Moonshine

I just said, I run 91o w/ a 93o program. NO PINGING. NO PINGING. NO PINGING. There's NOTHING to worry about.

cliffyk

That means it's a 91 octane tune--an proper 93 octane tune would ping like Hëll with 91 octane...

Moonshine

*sigh* You just contradicted your previous statement that there is no such thing as an octane tune.

Do you have the same programmer as I do? Does it have a '91' octane preset? No, it does not. It has a '93' octane preset. All possible parameters are adjustable. With my programmer I am set on a 93o preset. How many times can I tell you that my engine does not ping. Under any condition.


I run a 93o preset and feed the engine 91o fuel. NO PINGING. NO PINGING. NO PINGING.

Do you have a handheld programmer for your vehicle?

cliffyk

I realise that now that you have chosen to highlight same, I should have placed "93 octane tune" in quotes...

Quote:

Do you have the same programmer as I do?

I use a customised version of Delta Force Tuning's Special Forces/Delta Force/Commando tuning system.

Quote:

Does it have a '91' octane preset? No, it does not.

As to a 91 octane preset, the closest thing I have to a hand held (Delta Force's Special Forces software) does have a 91 preset--as well as 87, 93, 96, 100, 104, 106, 110, 111, 116 and 118 (these latter being common racing and aviation grades). However I only use Special Forces to create base tunes for further modification with Delta Force/Commando.

Quote:

It has a '93' octane preset. All possible parameters are adjustable. With my programmer I am set on a 93o preset. How many times can I tell you that my engine does not ping. Under any condition.

I do not doubt at all that your "93 octane tune" does not ping on 91 octane fuel--I am simply stating that what your tuning system put forth as "93 octane" tune was not--if it were it would ping with 91 octane fuel...

Quote:

Do you have a handheld programmer for your vehicle?

No, as stated previously I use Delta Force's Special Forces/Delta Force/Commando software, and their interface box, for flashing the tune.

However I have had the opportunity to do low-level analyses of many "canned/preset" tunes, for various octane selections, and produced by several hand held units.

They are mostly the same, bumping the Global Spark Adder by 1.0° to 2.0°, and the upper load/rpm cells in the Spark Borderline table by 0.5° to 1.5°. Some will also lean out the Open Loop Fuel table by a few percent for the later strategies/box codes. Other changes are typically to the delays for switching to open loop, pushing the max acceptable MAF voltage to 4.999, and a few other well known tweaks to make things a bit more "perky".

These are all changes that all but the worst example of 87 octane gasoline will support, and largely reflect the poor state of the OEM tune.

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PS: Sorry to have bored you in my previous post *sigh*

Moonshine

hehe Yea just a tad lengthy. I appreciate your knowledge in the matter.

Just out of curiosity have you used any hotter fuels than 91?

The flashpoint temps between 91 and 93 are so minimal dude it'd be hard to tell the difference.

All I'm sayin is the kid will be fine with a 93o setting running 91o. I'm just answering his question.

cliffyk

Flashpoint is only minimally related to resistance to detonation, a broad indicator at best, as it is the temperature at which a volatile liquid vapourises and forms an ignitable mixture with air (assumed to be somewhere near STP).

A fuel's resistance to detonation in an internal combustion engine is dependent on the fuel's (fuel here being a mixture of air and gasoline being compressed in a closed combustion chamber) autoignition temperature--a pressure, temperature, and AFR related parameter.

Have you read Heywood or Ferguson? If not you should, as either text would greatly expand your knowledge of internal combustion engine fundamentals.

jvog

Cliff just schooled you.

cliffyk

"Hotter than 91"--whooo-wheee!

93 is available all year here in Florida--it's all I run...

In the late 60s/early 70s we got 96 Octane at the Sunoco pumps, then 94 octane up 'til the early 90s. My '69 Charger Daytona (440 with 3 Holley 500cfm deuces--aka "6-pack") could pass anything but a Sunoco station.

When I was a lot younger I ran Hodaka 125 Wombats in motocross racing using a blend of 96 octane "blue" Sunoco and 8 oz/gallon of toluene (140 octane)--I used to keep 2 or 3 pistons "on the shelf" in the workshop at any point in time.

It's a sad state of affairs we find ourselves in when 91 octane is considered "hot"...

jojo2003

I run the 91 octane with a 93 tune as well, and the guys at Diablo said to just retard the spark by 2 degrees. I had the pinging before I retarded it, and after it went away.

cliffyk

Then you are no longer running a "93 octane tune"--it's a "93 octane tune" derated to a "91 octane tune" by retarding the timing...