93 octane gas only?
 

Does the boxster / S require 93 octane gas only?

allegedly (it's recommended). i'm sure there'll be disagreement, but i don't think you'll blow up if you run 87. you most likely won't be as fast, and i probably wouldn't flog the car through extreme heat/mountains/etc.

Nola Mike wrote:
> you most likely won't be as fast

Actually, it's rather the opposite -- lower octane (with no pinging) will give you more power, and hence, better MPG. Here's something from a previous discussion I had with my Ducati racing friends:

The term "Premium" is extremely misleading when it comes to gasoline. People assume that when they buy "Premium" they are buying the best there is to offer. This couldn't be further from the truth. 87 octane has more potential horsepower than 93 (or higher) octane. Octane is a rating. It is a calculation that predicts when pre-ignition will occur in any given engine. The lower the octane number the more volatile the gasoline -- by comparison, the higher the octane number the less volatile (combustible) the gasoline. Then why do racers use higher octane? Simple, the higher compression and more ignition advance an engine has, the more likely pre-ignition will occur -- hence, they need high octane fuel to prevent this from happening. If you want your engine to run the best possible, then run the LOWEST octane that you can without pre-ignition (pinging). If different terminology was used to distinguish grades of gasoline, people would think more accurately about it -- for example, instead of calling it "Regular" call it "Highest Volatility" and instead of "Premium" call it "Least Volatile".

I have run 91 with no issues.

Stick with 91/93 octane. Your engine will run best on it, and get the best efficiency.

In engines with higher compression ratios, where higher octane is recommended, you can lose power and possibly damage the engine if you use lower octane fuel.

Vice versa is not really true, either. In a vehicle that runs normally on regular, you gain NOTHING by using higher octane fuel.


Higher octane ratings in fuel only increase the fuel's threshold for detonation. In high compression engines, or forced induction systems, it is necessary.


You bought a Porsche. You didn't skimp. Don't skimp on fuel.

This is a damn ass thread... especially from a guy who owns a yellow Lambo and Ferraris. Pteam for Poseur Team?

Although, lately I see a lot of LAMBOS driving around Chelsea NY. Hmmm...Not like theirs anything wrong with that!

That doesn't seem to be quite accurate.

"It is important to note that the theoretical energy content of gasoline
when burned in air is only related to the hydrogen and carbon contents.
The energy is released when the hydrogen and carbon are oxidised (burnt),
to form water and carbon dioxide. Octane rating is not fundamentally
related to the energy content, and the actual hydrocarbon and oxygenate
components used in the gasoline will determine both the energy release and
the antiknock rating."

In short, octane rating defines how fast the gas burns, and how resistant it is to pre-ignition. It does not define how much energy content the gas has, so lower octane gas can't make more power. It doesn't have any more energy to offer than higher octane gas, it can just be burned in a less-demanding environment. Running a turbo or a high compression ratio? Then you need a better-behaved fuel (a higher octane rating). Same energy content, but better manners.

JackG wrote:
> That doesn't seem to be quite accurate.

I'm sorry if I rain on anyone's parade -- but the lower the octane you can get away with (without pinging), the more power.

-- peer

No rain here... the science just doesn't back you up on this. It seems you have a misconception on what "volatile" means. It is not a measurement of energy content.

You wrote "87 octane has more potential horsepower than 93 (or higher) octane." "The lower the octane number the more volatile the gasoline -- by comparison, the higher the octane number the less volatile (combustible) the gasoline."

You are asserting that the more volatile gas is, the more horsepower it can produce. That's simply incorrect. They have different burn characteristics, but the same amount of energy. Energy produces horsepower, not volatility.

I couldn't have said it any better. You're absolutely right! For example, my last car that I had used regular gas, then I dropped a Jackson Racing Supercharger in it and I had to switch to a higher octane fuel. More oxegen per ltr. of gas burns faster and therefore runs leaner, not richer. If a car requires a leaner mixture of gasoline I would not use a richer version because if will not co-inside with the cars CPU and air/fuel ratio. :cheers:

Did you run out of Vagisil???

HAHAHAHHA, LOL :D

High Test Gas
 

A gallon of gas whether high test or regular has the same amount of energy. The engine of your Boxster will convert the chemical energy of the gas to mechanical energy to move the car. Porsche designs its engines under the assumption you will use 93 or 91 Octane and sets ignition timing to ensure there is no knocking and the car gets the max power and fuel economy for the expected Octane. When you use lower Octane fuel the car will have a tendency to knock so the knock sensor will sense the beginning of engine knock and tell the ECU to adjust (retard) timing to protect the engine. Eventually if you consistently run low test the ECU will automatically assume there is something unusual and either automatically retard timing or spit out an error code (according to some Porsche Gurus the ECU will adjust after about 25 to 30 hours but I have never seen it in writing.) That assumes all of the protective features work proberly. If not, for example if you go full throttle and there is no early indication of knock you could knock before timing is retarded and harm your engine.

Since the car will frequently have retarded timing while running 87 Octane, it will not be operating at peak efficiency and thus produce less power and worst Gas Mileage. Cars that are designed for regular will see no improvement by using high test. However, many chip tuners get their best results by programming for 93 Octane vice the 93 or 91 octane spec called premium in various states and recommended by Porsche.

ATB.
Tom

I don't think I've run into higher than 91 octane. Is there a station that routinely sells 93 octane as their premium? I ran into 100 octane racecar gas once, but it was 5 bucks a gallon. Ouch!

Mike

come to east coast and see 93s. well, i think it all depends on which state you are in but in VA/DC/MD you have choice of 87, 89, or 93 and no option for 91. i think i saw 91 in Ontario and NJ.

i think i read somewhere that there are 2 methods of calculating the octane rating. maybe 91 served in CA is same as 93 served in DC area?

Octane Rating
 

It varies by state or locale. 93 Octane is available on the east coast, 91 is the max in many states. You will also see different maximums in Mountain areas. So ... yes it is available but probably not in your area. However, unless your Boxster has been chipped, the factory ECU is tuned for both 91 and 93 Octane U.S. gasoline. It should provide optimum power and torque with either. Increasing Octane to 95 without reprogramming the ECU probably won't buy you anything either. The ECU will be unable to advance the timing to take advantage of the higher Octane. Although I suppose you could burn hotter plugs which may get you something.
ATB,
Tom

are you asking me if i want some of your extra stash? no thanks bro i am not gay. not like theres anything wrong with that.

:D

Octane threads go nowhere.

Kind of like Oil threads.

:D

Quote:
"Octane threads go nowhere.

Kind of like Oil threads."


Interesting, though, for us Newbs. I was always under the impression higher octane gas was yielded more power. Now I know better.

LOL got me.... but im not gay either, not that there is anything wrong with being gay. :)