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YOUR RESEARCHWhat kind of Gasoline do you use for your 996?
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Check top tier website, the formulation
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Last time I checked the Top Tier website, the formulation for Top Tier gas contains 10% ethanol.
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I know that the way my Subaru ran versus the way my Porsche runs is different, but I still feel pretty confident about my choices.
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That's $5.29 - $6.05 per US gallon....and I use a lot of it.
Use premium without exception, purchased whenever possible
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I use premium without exception, purchased whenever possible from one of the major manufacturers (Chevron, Exxon, Shell) since their additive packages perform better and keep your injectors and valves cleaner.
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When the pinging was going on, it used regular gas, except for that month in the high desert.
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Suggestion
For those of us that live in the USA this means 93 octane is the upper octane limit while 91 or possibly even 90 -- I do not want to get up out of my easy chair and go outside in the cold to check the gas cap lid -- is the lower octane limit.
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However, unless you use the Techron (available in quarts at many locations) to clean the deposits, then you revert back to the pinging on the next tank of El Cheapo.
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The other day when I was gassing up my 996 i opened the gas lid and it stated to use ONLY 95 Octane or higher. I gas up at only one gas station which has 93 octane and which is about 10 miles from my house but I usually gas up when im in the area.
Which Octane do you use for your 911?
93 octane IS the recommended octane for the 996. Your car does not state 95 octane, and if it does(probably 95 RON not 95 octane) that is some type of conversion difference as octane ratings are stated differently in Europe compared to the U.S.
You can use 91 octane in the U.S. and still be safe, although the cars ECU will retard the timing a bit to avoid knock and thus hinder performance a bit.
However, I would NOT run less than 91 octane in your 996. If you do, it will cause the engine to knock during larger throttle inputs and cause damage to the engine over the long run.
The sticker in your car is referencing RON (research octane number), which is how gasoline pumps in much of Europe are marked--or at least were when I lived in the UK for 4+ years. In the US, pumps are marked with the average of RON and MON (motor octane number, which is a different test method), or "(R+M)/2". RON is the higher number, and is about 10-11 points higher than MON. Doing the math, this means RON will exceed (R+M)/2 by about 5 points.
So...using gasoline in the US that is 90+ (R+M)/2 will meet Porsche's requirements. That means using premium in all circumstances--no regular or midgrade, unless those are the only things between you and running completely out of gas. I use premium without exception, purchased whenever possible from one of the major manufacturers (Chevron, Exxon, Shell) since their additive packages perform better and keep your injectors and valves cleaner.
Using the lower grades won't harm your engine, as the DME computer will detune the engine to prevent knock (it retards spark timing, as DreamCarrera states). You will be a bit down on power however.
I've spent quite a bit of time driving up in your neck of the woods, and IIRC Exxon sells 93, whereas most other retailers in Southern MO sell 91; so, Exxon gets my business when I'm up there. (For the record, I'm not an Exxon employee--quite the opposite, I work for one of their largest competitors!)
Chevron 91. There is a station here that has 100 octane "racing fuel". Twice as much $$$ per gallon. I thought about trying a tank to see if there was that much of a difference. Has anyone else used it?
No real advantage in going to 100 octane. Octane is just a measure of detonation resistance. So unless you have an engine tuned to take advantage of the higher detonation threshold (high compression, forced induction, etc) you won't see any power increase with higher octane.
Chevron - top tier (91 or 93...I forget what we have)
techron additives will help keep your motor clean, its proven
and black cars are fastest - wait, make that RED - Red are fastest
Unfortunately all I can find in California is 91 octane with "10%" ethanol. I use that and have used it almost exclusively in my cars with.
Almost exclusively...One of the joys and and at the same time disappointments I experience on my long roads trips in my cars is encountering stations offering 93 octane gasoline and even 93 octane gasoline sans any ethanol.
In every case, most recently with my 03 Turbo and my 02 Boxster, the engine's positive reaction to being fed 93 octane gasoline is an eye opener. Sure makes me wish I could run this blend of gasoline on a regular basis.
(Another simultaneous joy and disappointment is this 93 gasoline is always priced below what I pay for 91 octane here in California.)
The '95' is the min. octane (RON) recommended which works out to about 91 here in the good old USA.
Anyhow, you did right using 93. Keep it up.
Because I an a Nerd I actually datalogged the performance from 2 tanks of every major gasoline brand around where I live. I had an STI with decent bolt ons and a basic tune and I wanted to see which gasoline gave me the least knock and timing retardation. I found that Shell 91 W/O Ethanol was the best gasoline available locally. When I go to BC I get that magic Chevron 94 with Techron. I know that the way my Subaru ran versus the way my Porsche runs is different, but I still feel pretty confident about my choices.
Shell 91 W/O Ethanol : 3-5 deg retardation
Esso (Exxon) 91 W/O Ethanol 4 -5 deg retardation
Petro Canada 94 10% Ethanol 6-7 deg retardation
Husky 94 W Ethanol 7-9 deg retardation
Petro Canada 91 W/O Ethanol 10-12 deg retardation
Chevron 94 with Techron : 1-2 deg retardation
LMAO!
lets see....umm...well - we get more rain than you guys and our Summer time highs are like 65!
wait, that's bad - um, I quit....anywhere is better then here
WHICH IS WHY - WE CAN SMOKE DOPE!
Well we have 94 octane wo ethanol....the best weed in the world and awesome free healthcare (that im thoroughly using after blowing up my knee 4 weeks ago). Wonder if i should drive my pcar to pick up my free prescription for some bcbud.
If thats socialism then im aok with it!
Doing a quick search I found this:
"Alberta�s Renewable Fuels Standard (RFS) requires an average of two per cent renewable diesel in diesel fuel and five per cent renewable alcohol in gasoline sold in Alberta."
So then escaping ethanol no longer looks possible so now I have to go back to the octane argument. How much is enough?
Lotsa Canucks on this site, that's for sure. I guess it's good to be in Texas because we like our oil and we like our gas, cheap. No probs finding 93 octane, but I do often see 10% ethanol. I didn't realize I was suppose to be avoiding it. Thanks for the insight!
Ditto, here in Florida.
We can get Ethanol Free gas here but it is only 89 Octane. It is sold near the marinas, primarily for the trailer boaters, but you can pump it into your car if you like. However, they charge on-the-water boater prices per gal (usually about 50 cents a gallon more than Premium).
I stick exclusively to 93 Octane (94 or 95 if I can find it), and mostly BP, Chevron, Shell, for my 996.
Dennis C, IIRC the reason that Colorado only has 91 Octane has to do with the average altitude above sea level. The higher you go, the lower the minimum octane rating required. Then again, it could just be a Green thing.
No, you are quite correct: additional octane isn't required at this elevation. In fact, I haven't seen anything higher than 92 lately, although I do remember a station in Fort Collins that sold 95 some years ago.
I believe when you use higher octane you consume less gasoline then when you would use lower octane. in the long run you spend about the same amount of money on fuel except your running on higher octane which equals to better performance Tell me if you think otherwise.
I read few other forums of German cars and I read that when you put in 100 Octane it gives you like 30hp boost or something like that. I looked around and couldnt find any racing fuel around springfield, MO. So I cant really back that up. Has anyone tried that in there 996?
Okay, here goes:
Every engine is designed to run on a specific octane, or within a specific range of octane ratings and chemistry (hence the existance of certain "Flex-Fuel" engines from GM, Chrysler, and Ford). Porsche exports its cars to over 100 different countries. Each country has its own rules about fuel grades and quality and chemistry. Porsche designed their engines to run within a certain range in order to get maximum performance. However, they also knew that often the gasoline customer must settle for less.
In order to accomodate those times, the computer that controls the fuel and combustion process was designed to adjust the timing and mixture over a broader range than just maximum power in order to protect the engine from pre-detination. Pre-detination is the fuel combusting before the desired moment inside the cylinders, which can burn valves, hole pistons, and bend gear trains. That pre-detination is controlled by octane, or by the computer adjusting the timing (retarding the moment of desired combustion). As the timing is retarded, the maximum amount of power is also lost. The computer can only do so much with the timing system and cam lobes, so at a certain point of low fuel octane, the Porsche engine will still begin to "ping" (the sound of pre-detination). The reverse applies as well, meaning that the system has a limit that it can advance the timing.
Buying the proper rating octane gas for your car keeps the car running at its maximum potential. Porsche engines WILL prerform better on 93, 94, and 95 Octane gas. The will perform without harm on 92, 91, and maybe even 90 octane. You will not be doing you engine any favors below that, and may even cause damage.
The same applies to higher octane rated gas. The engine and computer are designed to run inside a defined range. 100 octane is well outside that range. Your engine will probably run worse, not better, since it cannot burn all the fuel at the precise moment because the higher octane is actually INHIBITING that burn.
Your car is not a race car. It has a very high compression ratio, but not as high as many racing engines. The higher compression ratios of race cars require a higher octane gas in order to prevent pre-ignition in those engines.
You WILL NOT get 30 more horsepower by running 100 octane in your stock non-turbo Porsche engine unless you have a modified Turbo and an aftermarket chip to run that higher octane gas.
Saving 15 cents a gallon by running 89 or lower octane means two things:
1: You risk damaging the valves and pistions in your Porsche engine.
2: You really need to consider buying a Camry and walking away from Porsche cars.
Spending money on anything above 95 octane is a total waste of money unless you have re-engineered your Porsche engine INTERNALLY. The computer can only advance the spark so far and then it stops because the camshaft lobes are generally fixed. Newer model Porsche engines have cams with some running adjustabilty (Variocam), but even that is limited. Claims to the contrary are based on Urban Myth and wishful thinking, not engineering.
Higher octane ratings (above factory recommended rating) will NOT help your car at altitude.
Higher octane rating
will
give you slightly more performance than octanes below the recommended 93. But altitude above sea level, and other additives (ethanol content) all come into play.
The Porsche factory is 795 feet above sea level.
Porsche is pretty clear on this. The max octane required and the min permitted too is listed on the gas cap cover (for USA cars) and spelled out in the owners manual.
For those of us that live in the USA this means 93 octane is the upper octane limit while 91 or possibly even 90 -- I do not want to get up out of my easy chair and go outside in the cold to check the gas cap lid -- is the lower octane limit.
Some of us are limited to 91 octane either because state regulatory agencies and gasoline refiners have deemed 91 octane sufficient/good enough which is the case in CA. In other areas of the country, in areas of high elevation, 91 or even 90 is sufficient because an engine's octane requirements go down at higher elevations.
Using a higher octane -- up to the max. octane recommended -- is better because the DME can advance the spark timing to its optimum and the engine derives more useful mechanical energy from the combustion of the gasoline. Driveability improves as does fuel economy.
(In the case of my Turbo with 93 octane in the tank vs. 91 octane throttle response is better and gas mileage improves nearly 10%.)
Exhaust gas temps are lower too which reduces thermal wear/tear on the hardware exposed to exhaust gases.
For a stock engine there is no benefit in going over the max. recommended octane but there are benefits to staying above the min. recommended octane.
There are -- as is always the case -- exceptions.
For those that track/DE their cars they sometimes fill up with 100 octane gasoline for a bit more protection against detonation. Even if they run say 93 octane gasoline unless it is very fresh, and added to very fresh 93 octane gasoline in the tank, it might have gone a bit stale and adding 100 octane gasoline to the existing gasoline mitigates this by throwing in an excess of octane.
Also, as an engine ages, wears, its octane requirements can go up. For the street driving this is not a real issue. Tracking/DE though is different which is why in this type of usage filling up with 100 octane gasoline is a good idea.
It is important to note that gasoline like oil is a vital fluid the correct choice playing a role in the car's performance, fuel economy, emissions (both short and long term) and engine longevity.
Knowing the proper octane of gasoline to use for one's area and car is critical. It is comparable to back in the past knowing when harnessing a horse to a carriage which end of the horse faces which direction.
If you are using Shell, or any other Top Tier gas, you are most likely getting gas with 10% ethanol. Last time I checked the Top Tier website, the formulation for Top Tier gas contains 10% ethanol.
Ive seen this published in an article posted on a local car forum and it was discussed, It seems as though every gasoline has ethanol in it now except Shell 91 they still post on their pumps that their 91 is ethanol free and after giving them a call they maintain that their fuel is ethanol free. the reason I quoted Ethanol free Esso gas previously is because at the time I was datalogging it was available.
That's interesting but my experience was different. Was towing a trailer with a dodge ram and up in the high desert, the engine started pinging. I was there for a month and after started using 91, the detonation went away.
How many miles are on that Dodge Ram engine? What grade and supplier of gas do you
normally
put in it? If you normally buy whatever is the least expensive brand of Regular in your neighborhood for your Ram, then it is highly probable that you have deposits around your valves and on the piston, since the "El Cheapo" brands do not contain the "cleaners" such as Techron (found in Chevron and Shell and BP). Those tiny deposits become hot spots in the cylinder and cause pre-detonation. Under normal loads, you would not see a big problem. Under the stress of towing in the hills, the cylinders run hotter and thus you get the pinging. A higher octane will temporarily reduce that. However, unless you use the Techron (available in quarts at many locations) to clean the deposits, then you revert back to the pinging on the next tank of El Cheapo.
You may decide you only need to use the additive when you are towing in the mountains, but the additive itself is not an octane booster. And cleaning deposits via additives does take time.
Another source of hot spots is old or dirty spark plugs. If the spark plug is slightly fouled due to oil deposits from high mileage, or carbon deposits from a rich mixture, then the pinging would also be heard under the same circumstances as above. A freshly cleaned and gapped set of plugs may save you the money spent on higher octane gas, if that is the cause.
But that would explain your experience.
Increasing the load on most any motor at relatively low rpm will cause pinging. It will go away if you increase the rpm, pull back the timing or increase the octane rating of the fuel.
The truck was a company truck and this happened back in '01. Years later I ended up buying it and drove it until it was rearended by a transport. When the pinging was going on, it used regular gas, except for that month in the high desert. At some point it got new plugs but other than that, it was retired with over 200k miles.
How can you run E85 in your Porsche?
BTW, not to get into a green argument but ethanol is hardly as green a fuel as it is touted to be.
There are several arguments against it being green (just the opposite in fact) but one is that in most areas of the country and the world underground water aquifers are being depleted to grow corn. This involves pumping water from underground.
The real negative impact is this water is very old -- it is referred to as "fossil" water -- took a long time to accumulate, and will not be replenished by nature for a long time, probably not until the next ice age has run its course and then starts to pull back with the resulting melt water run off once again recharging the aquifers.
Another is that this water once removed from underground of course makes its way to the ocean. It is the use of fresh water from these large underground aquifers that is contributing to the rise in sea levels.
This increase in the influx of fresh water changes the chemistry of sea water which affects the ocean currents and this then changes the climate which can result in an increase in the melting of ice.
Another vote for Chevron - British Columbia - ethanol free - 94 octane. The Chevron refinery here in town is the last one operating in BC - and it basically serves only the BC market...hence the availability of this boutique fuel. They are feeling a lot of pressure from Alberta producers though...
The downside of course is that this product costs between $1.40 and $1.60 per litre. That's $5.29 - $6.05 per US gallon....and I use a lot of it. But that is all I use. My annual fuel bill for just the Porsche is $4988.
On the other hand - Regular 87 octane 10% ethanol gasoline still costs between $1.20 and $1.40 per litre (and as high as $1.50 when the oil companies are feeling particularly gougy). That's between $4.54 and $5.29 per US gallon.
If I drove a Chevy which could tolerate that swill I could reduce my annual fuel cost to $4323 per year.
Yeah - for the additional $665 - I'll drive the Porsche thank you very much.
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