correct fuel for skyline.

[neil reynolds]

HELLO GUYS,
I WAS JUST READING YOUR THREAD ABOUT THE RINGED MOTOR AND YOU SPOKE ABOUT USING THE CORRECT FUEL. I USE OPTIMAX WHERE POSS, BUT NOT SURE WHAT TO USE WHEN OPTI IS NOT AVAILABLE. THE IMPORTER OF MY CAR TOLD ME TO USE ANY UNLEADED. CAN ANYONE PUT ME RIGHT.
CHEERS.............NEIL

[Simon]

I wouldn't use normal unleaded unless you have a replacment ECU mapped to that grade of fuel. Use 97RON Super as a minimum.

I tend to use Optimax + Octane booster just be safe as its only £2 a bottle.

[Steve]

Optimax or any SUPER u/l if you can't get Opti and with octane boost for track days
Keep it on the Black Stuff

[stormuk]

I must say this seems a bit strange to me.

I can understand Hard Tuned GTR's needing it all - but I have been told that for a GTS just go down the list so if Unleaded is all they have then have it but dont drive like a nutter and keep the revs down - dont over fill it thus when you can get to the next station you can dilute it (is that the right word) with the good stuff.

[Draxx]

Would Standard unleaded be ok for mine then, being as it's normally aspirated 2.0 litre??

I've been using lots of Octane Booster!!!

Draxx

[neil reynolds]

DRAXX, WITH THE INFORMATION IVE BEEN GIVEN I WOULD STICK WITH THE SHELL OPTIMAX IF I WERE YOU MATE.
...............NEIL.

[Durzel]

Originally posted by Steve
Optimax or any SUPER u/l if you can't get Opti and with octane boost for track days
Keep it on the Black Stuff

Same here, SUL for me all the way (nowhere close does Optimax - but I fill up with it when in an area that has a station).

I personally wouldn't bother with octane booster unless it was a track day.

[Simon]

I know a lot of you will know, but for those that don't... In Japan the fuel is rated at 100RON, UK Optimax is supposedly 98.6, UK Super is 97 and UK NUL is 95, octane booster will generally add 1 or 2 points. RON relates (although I am not sure how) to the temperature at which the fuel ignites, the higher the RON rating the higher the temperature that is required to ignite the fuel.

Japanese engines are obviously mapped to japanese domestic fuel (i.e. 100RON) and running them on a lower quality fuel (i.e. one that ignites at a lower temp) can mean that the fuel will ignite before the spark, this is called det(onation).

When det occurs, the explosive force produces a sudden rise in cylinder pressure accompanied by a metallic pinging or knocking noise. The shock waves created by det subject the head gasket, piston, rings, spark plug and rod bearings to severe overloading.

All modern cars will have a 'knock sensor' that allows the ECU to detect det, and do something about it. The usual way the ECU will fix this is that it will retard the ignition (spark earlier), but often with Japanese cars the fuel quality between 100RON and 95RON is that different that they cannot retard the ignition enough, so under load/high temperatures the engine will be detting.

The solution to this is either to reduce the temp of the fuel/air mixture entering the engine (by fittment of a bigger intercooler, water injection etc.) or use a fuel that doesnt ignite until higher temperature, i.e. one with a higher RON rating.

It is obvious that using a higher octane fuel is a lot cheaper than fitting water injection, and certainly cheaper than an engine rebuild.

Turbocharged engines generally run hotter than the average NA engine because intake temperatures are obviously higher due to the air being compressed by the turbo. So I would say det is more of an issue to turbo'd cars than NA cars (I have no experience of NA Jap cars), but I for one wouldn't take the risk.

[Draxx]

Cheers Simon thats dead good, finally it is explained, I have been wondering why RON Ratings were so important!!!

I now know thanks matey!!!


Draxx

Future user of Optimax, if I can find a SHell near me that is!!!

[Durzel]

Originally posted by Simon
I know a lot of you will know, but for those that don't... In Japan the fuel is rated at 100RON, UK Optimax is supposedly 98.6, UK Super is 97 and UK NUL is 95, octane booster will generally add 1 or 2 points. RON relates (although I am not sure how) to the temperature at which the fuel ignites, the higher the RON rating the higher the temperature that is required to ignite the fuel.

Even less people know that the above isn't actually true (except the part about UK fuels)

There seems to be a lot of confusion about this - I used to believe that Japanese fuel was 100RON, but apparently it isn't, as Shin once said:

At first, many people believe Japanese petrol is 100, but the octan in Japan is not 100 actually.
It is usually 97.5 to 98.0.

See this thread for background.

[Draxx]

AAAARRARARARRRAAGGHHH

I am dead confused now but the lowdown is use super u yeah???

Draxx

[Simon]

You are right Durzel, I didn't know that , but everything I have said still stands. As I have said, the ECU will probably be able to retard the ignition enough to cope with 97/98RON, coping with 95RON NUL is a different kettle of fish.

Draxx, that's right, use SUL. What you'll probably find is that you'll get extra MPG from using SUL as the engine is running more efficiently. The money saved from the extra MPG will very probably more than equal the additional cost of SUL over NUL. This was certainly the case with my old UK Impreza turbo.

[polarbearit]

... I understand that if you use Optimax then Octane boosters have little or no effect as the fuel doesn't seem to respond the same way as SUL due to the additives it contains

Always used to run the Jap spec Modified Scooby on SUL or Optimax, but there are a couple of other problems with fuel etc-

1 Its not always use of the wrong fuel grade that kills the engine, but the fueling not being remapped correctly for modifications - There are lots of people who don't fully understand tuning japanese cars (though fortunately lots of good ones too)

2 SUL goes off... If the garage doesn't sell much then the chances are it will be stood around for ages and will degrade to a similar level to normal unleaded

- I hope that helps

[Simon]

I guess that means if we want to be 100% sure our cars are not detting then we should invest in aftermarket knock sensors/gauges like the scooby boys do.

Has any one fitted an aftermarket knock sensor/gauge? I guess there is no reason why the knock link (as used on a lot of modded Imprezas) wouldn't work with a Skyline.

[neil reynolds]

IVE RUN MY CAR ON OPTIMAX NOW FOR A YEAR , IT PERFORMS BRILLIANTLY AND I HAVE NEVER HEARD IT PINK ONCE UNDER ANY SITUATION.
...............NEIL