98 octane in 6 cyl

[POELWYK]

hey guys i have been running my car on the 98 octane for the passed week and i haven't had any probs with itso far its been working really well but i would just like to know if it would be doing damage to my 281,000km motor or will it be fine to run my car on it as i was told it burns slower and it could do damage to rings and stuff is this true??

[The Monty]

How can running a better, more refined higher octane fuel cause damage?
Anywhoo, I dont think it would be hugely beneficial to run it, but it wont hurt it, if you get my drift. Unless its tuned to 98, like mine is.

[POELWYK]

yeah that was my tought i was thinking huh but a guy at work told me it will do damamge im like hmm ill go ask and find out

on another note i have noteced a little more power gained only a little though

[LukeyST]

Ive never run anything other than 98 in the xr6. Slight increase in power (im sure of it), smoother (definitely) and better L/100km (definitely).

I dont see how it could harm your engine?? Its supposed to be cleaner and all ....

[JC]

The I6 in the AU is tuned to run on 91 ULP. It does not adjust timing etc if you run higher octane, so you are not getting full benefit unless you have a flash tune to adjust fuel trims etc. The additives will keep the fuel system clean, and this may account for the better economy (marginally) etc some people think they are getting.

[smally289]

The EFI system on the AU does have a knock sensor, so I will dispute the timing comments. It wont actually advance it tho, more like it won't retard the timing as early using 98 under load as the engine will not pre ignite as easily as it would on 91.

[aufairmontghia]

I believe the 98 octane fuel has a higher density so would burn easier & quicker... It would give you the same momentum for less effort. The detergents in the fuel clean your engine of carbon & keep your fuel injection clean as well.
I agree with the knock sensor & was going to mention that as well....

The 98 octane in my Ghia allows it to go harder & the idle is definetally smoother than 91 & even 95!!!! Of course a tune wouldn't hurt & enable you to get the full benefit of running 98 octane....

[mik]

low octane fuel can cause pinking or detonation in the cylander in certain conditions , it can damage to pistons ,bearings head, block in the extreme cases, and on turbo or blown engines damage can occur 10 times faster. http://www.youtube.com/watch?v=qZl1wSlT2po
http://www.youtube.com/watch?v=XiBzx...eature=related
the first clip the guy mentions heat but i think he did`nt mention shockwave which he should have its also damageing, the second clip gives you an idea of what pinking,or pinging sounds like , its almost like a fast rattle, its very pronounced when he first takes off, sometimes it occurs also higher up in the rev range and under less load, and some engines it is harder to hear this rattle, some engines have sensors that detect knock and alter the engine timing to cope, i have my doubts about au`s, i heard mine ping for the first time in 4 1/2 years, i put some of the cheap stuff in the other day as i was a little short(thats what my wife says : ) and the au did`nt bloody like it one bit, put some 98 in today and no more pinking.

[mik]

Originally Posted by aufairmontghia

I believe the 98 octane fuel has a higher density so would burn easier & quicker... It would give you the same momentum for less effort. The detergents in the fuel clean your engine of carbon & keep your fuel injection clean as well.
I agree with the knock sensor & was going to mention that as well....

The 98 octane in my Ghia allows it to go harder & the idle is definetally smoother than 91 & even 95!!!! Of course a tune wouldn't hurt & enable you to get the full benefit of running 98 octane....

nup low octane is more volatile,explosive if you like, the beuty of slow burning fuel (higher octane) is that your engine can run more advanced ignition timing because the fuel burns quickly but does`nt explode uncontrollably..

[bodes-sh]

Originally Posted by mik

low octane fuel can cause pinking or detonation in the cylander in certain conditions , it can damage to pistons ,bearings head, block in the extreme cases, and on turbo or blown engines damage can occur 10 times faster. http://www.youtube.com/watch?v=qZl1wSlT2po
http://www.youtube.com/watch?v=XiBzx...eature=related
the first clip the guy mentions heat but i think he did`nt mention shockwave which he should have its also damageing, the second clip gives you an idea of what pinking,or pinging sounds like , its almost like a fast rattle, its very pronounced when he first takes off, sometimes it occurs also higher up in the rev range and under less load, and some engines it is harder to hear this rattle, some engines have sensors that detect knock and alter the engine timing to cope, i have my doubts about au`s, i heard mine ping for the first time in 4 1/2 years, i put some of the cheap stuff in the other day as i was a little short(thats what my wife says : ) and the au did`nt bloody like it one bit, put some 98 in today and no more pinking.

i can vouch for au's pinging too, i had it about 3 years ago not long after we moved back to perth. threw some upper engine cleaner from coventrys through it, helped a bit, but was still pinging under high load. then i got a cheapie fuel pump off ebay and whacked that in and it's been fine ever since. only ever ran it on 91 until the lpg, now it still gets 91 very occasionally. whether it was a bad batch of fuel i'm not sure, but it was definitely pinging

[bartsau]

I tried runnin mine on 98 octane only to find when cold it wouldn't ever start untill the third try. Didn't really notice any difference in fuel consumption and did perhaps on occasion feel a little more spritely (very marginal though). As for damaging your engine. It burns more controllably so i can't see it doing any harm.

Rhys

[Stattic]

Originally Posted by smally351

The EFI system on the AU does have a knock sensor, so I will dispute the timing comments. It wont actually advance it tho, more like it won't retard the timing as early using 98 under load as the engine will not pre ignite as easily as it would on 91.

thats probably the most logical explanation

on a side note, poelwyk, dont ever listen to anybody ever lol so many people give you warped ideas about cars :P

mines tuned to 98 and once i put in 95 just to see how it went and whilst i didnt get any pinging, the power was very noticeably down
i suppose it didnt ping at all because i used it for 50km or so before i gave it a bit cuz i was a bit cheap that week so im assuming its had time to successfully back off the timing
i also noticed better fuel economy... wtf? i mean by 3-4L/100km
i put in 98 octane, used that.. normal fuel economy
then my 95 octane... used all that.. better fuel economy
then more 98... back to normal
what wrong there? crap tune? or is that normal? ive never ever heard of anyone getting better economy on lower octane fuel but the results were right in front of my eyes

[JC]

Originally Posted by smally351

The EFI system on the AU does have a knock sensor, so I will dispute the timing comments. It wont actually advance it tho, more like it won't retard the timing as early using 98 under load as the engine will not pre ignite as easily as it would on 91.

Correct - which is why i said it won't take full advantage!

[Mr Hardware]

I think i remember <s>God</s> Sox telling us one time that the knock sensors like 95 better but 98 produces no extra result over 95.

[Halfmo Rocks]

my car is unmodified, so i don't think of performance in my fuel choice, but i run the best fuel available - i'm assuming the higher octane is better as performance vehicles demand it, i figure it can't hurt...and will hopefully prolong the life of my engine.

i might be throwing my cash away...but i feel more confident in the premium fuels rather than the basic unleaded

[Mr Hardware]

Sorry to say adam but you're subscribing to the exact thoughts the fuel companies want you to have

AU I6 - tuned for 91, ok for 91, 91 is sold complying to minimum standards and there's nothing about an AU I6 that will die earlier because of 91 being used.

[The Monty]

Originally Posted by Stattic

thats probably the most logical explanation

on a side note, poelwyk, dont ever listen to anybody ever lol so many people give you warped ideas about cars :P

mines tuned to 98 and once i put in 95 just to see how it went and whilst i didnt get any pinging, the power was very noticeably down
i suppose it didnt ping at all because i used it for 50km or so before i gave it a bit cuz i was a bit cheap that week so im assuming its had time to successfully back off the timing
i also noticed better fuel economy... wtf? i mean by 3-4L/100km
i put in 98 octane, used that.. normal fuel economy
then my 95 octane... used all that.. better fuel economy
then more 98... back to normal
what wrong there? crap tune? or is that normal? ive never ever heard of anyone getting better economy on lower octane fuel but the results were right in front of my eyes

With my old Fairmont, I used to get 600L to every tank on regular, 650 on 98 premium, and between 730 and 780 a tank on 95 E10. Not one person believes me, but I know for sure these were what I got. I had the car for 4 years, and I knew it back to front. 14.9's and could go and get 780km to a tank, lol. Now I do 14.6 and get 600 if Im lucky.

[Stattic]

Well I believe you lol
bolt on aus are probably the best daily drivers in history

[mik]

Originally Posted by Mr Hardware

Sorry to say adam but you're subscribing to the exact thoughts the fuel companies want you to have

AU I6 - tuned for 91, ok for 91, 91 is sold complying to minimum standards and there's nothing about an AU I6 that will die earlier because of 91 being used.

unless it is pinking or pings , then your doing damage.

[Mr Hardware]

Yes that's right mik. I've never heard a stock I6 ping on petrol however.

[POELWYK]

so in short word is that it will be fine to run the car on 98

[The Monty]

Yes, no problems.

[Beer Baron]

I can notice a difference between 91 and 95 but not between 95 and 98. 95 is cheap at the moment too, In Brisbane anyway.

[Sox]

Originally Posted by Mr Hardware

I think i remember <s>God</s> Sox telling us one time that the knock sensors like 95 better but 98 produces no extra result over 95.

Thanks for the kind words.
I posted a few times in this thread on the subject -

http://www.fordforums.com.au/showthread.php?t=11267348

[Halfmo Rocks]

Originally Posted by MRHARDWARE

Sorry to say adam but you're subscribing to the exact thoughts the fuel companies want you to have

yeah, probably...but i figure i'd rather use better fuel than necessary than just enough to run it....i don't always run 98 as not all servos in my area have it, normally run 95