Dyno with 100 octane petrol?
 

Has anyone here in OZ done a dyno run with 98-100 octane?

I think the American guys only have 91 (correct me if wrong), so it would be interesting to compare stock power runs.

It varies here, some areas have 91 and some have 93. If 100 is the norm for premium fuel at service stations in your area, there's a good chance that your stock ECU might be tuned for it (in which case the owner's manual would highly recommend only running 100 octane gasoline).

It is my understanding that the ECU has to be tuned for it for octane boost to have an effect though. All octane does is make it harder for the fuel to detonate from heat+pressure (before the spark sets it off), which allows you to run a leaner air:fuel ratio without experiencing engine knock/detonation, and a leaner mix will make more power. However, I don't think the engine can sense this and adjust for it automatically, so you'd just have extra insurance against knock without a tune for it.

On the other hand, someone here mentioned/linked a 370Z dyno result where they saw horsepower gains in the US from running some sort of 'oxygenated' 104 octane fuel. I'm not sure what that means - maybe oxygenated means the fuel has extra oxygen in it, effectively leaning out the mix from within the fuel and thus allowing the engine to take advantage of the 104 without knowing it.

wstar - It's my understanding that the ECU will try to advance the timing above the base timing until pre detonation is detected, at those points it will pull the timing back until things settle. The higher octane allows the ECU to set slightly more agressive advancement timings throughout the maps.

I did a bit more research into octane and North America uses a different standard of octane measurement compared to the rest of the world. Classic.

Most of the world uses the Research Octane Number (RON)

...but North America who uses any combination of these - Anti-Knock Index (AKI), Road Octane Number (RdON), Pump Octane Number (PON), or (R+M)/2.

So, I guess a 95 American octane is probably equivalent to RON 98.

I'll still run a baseline power run on RON 100 to see how it goes.

related video
YouTube - XXX Race Gas gains 14whp on stock 370z

That's an interesting idea. I know older engines didn't do such things, but perhaps this new shiny Nissan stuff does. It would certainly help explain that dyno video AK posted.

Australian 100 octane is roughly equivalent to our 93 octane. We use a RON/MON average, they use straight RON.

It would be 100 ron + 90 mon / 2 = 95 octane.... A little better than anything at normal gas stations in the US.

Depends on the exact formulation. Shell Optimax+ was 99.4 RON / 87.5 MON which averages out to 93.45.

Do they even sell the Shell 100 RON in Australia anymore? I heard they were stopping last year and that now the best you could get is 98 RON (98.3 RON / 86.9 ). Probably not much different overall.

Usually motor and reasearch octane differ by 10 points. I wasn't sure about Shell in Australia, so I went and looked up the MSDS on it:

Shell V-Power Racing with new friction modification technology, a minimum Research Octane Number of 100 and a Motor Octane Number of 89, exceeds the requirements of the Federal Fuel Quality Standards Act (Petrol Determination) for premium unleaded petrol. The new friction modification technology is designed to enable optimum engine efficiency and improved acceleration, in comparison with Shell Optimax Extreme. Shell V-Power Racing is ideal for use in modern high compression and knock-sensor vehicles that are 5% ethanol compatible.


so it's 94.5 R+M/2

PS I read something about Optimax Extreme being phased out with the new product being called V-power racing, for whatever it's worth.