Question regarding Octane fuel for LFX

[DSX_Camaro]

I always have good luck with Sunoco, Exxon, Chevron, and Mobil, and awful luck with Shell, Hess, and BP. All of my vehicles seem like they have an "acquired taste" after filling up at a Chevron.

On topic, I understand that the book may say you can run 87, it has already been shown that running 91/93 gets the most out of the car. That's why you never see someone tuning for performance with 87. A few months ago there was a dyno sheet floating around from someone (I forget who) that I think had just an intake and a tune for 89 octane and picked up upwards of 20whp.

Anything above 87 octane is not needed. 91 or 93 will get the best performance. Those are both set in stone.

[tahoeacr]

103,000 miles Chevron 91 on my Evo. Sure the tune and boost, egt's ect. make a difference, but that is one clean piston. Photo from a cheepo harbor freight inspection camedra

[Gen-X45]

LOL, Sorry Dago...

[Z28bryan]

If the manual says 87 run 87. Some people may think running higher stuff is better let them waste their money.


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[DSX_Camaro]

Originally Posted by Z28bryan

If the manual says 87 run 87. Some people may think running higher stuff is better let them waste their money.


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Because there hasn't been any dyno testing or tuning to confirm that the LFX has low octane and high octane fuel maps, and you can't field test whether 87 vs 93 yields better fuel economy and performance.

No, none of that has been done...

[BlackoutLFX]

Screen shot shows high and low octane spark table menu. Proof enough that the ecm looks at more than one table on fuel octane? The ecm is very flexible and with the correct sensors and hard parts it can control a multitude of platforms, from di, to na to fi.

[stoopid]

I use my '14 2LS as a commuter/daily driver. I've only used 87 in it. It runs fine and there's plenty of punch when I need it. Like the other lone voices here, I've done some prior homework on the subject and while the car may adjust, I'm skeptical of any actual benefits using higher octane [modless]. In most other NA vehicles the car simply dumbs down the benefits and you end up with the same power/efficiency. While I'm new to this vehicle (~3,000 miles) I'm not new to the same types of arguments for/against the use of higher octane. It's all being replayed here for the unteenth time. Usually the conclusion is: "if it makes you feel better about driving your vehicle, then by all means buy 93."

The manual's mention of "87 and above" simply means that you can use higher octane without any negative consequences (or voiding your warranty), but that statement alone is not an implication there's any benefit to the vehicle's performance. It's like saying that "18 and older" means that the older you are the better cigarettes are for you.

[BlackoutLFX]

Originally Posted by stoopid

I use my '14 2LS as a commuter/daily driver. I've only used 87 in it. It runs fine and there's plenty of punch when I need it. Like the other lone voices here, I've done some prior homework on the subject and while the car may adjust, I'm skeptical of any actual benefits using higher octane [modless]. In most other NA vehicles the car simply dumbs down the benefits and you end up with the same power/efficiency. While I'm new to this vehicle (~3,000 miles) I'm not new to the same types of arguments for/against the use of higher octane. It's all being replayed here for the unteenth time. Usually the conclusion is: "if it makes you feel better about driving your vehicle, then by all means buy 93."

The manual's mention of "87 and above" simply means that you can use higher octane without any negative consequences (or voiding your warranty), but that statement alone is not an implication there's any benefit to the vehicle's performance. It's like saying that "18 and older" means that the older you are the better cigarettes are for you.

First of all you admit to never running 93. My vehicle is tuned for 93....oh and performance, but it wasn't always. I have never heard of a performance tune for 87 octane. Sure you can putt around on 87 with less aggressive timing with the stock tune however there is more knock on 87 octane, even with the low octane timing table, and generally way more timing is pulled. I have logs that show this. By the way it says 87 and above because 87 is the MINIMUM octane rating recommended, not what's best. Below 87 is not recommended because it could damage the engine. A major benefit to running 93 octane is less spark knock/pre-detonation. the use of a fuel with high octane rating, which increases the combustion temperature of the fuel and reduces the proclivity to detonate.

http://en.wikipedia.org/wiki/Engine_knocking

Just sayin.

[DSX_Camaro]

Beyond what Blackout has stated, the LFX has an 11.5:1 compression ratio. There's no reason not to use 93 octane, especially since the only reason the LFX can even run 87 octane is due to the knock retard.

Even further than that, the LFX cannot utilize the high octane fuel maps without a tune, so yeah, you won't realize the full benefits of 93 octane, but running it WILL give you better efficiency and power. That point cannot be argued - it has been proven time and time again. Here is a dyno graph of an 89 octane tune. Note the enormous midrange torque gains. http://www.camaro5.com/forums/showpo...3&postcount=10

Guys, we aren't here to argue with what you want to do. We are simply giving you facts - you do not have to agree with what we say or what we do, nor do you have to do it.

[stoopid]

Originally Posted by DSX_Camaro

... the LFX cannot utilize the high octane fuel maps without a tune, so yeah, you won't realize the full benefits of 93 octane, but running it WILL give you better efficiency and power.

That's a contradictory statement (?).

No one is arguing whether higher octane can achieve better performance with a tune/mod. From my understanding on how GM's ECUs work, running stock the vehicle won't see any gains.

[DSX_Camaro]

Actually it isn't. If you run 87 and data log, you can see the computer pulling timing in all rev ranges, but if you run 93 it only pulls timing right when you nail the gas (so, for about a hundredth of a second). Again, more power, but not maximum power. I mean... a few decades ago, an 11.5:1 compression ratio would NEED high octane gas, but now we can survive on the cheap 87 only due to direct injection and the knock retard.

On the flip side, maybe I am wrong. Technically speaking, if the car is pulling timing on 87, then using 91 or 93 would only allow the engine to work at the max stock specs, which wouldn't be a gain of any kind, just an improvement.

[BlackoutLFX]

Originally Posted by DSX_Camaro

Actually it isn't. If you run 87 and data log, you can see the computer pulling timing in all rev ranges, but if you run 93 it only pulls timing right when you nail the gas (so, for about a hundredth of a second). Again, more power, but not maximum power. I mean... a few decades ago, an 11.5:1 compression ratio would NEED high octane gas, but now we can survive on the cheap 87 only due to direct injection and the knock retard.

On the flip side, maybe I am wrong. Technically speaking, if the car is pulling timing on 87, then using 91 or 93 would only allow the engine to work at the max stock specs, which wouldn't be a gain of any kind, just an improvement.

Also using 93 it will allow the computer access to high octane charts, otherwise it would use the low octane charts.

[KaBoom1701]

Originally Posted by 14CV6

I have always used 93 octane from day one like others, I believe if you are going to throw performance mods on the vehicle and run the vehicle hard, it is better to have the higher octane.

+1

[BlackoutLFX]

Originally Posted by stoopid

That's a contradictory statement (?).

No one is arguing whether higher octane can achieve better performance with a tune/mod. From my understanding on how GM's ECUs work, running stock the vehicle won't see any gains.

Think of less detonation as a gain.