Padsy

iTrader: (1)

MaxAppeal

+3

jjs

You obvously have no knowledge of the petroleum industry. Even if there are stations across the street from each other, they are likely not going to be the same company. Even if they were, unless they sold the exact same amount over time, if there was a winter blend in one tank that has not been fully exhausted, there WILL be a difference in gasoline properties.

jjs

No, I have worked for years in an import/export consulting outfit with our primary clients being petroleum companies. You tend to learn a thing or two in that situation. Also, since major oilfields in IL are somewhat infrequent, I would sy a whole bunch of gas in 'imported' from out of state.

jjs

Ah, the voice of ignorance. Go ahead, think what you think. It is WRONG.

Also, when did I discuss branding, what it is, who did it, etc.?

Padsy

iTrader: (1)

MaxAppeal =

SteVTEC

Engine displacement has nothing to do with octane requirements.

I bet it will too.

Because when you get on it with only 89 octane in the tank and the knock sensor starts picking up the onset of knocking, it will tell the ECU to retard the timing to PROTECT the engine.

I don't doubt your story about getting good mileage on only 89, though. When you're just cruising on the highway there isn't much load on the engine and the higher octane levels aren't necessary. Cylinder pressures are low, therefore the engine can run full advance on the timing for maximum performance (at light throttle) without higher octane levels. The only time you need the higher octane is when you get on it.


Okay, so put your money where your mouth is and go dyno the sucker.

Just for reference, the new Accord V6 autos have a 10.0:1 compression ratio which is lower than the VQ35's 10.3:1. They run 15.3 @ 90 on 87 octane fuel, and 15.0 @ 93 on 93 octane fuel. This was at the same track under similar conditions also. And Honda engineers have even stated that the engine will gain 10HP and 10+ TQ by running higher octane, and dyno evidence supports this also. But I suppose the higher octane is "all hype".

Also, a person here took a 2002 auto rental to the track which undoubtedly had 87 octane in the tank and managed a best of 15.0 @ 90, which is a very low trap speed for an 02 auto. Others have managed 14.7 @ 92-93 on 93 octane. I guess the octane level in these cases are all hype as well.



You can run whatever the heck octane level you want to in these cars. But if you think you are "outsmarting" the system by only running 89, it's really the system that's outsmarting you rather, because it's smart enough to keep the engine running fine without blowing up in your face on the lower octane.

If you think you will run just as fast and dyno just as high on only 89 octane fuel then fine. I think you're wrong and challenge you to provide some dyno charts and timeslips that back that up. Octane requirements for engines are not a matter of "hype". It's a matter of engineering and scientific principles.

jjs

True, but it is not power related, that is the hype. Equal amounts of 87 and 93 octane gasoline have the same explosive power, it is just the point at which these explosions occur that is different. In truth, it is the engine that is fudging the power output. It would be very interesting to see what the dynos would show if 2 identical engines were run without the ECU retarding timing, etc. due to detonation. Granted, one would be subject to more stress and potential damage...but....

Hmmm....

naerok

iTrader: (6)

I hope this is finally settled. Nicely put SteVtech

SteVTEC

Say you have a VQ35 10.3:1 engine with 87 in the tank. At full throttle, the octane level is not high enough to prevent knocking, so lets say the ignition is only able to fire at 0-degrees. Meaning, the spark plug doesn't fire until the piston is at the top of the stroke. So how much power do you have built up from combustion of the compressed A/F mixture at the top of the stroke to force the piston downward with? None...zero...zilch. Nada. Sure, equal energy will be released, but not at an optimal point in the combustion stroke and you have much less overall power.


Now lets say you have the same situation, only with 93 octane fuel. 93 octane is much more resistant to pre-igniting (knocking) and the higher pressure and heat present in a high compression engine. Because of this, now the engine can run much more advanced timing. Lets say you can run 20 degrees of timing now. Being able to fire the spark plug and ignite the a/f mixture before the piston reaches the top of the stroke is advantageous and will give you more "power" because now when the piston reaches the top of the stroke there will be much higher pressure to force the piston downward with because the A/F mixture has already been burning for 20 degrees of a revolution. This makes a BIG difference.


The same energy is released, but the key is that you want the energy to be released at the right moment so that you have the maximum mechanical advantage. The sooner you can fire off the mixture the better, because having pressure from combustion already build up by the time the piston reaches the top of the stroke means more force will be pushing the piston downward with giving you more torque and power.

You can only run so much timing advance before you start having pre-detonation problems, in which case you either need less timing or more octane. Higher octane lets you run more timing and gives you more power. With lower octane in the tank, the threshold will simply be lower.

255HP_03_SE

Hey look, you can explain away all you want to... I have an engineering degree, I can grab the book, do the research, and have fun bantering back and forth all night.

point is this... using 89 octane WON'T blow up your engine... WON'T retract from power... because trust me, when I "get on it", it is STILL the same powerful response as with the higher octane. I'm not racing, so I don't need higher octane. You so eloquently pointed out why highway miles and 89 aren't bad at all.

I just want to deter the "oh my god, you HAVE to use premium" comments.

-R

SteVTEC

Go prove it on a dyno. And if you were an engineer, you'd realize that **** dynos don't prove a darn thing.


BTW, this isn't a Maxima, but it is a dyno of a car that REQUIRES 91/93 octane fuel. The dyno compares premium to 89 octane.

http://www.dynospotracing.com/octane.htm

Nyc2kMax

good gas milage but sorry 89 is not touching my car

jjs

Good attempt at making a point, however, you are clouding the issue. The issue is whether 89 or 93 octane makes more power. On its own, plain and simple. In a nutshell, the answer is NO.

Now, if we are talking about an engine's ability to utilize the power of the fuel and it is calibrated to make use of the higher octane delayed detonation (due to compression, etc.), that is a function of the engine, NOT the 'power' the fuel makes. Take a lower compression engine which works perfectly well with 87 octane fuel and put in 93, then show me dynos that prove a difference and I may agree with you.

Kind of like arguing about two sticks of equally made dynamite...one with a shorter fuse. Light them both...then throw them at a target. The shorter fuse may explode in mid air while the longer fuse may last enough to place it near the target and have more the desired effect. More power? No. Physics dictated that the power generated by one was simply utilized better. Much the same with fuel in an engine that 'expects' detonation at a specified point.

SteVTEC

There is less potential energy per gallon of 93 octane, and more potential energy per gallon of 87, simply because of the higher octane (prevents combustion) content of the 93.

Yet for more highly tuned engines, you need the less volatile and less energy packed fuel to make "more power". Isn't that ironic?

My favorite example is the jet fuel used in the SR-71 Blackbird. Forget what it was called, but apparently you could put an open flame to the fuel used in this sucker and it would *NOT* ignite. Pretty cool, eh? I wonder what the equivalent octane number of that stuff was.

jjs

A-HA!!

I think we finally are beginning to agree!!

I was simply trying to differentiate between power generation and power utilization.

Don't get me wrong, I have had the utmost respect for a whole lot of info you have brought to the forum...just wanted to clarify what the discussion was about.

gabe22

im not a mechanic so i dont know for sure but i heard that its recommended running 93 oct for foreign cars due to the engine compression they run. american cars are able to run the lower oct because they run a different compression.

255HP_03_SE

you're right... gabe, you aren't a mechanic.

And if you read your owner's manual, you would see that Nissan says running 87 octane or better is RECOMMENDED.

And the engine compression of the Max 3.5L isn't that different than the compression that ran in my American 3.5L I used to own.

-R

SteVTEC

No dynos yet?

255HP_03_SE

Yeah, here... let me just run right out in between working 13 hour days (including my train ride into the city and back), working one weekend a month keeping your freedoms safe, and other miscellaneous hobbies and time crunches to satisfy your immediate need for dyno numbers.

Smart a$$.

-R

guapsnaman

255HP_03_SE

soundmike

iTrader: (24)

Actually, the manual states is as:

"Use unleaded premium gasoline with an octane rating of at least 91 AKI (Anti-Knock Index) number (Research octane number 96)

If unleaded premium gasoline is not available, unleaded regular gasoline with an octane rating of at least 87 AKI (Research octane number 91) can be used.

However, for maximum vehicle performance, the use of unleaded premium gasoline is recommended.

Octane rating tips
In most parts of North America, you should use unleaded gasoline with an octane rating of at least 87 or 91 AKI (Anti-Knock Index) number.
However, you may use unleaded gasoline with an octane rating as low as 85 AKI number in these high altitude areas [over 4,000 ft (1,219
m)] such as: Colorado, Montana, New Mexico, Utah, Wyoming, Northeastern Nevada, southern Idaho, western South Dakota, western
Nebraska, and that part of Texas which is directly south of New Mexico.

Using unleaded gasoline with an octane rating lower than stated above can cause persistent, heavy spark knock. (Spark knock is a metallic rapping noise.) If severe,this can lead to engine damage. If you
detect a persistent heavy spark knock even when using gasoline of the stated octane rating, or if you hear steady spark knock while holding a steady speed on level roads, have your dealer correct the condition.
Failure to correct the condition is misuse of the vehicle, for which NISSAN is not responsible.

Incorrect ignition timing will result in knocking, after-run or overheating. This in turn may cause excessive fuel consumption or damage to the engine. If any of the above symptoms are encountered, have your vehicle checked at a NISSAN dealer or other competent service facility.

However, now and then you may notice light spark knock for a short time while accelerating or driving up hills. This is no cause for concern, because you get the greatest fuel benefit when there is light
spark knock for a short time under heavy engine load."

Padsy

iTrader: (1)

We were just confused about what the heck we were arguing about

I was not stating that 89 octane GAS IN ITSELF is less powerful than 93. I am saying your Maxima will utalize it (93) better gaining more power than 87.

Padsy

iTrader: (1)

Gotta love the newb's.

MaximaMan77

It's a kerosene blend. ON between 115-120.

Virus

iTrader: (1)

Ok, my wife and I both work more hours than that a day NOT including travel. Talk about a fallacy. Stay on the subject course. An engineering degree should've taught you that numbers don't lie. Numbers = proof in this instance. If you can provide me with dyno numbers that prove that running 89 octane in my Maxima will provide me with the same power as 93 octane, I'll switch. The burden of proof is on you. Nissan says so

255HP_03_SE

There is no burden of proof. It's already been stated... there is NO 'power' difference. You're trying to play games with engineering and dyno curves... the 'power' arrives sooner with higher octane, but there is NO difference.

Sheesh.

If you do work more hours, good luck.

_R

Virus

iTrader: (1)

My wife work is based on science and not on I feel. I can prove to anyone that Shaklee supplements are better than say EAS. I can prove this by showing research that has been published in refereed or peer review journals on the actual product being sold. We know that calcium increases bone density. That's a given. Provide me with such scientific proof that the calcium supplement your taking increases bone density.

Albanese AA, Lorenze EJ, Edelson AH, et al. Calcium nutrition and skeletal and alveolar bone health. Nutr Rep Int 1985; 31:741-55.

Albanese AA, Edelson AH, Lorenze EJ, Wein EH, Carroll LA. Effect of age and fractures on bone loss and calcium needs of women 45-85+ years of age. Nutr Rep Int 1985;31:1093-115.

This is where I'm coming from. I'm always skeptical of someone telling me that's somethings good. I need documented proof.

I think the worst week I've worked was 155 hours in 7 days! I loved the paycheck though

jeepik

iTrader: (2)

OMG, i think you win the Dork of the Org award for this week

Virus

iTrader: (1)

Prove it with scientific proof

Jeff92se

iTrader: (82)

How did I miss this thread?
All depends if the maxima's timing curve is calibrated to utilize higher octane gas or not. From the above, I would say yes. If it is this way AND if the ecu either sees more ping or can read the gas's octane(my old XR4TI could do this), it will dial back the timing to protect the engine. If the timing is dialed back, performance will suffer. You can't argue that.

You can say, "87 octane doesn't hurt performance" becuase you don't know. You just know it's good for mileage(as is premium probably)

soundmike

iTrader: (24)

I think only your doctor or your SO can do that :P

SteVTEC

That's right, on this car dynoed here that REQUIRES PREMIUM, there was definitely "no difference" by running only 89 octane.

Quicksilver

iTrader: (1)

Heh heh...someone just got

255HP_03_SE

OMG... Shaklee? That explains a lot.

155 hours in 7 days... interesting. 7 days times 24 hours a day is 168 hours, minus the claimed 155 hours is 13 hours, meaning less than 2 hours sleep a day that week.

Interesting.

Try continuous operations in a desert environment running LRRPS for a week.

-R

p.s. Please keep in mind, I never doubted what you say or how you go about it, I'm simply debating whether or not it is applicable or necessary. Running 89 octance won't hurt the vehicle and you still get the same *noticeable* results. You can dyno it and put up the engineering specs, but who REALLY notices that?

Padsy

iTrader: (1)

Jeff92se

iTrader: (82)

Since in order to notice a difference the hp would have to be like +/- 15hp or so......

Virus

iTrader: (1)

It sucked. I got to stay in a Marriott resort and spa, but never really got to stay in the room. 8 days, not 7 sorry for the misprint.

Using 89 MAY hurt the engine. Using 89 MAY NOT hurt the engine. No matter what, it won't blow up, but it MAY cause some expensive damage. 93 doesn't cost very much more where I live. Maybe $1.50 to $2 a tank more. I choose to think of this money as insurance. I'd rather spend the money gradually than have a huge bill in front of me someday. I don't plan on getting cancer, but it could be a costly process if you don't pay for insurance

255HP_03_SE

and my whole point was this... you say it MAY cause damage. Ok... I guess that is a safe bet.

I'm saying that the most likely result (99.99%) is that it WON'T.

I had a 3.5L engine in my Dodge that I ran 89 octane for the entire 115k miles I owned it, and it purred like a kitten even the day I traded it in. Because I took care of it... regular spark plug changes, plug wires, kept it clean, oil changes, filter changes... etc., etc.

So by taking care of the 3.5L in the Max, I'm saying running 89 octance won't hurt it... and when it comes time to trade it in (probably with 150 to 175k miles on it)... when any warranty is wayyyy past expiration (so no "Nissan doesn't like it" comments)... I'm betting that my Max will STILL run strong and get great gas mileage.

-R