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Discussion Starter #1
Title says it all. I had 5 runs over the past 2 days with my 93 octane cai tune and the most knock I've had was 2.5 degrees of ST knock. No LT knock whatsoever. To see if I could reduce it more, I uploaded the 91 tune. ( I later realized that I uploaded the 91 octane tune and not the 91 octane cai tune.)

What's odd is that after 3 runs with the 91 tune, I've had maxes of ST knock at 5 degrees, 11 degrees, and 15 degrees. All runs were done with the same tank of 93 octane fuel. How is this possible? Is it because I didn't choose the 91 cai tune? How significant is as much as 2.5 degrees ST knock here and there? Any help would be appreciated.


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Did you go back to the 93 tune just to see if it changed anything or not.
Funny you have that much KR.
I wonder if it was just by accident you pulled more timing than the 93 tune did and the reason may not be fuel but may be oil on the piston tops causing hot spots that detonate early causing KR
FT
 

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The Bacon Hauler (‘12 Cop Charger)
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Are any of the ST KR spikes occurring at the shift points?

From what I understand, some KR at shift is acceptable and should not be pursued too diligently when attempting to minimize/eliminate occurrences of KR.
 

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Intermittent 2.5 ST KNK is nothing to worry about.
 

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Discussion Starter #5
Are any of the ST KR spikes occurring at the shift points?

From what I understand, some KR at shift is acceptable and should not be pursued too diligently when attempting to minimize/eliminate occurrences of KR.
A few points were, and were dismissed. The KR from the 91 tinge and the 93 tunes were typically at WOT or occasionally when cruising around 1700 rpms.

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Discussion Starter #6
Did you go back to the 93 tune just to see if it changed anything or not.
Funny you have that much KR.
I wonder if it was just by accident you pulled more timing than the 93 tune did and the reason may not be fuel but may be oil on the piston tops causing hot spots that detonate early causing KR
FT
Just went back to the 93 tune this morning... I have about a 35 minute drive to do today, so will log it with the 93 cai tune on the way there and the 91 cai tune on the way home to see.

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Discussion Starter #7
So I posted on The Diablo forums and the response I got was that there is more fuel and timing added with the cai tunes so the fact that I accidentally used the regular 91 tune may have had something to do with it. Anyway...

Ran 2 logs today, both CAI tunes. Each log was about 30 minutes with some WOT runs and highway. The highest ST knock I saw in the 93 tune was 4 degrees once, and a few 2 or less degrees of knock. I ran the 91 later, and this time I had 2 degrees of knock once, and very few occasions of 1 or .5 degrees of knock.

I guess my last question would be how many degrees of ST knock is acceptable?


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The Bacon Hauler (‘12 Cop Charger)
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So I posted on The Diablo forums and the response I got was that there is more fuel and timing added with the cai tunes so the fact that I accidentally used the regular 91 tune may have had something to do with it. Anyway...

Ran 2 logs today, both CAI tunes. Each log was about 30 minutes with some WOT runs and highway. The highest ST knock I saw in the 93 tune was 4 degrees once, and a few 2 or less degrees of knock. I ran the 91 later, and this time I had 2 degrees of knock once, and very few occasions of 1 or .5 degrees of knock.

I guess my last question would be how many degrees of ST knock is acceptable?


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If you are seeing the ST KR spikes in WOT driving only, you're probably good to go - no "issues" to worry about.

If it is spiking only during WOT, you can try modifying the fuel parameters of the loaded tune to enrich the air/fuel mixture in the RPM ranges in which the spike occurs to minimize the KR.

Not everyone subscribes to this paradigm of addressing KR, but it has worked for some (including me), so there is some precedent for using it in this scenario.

If you do adjust the fuel parameters while chasing KR, I would suggest using small increments each time, i.e. 0.5%-1.0% fuel per 2 degrees of KR.
 
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Discussion Starter #9
If you are seeing the ST KR spikes in WOT driving only, you're probably good to go - no "issues" to worry about.



If it is spiking only during WOT, you can try modifying the fuel parameters of the loaded tune to enrich the air/fuel mixture in the RPM ranges in which the spike occurs to minimize the KR.



Not everyone subscribes to this paradigm of addressing KR, but it has worked for some (including me), so there is some precedent for using it in this scenario.



If you do adjust the fuel parameters while chasing KR, I would suggest using small increments each time, i.e. 0.5%-1.0% fuel per 2 degrees of KR.

Thanks for the input! Much appreciated!


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After looking over my logs, I have 0 short term knock. And that even includes the custom tune files with WOT up to 110 mph.
 

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Discussion Starter #11
After looking over my logs, I have 0 short term knock. And that even includes the custom tune files with WOT up to 110 mph.

Yea, it's probably the gas I'm using right now. Had to fill up with lukoil... Dk too much about them.


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Yea, it's probably the gas I'm using right now. Had to fill up with lukoil... Dk too much about them.


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It has my experience that when buying premium grade gasoline, it is good to stick with name brands, but it's not absolutely necessary. More important than the brand is the age/freshness. Old, stale gas is not your friend!

Unfortunately, gas stations don't publicly post when their last refill occurred, but we can get around this by getting gas from stations that see the most traffic, e.g. ones located along busy streets and highways.

You will likely pay a few cents more at these type places, but if you are looking for the gas that's been sitting in the tank the shortest amount of time, they're your best bet.

For instance, I have a Chevron gas station right down the road from me which has moderate traffic, and I have never had a problem with their 93 octane, so I go there anytime I'm only going to get 4-8 gallons worth of gas.

But they are about $0.08 more per gallon than everyone else, so for 10+ gallons or fill-ups, I go to the QuikTrip or RaceTrac further on down at the highway intersection. Even though those two aren't name-brand gasolines, they are always busy, and I know the gas will be relatively fresh (and less expensive).

I constantly monitor the quality of the gas I buy by datalogging, and so far my approach has proven to be a good one for me. Feel free to use it, whole or in part, for yourself and your car.
 

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Discussion Starter #13
It has my experience that when buying premium grade gasoline, it is good to stick with name brands, but it's not absolutely necessary. More important than the brand is the age/freshness. Old, stale gas is not your friend!



Unfortunately, gas stations don't publicly post when their last refill occurred, but we can get around this by getting gas from stations that see the most traffic, e.g. ones located along busy streets and highways.



You will likely pay a few cents more at these type places, but if you are looking for the gas that's been sitting in the tank the shortest amount of time, they're your best bet.



For instance, I have a Chevron gas station right down the road from me which has moderate traffic, and I have never had a problem with their 93 octane, so I go there anytime I'm only going to get 4-8 gallons worth of gas.



But they are about $0.08 more per gallon than everyone else, so for 10+ gallons or fill-ups, I go to the QuikTrip or RaceTrac further on down at the highway intersection. Even though those two aren't name-brand gasolines, they are always busy, and I know the gas will be relatively fresh (and less expensive).



I constantly monitor the quality of the gas I buy by datalogging, and so far my approach has proven to be a good one for me. Feel free to use it, whole or in part, for yourself and your car.

Lukoil is pretty big around here, however, they're prices are higher than just about any other gas stations nearby. The owners posted $9 prices per gallon like a year ago in protest of Lukoil since Russia was charging them more for gas. This caused the higher prices to compensate and the owners were losing money. Because the owners are charged more, the consumer gets charged more. This leads me to believe their gas probably sits more than the other gas stations. I'll fill up at Sunoco and data log it.


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From my experience, either these motors require higher octane than recommended or, and most likely the case, octane ratings and quality fall short on modern gas, especially the liquid corn. The best solution I have found is Chevron 93 (even with stock or 91 tune) and NOS octane racing booster. It's for "off road use only", but it's the only solution I've found other than getting a custom tune that shouldn't be necessary with my few bolt ons.

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