octane

Michael Hay · Post by **Michael Hay** » Tue Mar 12, 2002 8:11 am

i'm only into my 2nd week of ownership so i can be forgiven for this
question... what octane fuel is recommended for the engine (1.6)?

thx
mike

Keith Cook · Post by **Keith Cook** » Tue Mar 12, 2002 9:13 am

Mine was driven to In'gill from Ak by my son on 96 but I always use 91. I must note though that he got a better fuel consumption figure than I do on open road. (Must try a tank of 96 myself sometime) Also as an added difference. The tyres were pumped up to 30 by the tyre warehouse in Ak that fitted them where I use 26. How many variables do you need?

Graeme Naisbitt · Post by **Graeme Naisbitt** » Tue Mar 12, 2002 9:40 am

It depends on timing settings (and other modifications), 91 is fine for
standard timing but if its advanced to 14 degrees or more, you may find you
need to up the octane to 96 - listen for 'pinking' (pre-detonation?). I'm
sure that this has been discussed a lot by more knowledgable people than me

I don't know whether the search is working yet, zorruno? But thats
probably the best place to start.

Mine is advanced to 14 degrees but there is no pinking and runs fine on 91

Hope this helps
Graeme
D4NGER

jeff · Post by **jeff** » Wed Mar 13, 2002 12:21 am

anyone else here found that Gull "91" runs better on a timing-mod'd engine ?

I did the timing bump, but I used the Force (instead of timing light

Graeme Naisbitt <graemen@dmd.co.nz> wrote: It depends on timing settings (and other modifications), 91 is fine for
standard timing but if its advanced to 14 degrees or more, you may find you
need to up the octane to 96 - listen for 'pinking' (pre-detonation?). I'm
sure that this has been discussed a lot by more knowledgable people than me

I don't know whether the search is working yet, zorruno? But thats
probably the best place to start.

Mine is advanced to 14 degrees but there is no pinking and runs fine on 91

Hope this helps
Graeme
D4NGER

Michael & Kate Cooper · Post by **Michael & Kate Cooper** » Wed Mar 13, 2002 5:01 pm

Hi,
I think you will find that the reason is that Gull, as do Challenge,
sell imported fuel which is actually at a slightly higher octane rating, I
believe about 2 higher. So 91 octane is actually 93 and 96 is 98.

regards
Michael
WG3755

ross campbell · Post by **ross campbell** » Wed Mar 13, 2002 6:17 pm

The Gull gas comes from Singapore and is a bit higher octane than
stated.Advance your timing to 14 degress and put in some 96 and you will
certainly notice a difference.Ross.

Nigel Hughes · Post by **Nigel Hughes** » Wed Mar 13, 2002 6:28 pm

This may still be true of 91 and was certainly true of 96 Gull fuel
initially (usually rating 98 and 99 octane), but the latest consumer
magazine indicates that Ministry of Economic Development tests over the last
couple of years "have not found Gull fuel with an octane rating
significantly higher than 96."

Nig.

JST4FN

jeff · Post by **jeff** » Wed Mar 13, 2002 7:04 pm

I thought I'd try Gull since I read this:
The small number of samples with significantly higher octane appear likely to have been sourced from overseas.

in here:
http://www.ess.govt.nz/rules/petroleum_fuel_2000.htm

seems true so far. Definitely less pinging when pulling out of intersections etc.

Rowan Hick · Post by **Rowan Hick** » Wed Mar 13, 2002 7:24 pm

This isn't in an MX5 but is all about Octane - Having a modded twinturbo
car Octane ratings are quite near and dear to my heart (and to save
expensive holes in pistons).

I've found the cleanest, highest octane fuel is BP "Ultimate" 98. Gull
96 tends to run quite dirty with the exhaust turning a bit blacker than
BP, and after a couple of tanks my car starts running a little rough low
down. Caltex 96 seems to be quite clean burning like BP and is my 2nd
choice after BP 98, but doesn't have the octane. I've heard reports that
BP 98 burns a lot hotter than normal fuels so probably suits my car best
as I run cold race plugs in it - might explain the clean idle as it
keeps the plugs at their self cleaning temp.

I usually get a pinking around 3000rpm before the engine comes on boost,
the current program advances the timing a tad too late for "normal" 96's
(I can actually feel the ignition change on the bridge). So a 80kph 4th
gear WOT experience on the bridge, Caltex pinks a little, Gull a little,
BP hardly anything.

Mobil Synergy 98 I tried twice from two different places (Quay St and
Parnell). The dirtiest fuel I have ever put in my car.. backfired on
changes and ran rough as after each tank.

Then theres Challenge Racegas

Rowan

Michael Hay · Post by **Michael Hay** » Thu Mar 14, 2002 8:24 am

ok, without me rummaging through auckland library for the mx5 manual, can
you guys advise hints/procedure on altering the timing. i have all the tools
and timing gun and have done this many times on previous vehicles. Due to
this i know there are little tricks that only mx5 owners would know of.

What is the standard degrees advance on the 1.6?

THANKS!

Graeme Naisbitt · Post by **Graeme Naisbitt** » Thu Mar 14, 2002 9:41 am

Hi,

Stock timing on a 1.6 is between 8-10 degrees. All the info you need to set
up the timing (including the tricks) is here :

http://www.miata.net/garage/ignition.html

Hope this helps

Graeme
D4NGER

Bill Rehm · Post by **Bill Rehm** » Thu Mar 14, 2002 9:52 am

So will someone offer an opinion about Shell gas...as I'd like to know what I'm sacrificing to earn fly-buys

Fletcher Blades · Post by **Fletcher Blades** » Sun Mar 24, 2002 8:37 pm

The four majors all take their fuel from Marsden point (which they all
own shares in)... its the same fuel.

They agree this is true, but claim to each add their own additive
package, to individualise it... They do all add a package, and they
each call it a different name, but I wouldn't be surprised if they
were all actually the same bunch of chemicals...

Some people report bad fuel from the same station again and again
(water in the tanks?) but I've never heard of bad gas from the same
brand in areas covering a wide selection of service stations...

The exception to this is Gull, who source their fuel from Asia.
Challenge! used to source theirs overseas, but it too comes from
Marsden point, now that they sold out to one of the majors (Shell?)

My point is, unless theres something wrong with your local Shell's
tanks, I doubt you'll notice a difference...

Fletch.

Mark Roberts · Post by **Mark Roberts** » Mon Mar 25, 2002 8:14 am

Some people report bad fuel from the same station again and again
(water in the tanks?)

It wouldn't be that. Water collects at the bottom of the tanks and
is not drawn into the pumping system. I remember 20 years ago doing
daily tank measurements with a long dipstick. We put "ullage paste" -
water-reactive paste - on the end of the dipstick to judge how deep
the water was.

Mark

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