Ford Focus ST Forum banner

1 - 8 of 8 Posts

·
Registered
Joined
·
32 Posts
Discussion Starter #1
Hi all, new ST owner from Australia here.

This has most likely been asked a tonne of times here, but couldn't find the exact answer I need.

For the Stratified OTS tune form there's the option for 91 and 93 fuel types, is this fine if expecting to only use 91 and 95? Or will I need a custom?

I figure 91 and 95 will be the most commonly available fuel in AU, and I'll be running 95 most of the time.

Cheers!
 

·
Registered
Joined
·
19 Posts
They use a different fuel rating system in the states. Their 91 is our 95 and the 93 is our 98.



Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
1,548 Posts
Another thing I do with the OTS tune to account for varying fuel quality. I run the 91 tune and I fill with a higher octane. 93 here. I get negative corrections and knock if I run the 93 OTS tune with 93 fuel. Runs great on the 91 tune with 93 fuel.
 

·
Registered
Joined
·
344 Posts
In the US they use what is called Anti Knock Index (AKI) which is uses both the Motor Octane Number (MON) and Research Octane Number (RON - what we use here in Australia). Our RON is equated approximately as follows:

91 RON ~ 88 AKI
95 RON ~ 91 AKI, and
98 RON ~ 93 AKI.
Google AKI and fuel ratings if you want to learn more, but the TL;DR version is use 98 RON such as BP Ultimate (my preferred choice), Caltex Vortex 98 or Shell Vpower Max 98 and select a 93 octane stratified tune. You can also tell them you are in Aus and they know what our 98 RON is like as they have tuned hundreds. Once tuned for 98 DO NOT RUN 91 or 95, it will knock like crazy and damage your engine.
 

·
Registered
Joined
·
32 Posts
Discussion Starter #6
Ah right, so I'd get the 91 and 93 fuel maps, so I can switch between 95RON and 98RON respectively, depending what's available.

Cheers!
 

·
Premium Member
Joined
·
372 Posts
I'm running 98 and 102 (RON). Never used 95 and probably never will. I'm tuned for 93 AKI (98 RON).
A friend of mine had his ST on the dyno with 91 and 93 and the respective maps for it. I don't remeber the exact numbers, but it wasn't too much of a difference. Max power was around around 10 hp lower with 91 while max torque was within the margin of error, iirc.
 
1 - 8 of 8 Posts
Top