A car's ECU does not have a way to detect that a higher grade gas has been put in, and then adjust by advancing the timing and giving you more power. As long as the engine is not detonating, the ECU will retain it's programmed mappings and ignition settings.

 

Thats what i said just use what Honda says on the Gas door (i.E. 91 octane). My comment regarding using the lowest octane possible without detonation wasnt necassarily in regards to the S2k as much as just a general performance guidline. Just to clear up what i was saying.....

 

oh mah bad...

 

Hey,

Tunerjetta I am not so sure on your comment. Although the higher octane allows for better timing which can give you more timing, it can also be true, TO A EXTENT, that just higher octane alone will give your car more power. The gas does explode slower giving you a even burn threw the stroke, ie. more power. While a lower octane may not be able to sustain power through the stroke due to quick burn off. The avg. butt dyno will feel no diffrence, but to say that you would actually get more power from using the lower octane if you could is just a wrong statement. Sorry bout that.

But your advice is good. Follow whats on the door. But to be honost, a car will on avg make more power on higher octane. WE ARE TALKING very very little, but still. I was really only replying because it is backward to think that with no timing advancing the lower octane is better. You want a burn completly through the stroke, not a BANG, firecracker one quick push and thats it kinda delivery.

ANYWAY, my post really has nothing to do with this thread of what is better to use between the higher octane so I will stop. Probly should have just pm'd this to tunerjetta, but who knows, maybe some of you others could gain some understanding from this.

If anyone really wants to start a conversation with me, lets talk about how I mix water vapor into gas to get 50+ mpg in a civic? Because isn't that what a higher octane is all about. Slowing down the burn baby! But DON"T DO IT ON THIS THREAD. I don't wanna destroy it.

J. R.

 

Your synopsis is incorrect as well. Sorry bout that.

 

I believe the manual calls for at least 91 octane. This implies the engine may run better on a gasoline with an octane rating higher than 91. If so, this would only be noticable in VTEC @WOT.

The real question, yet unanswered, is "what is the ideal octane rating for the car?", ie; what is the octane rating which if increased will cause no noticable difference in performance?

 

[QUOTE=tunerjetta29,May 7 2005, 06:28 PM]Adding a higher octane fuel into a stock car is like retarding your timing.

 

no, higher octane gas will not give you more power. your car is made for a specific octane running under appropriate conditions. your car's ECU is set to use specific timings and fuel mappings for that fuel rating and those conditions.

the ONLY time you'll get more power from a higher octane gas, is if you are detonating on the lower octane gas.

so if you are not detonating on 92 octane gas, putting in 94 or 100 will NOT get you any extra power. in fact, 100 may actually cause you to lose power, as your ECU will not advance ignition timing to efficiently burn the 100 octane gas.

 

first the answer to your question of "what is the ideal octane for the car". the answer is 91 octane or higher. in other words, as stated, you want to run the lowest possible octane to your car's minimum rating without detonation.

secondly, a common misconception is this "at least" theory people have. it does NOT imply that higher octane gas may run better. they must use the words AT LEAST because they won't say "you must use 91 octane gas". why? in my area 92 is the lowest possible before 89, so some moron would be like "oh no there's no 91 octane gas around here!". secondly, they don't give a range, because while your car will run fine on 94 or 100 octane, it will not benefit the car any more than 91.

 

100 octane will disengage VTEC in a stock ECU s2000. I had a friend do it, and his car wouldnt go to 6k (like trying to VTEC when there arent 3 bars on the temp gauge) with 102 octane i believe.