one called Ultimate, these are (98ron) and from what I know Shell has a fuel that has only been available for about 6 months and only in major city's called Optimax Extreme and it has 5% ethanol and an octane rating of (100ron). It's not available anywhere near where I live and I have heard its not good anyway so I will be running it on (98ron). Is the 98 higher than your premium seeing? As we have premium rated at (95ron). 98 is going to be about the same as the high-end premium here in the states, that'd be approximately 93-94 octane here in the US. We have some premium here that's only 91-92 though. With regard to the ethanol, yeah, that stuff's definitely not good for small engines. Quote
GNR101 Posted June 23, 2008 Report Posted June 23, 2008 i live in perth australia... i ride near on sea lvl... im running 20cc domes with dune porting fmf ssts 28mm carbs and +5 timing.... havent had any issues so yeh i run bp 98... so yeh dude should be safe... just keep n eye on that jettin Quote
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