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YOUR RESEARCH93 octane question
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Use enough not
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In the Porsche it gets the highest Octane I can buy, and it gets used enough not to worry about a little Alcohol...
Leading evidence: 'Use enough not' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Adjust 91 octane' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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All of these toys are used regularly, stored with stabilizer.
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I use stay-bil for anything that sits over the winter and have no issues with anything, fuel injected or carbureted.
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Knock sensors will also adjust for 91 octane to resist detonation.
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Also, if the 996 has to adjust the timing with 91 pure gas, it might not perform better than lower-energy E10 93 where no ignition timing adjustment is needed.
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Also, if the 996 has to adjust the timing with 91 pure gas, it might not perform better than lower-energy E10 93 where no ignition timing adjustment is needed.
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Since avoiding pre-ignition is super critical for the 996, it's safest by far to run 93 to avoid any need for knock control or any possibility of pre-ignition occurring.
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91 in the fall with stabilizer.as mentioned - A little ethanol is no big deal when the car is being used regularly , besides mine pings if I run anything less than 93 anyway and it's stock !
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So now that I have the (new to me) ride home, NW Illinois, I spent a day trying to find stations that offer
ethanol free
93 octane. The various apps to locate such stations proved largely worthless as most of what they showed as carrying 93 octane were either obsolete or included 93 with ethanol. It seems fewer and fewer stations now carry 93 octane.
I did find two stations, one 30 minutes away and another 40 minutes away, and whenever I'm in Dubuque IA I can run by either, but my question is, has anyone used octane boostsers? Is this a viable option when I can't find 93 octane? I know it'll run on 91, but I'd rather feed it what it wants.
So I did find an old thread here on the subject. It doesn't seem there's such a thing as a "good" octane booster additive. 91 octane when I have to, and 93 when I can.
Yeah I believe that's the consensus. I learned something interesting about engine additives recently. Apparently the profit margin or markup for petrol at the pump is very thin. Conversely, and I cannot confirm this but the source was legit, markups on additives are extremely high. Make of that what you will. It probably explains the massive marketing around the big oil additive packs in their fuels and oil. I'm in NC and I can get ethanol free 93, so my car is tuned for it. If I move somewhere that has noticeably different fuel, I guess I'll need a different tune. Ideally anyway...
All normal gas has up to 10% ethanol unless you specifically buy ethanol free gas. Is no-ethanol better? Probably, but it doesn't really tend to cause issues on newer cars (80s+ with EFI), especially if you drive them moderately often. They wreak havoc on carbs if you let ethanol fuel sit in the bowl without running for a long time though. Octane is far more important than ethanol percentage within the 10% legal limit. I wouldn't stress about 91 vs 93 though. These cars aren't turbo'd running aggressive tunes or anything. They are moderate compression NA engines that were sold all across the US including the West Coast where 93 is virtually impossible to find and there are plenty still on the road out there. I put about 5K miles on mine with 91 and never once heard any pinging/knocking even during spirited driving.
consider all the high performance and classic Porsches running around California on E15 91.
the UK govt operates this website to tell you if E10 is safe for your car if you're curious about their opinion
https://www.gov.uk/check-vehicle-e10-petrol
(Edit: I'll just post what they say about Porsche here: "E10 petrol is cleared for use in Porsche vehicles with petrol engines since the 1998 model year and all Boxster models with petrol engines since the 1997 model year. The Carrera GT is not cleared for use with E10 petrol.")
I live in California and I go to shell for E10 91 as it's the best I can get. If I could get E10 93 I'd use that instead.
What ethanol really killed is the carburetor.
Definitely 93. It will probably be cheaper and like I said octane is more important and 93 is technically what Porsche calls for. If I was going to let my car sit for an extend period of time I might opt for ethanol free though. All of the issues associated with ethanol damaging fuel components is from extended sitting and manly on carbureted cars.
Yeah, that is what I would probably do. That Is what I typically do on my carbed cars and what my dad does on his Supra and it has always worked well for both of us.
I use stay-bil for anything that sits over the winter and have no issues with anything, fuel injected or carbureted. And that�s with the 10% ethanol fuel.
The ethanol argument has been going on for a long time. I have been running e10 87 in the jeep, four stroke yard equipment, 2 stroke yard equipment, atv, 90 hp 2 stroke outboard, 15 hp 2 stroke. I also had the last year of carbed mustang with a factory Holley that I would run 91 e10. All of these toys are used regularly, stored with stabilizer. In 25 years, I have had one carb on the 15 hp rebuilt. It is a 2003 and easily has 2500 hours on it.
Porsche gets 93. 91 in the fall with stabilizer.
I don’t agree with ethanol as I don’t believe it to be beneficial economically. Too much energy to produce it.
I have no concerns running e10 in any motor....
overblown concern on marine forums too.
Porsche gets 93. 91 in the fall with stabilizer.as mentioned - A little ethanol is no big deal when the car is being used regularly , besides mine pings if I run anything less than 93 anyway and it's stock !
Ethanol/Methanol Alcohol is a great motor fuel. Very high Octane ...I used to buy it by the 55gal barrel back in the 80's for my Race Car. But it absorbs water/moisture like crazy and has no lubrication...
A 55gal barrel will start to turn cloudy with water in a month especially if you leave the cap off the barrel for any length of time..
I had to add Ester Oil for lubrication because the Alcohol is so dry..and Methanol will not mix with petroleum oil but will mix with Ester Oil..
Alcohol mixed with gasoline in low percentages E10 or E15 is fine in modern cars when used regularly, but will play hell on small engines with carbs if not used regularly..
The smaller the engine the worse the problem because the smaller the engine the smaller the jets are in the carbs and the easier they are to be plugged by the corrosion of the aluminum carbs caused by water absorption of the alcohol...
I only use Alcohol Free gasoline in my small engines and boats with aluminum carbs..
In the Porsche it gets the highest Octane I can buy, and it gets used enough not to worry about a little Alcohol...
Yes running and burning ethanol in an older engine isn�t a great concern, it�s when it sits for a couple of months or more that the problems start. Sealed fuel systems aren�t as problematic as open style systems like chainsaws and mowers with carburetors With the open systems the ethanol causes plugged jets and lots of sugary crap when it evaporates, and it will quickly.
By 1997 the cars were designed for running 10% ethanol. Ethanol came out in the '80's. Plastic/rubber parts are built to withstand ethanol. Use a stabilizer if stored for long periods. Knock sensors will also adjust for 91 octane to resist detonation.
It's important to understand the role of octane and fuel composition (e.g. pure gas vs E10/E15).
Octane, by itself, does not add any power at all. Higher octane fuel has the same energy as regular fuel, the only difference is that high octane fuel is actually more difficult to ignite so that it prevents pre-ignition (pinging).
Ethanol has 33% less energy than pure gas, so Ethanol (despite having naturally high octane) will reduce both power output and gas mileage -- the reductions are pretty severe in specialty E85 fuel/cars (85% Ethanol) and less severe in E10 and E15, but still very noticeable (especially gas mileage).
The most important thing is to prevent pre-ignition (compression ignition that occurs while the piston is still on the upswing) because that will damage the engine over time due to physical stress of early ignition and superheated cylinder temperatures -- which are especially critical for 996 engines where the cylinders aren't encased inside a solid block (high temps cause the cylinders to go out of round, which is what causes bore scoring).
The owners manual recommends 93 octane (AKI used in US) and will operate on 90 with the adaptive knock control adapting if needed.
Since avoiding pre-ignition is super critical for the 996, it's safest by far to run 93 to avoid any need for knock control or any possibility of pre-ignition occurring.
You might get slightly better gas mileage and slightly better performance with 91 pure versus 93 E10 because pure gas has more energy, but it still better to prioritize avoiding pre-ignition. Also, if the 996 has to adjust the timing with 91 pure gas, it might not perform better than lower-energy E10 93 where no ignition timing adjustment is needed.
I'd always pick 93. If 93 pure is available, that is best, but 93 E10 is better than 91 pure, especially with the 996 cylinder design.
Nice writeup
@peterp
. The only thing I'd add is that ethanol has lower energy
per unit of volume
than gasoline. My old Subaru turbocharging buddies used to love E85 because it kept combustion temps down and let them run insane boost levels. They'd run fat fuel lines, bigger injectors, and humongous fuel pumps to deliver enough liquid.
I use Marvel Mystery Oil in vintage cars religiously in every tank, which I think contains Ester Oils as part of its ingredients. MMO is great for vintage cars. Many use it for modern cars also. I don't use MMO regularly in the 996, though I will run a tankful with MMO (4 oz per 10 gallons) to clean deposits before an oil change.
