Normally I use 91 octane... but, technically, would the Hp increase if I ran it with 94 oct. instead of 91? Does it depend on whether I'm modded?

 

FAQ's guy

http://forums.maxima.org/showpost.ph...65&postcount=8

 

Of course not. Modding will only require a higher octane if you're running at a higher compression. As the FAQ specifies, all that octane is is an indicator of how resistant to spontaneous combustion the fuel is. If your engine is set to run optimally at 91, you could run a 50000000 octane through it and you'll receive absolutely no power increase whatsoever. This is why people with a car that asks for 87, but they put in more than that, should be summarily executed.

 

Power increase? No, but higher octane gas can help prevent engine knock. So it certainly won't hurt your car, but it won't make more power.

 

Unless he's got problems with his engine, it shouldn't prevent knocking (knock sensors notwithstanding), since his engine is only speced to run at 91 anyway. In some cases if you have a car tweaked for an 87 octane and the combustion chamber is filthy, you may get some knocking in a car, and notice it lessen with an 89, but he really shouldn't be having knocking with his 91.

 

SkoorbMax is absolutely correct, I used 94 fairly often in the past while there is no extra power I did notice a little smoother throttle response but thats it.

 

There ya go, you worded it better. Existing knock can be reduced.

 

Sorry to ***** the thread but if you were to switch from 94-91 octane to 87 octane, would it harm the engine?

Just asking cuz gas prices are a bich now a days.

 

quick question.. my friend pumped gas for me not so long ago and i checked my ecu the other day for any codes and the 0304 (knock sensor) came up. could it be just a bad tank of gas and the codes would go away after a take of better octane? or is it that time to replace the sensor? my max has almost 80,000 miles on it now

 

aznprid: time to replace the sensor. Very common problem and takes about 30hp away. It is not hard to change but just not easy to get to without getting cut or something. It should just be part of scheduled maintenance or something. Look at the FAQs.

94 or 93 may give you some gain. The ECU may be able to not retard your timing since you are not knocking. If you have an ECU like JWT or TS then it becomes even better. Also if you are running any big mods (turbo, SC, n20, or even high compression) then higher octane is a really good idea.

For a stock car or even intake/y pipe it may be somewhat noticable but it may not. I run 93 chevron since most gas stations around here have 93 but it is up to you on whether or not it is worth spending money on octane booster or some higher octane gas if most of them use 91 there.

Gas prices are not that high historically considering inflation. They are higher than they were in the 90s, and then again I would not complain if they were to go down.

http://money.howstuffworks.com/gas-price1.htm

 

I heard on some news show that some gas stations try to be slick and throw in some lower octane gas than what is specified. For example 87 is 87, 87 is also in 91, and 91 is in 93. Everybody makes mistakes sometimes on purpose or by accident. One time I accidently put premium in a renter car.

 

Car and driver did a nice review of this exact topic a while back to back me up on this....before and after dyno's and all.

If a car has the proper sensors...knock sensors, exhaust temp and others, as well as the programming necessary...using a higher octane can increase horsepower. If the engine does not have these tools, you can actually loose some HP as the higher octane fuel doesn't combust as fast and or fully. You need higher compression to make use of the fuels energy potential. Cylinder pressure increases when you open the throttle and is the most likely time for knocking...so as some one said, a higher octane fuel will improve transient throttle response.

I suspect the knock sensor in the maxima is there more to protech the engine from bad gas, or overheating more than to squeeze as much power as it can before detonation.

 

i get a hell of a much more throttle reponse when I run premium..Not only that, but low ocatane give maximas an "octane ping". Even if your sensors are top notch, your still gonna have "ping". I run nothing but premium....And only Amoco fuels at that. Chevron if in that area.....

 

I only use sunnoco 94 octane. Im thinking about using that Shell V-Power.

 

ok, you guys with 94 octance..........i hate you!!! i am soo jealous.
no actually, i dont hate you guys, i hate CALIFORNIA!!!!!!!!!

 

For N/A purposes its not going to make much of a difference just use 91 or 93. For boosted guys its a different story

 

The Sphnix up in Greenville,SC has what they call "race fuel"...100 octane rating....pulled up and saw four pumps instead of 3....was like, "ok, they got diesel too" Saw what it was and was like, BOOYAHKA...Prepayed with the plastic and tried to pump the 100 octane. it wouldnt let me. So i walked in and the woman said that I could only get from the three pumps on the left. I was late for work and didnt feel like arguing so I went with the 94. I want some of that race fuel..

 

Just got done running through a tank of shell v power...Normally I hate shell but this new additive runs clean... Go for it

 

If your sig is correct and your running the JWT ECU, then I would in no way run 87 octane. You will definately get knock and your timing will be retarded. Will it hurt the motor?....Well, you will get knock for a few moments untill the ECU retards the timing, so technically yes it does hurt the motor. A little bit of knock every once in a while is not going to make a big impact in the long run. But since your running the advanced timing, on 87 octane you will constantly be gettting knock and the ECU will be constantly retarding timing. It will horrible for your performance and gas mileage.

 

ok, wtf gas r we supposed to be using i use special, not premium, not regular, am i wrong here? i just have a CAI, help me out this thread confused me

 

91 octane or higher.

 

theres no more sunoco 94 octane atleast in ny. anyone know why they did this to me

 

if u doubt the grade, read the gas cap...says premium