At 05:13 PM 2/15/00 -1000, you wrote:
>I apologize in advance, but I can't remember if this topic
>was discussed before, but do Octane boosters really help?
>I have the following set-up Jet Stage II chip, 180 Degree T-stat,
>Jet Underdrive Pulley, Gibson Shorty Headers, Gibson Single Cat Back,
>Quick D TB, K&N (stock box). My understanding is that it will probably
>not help, unless I am experiencing knocking (and I am not).
>Highest Octane here is 92 (in Hawaii). Any recommendations appreciated.
>Neal Arita - from Hawaii '97 5.2L, CC, Auto (ordered silblades today)
Neal
I came across an article on the net quite a while ago that did a study
on the effects of octane boosters. I bookmarked it but have not come
across it yet. I do remember that the addition of boosters raised
the octane by a very small amount (decimal something). If you like,
I can post the URL if I come across it.
Maybe clearing up some myths about octane might be helpful.
Octane is not a fuel additive or even a substance. It is strictly
a scalar that indicates a fuel's resistance to detonation. Octane
is to fuel as feet are to distance. There are 3 different ways
in which octane rating is usually expressed: Research Octane Number
(RON), Motor Octane Number (MON), and R+M/2 value. The last one
is what is seen on the yellow stickers at the gas pumps.
By itself, a high octane rating does not add any hp to an engine.
What high octane ratings do is allow engine builders to use
higher compression ratios with advanced timing that would detonate
using lower octane values. However, using a higher octane value
than the engine requires, while not hurting performance, also does
not help it either.
Another common misconception is that higher octane ratings react (burn)
at a slower rate. A fuel's octane rating has nothing to do with how
quickly it will burn in the combustion chamber. However, different
fuels can have different rates of reaction (flame speed) within the
cylinder. It is what is called the distillation curve that provides
hints as to how a fuel will react in use.
The distillation curve provides an approximation of the fuel's distribution
of front ends to medium and heavy fractions and the temperatures at which
they vaporize. Knowing this is important because a fuel must vaporized
before it can reacted. One of the things to look for in the distillation
curve is for the fuel to vaporize relatively evenly over the temp. span.
If a fuel's maximum vaporization temperature is too high for a particular
application, all of the fuel may not be vaporized in the combustion
chambers leading to an incomplete reaction. If the initial temp.
is too low, the engine may be prone to vapor lock. If, too high,
the engine will be hard to start, although this varies somewhat with
application. A N2O application may not need a low intial boiling
point because of the additional cooling from the nitrous. Turbos and
SCs may require a higher vaporization temp. because of the added heat
in the intake tract. What is important is that the distillation curve
of a fuel provides a lot of info that can be used to help determine
the curren fuel for a given comination.
P.S. the above is not the result of using leaded, premium in my youth.
Bob. Southern Ontario, Canada.
'97 Dakota CC Sport, FR, 5.2L, 3.55 SG, auto.
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