# fuel question...



## Sentra4Me (May 21, 2002)

Does premium really help performance?... will it help my 115,000+ mile 96' Sentra??? 

Hope this isn't a really stupid question...


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## rios (Jun 10, 2002)

unless its my imagination, 94 octane feels more lively than 87 in my sentra.


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## Sentra4Me (May 21, 2002)

thanks!


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## bahearn (Jul 15, 2002)

You can try a few tankfuls to see if you FEEL a difference. I'll wager you get no benefit unless you advance your timing beyond factory spec.


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## 200sx Se-T (Jun 24, 2003)

Yea, you should just advance your timing then run higher octane fuel. That should free up a few ponys.


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## Sentra4Me (May 21, 2002)

how do you advance timing?


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## verno-dub (Sep 13, 2002)

By searching, you dont want the Mods to start harpin' on you, do you?



-verno


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## IXLR8se-r (Apr 14, 2003)

he speaks the truth


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## Sentra4Me (May 21, 2002)

no honestly I don't... I've already searched, but I haven't been able to really find a "how to". And as you can see I'm a newbie, so I would like to apologize for making stupid questions, and I would also like to apologize before I make anymore!


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## LaRon (Aug 22, 2002)

well if you got a timing light, you can get it yourself. I think a how-to can be found on b14nissan.org . 

However.. you can take it to a shop and tell them what you want it advanced to and they do it and ya know it's done right for like $20. That's what it cost me when I took mine to get the shop to advance it to 15* when my timing light decided to quit working and that was cheaper than buying a new light.


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## Sentra4Me (May 21, 2002)

thank you so much... so I should advance it to 15* then? or what would you suggest?


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## Gimp (Jun 9, 2002)

Sorry.....that's the one "how-to" I don't have on there. Try going to either www.sentra.net or www.se-r.net.


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## Sentra4Me (May 21, 2002)

thanks... I think I've found all that I'm going to find on the subject... but I do appreciate your help!

~Jesse~


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## NismoUrje (Jun 26, 2003)

About the fuel making a difference on a stock 100k+ mile sentra, the effect of better fuel will be:
Better combustion
Slightly more hp + torque
Better fuel economy (won't make up for the higher price)
Cleaner Exhaust.

Nothing that amazing, but that's what the difference in octane rating effects.


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## AznVirus (May 8, 2002)

Sentra4Me said:


> *no honestly I don't... I've already searched, but I haven't been able to really find a "how to". And as you can see I'm a newbie, so I would like to apologize for making stupid questions, and I would also like to apologize before I make anymore! *


http://nituning.cjb.net - under how-to section.


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## Sentra4Me (May 21, 2002)

wow... thank you very much!!


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## niky (Jul 20, 2002)

hmmm... gotta try that. Lucky premium gas is cheap here. We get 96-97 octane for something like 40 cents US.


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## UNISH25 (Aug 12, 2002)

NismoUrje said:


> *About the fuel making a difference on a stock 100k+ mile sentra, the effect of better fuel will be:
> Better combustion
> Slightly more hp + torque
> Better fuel economy (won't make up for the higher price)
> ...


Better Combustion= false!
Slightly more hp +tq=false!
Better fuel economy=false!
Cleaner exhaust=false!

The octane rating of the fuel you use is a reference chart for automotive engineers and people.
What does the octane rating tell people?
Well lucky you asked...
The octane rating tells us the "ability" of the fuel to withstand a certain amount of compression. 

87 octane combusts with less compression than 93 or 89 octane.
The octane rating of fuel tells you how much the fuel can be compressed before it ignites without the spark!!!!!! Yes...if a fuel is compressed to a certain point it cannot handle, then it will ignite without the spark!!!!

Better combustion? (FALSE)!!
Well in theory you shouldn't be getting better combustion!
Ok...so you put more octane into the chambers...
But the amount of air going into the chambers is the same as well...so lets see...
Take about 1lbs 87 octane mix it with 15lbs air and compress it...
Combustion happens...and about .1lbs of 87 octane is left over.
Now take about 1lbs of 93 octane mix it with 15lbs of air and compress it...
You get about .2lbs of 93 octane left over!!! Hey so you just wasted gasoline and money!!
Unless you put in more air into your combustion chambers with a turbo charger that gas is just been waste! 
The formula for combustion is the same regardless. You might be putting a little bit more octane into your combustion chambers, but its not gonna make a bit of difference, because you are not getting enough air to burn that octane!

Better Fuel economy?(FALSE, yes its a myth)
Explain to me the principals of how you get better gas mileage on higher octane rating? Our fuel injectors are injecting fuel at a rate of lets say x lbs/minute! Now if you shoot x lbs/minute of 87 octane gas or you shoot x lbs/minute of 93 octane gas into the fuel chambers? Won't you in theory be using the same amount? Thus be getting the same gas mileage??? Kinda of defies logic right?

Cleaner Exhaust?(FALSE)
What additives they put in there??? Does that shit go into the fuel injectors to clean it? HELL NO! Theres nothing different about 87/89/93, when it comes to cleaning.


So whats the big deal about putting higher octane then when doing timing advance?
When we advance the timing what we are actually doing is 
moving the distributor cap so that the spark happens at a higher compression!
Thus...
So yeah by advancing timing you are actually fine tuning the compression ratio;by giving the fule and air more time to compress before ignition by the spark. 
Thats why u must use 93 octane if you have the timing up.
Don't go too up though then you have to use higher octane gas or an octane booster of some sort...
And that is the truth about HIGHER FUEL GRADE
Just pump regular at the pumps ok...Theres no difference.
Unless you running a turbo charger or somesort and getting more air into the chambers then theres gonna be no performance values to fuel!


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## zakezuke (Mar 22, 2003)

Well ya know.... it's a funny thing about fuel grades and brands.

Personaly i'm an advocate of testing diffrent brands and observing the results.

For me... I just go for the greatest MPG as well as cost per mile. I've had one car that loved Texaco Premium, and got 40mpg, where under ARCO regular I only got 30mpg. My worst result was from Jackpot premium leaded gas 10% ethenol (yes this was from some time ago).

A friend who peformed the same test got consistently better results from Cheveron fuel. Can't remember if it was premium or not, but pretty much the same thing, got closer to 40mpg on cheveron vs arco. 

While you can look at scientific accurate information indicating what's what as far as chemistry, reactions under what particular presures, nothing beats actual field tests. 

I just went for the gas that gave me the best range, as well as best bang for the buck. In some cases it was more cost effective to go premium. In other cases I couldn't measure a diffrence.


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## Sentra4Me (May 21, 2002)

Thanx for the advice, honestly it's a little more work and time consuming than what I had hoped but hey... we're f*cking talking about cars. I'm used to it! Thanks again!

~Snaral~


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## niky (Jul 20, 2002)

the truth about octane.... 

...this is basically a long and long-winded article about how high octane is BS... hey the guy knows what he is talking about...

but the thing is, when you advance your timing and switch gas (in combination...)... this is dyno-proven by a bunch of people to make _slightly_ more power... why?

in another mag article (i'm too lazy to remember the mag, so look it up if you want to...  ) they compared the performance of a Mustang (i think), an M3 (i'm sure), an Accord (  ) and three other cars on both 87 octane and 95 oct... the results were, suffice to say, *strange*... most of the sports cars posted somewhere between a *3-7 hp increase* on high octane, while one dyno'd at about the *same* for BOTH KINDS. The Acoord, on the other hand (which is supposed to run on regular gas...) *LOST HP with HIGH OCTANE.*

eh... the point? if you go high octane, your car should be built for it or optimized for it.

i don't think the timing advance + high octane is total BS... 

high octane means that you can spark at a higher compression (which you do with an advance...), which means your 16lbs of mixture is compressed into less space, which equals higher compression, which means a greater amount of pressure caused by the exploding fuel... (same amount of A/F mixture, higher pressure = more power) so even if the energy released is EXACTLY the same, the increase in pressure is DEFINITELY going to be a factor... (IMO, but i'm likely wrong...  ) 

...there must be SOME reason racing engines use 100++ octane... 

*basically*, a lot of people say high octane is BS, a lot of people swear by it, they're BOTH right... it depends on your car and set-up.

in my country, it is kind of a toss-up... our two choices of fuel range between 93-97 premium and 92-93 unleaded, and i'll be damned if i can tell the difference between any of them! Most cars are optimized here to RUN high octane, so the power loss on 87-89 octane for us is VERY REAL.

it's a gas company plot to make us buy more expensive gas!

who cares if it's not supposed to work... do some well-controlled field tests, take accurate measurements of the results, and go with what's best for you!


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