96 or 91 unleaded?

[Jazza]

Well after deciding my legnum (Yeh, just got a legnum too) was running shit on 91, ive switched to 96 on it and it runs NICE. So, will my curren feel better running on 96 too?

[Gtz_xtc]

i've personally found all of my cars have run better on higher octane petrol so i'd say yea

[matt dunn]

General rule is if it's twin cam or japanese it will run better on higher octane.

[Adamal]

96? Where are you getting that from?

[Adamal]

General rule is if it's twin cam or japanese it will run better on higher octane.

If I may digrees on this matter, I have heard from many knowledgeable sources, that with the timing adjusted, running on a lower octane will provide more power as long as there is no detonation.

An example (I guess) would be a bigport 4AGE, with the lower compression, making it less suseptable to detonation.

[Voodoo]

i thought i was the other way around , advance timing to take advantage of the high detonation limits of higher octanes

[matt dunn]

General rule is if it's twin cam or japanese it will run better on higher octane.

If I may digrees on this matter, I have heard from many knowledgeable sources, that with the timing adjusted, running on a lower octane will provide more power as long as there is no detonation.

An example (I guess) would be a bigport 4AGE, with the lower compression, making it less suseptable to detonation.

Running a lower comp engine with timing retarded will run fine but not make more power.

More compression = more power
More advance = more power

So less advance and less timing is less power.

Anything with a knock sensor makes fuel type more important.

Matt

[Jazza]

Cheers guys

[BlakJak]

Of course higher octane is better. It costs more too.

[Adamal]

Not in all cases though. If its not going to give you more power, and you're not getting detonation under load, then its actually doing harm.... To your wallet

[BlakJak]

[well yes, its all subject to design, and tuning, etc etc]

[Dirtbag]

Costs more to put 98 in my car dollar per litre, but it works out the same/a lil better if u calculate dollars per k, and the saving by putting in cheaper fuel eg 95 rather than 98 isnt that big, 5 cents a litre? a dollar per 20 litres? If you put about $80 a week in, the savings per week would only be around $10 a week... but then again $10 is $10, depending on your circumstances it could be worth the saving

[Adamal]

Well, for example, the bluetop 4AGE in my AW. I've tried 95 and 98 and theres no difference in power or how far I can get with it. Hell, I've just put in 91 and the butt dyno reports no differences and I can't hear/feel any detonation and I'm pretty sure it'll get me the same distance.

In a case like mine, it's not worth the extra octane

[Dirtbag]

Yea, most places I have read, 87 is the octane rating for the bigport 4ages

[Chickenman]

Well, for example, the bluetop 4AGE in my AW. I've tried 95 and 98 and theres no difference in power or how far I can get with it. Hell, I've just put in 91 and the butt dyno reports no differences and I can't hear/feel any detonation and I'm pretty sure it'll get me the same distance.

In a case like mine, it's not worth the extra octane

Ignorance is bliss aye

I take it back, seems that the comp ratio is only 9.4 which with standard timing should run fine on 95.

[QikStarlie]

Yea, most places I have read, 87 is the octane rating for the bigport 4ages

you'l find thats mon rating not ron rating like here.


if your car makes a bit of noise (exhaust or intake) you'l be very lucky to here det. unless its realy bad

[matt dunn]

Well, for example, the bluetop 4AGE in my AW. I've tried 95 and 98 and theres no difference in power or how far I can get with it. Hell, I've just put in 91 and the butt dyno reports no differences and I can't hear/feel any detonation and I'm pretty sure it'll get me the same distance.

In a case like mine, it's not worth the extra octane

Maybe. Your car will have no Knock sensor.
What is the ign timing set to, and wes the diagnostic connector bridged and the IDL contact closed? It may already be retarded,
or you may have one of the vehicles that does not mind 91.

[Voodoo]

well if timing isnt advance with higher octane then u wont notice any differance

only advantage of higher octane in a na is that u can advance timing

which as matt said = more power

thats right isnt it?

[flygt4]

well i always thought the difference between 95 and 98 would be f all on most cars.
our wagon came with the jap satnav that reads km/L and average speed etc.
it soon became clear that using 98 made a significant difference to economy. in the realm of 2km/L. i didnt believe it at first , so ive kept an eye on it after topping up with either fuel and the difference consistently shows through for mixed city/motorway driving at least.

[Mr Revhead]

well if timing isnt advance with higher octane then u wont notice any differance

jap vehicle with a knock sensor will automaticlly advance the timing
eg if you run ya beams 3sge on 91 the ecu will retard it.
switch to 98 and the ecu will advance it within its limits. alos the difference will feel like shoving 5psi in it!