I just found out that the convenience store down the street sells 109.5 Octane fuel (there's a local racetrack nearby).

I'm not really interested in racing my Z, but I thought about putting a tank or two of it in the Z just to see what it does.

What kind of performance changes should I expect? There's not any danger in using too high an octane fuel is there??

 

109.5 octanes, eh? Man, the highest I've ever seen is 95 - and that was in Venezuela. Here's some info for you from the Federal Trade Commission. My $.02: don't put that in your Z. That stuff will burn at a higher temperature - octanes: more oxygen in the gas - and it will burn quicker.

The Low-Down on High Octane Gasoline

Are you tempted to buy a high octane gasoline for your car because you want to improve its performance? If so, take note: the recommended gasoline for most cars is regular octane. In fact, in most cases, using a higher octane gasoline than your owner’s manual recommends offers absolutely no benefit. It won’t make your car perform better, go faster, get better mileage or run cleaner. Your best bet: listen to your owner’s manual.

The only time you might need to switch to a higher octane level is if your car engine knocks when you use the recommended fuel. This happens to a small percentage of cars.

Unless your engine is knocking, buying higher octane gasoline is a waste of money, too. Premium gas costs 15 to 20 cents per gallon more than regular. That can add up to $100 or more a year in extra costs. Studies indicate that altogether, drivers may be spending hundreds of millions of dollars each year for higher octane gas than they need.

What are octane ratings?

Octane ratings measure a gasoline’s ability to resist engine knock, a rattling or pinging sound that results from premature ignition of the compressed fuel-air mixture in one or more cylinders. Most gas stations offer three octane grades: regular (usually 87 octane), mid-grade (usually 89 octane) and premium (usually 92 or 93). The ratings must be posted on bright yellow stickers on each gasoline pump.

What’s the right octane level for your car?

Check your owner’s manual to determine the right octane level for your car. Regular octane is recommended for most cars. However, some cars with high compression engines, like sports cars and certain luxury cars, need mid-grade or premium gasoline to prevent knock.

How can you tell if you’re using the right octane level?

Listen to your car’s engine. If it doesn’t knock when you use the recommended octane, you’re using the right grade of gasoline.

Will higher octane gasoline clean your engine better?

As a rule, high octane gasoline does not outperform regular octane in preventing engine deposits from forming, in removing them, or in cleaning your car’s engine. In fact, the U.S. Environmental Protection Agency requires that all octane grades of all brands of gasoline contain engine cleaning detergent additives to protect against the build-up of harmful levels of engine deposits during the expected life of your car.

Should you ever switch to a higher octane gasoline?

A few car engines may knock or ping — even if you use the recommended octane. If this happens, try switching to the next highest octane grade. In many cases, switching to the mid-grade or premium-grade gasoline will eliminate the knock. If the knocking or pinging continues after one or two fill-ups, you may need a tune-up or some other repair. After that work is done, go back to the lowest octane grade at which your engine runs without knocking.

Is knocking harmful?

Occasional light knocking or pinging won’t harm your engine, and doesn’t indicate a need for higher octane. But don’t ignore severe knocking. A heavy or persistent knock can lead to engine damage.

Is all "premium" or "regular" gasoline the same?
The octane rating of gasoline marked "premium" or "regular" is not consistent across the country. One state may require a minimum octane rating of 92 for all premium gasoline, while another may allow 90 octane to be called premium. To make sure you know what you’re buying, check the octane rating on the yellow sticker on the gas pump instead of relying on the name "premium" or "regular."

For More Information

The FTC works for the consumer to prevent fraudulent, deceptive and unfair business practices in the marketplace and to provide information to help consumers spot, stop and avoid them. To file a complaint or to get free information on consumer issues, visit www.ftc.gov or call toll-free, 1-877-FTC-HELP (1-877-382-4357); TTY: 1-866-653-4261. The FTC enters Internet, telemarketing, identity theft and other fraud-related complaints into Consumer Sentinel, a secure, online database available to hundreds of civil and criminal law enforcement agencies in the U.S. and abroad.

 

damm the highest I've seen here is 103 octane. My friend pump it once and he say he feel a quick response but that is on his Civic.

 

Actually octane is and additive in the gas (NOT oxygen) that makes the gas more RESISTANT to being ignited, hence it will burn SLOWER and therefore your car will advance the timing=more power. Also the temperature of the burning gasoling does not burn any hotter.

 

Well, ACTUALLY, I guess I must have heard wrong then ...

 

Read this post

https://my350z.com/forum/2003-2009-nissan-350z/36439-higher-octane-gasoline-is-a-waste-of-money.html


Unless your engine is knocking, buying higher octane gasoline is a waste of money, too. Premium gas costs 15 to 20 cents per gallon more than regular. That can add up to $100 or more a year in extra costs. Studies indicate that altogether, drivers may be spending hundreds of millions of dollars each year for higher octane gas than they need.

Will higher octane gasoline clean your engine better?
As a rule, high octane gasoline does not outperform regular octane in preventing engine deposits from forming, in removing them, or in cleaning your car’s engine. In fact, the U.S. Environmental Protection Agency requires that all octane grades of all brands of gasoline contain engine cleaning detergent additives to protect against the build-up of harmful levels of engine deposits during the expected life of your car.

http://www.ftc.gov/bcp/conline/pubs/autos/octane.htm


Bottom Line:

Most newer cars, which have very sophisticated engine management systems, can run on virtually any fuel. These engine management systems actually "listen" to the sound of the engine and determine if predetonation, or pinging, is occurring or is beginning to occur. If this situation is detected, the engine management system actually retards the timing somewhat to eliminate pinging. However this situation does eliminate some of the engine’s performance and, if you purchased your vehicle for its performance it is worthwhile to use fuel that will maximize that performance.

Many of the engines in today’s cars are designed to operate effectively on the least expensive gasoline available although it’s always a good idea to purchase a quality gasoline no matter what grade you are choosing.

 

Oscar & Austin-
Thanks for the info, but this has nothing to do with the age old discussion of "don't waste your money on higher octane".

This is a discussion of pure performance and my curiousity as to what this high octane fuel will do for a few tankfuls. Obviously, 109.5 octane isn't something I'd burn everyday, especially not at $3.95 a gallon. But I have no problem spending a hundred or two just to see what it would do. . I'm just curious as to what it would do "for fun".


So if anyone has any info about the likely effects of this, I'd appreciate it.

 

The majority of the posters in this forum have been quoting from sources aimed at the lowest-common-denominator driver of a car that is made for 87 octane. The information isn't necessarily wrong, it's just not pertinent to this situation.

I suggest you post this question in the racing forum and/or PM raceboy.

 

Actually, it is pertinant; you just have to put it in slightly different context. They say putting 92 Octane in a car rated for 87 won't improve performance, and that is correct. That said, putting 110 octane in a car meant to run at 92 is the same waste of money.

Most cars designed to run at 92 will also run fine (i.e. won't blow up) if you put in 87, because most have knock sensors and will retard the timing, so you will lose performance, but not damage the engine. Now, if you put in gas with a higher octane than 92, the car will run normal. It will NOT advance the timing (which is what would give you higher performance).

In short, high octane gas is for cars that have been tuned for performance, and the timing advanced, and requite higher octane to prevent detonation. If the Z were to advance the timing for even higher than rated octane, that would mean then whever you run on "just" 92, you'd be on the verge of knocking, and I doubt that's how it's designed.

 

Sport Compact Car tested the Z with 91 Octane (Premium in CA) as well as 100 octane.

They found that the 100 octane gas gave the Z +5 HP, with most of the gains above 5000 RPM.

This indicates that the Z's engine management system may be pulling timing due to knock even when using the "premium" 91 octane gas. Hence, the higher octane gas performs slightly better.

Now, I have heard stories of a similar test that C&D or R&T did with a BMW M3, and that car lost a little power with the higher octane gas, perhaps due to the slower burning nature of the fuel.

Anyhow, the point is this: the Z may occasionally pull timing when using 91 octane in order to prevent knock. If this is indeed the case, then going to a higher octane gas will help slightly. However, as evidenced by the BMW example (if it is true), at some point you will reach an octane level high enough to cause the engine to loose power.

So, is the marginal extra power worth the extra cost of the gas?

Now, if you are running an FI setup, then the extra knock resistance might allow you to run higher boost, which could significantly increase power.


-D'oh!

 

So perhaps the Z is more advanced than I gave it credit for. Either that or the 91 octane pump gas in Cali has too much other crap in it that hinders performance that the 100 octane didn't... Hard to tell if it was because of the octane or other factors. Do you have more details on the test?

 

109 is too high for the Z. I donno if 100 is good, probably so.

but 109 is too high, the Zs compression is 10.3:1 high... but there is much higher. 109 is made for FI with huge compression ratios, and more importantly cars without cats

the Z will actually have the opposite of detonation, and you will fry your catalytic converter. no more passing emmisions tests ect. dont use it, the Z cant take it.

you could put like a gallon or 2 in with each tank, to boost the octane to high 90s, but 109 is way too high. oh and it should cost in the range of 4$ a gallon, ouch!