L8T and 93 octane or 90 rec gas.

[GAMark]

Does anyone know if the L8T can advance timing i.e., could it advance it enough to take advantage of 93 octane while towing on a hot day, not to pull timing due to pinging?

 

Per AI. No idea if it is true.

 

 

Yes, a GM truck with the 6.6L L8T V8 engine can benefit from 93 octane, though the gains depend on how you use the truck. [1, 2, 3, 4, 5]

Because the L8T features advanced engine management and variable valve timing, its computer will automatically advance the ignition timing when it detects higher-octane fuel. The primary benefits of 93 octane in an L8T include: [1]

• Improved Towing Performance: When pulling heavy loads or driving up steep grades, your engine runs hotter and is more prone to engine knock. The ECM will pull timing to protect the engine on lower-octane gas, whereas 93 octane allows the engine to maintain full power under stress. [1, 2, 3, 4]
• Better Throttle Response: You may notice a sharper throttle feel and slightly better low-end torque. [1, 2]
• Maximum Output for Tuners: If you add an aftermarket handheld programmer, the engine can be fully optimized to take advantage of 93 octane, yielding noticeable horsepower and torque gains over the factory tune. [1, 2, 3]

If you are just driving unloaded without a trailer, the standard 87 octane recommended by GM is perfectly sufficient and cost-effective. However, if you are regularly towing, hauling, or looking for peak performance, 93 octane is highly beneficial. [1, 2]

If you want to optimize your truck's performance, tell me:

• Are you planning on adding any aftermarket tuners or programmers?
• How often do you use the truck for heavy towing or hauling?

I can help you decide whether the premium fuel upgrade is worth the cost for your specific driving habits.

Edited June 1 by GAMark

[GAMark]

Maybe I have not towed heavy enough. I cant tell the difference.

[riddler]

2 hours ago, GAMark said:

Does anyone know if the L8T can advance timing i.e., could it advance it enough to take advantage of 93 octane while towing on a hot day, not to pull timing due to pinging?

 

Per AI. No idea if it is true.

 

 

Yes, a GM truck with the 6.6L L8T V8 engine can benefit from 93 octane, though the gains depend on how you use the truck. [1, 2, 3, 4, 5]

Because the L8T features advanced engine management and variable valve timing, its computer will automatically advance the ignition timing when it detects higher-octane fuel. The primary benefits of 93 octane in an L8T include: [1]

• Improved Towing Performance: When pulling heavy loads or driving up steep grades, your engine runs hotter and is more prone to engine knock. The ECM will pull timing to protect the engine on lower-octane gas, whereas 93 octane allows the engine to maintain full power under stress. [1, 2, 3, 4]
• Better Throttle Response: You may notice a sharper throttle feel and slightly better low-end torque. [1, 2]
• Maximum Output for Tuners: If you add an aftermarket handheld programmer, the engine can be fully optimized to take advantage of 93 octane, yielding noticeable horsepower and torque gains over the factory tune. [1, 2, 3]

If you are just driving unloaded without a trailer, the standard 87 octane recommended by GM is perfectly sufficient and cost-effective. However, if you are regularly towing, hauling, or looking for peak performance, 93 octane is highly beneficial. [1, 2]

 

If you want to optimize your truck's performance, tell me:

• Are you planning on adding any aftermarket tuners or programmers?
• How often do you use the truck for heavy towing or hauling?

I can help you decide whether the premium fuel upgrade is worth the cost for your specific driving habits.

Only if you tune will it be needed and bemnificial  otherwise its wasting money.

[Epsilon Plus]

It will not go beyond the numbers placed into the stock timing tables which are very conservative. It will get better MPG as higher octane burns slower, but not enough to offset the enormous cost difference. 

[Pryme]

Run 87. 

[Grumpy Bear]

10 hours ago, GAMark said:

Does anyone know if the L8T can advance timing i.e., could it advance it enough to take advantage of 93 octane while towing on a hot day, not to pull timing due to pinging?

 

Let's reason it out. If the motor is equipped with a knock sensor and that sensor is telling the ECU to pull timing then more timing is available if it gets more octane. Octane that eliminates that KR (knock r-e-t-a-r-d) adds timing and nine times out of ten increased BMEP (torque). The improvements are measurable on an engine dyno but can be small enough that your seat of the pants may not notice. Sometimes it will. More torque at the same rpm allows lower TPS values for the same load which leans the motor a bit in the part throttle part of the map. Will you notice it? 

 

Ever watch Engine Masters dialing in a motor bumping timing 2 to 3 degrees at a time UNTIL power drops off (incipient knock point). There's a Aussie tuner that tunes the entire map by this method.

 

Further reasoning. A knock sensor has to HEAR the knock to react to it so doesn't move the timing until the shock wave is pounding the rings lands. Yes there is a difference in "Intensity" and the maps are well fretted to prevent most engine damage...until it isn't. KR is driving in the rearview mirror. Give it a bit of thought. Peck at the ring lands often enough even micro pecks will eventually hammer to the ring grooves. 

 

In my Ecotec3 4300, which is a flex fuel rig, the base map is 87 Octane but, and I watch it via a Scan Gauge II device along with fuel trims, will pull up to 9 degrees of timing on a 6% grade on a warm day with zero load at 60 mph in high gear. When I use 93 that value drops to under 3 degrees on any hill. When I use E-85 at over 80% it is ZERO KR. The milage difference between 87 and 93 hasn't been noticeable over the 150K miles i played with that. Been on E-85 and now at 193K+. In fact none of my 87 octane recommended vehicles of several makes looses even a fraction of a mpg using 93 and every one of them reduced KR. 

 

Lastly. Shell V Power Nitro + 91 or 93 and Exxon Mobil Supreme Premium 93 all three contain a proprietary antiwear/anti friction additive that has been PROVEN to significantly reduce bore/ring wear.  Both Shell and Lake Speed Jr have some pretty good videos on this product with receipts. Dyson Labs LLC was my intro to the product. The fuels listed are the ONLY fuels of any rating CURRENTLY using these additives. Shell was there first and has the most data. FYI. 

 

Like Ripley....Believe it or Not. This will get some blow back so I won't respond to it. 

Edited June 1 by Grumpy Bear

[GAMark]

13 hours ago, Grumpy Bear said:

 

Let's reason it out. If the motor is equipped with a knock sensor and that sensor is telling the ECU to pull timing then more timing is available if it gets more octane. Octane that eliminates that KR (knock r-e-t-a-r-d) adds timing and nine times out of ten increased BMEP (torque). The improvements are measurable on an engine dyno but can be small enough that your seat of the pants may not notice. Sometimes it will. More torque at the same rpm allows lower TPS values for the same load which leans the motor a bit in the part throttle part of the map. Will you notice it? 

 

Ever watch Engine Masters dialing in a motor bumping timing 2 to 3 degrees at a time UNTIL power drops off (incipient knock point). There's a Aussie tuner that tunes the entire map by this method.

 

Further reasoning. A knock sensor has to HEAR the knock to react to it so doesn't move the timing until the shock wave is pounding the rings lands. Yes there is a difference in "Intensity" and the maps are well fretted to prevent most engine damage...until it isn't. KR is driving in the rearview mirror. Give it a bit of thought. Peck at the ring lands often enough even micro pecks will eventually hammer to the ring grooves. 

 

In my Ecotec3 4300, which is a flex fuel rig, the base map is 87 Octane but, and I watch it via a Scan Gauge II device along with fuel trims, will pull up to 9 degrees of timing on a 6% grade on a warm day with zero load at 60 mph in high gear. When I use 93 that value drops to under 3 degrees on any hill. When I use E-85 at over 80% it is ZERO KR. The milage difference between 87 and 93 hasn't been noticeable over the 150K miles i played with that. Been on E-85 and now at 193K+. In fact none of my 87 octane recommended vehicles of several makes looses even a fraction of a mpg using 93 and every one of them reduced KR. 

 

Lastly. Shell V Power Nitro + 91 or 93 and Exxon Mobil Supreme Premium 93 all three contain a proprietary antiwear/anti friction additive that has been PROVEN to significantly reduce bore/ring wear.  Both Shell and Lake Speed Jr have some pretty good videos on this product with receipts. Dyson Labs LLC was my intro to the product. The fuels listed are the ONLY fuels of any rating CURRENTLY using these additives. Shell was there first and has the most data. FYI. 

 

Like Ripley....Believe it or Not. This will get some blow back so I won't respond to it. 

Thank you.

[GAMark]

I only run top-tier fuel. But recently, with my Chevron discount, I have been running 90-octane rec gas, no ethanol. 

[Grumpy Bear]

2 hours ago, GAMark said:

I only run top-tier fuel. But recently, with my Chevron discount, I have been running 90-octane rec gas, no ethanol. 

You may find this of interest. Not addressed in this article is that the UFP produced has some impact on elevated soot in the oil which only means it gets dirtier quicker. Just information and not a deal breaker. I use E-0 when it's cheaper. It does give a bump in fuel efficiency. 

https://www.enginelabs.com/tech-stories/mixing-e85-with-pump-gas-getting-higher-octane-for-less-money/

(Excerpt from above link below)

Concerns About Ethanol

These small blending mixtures of E30 to E50 maintain a large percentage of gasoline. The advantage here is that if the electric fuel pump in your street car is not rated for use with E85, a blending ratio of E50 or less can generally be considered compatible. You should consult your particular pump manufacturer to be sure, but a light blend of E30 should not cause any problems.

 

Let’s also address the claimed issues attributed to using ethanol in older cars. Our own experiments and investigations have traced the source of many ailments not to the alcohol in the fuel but rather to the high percentages of aromatic additives used in all pump gasoline. These aromatics are often lumped together under the acronym “BETX.” This is chemical shorthand for benzene, Ethyl-Benzene, Toluene, and Xylene.

 

These aromatics are present at anywhere from 20- to 25-percent (and sometimes more) by volume in gasoline. By themselves, BETX aromatics are not necessarily dangerous. But they are responsible for many of the problems in fuel systems, such as killing rubber fuel lines and affecting small rubber parts in carburetors.

 

Of equal concern is a dangerous by-product created after combusting BTEX, creating what are called ultra-fine particles (UFP). These particles are small enough to enter your lungs and travel past the membranes and directly into your bloodstream. Not good. By mixing ethanol with the fuel, fuel companies are able to reduce the concentration of BETX in the fuel. Conversely, alcohol-free fuels as sold in many Midwestern states contain much higher percentages of BTEX to compensate for the loss of ethanol in the fuel.

[GAMark]

22 minutes ago, Grumpy Bear said:

You may find this of interest. Not addressed in this article is that the UFP produced has some impact on elevated soot in the oil which only means it gets dirtier quicker. Just information and not a deal breaker. I use E-0 when it's cheaper. It does give a bump in fuel efficiency. 

https://www.enginelabs.com/tech-stories/mixing-e85-with-pump-gas-getting-higher-octane-for-less-money/

(Excerpt from above link below)

Concerns About Ethanol

These small blending mixtures of E30 to E50 maintain a large percentage of gasoline. The advantage here is that if the electric fuel pump in your street car is not rated for use with E85, a blending ratio of E50 or less can generally be considered compatible. You should consult your particular pump manufacturer to be sure, but a light blend of E30 should not cause any problems.

 

Let’s also address the claimed issues attributed to using ethanol in older cars. Our own experiments and investigations have traced the source of many ailments not to the alcohol in the fuel but rather to the high percentages of aromatic additives used in all pump gasoline. These aromatics are often lumped together under the acronym “BETX.” This is chemical shorthand for benzene, Ethyl-Benzene, Toluene, and Xylene.

 

These aromatics are present at anywhere from 20- to 25-percent (and sometimes more) by volume in gasoline. By themselves, BETX aromatics are not necessarily dangerous. But they are responsible for many of the problems in fuel systems, such as killing rubber fuel lines and affecting small rubber parts in carburetors.

 

Of equal concern is a dangerous by-product created after combusting BTEX, creating what are called ultra-fine particles (UFP). These particles are small enough to enter your lungs and travel past the membranes and directly into your bloodstream. Not good. By mixing ethanol with the fuel, fuel companies are able to reduce the concentration of BETX in the fuel. Conversely, alcohol-free fuels as sold in many Midwestern states contain much higher percentages of BTEX to compensate for the loss of ethanol in the fuel.

We run VP-X85 in our race car. But I was running Rec gas because I fill up the boat at the same time and was getting 50 cents a gallon off.

[Atlas]

The main reason I've run ethanol-free in my project/hobby cars is because it's not uncommon for the car to take anywhere from 3-6 months to consume most of a tank of fuel. All of the cars were manufactured after E10 was in widespread use but ethanol is hygroscopic and I've read phase separation will begin to occur over time, which accelerates corrosion of metal fuel tanks, pumps, and associated hardware. One of the cars still has a metal fuel tank.

 

So you're saying potentially increased BETX in non-ethanol to combat particulates may actually be a higher liability to the car considering corrosion of soft pieces, rubber, plastic lines, etc?

[Grumpy Bear]

4 hours ago, Atlas said:

The main reason I've run ethanol-free in my project/hobby cars is because it's not uncommon for the car to take anywhere from 3-6 months to consume most of a tank of fuel. All of the cars were manufactured after E10 was in widespread use but ethanol is hygroscopic and I've read phase separation will begin to occur over time, which accelerates corrosion of metal fuel tanks, pumps, and associated hardware. One of the cars still has a metal fuel tank.

 

So you're saying potentially increased BETX in non-ethanol to combat particulates may actually be a higher liability to the car considering corrosion of soft pieces, rubber, plastic lines, etc?

 

Here's a good paper on this topic. 

 

https://www.epa.gov/sites/default/files/2015-09/documents/waterphs.pdf

Edited June 2 by Grumpy Bear

[GAMark]

4 hours ago, Atlas said:

The main reason I've run ethanol-free in my project/hobby cars is because it's not uncommon for the car to take anywhere from 3-6 months to consume most of a tank of fuel. All of the cars were manufactured after E10 was in widespread use but ethanol is hygroscopic and I've read phase separation will begin to occur over time, which accelerates corrosion of metal fuel tanks, pumps, and associated hardware. One of the cars still has a metal fuel tank.

 

So you're saying potentially increased BETX in non-ethanol to combat particulates may actually be a higher liability to the car considering corrosion of soft pieces, rubber, plastic lines, etc?

Yes, when we put the car up for the winter. We run all ethonal out and add rec gas with stabilizer. Otherwise, as you know, it will attract too much water sitting for the winter. Our race car was built to run high ethonal, so from the fuel cell to the injectors are braided ethonal safe lines. Have not had any problems. But last year, my mother ended up in the hospital, and I took 3 months off, and the car was a true PITA to get running again with the old VPE85.

Edited June 2 by GAMark