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6.6 gas engine premium fuel?

HP4

By HP4
in 6.6L Gas V8 (L8T)

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HP4 Enthusiast

HP4

Posted
Posted

Is there any performance advantage to using higher octane fuel in GM’s 6.6 gas engine? There is in my Ford 2.7 eco boost so I’m curious about this engine. Haven’t been able to find the answer anywhere so far. 

diyer2 Senior Enthusiast

diyer2

Posted
Posted (edited)

YES!

EDIT

Doing a search it requires 87 octane. Premium fuel would be a personal decision. It can't hurt anything but your wallet. 

Edited by diyer2
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Another JR Senior Enthusiast

Another JR

Posted
Posted
4 minutes ago, diyer2 said:

YES!

Diyer2 - can you explain the basis for your answer?  Since the L8T is a relatively low compression engine, I was about to answer the opposite, but I have no actual test data.  Maybe you have experimented?

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sheath Enthusiast

sheath

Posted
Posted

Short answer is the 87 Octane will work best, unless you're in at high altitude, in which you'd run 85 Octane.   Places like Utah & Colorado will have 85 Octane.

 

Octane rating is a measurement of the ignition point of gasoline.  The higher the number, the more resistant to detonation (as in when the initial burn <oxidation> starts), but it doesn't change the amount of energy in the fuel. 

That said, it is important to run quality fuel, and some stations sell fuel that barely meets the requirements.  So rather than go to a higher Octane, go to a higher quality gas station that has high traffic volume so the fuel you put in your truck is fresh, and of high quality.

 

Some great YouTube video, and complete explanations on the internet.

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MORSNO Enthusiast

MORSNO

Posted
Posted

Your Ecoboost likes premium due to the turbo compression.  The GM 6.6 can run great on regular.

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HP4 Enthusiast

HP4

Posted
  • Author
Posted
35 minutes ago, sheath said:

Short answer is the 87 Octane will work best, unless you're in at high altitude, in which you'd run 85 Octane.   Places like Utah & Colorado will have 85 Octane.

 

Octane rating is a measurement of the ignition point of gasoline.  The higher the number, the more resistant to detonation (as in when the initial burn <oxidation> starts), but it doesn't change the amount of energy in the fuel. 

That said, it is important to run quality fuel, and some stations sell fuel that barely meets the requirements.  So rather than go to a higher Octane, go to a higher quality gas station that has high traffic volume so the fuel you put in your truck is fresh, and of high quality.

 

Some great YouTube video, and complete explanations on the internet.

Totally agree and understand. I was just curious since the eco boost is engineered to make more horsepower using premium fuel. For my 6.6 though.... 87 it is! Thanks. 

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HP4 Enthusiast

HP4

Posted
  • Author
Posted
2 hours ago, diyer2 said:

YES!

EDIT

Doing a search it requires 87 octane. Premium fuel would be a personal decision. It can't hurt anything but your wallet. 

And at today's prices it sure would hurt the wallet too. Thanks.... 87 it is.

CamGTP Senior Enthusiast

CamGTP

Posted
Posted

Is your wallet a real concern when you already spent $60-70,000 though?

 

just sayin GIF

 

 

🙂🙃

HP4 Enthusiast

HP4

Posted
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Posted
2 hours ago, CamGTP said:

Is your wallet a real concern when you already spent $60-70,000 though?

 

just sayin GIF

 

 

🙂🙃

Not if I could get more HP.

HP4 Enthusiast

HP4

Posted
  • Author
Posted (edited)
On 3/23/2022 at 6:47 PM, MTU Alum said:

It was designed with fleet applications in mind so its calibrated for 87 octane.   

 

#iworkforGM

The GM HD engineering crew knocked it out of the park with this truck! I haven't pulled with it yet, but I won't come close to maxing it out, so the gasser is perfect. Plus I can completely remove DEF and "limp mode" from my vocabulary. 

Edited by HP4
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sheath Enthusiast

sheath

Posted
Posted
14 hours ago, HP4 said:

Not if I could get more HP.

Good point.  I'm looking forward to see what the aftermarket will eventually come out with.  With the tightening of emissions standards, and GM locking down this ECM it is a pretty tough ask.  In another thread guys were hoping to see a supercharger.  Not sure that would work with heavy towing due to the amount of heat generated, but it would be pretty fun on the drive over to Home Deopt! :thumbs:

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