- Banned
- #241
Not sure about Cali. But here in CO it's due to altitude.
At our altitude there is less oxygen thus less propensity to preignite, knock, and detonate.
In Colorado 91 is equivalent to 93 due to the altitude.
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At our altitude there is less oxygen thus less propensity to preignite, knock, and detonate.
In Colorado 91 is equivalent to 93 due to the altitude.
AzScorpion
Moderator
I've heard that too that altitude and less humidity like we have here are one of several reasons for only having 91. Cali...Well they'll ban anything they can there! ?
awd.nv
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I honestly never looked into it because if 91 would knock but 93 wouldn't, I would think that is not enough of a safety margin anyway and I should go 100 octane.
- Banned
- #244
Hadn't thought about or heard of humidity being a factor. But that totally makes sense.
crash77
Member
So a few questions in regards to the applicability of the tune: if this is for '19-'20, will they not sell it to me for my '21? Also, when it says that 91 octane is required, will it run like garbage on less, or just not provide the added performance and run more like normal? Aside from the price, I'm hesitant to get a tune that requires 91 octane, as the higher grades are always hard to get when fuel is scarce, and it's like $10 more per fill up, as I would need to use 93 because 91 is not available close to me.
Dr. Zaius
Well-Known Member
A tune requires higher octane because it advances the timing to achieve a better burn of the air/fuel mix.
Advanced timing can lead to pre-ignition with lower octane fuels.
Higher octane fuel burns more slowly and is more resistant to pre-ignition so timing can be advanced to create more power.
There is not more power in higher octane fuel, the higher octane allows you to tune your engine to get more power.
All that said, if a tune requires higher octane you need to run it because lower octane fuel can damage your engine.
Think of it this way:
The piston is coming up in the cylinder on its compression stroke. You want the fuel mix to be ignited before the piston is at the top so that it can get the maximum expansion to push the piston down for the power stroke.
Ignite the fuel/air mix too late, and the piston is already on its way back down and you will lose much of your potential power.
Ignite the mix too soon and you will try to push the piston back down before the crankshaft has come over the top of its revolution, like trying to push the crankshaft backwards. This is very bad and you hear it as knocking. It WILL damage bearings.
TLDR:
Lower octane fuel can burn too fast causing the mix to ignite too soon and cause knocking, which will damage your engine and your wallet.
Advanced timing can lead to pre-ignition with lower octane fuels.
Higher octane fuel burns more slowly and is more resistant to pre-ignition so timing can be advanced to create more power.
There is not more power in higher octane fuel, the higher octane allows you to tune your engine to get more power.
All that said, if a tune requires higher octane you need to run it because lower octane fuel can damage your engine.
Think of it this way:
The piston is coming up in the cylinder on its compression stroke. You want the fuel mix to be ignited before the piston is at the top so that it can get the maximum expansion to push the piston down for the power stroke.
Ignite the fuel/air mix too late, and the piston is already on its way back down and you will lose much of your potential power.
Ignite the mix too soon and you will try to push the piston back down before the crankshaft has come over the top of its revolution, like trying to push the crankshaft backwards. This is very bad and you hear it as knocking. It WILL damage bearings.
TLDR:
Lower octane fuel can burn too fast causing the mix to ignite too soon and cause knocking, which will damage your engine and your wallet.
DROZ23
Well-Known Member
reset KAM on the module back to stock and it will clean up the issue. Original flash did the same. I also clear the adaptive kam which resets the fuel trim levels so you can go run ham and fit them to the calibration.
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