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Octane
#21

OK

Maybe I can figure out how to put this on a map and share. Where is our map master - I might need some help.

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#22

Ok,



Sooo trying to figure out which way to go, now that it seems the car is ready. Took it out for a shakedown cruise tonight and everything seems to be running fine. <img src="/forum/images/smilies/968/rock.gif" class="smilie" alt="" /> Got her all warmed up and had her up to 95 ish (lol - just kidding - am I?) put 140 miles on her today. Farthest cruise to date.



Now, do I run 93 with 10% ethanol? What about a 93 with ethanol with some sta-bil in it? or do I run a mid-grade ethanol free with maybe an octane boost to get it up to 93? I have a local fuel supplier that makes a nice mid-grade ethanol free blend.





What are you guys running?
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#23

In BC, Chevron has 94 octane that has NO ethanol, which is what I use almost exclusively. I think that some of the rubber components of the 968 fuel system were not made for fuel with ethanol.
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#24

98 RON available pretty much everywhere (also 95 and 91). We used to have 100 Octane available, but this has dropped by the wayside. If you want to go wild, 85% Ethanol pretty much allows you to run stupid advance with no pre-detonation. Somewhat rare to be able to get it though and not sure what it does to the o-rings, etc in your engine.



We can also buy Octane booster additives, which they claim nominally adds around 5 points to the Octane rating. Perhaps this will become more widespread in the USA is 93 is dropped. The USA also "oxygenates" it's fuel - we don't.
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#25

I can only get a mid grade non ethanol product. If I had to guess it's an 89 Oct rating.
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#26

Running 91, but once or twice a year I used to top it off with about 5 gallons of 100 just to add a bit more umph to a few runs. Not sure I want to have anything higher than 91 with the SC ..do I ?

Is higher octane always a good thing ? i thought even Eric Clapton praised its merits : " If you wanna hang out, you've got to break it out, octane ..If your day is done and you wanna run, octane...If you got bad news and wanna kick them blues, octane.. She don't lie, she don't lie, she don't lie.. octane ! " Or something like that.. :-) :-)
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#27

Nice. I have the stock chip - no engine mods. I have never run into trouble with the Hondas, but I think this thing can get picky.
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#28

I have run 93 since I purchased both 968's. the sc has run fine with 93. Flash time to speak up please.
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#29

Ok, well that is a start. Are you guys using any kind of injector cleaner? Gumout etc....
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#30

When I lived in Alaska I had to use an octane booster additive for my modified VW turbo. Torco. It was pricey but worked well.
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#31

Thanks. I should have added that I live in Florida, so I am more interested in what works in the hot stuff down here in the south. Summer temps are usually in the 90's with lots and lots of humidity.
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#32

ok - first off, the US rates it's fuel by RON+MON / 2, whereas other countries rate it RON only. 98 RON is 93 RON+MON/2. 95 RON is 90 RON+MON/2



second, higher octane does not mean higher power. octane increase only adds more knock protection. it has no higher energy content. the only thing it can do to help power output is to allow the timing to be unretarded, but this assumes you have a system capable of adjusting for that to begin with (our car does).



our cars will adjust timing (and therefore cost you power) below 93 RON+MON/2, and require a minimum of 90 RON+MON/2 before the ECU runs out of ability to retard timing. below that rating and you can have knocking.



there is absolutely no benefit of running anything beyond 93 RON+MON/2. in fact, the hotter burning fuel of higher octane can actually damage valves.



the SC is tuned to run on 91 RON+MON/2. there is absolutely no benefit of running higher octane under normal conditions. if it is extremely hot, slightly higher octane fuel can help prevent detonation, but under no circumstances should you exceed 93 RON+MON/2..



that being said, high temperatures can cause detonation. for this reason, it is best to run 93 RON+MON/2 in a naturally aspirated 968, assuming you can find it.



beware of fuel additives. they are well known to cause issues with seals. octane boosters are mostly toluene or acetone, neither of which are good for your system.



sea foam, run rite, and techron are the only three cleaning additives that i know of that have been shown to be safe.
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94 Midnight Metallic Blue Cab Porsche 968 w/deviating cashmere/black interior and WAY too many mods to list - thanks to eric for creating www.968forums.com



"It isn't nearly as expensive to do it right as it is to do it wrong."
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#33

Ok, so run 93 when I can find it. 91 when I can't and a bottle of techron every few months and not worry about non-ethanol fuel. Correct?
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#34

so far, there has been no indication that ethanol does any harm to our systems.



otherwise, yes, correct.
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94 Midnight Metallic Blue Cab Porsche 968 w/deviating cashmere/black interior and WAY too many mods to list - thanks to eric for creating www.968forums.com



"It isn't nearly as expensive to do it right as it is to do it wrong."
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#35

Okey Dokey, That was what I thought, but wanted to find another opinion or two...



Thanks again....The car is running great except there is occasionally a slight hesitation when starting out..I am sort of thinking that it is due to have been sitting at the garage for the last three weeks and not being run...I will keep an eye on it. I need to go down to my guy as he has a new battery coming in for me tomorrow as Porsche warrantied the first one out due to a problem. I wonder if the clock drained it.
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#36

is it a tip?



if so, tips start off in second in tip mode. also, they need to warm up before allowing full use of power. further, there are 5 programs, and the tip computer "learns" based on your driving, and adjusts the programs accordingly. the more aggressive you drive, the more performance it allows you,and visa versa.
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94 Midnight Metallic Blue Cab Porsche 968 w/deviating cashmere/black interior and WAY too many mods to list - thanks to eric for creating www.968forums.com



"It isn't nearly as expensive to do it right as it is to do it wrong."
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#37

Nope - It is a glorious shifter, speed of six. No tippy toes for me!
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#38

hmmm



old fuel? gasoline loses about an octane point a month from sitting. it also turns to varnish, so the injectors could be sticky.
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94 Midnight Metallic Blue Cab Porsche 968 w/deviating cashmere/black interior and WAY too many mods to list - thanks to eric for creating www.968forums.com



"It isn't nearly as expensive to do it right as it is to do it wrong."
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#39

Not ruling it out, the car sat while he was waiting for all the hoses under the hood to come in. I will run a couple of tanks through it and see. It was bad starting out when I picked it up Sat, and was rough starting out today. Ran it for 140 miles today and it seemed to be doing well, but it kind of stuttered once or twice.

We just got a new fuel sender put in, so I can actually finally tell how much gas is in the tank. I will take it out tomorrow weather permitting and see how she does.
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#40

Bob, if your tracking your car is there value going to 93?
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