500... Premium gas... Huh

Probably better get used to it.

As manufacturers squeeze more and more power out of smaller and smaller engines premium fuel is likely going to become the norm.
 
Octane grade rating

Regular - 87 Octane
Mid-grade - 89 Octane
Premium - 91-93 Octane

Premium runs about .30-.40 Higher per gallon cost...but varies depending on what state you live in!

htfx19 said:
We have here 95 and 98 Led free only.

Enjoy -
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I was thumbing through the Bertone service manual the other day and I saw that they recommend premium for the X1/9 too. I was a little surprised.
 
Careful - those numbers probably aren't comparable

Regular - 87 Octane
Mid-grade - 89 Octane
Premium - 91-93 Octane
Click to expand...

We have here 95 and 98 lead free only.
Click to expand...

There are two ways of measuring octane: Research Octane Number (RON); and Motor Octane Number (MON). In the US we use the average of RON and MON, while most of the rest of the world uses the RON number - and MON is generally 10-odd points lower than RON, so the US ratings are 5-odd points lower for the same fuel. Our 93-octane premium will be fairly close to Herzel's 98-octane premium.
 
My Bertone user manual says to use 91 octane RON, but what is listed on the pumps in the US is PON or AKI ( =(RON+MON)/2). There is no conversion factor from RON to PON, but most sources I have found say that a RON of 91 corresponds to a PON of about 87. I use regular in my '85.
 
X19King said:
I was thumbing through the Bertone service manual the other day and I saw that they recommend premium for the X1/9 too. I was a little surprised.
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That IS odd... No way the US-spec 1500 motor should need premium to prevent detonation... Two possibilities that I can think of:

1) Back in the day, when the industry was still transitioning from carbs and leaded gas to FI and lead-free... Some leaded regulars wereformulated to pretty minimal standards, so Bertone may have been recommending premium just to get a better additive package.

2) Marketing. How can it be a finely-engineered high-performance Italian sports car if it drinks the same mundane swill that you'd put in a 15-year-old Chevy pickup? (Rumor has it that a US-spec two valve injected Ferrari 308 will run quite happily on unleaded regular... But the horsey would die of embarassment if it were ever seen in from of the 87-octane pump).

Back when I bought a non-cat '78 X1/9 new, the recommendation from Fiat was leaded regular.
 
My '03 Infiniti G35 Sedan is the same way, on the filler door it says "Premium fuel recommended for maximum performance" and pretty much the same in the Owner's Manual.

The '04 G35 Coupe with the same engine is rated at 20+ horsepower more and the label on the filler door says "Premium fuel required."

The engine management system in the car will just dial back the power curve based on what the knock sensor is telling it.
 
While we are on the subject--I am a BMW guy. Most BMW's since the late 1990's can run on regular, mid, or premium. There is this fancy thing in cars called computers. The cars can adjust to pretty much whatever you put in it. You WILL get lower horsepower.

In my 2009 Mercedes R350 you had to run mid-grade or higher. If not the engine would lug up hills. It was a big car/van and AWD. It needed the extra power.

In my 1991 BMW M5--I used to have to run premium when the outside temp got above 95 degrees or the engine would stumble and want to die at idle.

In my 2001 BMW 750il with a V12. I always run regular unleaded and there has never been an issue.

My advice 100% of the time--run a lower grade fuel and see how your car reacts.
 
OCTANE BOOSTER?

[FONT=&quot]Anyone running regular 87 and a “OCTANE BOOSTER” to close that 45 cent a gallon gap?

Vincent dba enzo mac
[/FONT]
 
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87 octane? That low?!?!! I'm not surprised they recommend premium fuel.

I run my 500 1.4 on 97 or above octane. And despite what people say I know from first hand experience that you can feel a power sapping difference when I run 95. I also feel a bit more kick when I run it on 99 octane.

Running it on 87 would be hideous. Especially in the cold.

Run it on high octane. It gets 2mpg better economy on higher octane as well.
 
The question is...

Is the 20¢ higher price per gallon worth the extra mileage? The math says it's not a financial gain.
 
OregonMTB said:
While we are on the subject--I am a BMW guy. Most BMW's since the late 1990's can run on regular, mid, or premium. There is this fancy thing in cars called computers. The cars can adjust to pretty much whatever you put in it. You WILL get lower horsepower.

In my 2009 Mercedes R350 you had to run mid-grade or higher. If not the engine would lug up hills. It was a big car/van and AWD. It needed the extra power.

In my 1991 BMW M5--I used to have to run premium when the outside temp got above 95 degrees or the engine would stumble and want to die at idle.

In my 2001 BMW 750il with a V12. I always run regular unleaded and there has never been an issue.

My advice 100% of the time--run a lower grade fuel and see how your car reacts.
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The probable reason your 2001 750iL ran fine with regular is because it likely had a low compression ratio. Since the early 1970's smog debacle, BMW didn't begin raising their CR's again until the mid-1990's (except on the higher performance models, such as your M5).

My 1985 635CSi was born with a measly 8:1 CR and ran fine on regular grade gas. However shortly after I bought it I added a Dinan chip (which of course alters the advance curve and fuel delivery), and since then it has required premium fuel.
 
Octane booster is not cheaper

enzo mac said:
[FONT=&quot]Anyone running regular 87 and a “OCTANE BOOSTER” to close that 45 cent a gallon gap? [/FONT]

[FONT=&quot]Vincent dba enzo mac[/FONT]
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than just buying the better gas. The octane booster marketing people use misleading terms like "raises octane a full 2 points", making you think that can will turn your tank of 87 octane into 89 octane. Not so. They are talking about "points" of percentage. In other words it will raise your octane rating by 0.2%.

So I've heard, anyway. I'd love to get the full story from a chemical engineer.

Pete
 
budgetzagato said:
Is the 20¢ higher price per gallon worth the extra mileage? The math says it's not a financial gain.
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Ahh to have the choice of only paying only 20c per gallon more......

It's an emotional choice. I like the way the car behaves on premium petrol. I don't like the way it handles on 95 octane regular petrol. For me that's worth the price. For some it won't be.

ng_randolph said:
Keep in mind that our 87 corresponds to your 91 or thereabouts.
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91 is still frighteningly low though. If that was the regular grade then I'd be putting premium into it.
 
RON schmon

One of the members of the UK X1/9 OC contacted Bertone when unleaded first became available in the UK. Their instructions were to use standard fuel NOT PREMIUM, on the exxy engine as it was supplied with hardened valve seats.
If you were to alter the CR for tuning purposes I can see how premium fuel would help chase horsepower.
 
I tried to use Octane 108 boost

In a 1980 fuel injected Fiat Spider back in 1987 and I swore it did improve the performance of the car. I was afraid to use it more than a few times because I didn't know if that would kill the engine.
 
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