I found that some Union 76 gas stations sell 100 octane race gas!!! My understanding is that an increase in octane by even a few points does in fact have an effect on horsepower. I think those with modded ECUs will have a greater effect since our timing is more advanced. I found the gas station on this website for So Cal - http://www.osbornauto.com/racing/100locations.htm.

When I got there, an Sti was gassing up. The pump is so secure that they had a lock on it. I told the guy I wanted the 100 octane. He unlocked it and told me, "Don't look at the pump when you're filling up. " I know why he told me that. At $5.89 per gallon, it goes up REALLY fast. I only got in 4.3 gallons since I just filled up a couple days ago.

Cant tell if there is a difference. I understand the ECU adjusts to the gas. I dont think 100 octane benefits us more than say 95. Soooo, I think the thing to do is to half fill tank with 91 and put 8 gallons of 100. That should raise it to 95 which I think is plenty. That will cost you big spenders about $20 per tank more than you're already spending.

Is it worth it? I dunno. Its kind of exciting running 100. Ill reserve judgment when I can put in enough to raise it more than 1 or 2 points.

{Note to moderators} This thread is relevant to 6th Gen Maxs only and particularly those with or contemplating ECU changes and/or future turbo/SC applications. So PLEASE dont move this to another section.

 

I think you should have waited till you were below a 1/4 of a tank to get the full effect. I would like to see how it works with just the 100 octane. That would be like 75 dollars for a fill-up.

 

you say no gains in power, you didn't feel any better?

is it worth the extra money for a fill?...

 

In Springfield, MO, I'm told that there were a few stations 2-3 years ago that sold 120 octane fuel for something like $4.25 (when regular unleaded was like $1.50 or so). Not sure if they still sell the 120, but I'm sure it would be pricey now.

I think that some here (namely lightonthehill) mentioned that our ECU's probably wouldn't adjust to anything higher than 95, so you are probably right about anything over 95 not benefiting us anymore than 95.

 

Well I only put in 4 gallons so Im not sure thats enough to raise it enough points. I know I should have waited til I was down to 1/4, but I was right there so I figured wtf. Check your local area for 100 octane and try it and see.

 

dunno if we'll feel the difference in everyday driving. i mean if you're easy on the car, i doubt you'll feel a difference in the octane levels. i honestly can't feel a difference between 87, 89, and 93 octane.

 

I know it does something, cause its racing fuel for a reason, maybe a full tank or atleast 1/2 maybe. keep me updated I have 100 octane up here.

 

Remember he didn't have a full tank, it was mixed with lower octane gas. He has to try it with a full tank. I used the station locater and nothing here NY. I did a 100 mile search.

 

Well even though this will probably turn into one of those threads, I have to say that I doubt seriously that you'll see any significant performance improvements out of just using 100 octane gas.

Higher octane gas helps prevent detonation due to compression... unless you start fiddling with the engine to boost the compression ratio, it probably won't perform any better than 93-94 octane. If anything, it will burn cleaner, but I would be extremely surprised if you noticed any measurable amount of hp gain out of running 100 vs. 93.

But maybe I'm wrong...

 

We have 91 here in Cali not 93, so I think there will be a difference in performance, even if it is marginal.

 

I agree. The car with reprogrammed ECU will perform better with higher octane gas, but 100 maybe unnecessary unless the compression is raised. Higher octane gas might not show significant improvement, but it will give you the edge over lower octane.

 

Have your timing advacned then use 100 octane, car will run like an animal. As far as using straight 100 octane in your tank without mixing it will melt your spark plugs and do other damage to your engine. its good to do around a half and half mix, to 1/4 - 3/4 kinda mix. Dont use straight 100.

 

and warren I know a place in brooklyn that has 100 octane.

 

Well think about how internal combustion engines work, and you'll see that higher octane gas is only better because it helps prevent compression-related detonation -- detonation that only happens when you have poor octane fuel in a high compression engine. With our engines obviously 91 is good enough (or you'd be knocking or retarding like crazy even with premium gas), and while 93-94 are better, using such high grade as 100 is only reasonable when your engine has an even higher compression ratio -- certainly higher than the engine in our cars.

The REAL reason why some of the race gas will make your car seem to run smoother is because it has a much higher enthalpy of vaporization -- the fuel won't evaporate as quickly when it comes in contact with the hot cylinder wall, which creates additional pressure inside the cylinder and reduces the amount of fresh air/fuel mix that's taken in. CHEAP gas (whether it's 87 or 89) will have problems period... GOOD gas (whether it's 91 or 100) will burn better. With the compression ratio of the 6th gen engine, I'd be willing to bet that you won't see any measurable gains between 91 and 100.

But like I said, I could be wrong... my guess is that the All Motor guys will probably have some real good insight into this.

 

Just like adding a mod to the car, I thought it would take 3-5 days (depending on driving length and habbits) for the ECU to learn how to use the leaner fuel and feel any difference...

 

I have sunoco race gas available near my house, its over 100, i think its 105 octane, and its $5.00+...

Do you normally run 91? Here I have 93 available so thats what I use.

You are completely wasting your money....but I understand why youd atleast put $20 in and see what happens.

You need to boost the compression of the motor first, does anyone know what the timing is set to currently on our cars? You could have to dial it so that the spark fires with the piston closer to dead center...is this something anyone could do through the ecu?

If you put forced induction on the motor and coupled that with higher octane you's definately see gains...but just using the gas alone is putting the cart before the horse.

 

i believe our timing is set to 15, all i know is advancing maximas to 17 and using 100 octane YOU will feel a difference. done it.

 

Yeah...but at $80+ for a tank of 100 octane...you'd be better off spending that money on a faster car that runs on regular....I couldnt justify it for the gains.

 

.........................................

 

The thing you don't want to do is constantly shift between octanes. depending on who is speaking, the ECU takes from one tankful to several tankfuls to adjust between octanes. During that adjustment period, things are set wrong for the fuel on hand, and efficiency is lost.

Unless one adjusts the compression ratio on their Maxima, I would not think octanes above 93 would offer improved performance. But then I did not stay at a Holiday Inn Express last night . . .

 

I'm wondering if that "adjustment period" can be reduced by resetting the ECU by disconnecting the battery, or however its done?

 

So unless you go to the track or run a before-and-after dyno run, it appears that you'll never really know if the high octane changes performance. Even if it does add power, do you think it will be enough to justify throwing $30 to $50 in the tank everytime you fill up?

 

ive put 100 octane in twice...25 bucks worth and the car runs like its on crack. For the 2nd time there is no FILLING UP with 100 octane with 80 bucks worth of gas unless you want to ruin your engine. YOU NEED TO MIX IT.

 

What station did you buy it at?

 

100 octane straight will not ruin your engine.

The 100 octane will only prevent detonation at high compression.

You would only see a benefit from it if you changed the compression ratio of your engine. This can be accomplished with a SC, turbo, heads or pistons and perhaps with a agressive ecu flash that affects our variable valve timing.

The vast majority of people running 93 octane are wasting money as it is not recommended by their cars manufacturer.

Knowing Nissan recommends higher for our cars means run 93 but 100 in a stock max would only be a waste of $.

I would expect some will disagree so do us a favor and dyno you car before and after but make sure you reset your ecu after you fill it with 100.


Peace

04WHITESE

 

When the high octane fuel such as 106 is introduced to the combustion chambers, due to it's high octane level, which requires less oxygen to burn, it can create early or post detonation. Which means, unburn fuel will pass through exahust valves and will and can deposit around post and after O2 sensors.

Our ECU's do not have the fuel/air mapping software to handle racing fuels, why would it? If an ECU upgrade was available that is tuned to take advantage of racing grade fuels then there might be some reason to use this gas...you'd also be the gas stations best friend.

 

Last thing I need right now is to buy more expensive gas! Maybe after an ECU upgrade and I'm ready to hit the track for a 1/4 mile ticket I may add some, however you can probably achieve the same results with a high end Octane Boost that adds like 7 points.

 

The rhetorical question has been asked "WHy should I spend $20-80 per tank for 100 octane gas?" It is like asking "Why should I spend $30 for Mobile 1 oil when I can put in Pep Boys brand for $8?" Even if you completely disregard possible or probable performance, 100 octane (I believe) its better for your engine. Now, its true that running better oil is more critical than running better gas (maybe). But if you want a better quality gas, smoother running motor, and a bit of performance, then choose 100 octane mix. I think a good balance is to use it as a mix so it is running around 93-95 octane.

 

wont ruin your engine but it will melt your spark plugs if you do not upgrade them.

 

well from my race experience and this is with natural aspirated engines in cars and bikes. high octane gas is to help stop detonation. i have raced cars and bikes. when the comp geats around 10.5:1 pump gas has a tedency to detonate. it burns to rapidly at the high cyclinder pressure and causes detonation or if your lucky youll get a spark knock letting you know whats going on. if not youll notice over time that the spark plugs are pitted and buring the electrodes off from the heat and a lean condition. will running high octane gas in a low compression car like the max hurt it no. will it help it not really. if you let the car get low and run it then it will defintely give off a great smell and turn the pipes on the white side if you look in them. most of the fuels in my area like CAM2 has lead in it. its rated anywhere from 105 to 110. a lot of the older cars required lead in the gas to help prevent the valves from getting messed up during operation. in the max it wont hurt by its hard on the injectors and likes to clog up fuel systems if used for a sustained period of time. it also likes to dry out the o rings on injectors and i have learned that the hard way. also a few of my friends have learned from racing down the track that running 100+ octane actully slowed the car down over 93 octane. now this is in a stock engine. the 100+ octane burns slower so the motor actually makes less horsepower and is not as efficient. it is good to have if you use nitrous becuase it helps stop detonation and since nitrous raises the cyclinder temps it burns 100+ octane more efficiently. im no expert on the subject but from experience if you have a stock max and by that i mean nothing to raise cyclinder pressure your wasting your money. if you are spraying nitrous then it will allow you to avoid running lean under the spray. oh and one more thing that i have learned over the years of racing and using race fuels is that you need a good electrical system. i have never read up on the firing system of the max because my wife has stated that it wont be raced everyday up and down the road. but when burning high octane fuel its flash point is higher so mark sure that you are producing the spark that is needed to burn the fuel. some close the gaps on their plugs to help out with this and some upgrade ignition systems to help out with this. hope this helped but if your stock you make better time investing the extra money your spending in a mutual fund and start saving for the next max.

 

Being that our cars are designed to run on 91, I would typically fill up with that or somethign slightly higher for piece of mind against detonation. 100 octane should do nothing (or be slightly deterimental) unless you have the timing/compression/boost etc to make up for it. That is not something that is easily changed on our cars.

As for melting plugs, higher octane typically doesn't burn as hot, so I don't see how you would ruin your plugs.

 

I just put in 8 gallons today which raises my octane to 95-96. From all the reading I have done, this is probably as high as you can go and really not improve it much. The car feels strong, really strong. Only a dyno can tell for sure what the difference is.

 

I disconnected ECU so it adjusts to the higher octane and then ran it hard. Goes like a bat of of h*ll!!!!!

 

I just came upon this thread or I would have commented earlier. The 100 octane racing fuel is based on Research Octane. The 91 octane fuel at the local station is based on the government mandated octane number which is expressed as the fromula (R+M)/2. This means that the government octane number is an average of Research Octane and Motor Octane. So you can not add 10 gallons of 91 Octane Number with 10 gallons of 100 Research Octane and assume that 95.5 is the correct number in either system. The numbers do not "add." So I suspect that those of you trying this blend of racing fuel would like to know what you are "getting" with these blends.

Coming from the refining industry, I can say that most premium gasolines have a "sensitivity" of about 10. What does that mean? It means that if the Research Octane is measured at 100, the Motor Octane will be about 10 less, or 90 Motor Octane. This fuel would then have an (R+M)/2 rating of 95 (not the 100 Octane that it is know for at the racing fuel pump -- which is not the same octane). So don't think that you are getting a substantially better gasoline than 93 Octane Number at your local station -- you are getting about 95 Octane Number at a substantially higher price.

As was mentioned in a few of posts on this thread, racing fuel is not strictly controlled by the government, so it may well contain lead to get the extra octane. But the lead will void your warranty on the emission system in your Max. It is also illegal to run leaded gasoline on the streets anywhere in the USA. So be certain to check that the racing fuel you buy does not contain any lead. I could go on and tell you more about how a little lead in gasoline really boosts the octane of lead-free gasoline, but it is not linear. A little lead does a lot, but even more does very little more. For racing fuels above about 100 Research Octane, you can be fairly certain that the extra Research Octane (over 100) was achieved by adding lead to the fuel. There is also an aviation gasoline known as 100/130 that definitely has lead in it. Great for gasoline powered airplanes, bad for cat control systems.

A number of posts here correctly predict that unless you have modded your Max you are wasting your money buying racing fuel. You need something like a turbo-charger to see any benefits from racing fuel. Otherwise save your money and stick to 91 to 93 octane. Nissan claims that the VQ is designed for 91 octane number (that would be about 96 Research Octane). If that is the case (and without mods) you should not pay any more for premium than the cost of 91 octane number.

Finally, if you want to know more about octane (and it's clear that some of you do need to know more), check out my thread on the topic: "Octane Number and What It Means" here:

http://forums.maxima.org/showthread.php?t=396716

It will probably tell you more than you want to know, but there are so many myths about octane "flying around," that there needs to be some sense brought to the wild discussions.

I have been told (but don't know this as a "fact") that the reason you can only buy 91 octane number premium in California is that the state feels that higher octane gasoline is not as clean burning and so limited premium in CA to no higher than 91. I believe that SteVTEC is the one who told me this. Steve also pointed out that it takes a few hundred miles for the VQ fuel control system to recognize a change in the octane in your tank. So don't assume (like I did earlier) that the engine will quickly correct for a higher octane in the tank. Also (without mods), don't assume that it can correct for octanes above 91 Octane Number.

 

I went back to look at some of the earlier post on this thread (after my long-winded discussion, above). Remember Ascendant, it will take a few humdred miles for your VQ's computer to correctly adjust to handle a higher octane in your fuel tank.

Now, I hardly ever call for WOT, so I don't pop for premium gasoline. Regular works fine for my driving style -- and on the highway should actually give me better mileage. If I were racing my Max and frequently calling for WOT, then it would be worth the extra money for premium. Given my driving style, it would be a waste of money.

 

Some of this is right and some wrong. 100 Research Octane gasoline needs just as much oxygen to burn properly as 91 Octane Number gasoline from your local station. The VQ's O2 sensor should properly control the Air/Fuel mixture to prevent any of this from happening in the first paragraph in this quote.

The second paragraph seems correct to me.

 

Your first paragraph was correct, so I did not copy it.

In the oil industry what you call "enthalpy of vaporization," the industry calls RVP (or Reid Vapor Pressure). It is a measurement of how well a given gasoline evaporates (vaporizes) at a fixed temperature. Today the Federal Government strictly controls the maximum RVP for all grades of gasoline by the season of the year and by location -- for environmental purposes. In the winter in most of the country, a higher RVP is needed so that engines will start on cold mornings. So winter gasoline RVPs are higher than they are in the summer (or in CA or FL). But high RVP gasoline also evaporates more quickly from your fuel tank, particularly at higher temps. So the RVP of summer gasoline is lower. Both are needed, depending on the time of year. The maximum RVP is the same (in any given location and time of year) for all grades of gasoline. So I doubt if you will see any RVP differences between 91 and 87 octane number gasolines.

The RVP for racing fuel is not government controlled, so the company blending this fuel has quite a latitude in the final blended RVP. I suspect you are correct that racing fuel has a lower RVP because the customers demand it because there is very little racing at temps below 30 degrees F.

I agree with you that, without mods, VQ engine owners will not see any difference between 100 Research Octane (95 Octane Number) racing fuel and 91 Octane Number premium gasoline.

 

A few final comments from a Mechanical Engineer. A motor takes energy from outside the motor and converts this energy into rotating motion -- thus an electric motor with the electricity coming from the electric company (or your car battery). An engine takes energy into itself in the form of fuel and converts this fuel into rotating motion -- thus a gasoline engine (burning gasoline) or a diesel engine (burning diesel fuel). There are a number of motors in your Max, but it's not a hybrid and does not use electricity to turn a motor to drive the wheels. A gasoline engine does that job of driving the wheels. So remember, your Max is powered by a gasoline ENGINE with the name VQ.

It was reported by dirtyo that: "a few of my friends have learned from racing down the track that running 100+ octane actully slowed the car down over 93 octane. now this is in a stock engine." From a Mechanical Engineering standpoint, that observation makes complete sense. Higher octane in a gasoline means that the gasoline is harder to ignite and burn -- it resists pre-detonation. Engine Lab 101 taught us that the most efficient fuel for a gasoline engine was the fuel that was almost ready to pre-ignite (or knock). The ability of the VQ engine to advance or retard the spark has some effect on this efficiency curve versus engines without this feature. But the range of this spark adjustment does not (IMO) go beyond about 91 Octane Number gasoline. So that any higher octane could well result in the vehicle not performing as well as it would with 91 octane number -- the octane used by Nissan to design the VQ engine when looking for maximum performance at WOT (= wide open throttle).

 

I understand that the 100 octane gas i bought at Union 76 from the pump is in fact street legal, necessarily meaning that it is completely leadfree, as leaded fuel is illegal. Since my ECU has been reflashed, and among the parameters changed is the timing parameter, I believe there will be more of an effect on my car, than a stock vehicle. Another parameter changed is the drive by wire, wherein the parameter has been changed to operate more like a cable driven throttle. ANy thoughts?

 

You appear to have one of the needed mods to take advantage of higher (than 91) octane. But if you go to my detailed post on octane, you will see that higher pressure is one of the factors that increases an engine's requirement for higher octane. You need either a turbo-charger to increase the pressure inside of the cylinders or different heads (etc) to increase the VQ's compression ratio above 10.3 -- otherwise why would your engine need a higher octane than 91?