Mazda Miata: 14 Degree Octane?

In article <Np7Pc.52555$rdc-kc.rr.com>,
"Diane" <rr.com> wrote:
 

No, if it's not pinging, you're fine. But pay extra attention in very
hot weather, which increases the engine's propensity to ping.

--
Lanny Chambers, St. Louis, USA
'94C
the alignment page:
http://www.hummingbirds.net/alignment.html

This is what I was told:

I have an '03 and that it has an "Anti-knock system." As explained to me
the system will automatically retard the timing to prevent pre-ignition
pinging. So if you use a lower octane the system will retard the timing and
prevent the pinging, but you will lose the power you gained by advancing the
timing.

That is what I was told, so that is what I'm passing along.


"Lanny Chambers" <net> wrote in message
news:news.prodigy.com... 

right on...
the first hot weather in June usually reminds me to top up the tank with a
higher octane.
but, other than in June, July & August, 87octane is just fine... no
pinging.

Pete Breemhaar
Georgetown, Ontario
94BRG


"Lanny Chambers" <net> wrote in message
news:news.prodigy.com...

No, if it's not pinging, you're fine. But pay extra attention in very
hot weather, which increases the engine's propensity to ping.

In article <com>,
"Clark Friedrichs" <net> wrote:
 

Correct, but if Diane has set her timing to 14 BTDC, she presumably has
a 1997 or earlier, with fixed base timing, hardwired ignition maps, and
no knock sensor.

Those with 1999 or newer models should use whatever octane their owner's
manuals recommend.

--
Lanny Chambers, St. Louis, USA
'94C
the alignment page:
http://www.hummingbirds.net/alignment.html

"Diane" <rr.com> wrote:
 

You mean, if you do not hear knock, I assume.

I think the common wisdom is that if you do not have audible
knock accelerating at high load, (hill, high gear), you should
be OK on the highway, where engine noise might mask the knock.

Leon

--
Leon van Dommelen Bozo, the White 96 Sebring Miata .)
To reply to me, the word Miata must be in the subject.
EXIT THE INTERSTATES (Jamie Jensen)

"Leon van Dommelen" <net> wrote in message
news:com...
 

Perhaps slightly off topic, but my '03 and I live at 6200 feet in elevation.
The manual recommends premium fuel, which, around here, is 91 octane. Our
regular grade fuel is 85 and mid-grade is 87 or 88. I note that at lower
elevations, 87 octane is the lowest you can buy ("regular - unleaded").

I am assuming that at higher elevations, the engine tends to run richer and
therefore, needs less octane. My question is, can I "get away" with running
my '03 on 87-or-88-octane fuel, locally a.k.a "Mid-grade?"

Alan
MiniMi the '03 SE

Think for a minute or two--
The Miata has an altitude sensor.
The computer controls the amount of fuel.
The O2 sensor tells the computer how rich or lean things are.
The computer "normally" sets a an A/F ratio of about 14.7:1 unless a loading
condition calls for a rich or lean mixture.
Less air in at a throttle (plate) setting means less fuel in when all is
said and done.
Less fuel and air in mean less power out.
The throttle plate would need to be open more at altitude than at sea level
to allow a given amount of air(and fuel) to produce the same amount of power
out.
Would not the engine need the same fuel octane?
If not why not?
(The effective compression is a bit lower?) (Remember we had to open the
throttle plate farther to let in more air.)

(I'll admit I have an additional set of variables to deal with on my 99, due
to a slight modification that produces up to 9-10 PSI of boost above outside
air pressure.) (Hill? What Hill?)

"AlanRab" <com> wrote in message
news:com... 


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OOOOhhhhh ! Chuck !
I loved that reply and you didn't even twist the knife when you were
done! :-)
I live at about sea-level and mild temps so I don't get into that too
much, but that was a very nice reply.

Bruce RED '91 (with no "huffer")