As I had previously mentioned to you on FB. Japan has a higher RON rating of fuel to us. Just because the ECU may have better knock control it certainly isn't an excuse to run it on the OE JDM map. The cost of running octane boosters to work around this will soon amount up and the price of a remap will prove more cost effective in the long run whilst also netting you more power safely. If you choose otherwise, you may be fine, you may not. But I certainly wouldn't be taking that chance on a £10k+ import. Is there a reason you DONT want to have it mapped as it seems like your trying to avoid having it done?

 

 

Well in my personal opinion I would say it's best practice to have it mapped. It's one less thing to worry about going wrong. Look at Hurst Cars, pretty sure every car they get in is mapped for UK fuel before sale. Litchfield cars were all mapped when hitting UK too and im sure many others were also.

 

Pretty sure the jdm map on uk fuel still has room for timing so wont be knocking or causing damage without a tune.

It just wont be running at its best.

 

 

Got mine for Hurst Cars and was map checked on UK fuel (momentum 99) not mapped.

 

Learn something new every day. At the least it's been checked though and not an assumption.

 

I really wouldn't think you would see any Det/Knock with a stock JDM map on UK fuel,

Surely if that was the case they would be limited to stock power ? But we know there are gains on the table from a map alone.

What I'm saying is that i doubt Subaru sent it from factory with so much timing in it that UK V-Power would make the car run any different, ( Cooncil 95 is a different story tho...)

Wouldn't be too hard to compare both the stock ROM and see what the differences are ?

I'm also sure you can even add timing to the JDM cars on UK fuel which again would show it's not that close to it's knock limit.

 

Hurst are knowledgeable about this and confirmed Tecso 99 will do fine so you can check back with them.
However when driving in Japan you are mostly personally served , when you buy fuel you ask for Hi-oku
This means fuels >96 Octane that are typically always 98-100 Octane , but here is the trick
forget the Octane for a moment , on turbo cars you need to know about the AKI chemistry (Detonation Resistance)

On Hi-Oku the Japanese use Anti Knock index >93 so this means you are pretty safe to use the Tesco 99 on the Japanese imports
because it also has AKI of 93 . But what you cannot use normal Super 95 as typically these are only AKI 90.

With most Euro Super you will experience considerable power loss on the Jap import as the ECU will be pulling things back considerably.
If you have also tuned then I can imagine damage through detonation as knock event is far more likely.

Spinning this a little further, My car is mapped on Aral 102 and this fuel has an AKI index of 95 so when I drive to the UK I have
a minor problem with higher boost as knock events start to occur and surprise surprise the ECU will hear this and it pulls the timing back a little.

I have also noticed this when "only" using Super Plus here in Germany which is Octane98 and AKI 93 , therefore sadly when I return to the
UK to live I will need to remap for Tesco99 Momentum.

To get over from Germany in the past I fill up 102 in Luxembourg and then empty another two jerry cans at Dunkirk/Calais.

I am assuming that as I can really feel the engine response difference already within a few meters of leaving the fuel station
that the power loss must be considerable and that the fuel type is rapidly noticed thru the ECUTEK monitoring of the knock sensor / throttle position.

 

You can't get 102 in Luxembourg, the ARAL in Lux is only 97 and the one before the border still in Germany is equally crap and does 97 same as the others round that area just before you go through the first tunnel, the Q8 and Shell in Lux also only does 97/98.

But if you know of 102 in Lux then please let me know where.

Steve

 

https://www.aral.de/de_lu/luxembourg...imate-102.html

Not many I know , text below shows where 102 replaces 98

• Merl 2: 225, route de Longwy (Ultimate 102 ersetzt Ultimate 98, aber Ultimate 98 wird noch erhältlich sein bei Merl 1:246, route de Longwy)

• Remich 2: 6, route de l'Europe (Ultimate 102 ersetzt Ultimate 98, aber Ultimate 98 wird noch erhältlich sein bei Remich 1: 18-20 route de l'Europe)

• Rodange 3: 446, route de Longwy (Ultimate 102 ersetzt Ultimate 98, aber Ultimate 98 wird noch erhältlich sein bei Rodange 1: 515, route de Longwy)
• Niederkorn: 142, route de Bascharage