I got some octane booster and dumped it in today, it felt like it performed a little better, but does it really make a difference? Is there anything you can just dump in your gas tank that can really add a decent amount of horsepower without hurting your engine?

 

Octane booster (and high octane fuels for that matter) actually give you LESS power than you would normally have. The only reason to use high octane fuels is to keep detonation from occuring, and the only time you might detonate is if you are running very high compression, or some type of forced induction. at ALL OTHER TIMES use the LOWEST octane rating that is listed by the manufacturer OR the lowest that your car will run smoothly on. (No comment JG Luder, your car NEVER runs smoothly, darn cams... )

 

wait.. so honda recommends Premium
but you should use the lowest you can
get away with?

also, why do honda and other car companys
recommend premium if detonation isnt an
issue?

any sites have a good explination of all this?

 

So there is nothing you can dump in your gas tank that will add horsies?

 

it is possible for octane to help an engine make more power, but only if timing is advanced or the engine is pinging or knocking <with a knock sensor>.
If you can get some dyno time and are going to use a set octane,a car with basic bolt-ons can be tuned for a few more horses.

 

Most stock honda engines aren't high compression...


[Modified by B21A, 6:12 AM 9/30/2001]

 

H22A's are "high compression" motors. Even when I was stock my car always ran it's best on 93 and that was it. 91 or 92 and it had a... well, a "lag" before VTEC. Hard to explain.

Anyway, since everyone knows I have to use 1 bottle of octane booster for every 8 gallons of 93 octane just to make it to and from work with my timing retarded, I'll keep my mouth shut.

 

By the way... Stupid Street did an AWESOME article on octane and octane boosters a few months ago. I'll try to find it this week sometime.

 

That is absolutely not true. 93 octane fuel has the same amount of BTU's (i.e. chemical power) as 87 octane fuel but is mixed with addatives to resist detonation. Octane rating has absolutely nothing to do with power, it is simply a measure of the fuels resistance to detonation.

Gabe

 

so it is simply a measure of the fuel's resistance to detonation huh? Okay, answer me this. Just HOW, pray tell, do those additives increase the fuel's resistance to detonation, O all knowing one?

Before you answer, I would like to point one thing out. JG Luder is known for jumping on incorrect information and chewing out whoever gave it. I know this from personal experience. If you will take a look at his post count and his car, I believe you will find that he might know just a little about engines and high compression. He didn't correct what I said, so think your answer through very carefully.




[Modified by spyder, 10:05 PM 9/30/2001]

 

They increase their resistance to detonation by raising the temperature at which they burn. This is acheived by changing the bonding between atoms in the fuel. The stronger the bond the more enrgy it takes to break that bond and begin combustiuon. Now there is some minor loss in the chemical engery due to the addition of oxygenates to the fuel but the difference between the energy contained in 91 and 87 octane fuel is very small (less than 10%). If you added enough oxygenates to the fuel then you could acheive a large difference.

As for JG, yeah he's a pretty smart guy but that doesn't mean he knows everything. If you're basing the correctness of your answer on JG's non-response to yours then I think you're misleading yourself.

Gabe

 

Very good. Higher octane fuels have (of course) a higher level of octane and a lower level of heptane than the lower grade fuels. As you said, there is some minor loss. Did I ever say there was a large loss? No, I just said there was a loss, and if I understand what you said correctly, you agreed that there is a loss.

No, I am not basing the correctness of my answer on JG's non-response, I was just pointing out that he had not corrected me when he usually corrects info he believes to be incorrect. Was not using it as a basis for anything, just as food for thought.

 

..is a mixture of various hydrocarbons of varying lengths, and are not neccessarily mixtures of say 87% Octane and 13% Heptane, althogh they could, but for fiscal reasons they most likely arent. Hence, the term "octane" is an arbitrtary one used for reference or bookeping if you will, b/w varying blends of gasoline. For example, if you were to compare gasoline a vs. gasoline b. vs. gasoline c, you would use the octane term/rating in qualitativly assesing that gasolines resistance to knock in reference to octane itself, or a given mixture of octane blended w/ heptane.
So, like gabe pointed out, the utility of high octane gasoline is the anti-knock propertyor deterering fuel ignition by compression. And as we all know the compression ratio of a given motor is what ultimatly generates the power and calls for the use of higher octane fuels, not the other way around.

[Modified by bb6h22a, 4:03 PM 10/1/2001]


[Modified by bb6h22a, 4:05 PM 10/1/2001]

 

Goddamned chemists.

 

hahahahaha

 

Sorry to have misunderstood you then, I thought you were saying there was a tremendous heating value difference between a high and low octane fuel. It can be argued that the loss is negligable though. As an engineering approximation they are probably assumed to have the same heating value.

Gabe

 

uh, wow. So you guys would suggest I DONT use octane booster? Its not worth the money...?

 

Nope, no real need for octane booster unless you are detonating on 93 octane or higher fuel.

Gabe: Yes, I definately agree that the losses are negligable...

 

SO WHAT IF YOUR MOTOR STOCK MIND YOU IS 11.0.1



[Modified by quicklude, 1:49 PM 10/2/2001]

 

..considering the new M3 w/ 11.5:1 compression is sleighted for N. American sale, I would say that 91 octane should be sufficent, w/ 93 being optimal.