High octane Loses power

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A

asmallsol

Super Moderator
Read this on teamintegra.net and since I can not link them (pointless because you must be a member to view) so I ended up just quoteing it.

Originally posted by austin on Jul/09/03
Since there have been a rash of questions concerning using higher octane gas in the car...I've decided to round up a few dyno plots that I have of when I tested out running a higher octane mixture without having the car tuned to run specifically on the higher octane.

Why run higher octane?

1. higher octane slows down the combustion process giving you a slower, more controlled burn.
....A. advantage to this is that it allows you to increase your timing, and/or compression as you're less likely to have detonation.

....B. advantage is that it helps to prevent pre-ignition, preventing detonation from hot spots in the combustion chamber.

....C. advantage is that you can run run more advance, and/or higher boost levels on forced induction vehicles, the slower burn helps to prevent the combustion process from blowing up, rather allowing it to burn(when it blows up you have bent rods, burnt valves, holes in pistons...)

....D. advantage is that you can run nitrous oxide with more ingnition timing, and a smaller chance of pre-ignition(read C above)

....E. disadvantage is that if you don't have the car tuned to run specifically on the higher octane gas, you'll end up with less power since the combustion process is still attempting to burn the fuel when the exhaust valves open, dumping still burning fuel into your exhaust.

....F. disadvantage is that it's going to make your wallet considerably lighter.


Information on the plots:

The difference in air temperatures was ~4 degrees, the barametric pressure were fairly similar, this is an SAE corrected graph.  The only changes between the two graphs is that I added in a few gallons of 100 octane gas, the net octane was ~96.X that I computed at the time.

fbb758d6.jpg


full size, cut and paste: http://www.imagestation.com/picture/sraid6...d6.jpg

Have a good day...

Austin
Click to expand...
 
Well I run 93 and will always run 93, when I go to the track I dump in a little amount of the 100. Honda motors are pretty high compression motors from the factory though as opposed to most other cars so in that case I think it's fine.


Milan
 
so basically your saying you should run the correct octane called for by your engine? Boy, and people call me Captin Obvious

:lol:
 
I ran 87 in my B16 everyday till I went turbo
never had any problems
 
Originally posted by Silverchild79@Jul 13 2003, 08:33 PM
so basically your saying you should run the correct octane called for by your engine? Boy, and people call me Captin Obvious

:lol:
Click to expand...

Yes that is exactly what I am saying (as is this) If you have a b16a2 and honda says to put 91 in there, put 91 but if you have a d16z6, 91 octane will do jack crap. Same thing if you have a b16a2 and normally you run 91 but on a track day, you run 100 octane, your just wasting your money.
 
In Japan where all Hondas are born they use 100+ octane from the pump (thats all they use) so the Honda engineers anticipated this and tuned the ECU accordingly. That being said i dont think USDM motors and ECU's were designed to use 100+ octane since they dont allow that in the US on the road for pollution reasons (i think!?).

The JDM motors and ECU's were designed to use 100+ octane (higher compression, more advanced timing,etc) and they should respond better to higher octane. My car (JDM Accord SiR-T) is like Jekyll and Hyde when i use 104 compared to the 93 pump gas i use regularly. And all the Turbo's (Skylines, Evo's, Impreza's, Soarer's etc, etc) and Hondas alike all say the same thing when they use 104 and they all are JDM.

Im just throwing this in also but certain JDM turbo cars that are used to running on 100+ octane are suddenly switched over to 93, the ECU's knock sensor detect the inferior octane and then lower the boost to compensate for the less knock resistant fuel. The engine therefore produces less power than before. I've heard that you have to disconnect the battery to allow the ECU to reset and to recognize the higher octane fuel when you switch back.

Just adding my 0.02 cents.
 
I belive you are right JDMSpec...all usdm dohc vtec motors call for 93 octane gas from the factory. To gain power from a higher octane gas, the ecu and timing must be adjusted accordingly.
 
But also relize that alot of people when doing swaps dont use the JDM ECU which is designed for the high octane because the JDM ecu also limits everything at 112mph or some crazy speed.
 
also the JDM motors have slightly higher CR.
 
so what octane does honda call for on the b18c1? or any other USDM DOHC VTEC engines for that matter?
 
I always assumed the minimum was 91?


hey, what was the actual whp loss on that dino, i can't seem to visually see it.



Milan
 
looks like 5hp and tq
 
My experience with Hondas, don't use 10% Alcohol (Ethanol Fuels).

Safe Stock Gas Performance
8.1:1 to 9.6:1, max rev < 6300 - 86 Octane
9.6:1 to 10.1:1, max rev < 6300 - 87 Octane
8.1:1 to 9.6:1, max rev < 7300 - 87 Octane
9.6:1 to 11.0:1, max rev < 9300 - 90.5 Octane (91 to be safe)

The S2000 is a high rev, high compression motor, and all honda asks for 240hp 4 banger is 91, so why on earth would Honda require a motor like in most civics and accords (which are economy vehicles!!!) to use anything greater than 87? GSR and ITR are different stories and their valvetrain and pistons show you that.

Now until our B series get advanced timing, high comp pistons, and redline at 9000, or until we have a performance package that brings crank hp to 240, we have nothing to worry about.

Octane booster not required and not recommended in cars with headers and an exhaust. make something significant internally, then it's a different story. nuff said.

EDIT: But! SCC did a 350Z test and upped the octane on a stock car and saw same performance in the low end but the top end pulled 1-2hp.
 
i always use the highest grade octane 91-93.5 , i like to baby my car with stuff like that, and i only use one fuel, and that is amoco fuels. untill i take my car to the dyno to see it for myself, i will continue to use the best legal octane there is.
 
dude it's only like 20cents more a gallon for high octance. Thats 2$ per tank. My attitude is that I'd rather spend the extra 2$ and be sure I have the best gas.
 
Originally posted by liquid00meth@Jul 18 2003, 11:50 AM
dude it's only like 20cents more a gallon for high octance. Thats 2$ per tank. My attitude is that I'd rather spend the extra 2$ and be sure I have the best gas.
Click to expand...

but what they're saying is it *isn't* the best gas for our applications.
 
bottom line is....higher octane will help ONLY if your car needs it because it misfires/preignites with lower octane. higher octane gas has no power-enhancing effect in itself.

when u advance yor timing, you are effectively causing some misfire, so using high octane with advanced timing MIGHT give u some kind of extra pep, but i am not sure. honda engines' timing is computer controlled.

in a nutshell: octane is a gasoline's ANTI-KNOCK rating. has nothing to do with adding power.
 
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