kiessig@idi.UUCP (Rick Kiessig) (04/18/85)
I'm having some problems with knock and ping in my
fuel-injected European (BMW) engine, and so I have some
questions about fuel octane ratings and octane boosters:
I think this has been hashed around here before, but I
don't remember the answers.
1. What's the difference between the two octane
rating systems? What do the numbers mean?
Can someone explain the chemistry behind this?
2. What exactly determine's a fuel's octane rating?
3. What do octane boosters do, chemically, to the fuel?
Is it more than supplying more BTUs/gallon?
4. Why have I been told that too much octane booster
can clog my injectors?
5. Are there different kinds of octane boosters?
Someone told me that the same basic substance -
alanine, perhaps? - is used in all boosters,
and that everyone even gets the stuff from the
same place.
6. Why do they use toluene as fuel when doing EPA
certification? Would adding toluene to my fuel
be an effective alternative? I heard it has
an octane rating of around 103.
7. What are the pros and cons of using a booster on
top of Shell 92 octane vs. buying 101 octane
unleaded and mixing it with standard Super (91 octane)
or Shell Super? [At least I've heard that it
is possible to buy 101 or 103 octane fuel in
5 gallon quantities from a local "Speed & Marine"
shop].
8. What about cost? I know pinging isn't good for
the engine, and it reduces available horsepower,
etc. What's the most effective way to go? 1 pint
of booster to 17 gallons of fuel, at $6/pint (or
about an additional 35 cents/gal) - helps but doesn't
solve the problem. They say you can use up to
2 quarts per 10 gallons (an extra $2.40/gal) if
you are running a high compression turbocharged
engine. 1 pint per 17 gallons isn't enough for
me, so I'm looking for cheaper alternatives, too.
9. Are there other solutions to pinging other than
higher octane fuel?
10. How much do boosters change the octane rating?
(I've heard 2 to 2.5 points). How much would
adding toluene or 101 or 103 octane unleaded
change the rating?
Thanks for your help. Mail me directly and I'll summarize
to the net if there's interest.
Rick
--
Rick Kiessig
{decvax, ucbvax}!sun!idi!kiessig
{akgua, allegra, amd, burl, cbosgd, decwrl, dual, ihnp4}!idi!kiessig
Phone: 408-996-2399prg@mgweed.UUCP (Phil Gunsul) (04/19/85)
[] Rick, The "National Corvette Restorers Society" published an article about a year ago on octane ratings and how to improve them. For some strange reason that was never explained, when two different octanes are mixed as you suggested, the octane is higher than either of the two original octanes. I'll try to find the article and post it again. Also, several months back, someone talked about the ol' moth balls in the gas tank trick. This is suppose to increase octane ratings also, but no one ever said how many moth balls to put in (PLEASE, no comments on how hard it is to get their legs apart!). Phil Gunsul