Polished2002

Just thought I would share this with our VQ35 brethren. I drive a 3.5SE 5MT Altima and due to the high gas prices we had, I started using 89. Now that the gas prices are down I started using 93 again. Of course the computer adjust for 89, but alas it doesn't adjust back up for 93 (had to disconnect the battery to reset the ECU).

89 (run 1) vs 93 (run 3)

Fezzik

iTrader: (2)

Very Interesting. Good to see someone do this. Thanks for helping sooth my mind about always getting 93 Oct.

RobWilson

That is interesting. Are you sure you gave your computer enough time to adjust for the 93 octane? Maybe it just takes longer to adjust back up? I accidentally put 87 octane in my wife's car last week (I run 87 octane in my daily driver Explorer and had my head up my *** that day). I realized what I had done and have put about a tank and a half of 93 octane in since then.

I'm going to be dynoing the Max on Friday, but the battery will get disconnected for the CAI install, so I won't be able to confirm or deny your theory.

Polished2002

Trust me - it has been over a MONTH+ since I used 89 octane...

Quicksilver

iTrader: (1)

The ECU will retard timing to the point that detonation is no longer occurring (when using a lower grade of fuel). It's good that someone finally posted a dyno about this as there have always been many false rumors flying around (about the effects of a lower fuel grade in an engine that requires premium).

BEJAY1

iTrader: (19)

I find it hard to believe that 6-7% is gained/lost using 89. Isn't the min suggested like 91? I assume the pulls were on different days and thus conditions could have been different (yeah it shows SAE though). Thanks for posting

GreenSeMax

yeah i'd be interested to see the comparison between all the grades, and perhaps even 94 or 97, but that's great, gives us some evidence for that a$$ dyno

bgates1654

Could you give a little more detail as to the methodology of your dyno runs? What happened to run 2? What octane was used for run 2? Did you buy 3 successive runs and switch gas and reset the ECU at some point? I would guess by what you wrote that you used 93 octane on the second run but did not reset the ECU and did not see much of a difference in power right?

F23A4

Any chance you can do a dyno run with some Sunoco Ultra 94??

kratz74

I think it was Road and Track that DYnoed a few high perf cars a few years ago to show the power loss of using lower octane fuel in cars whose computers (like the MAximas) can adjust the timing. If I recall corectly the BMW 540 power loss was like 20 hp dropping from 93 to 87 Octane. So I can believe a 10-15 hp diff in the MAxima. Makes sense. Problem is people don;t realize that many cars computers dont adjust timing and they get better hp from a lower octane fuel.

mdloops

I am a little surprised that there is such a big difference, but not surprised there is a difference. Nissan obviously didn't just want you to spend more money on fuel. If Nissan was based in the Middle East wouldn't that be sketchy

Mark

Epacy

iTrader: (6)

Actually, premium fuel is only recommended for the Maxima. It is not mandatory.

LA02MAX

iTrader: (3)

well ****....i just started using 93 as opposed to 89 and never reset the ECU...will that cause any trouble? i havent even gone through 50 miles yet, so im sure it wont

NYPD-Arnold

iTrader: (8)

Holy crap. I never knew you'd lose so much performance using cheap gas. That's pretty damn cool. I wonder what Sunoco's 94 would produce. I'm gonna' have to try and fill the car up one day with 94.

BEJAY1

iTrader: (19)

Somewhere around the 93ish octane point N/A cars see diminishing returns on better fuel. Unless they have reprogrammed ECU's which can make some use of higher octanes. I thought I30tMikeD ran at the track and showed no gains a year ago with like 95/96 blend.

http://forums.maxima.org/showthread.php?t=357948

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

Curious what the best way to dyno compare would be. Pull on empty 93 octane, go fill with 95, drive around 30-50miles, and pull again with similar dyno conditions that same day?

Virus

iTrader: (1)

After 93 octane your not going to see much performance gain. The engine was designed around 91 octane. 91+ octane does not produce more power. Theoretically 87 produces more power, but only if the engine was designed to use it. Like mentioned previously, I'm sure Nissan knew that 93 octane wasn't going to be a strong selling point.