What kind of Gasoline do you use for your 996?
12-23-2012, 09:13 PM
#31
Instructor
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!
12-23-2012, 09:14 PM
#32
Rennlist Member
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.
Last edited by Thundertub; 12-24-2012 at 10:30 AM.
12-23-2012, 11:21 PM
#33
Intermediate
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.
12-24-2012, 05:19 AM
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12-24-2012, 05:35 AM
#37
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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?
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?
12-24-2012, 10:23 AM
#38
Rennlist Member
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.
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.
12-24-2012, 11:28 AM
#39
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.
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.
12-24-2012, 12:55 PM
#40
Race Director
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?
"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?
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.
12-24-2012, 01:46 PM
#42
Drifting
93 from major retailers. Usually Shell.
I also try to find ethanol-free fuel, though I'm not obsessive about it.
http://pure-gas.org/
I also try to find ethanol-free fuel, though I'm not obsessive about it.
http://pure-gas.org/
12-24-2012, 02:36 PM
#43
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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?
"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?
12-24-2012, 03:18 PM
#44
Captain Obvious
Super User
Super User
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.