95 or 98 octane fuel in Australia??

[NSX9]

This might seem like a basic question and I have used 98 in my car nearly always with no issues. But recently speaking to a importer of HRC powered motorbikes who said 98 is crap and is only 95 RON with additives to boost octane. He had the world champions come out from Europe with their bikes (4 stroke HRC engines) last year and they specified 98 octane fuel. He suggested this was not a good idea and to use 95. They arrived did some practice with 95, after setting the engine mapping to suit. Next day the team redid the mapping for the 98 and did not even get the bikes out of the pits as they were running very poorly on the 98. Back to 95 and no problems. (they won!) So, our manuals say 95 RON or higher and we know Aussie fuels are substandard compared to EU fuels. Has anyone any ideas or experience on this apart from 98 RON must be better cause BP, Shell etc say so! Cheers Scott

 

[noisuf]

Hi Scott! I always use 98 octane for all our cars.......no issues. One of my other cars is tuned to 98. I use Caltex/Woolworths, BP.......anything except Shell.

 

[funkynsx]

Hi Scott! I always use 98 octane for all our cars.......no issues. One of my other cars is tuned to 98. I use Caltex/Woolworths, BP.......anything except Shell.

I use BP 98.
Whats wrong with Shell?

 

[noisuf]

I use BP 98.
Whats wrong with Shell?

You know, it's something that's stuck with me since I bought a new turbo car back in 2004......did a bit of research regarding fuels and back then at least, there was conjecture on the net that Shell RON ratings and detergents were questionable. So I use to pump up at any of the other outlets including Mobil. So it's stuck with me since so things may have totally reversed/changed. Nowadays, I only use Caltex or BP (BP only for the NSX).

 

[AU_NSX]

I have a knock sensor gauge fitted to my race car as it is twin turbo. Basically a precaution...

I will say that having tried the top 4 98RON fuels supplied by Mobil, Caltex, Shell and BP...

Mobil and Caltex I found that the knock sensor gauge went off at anything over 5500 - 6000 RPM

Shell and BP have been fine on days less than 30 deg C (no lights on the knock sensor gauge) however, on days over 30 deg C, I would start to get lights on the gauge around 7000 RPM. 100ml - 200ml of the expensive Nulon Octane booster ($24.95/250ml not the cheaper one at $12.95) would fix the problem on hot days and give me the full 8000 rpm to play with should I need it.

So for our NA cars, it won’t really matter because the computer will adjust to suit whichever fuel you put in! BUT... if you really need 98RON fuel or you just want to put into your car what you're paying extra for SHELL and BP are the only ones I have found with a noticeably more consistent and higher RON than Mobil and Caltex.

I have heard all the arguments about which one is better and why... like "they have changed their formulation now XXX is better and XXX is sh!t..." and "they are all the same because they come out of the same refinery"... Well I'm just telling you what my gauge says...

 

[noisuf]

Yeah, even back then they said the fuel basically came out from 2 refineries. I just make sure 98 goes into my babies.

 

[ChickenWing]

I have a naturally aspirated V8 in my race car with 13.8:1 compression.
It runs notably better on BP than Shell. While tuning with shell we had to pull timing.

 

[funkynsx]

I have a naturally aspirated V8 in my race car with 13.8:1 compression.
It runs notably better on BP than Shell. While tuning with shell we had to pull timing.

More info on your V8 please.
What class you racing in?