Octane and Towing

[69 Post Sedan]

Originally Posted by markjohnson

I would've thought that higher octane fuel lets the motor run max timing without fear of detonation or killing power when pulling timing out.

My thoughts exactly......but I’ve been wrong before....lol

Kurt

[x33rs]

When I tune the LS engines, there are 2 sets of timing tables. One with much lower timing figures. The computer will revert back to the lower numbers when the knock sensors pick up anything. Generally the slight loss in power and MPG isn't even noticed by most owners.

I know the truck timing tables are extremely conservative due to the intended purpose the trucks are built for. I haven't been into the tunes on the newest trucks much past 2006, but I would assume not much has changed.

Some tuners will copy/paste the high octane timing tables over the low octane timing tables to keep everything consistent, and still leave the knock sensors active to pull 3-4 degres when knock is present. But at this point I wouldn't recommend running the cheapest fuel in it.

[martinbrown239]

I respectfully disagree on it being a waste of money. In my opinion, its waste of money.

[Canuck]

I have been running the higher octane in my 2003 Yukon XL2500 from about 60,000 miles, I noticed a performance difference and slightly better fuel economy by constantly running 91. It now has 140,000 miles and have only had to replace the map sensor.

[PeteLeathersac]

Originally Posted by martinbrown239

I respectfully disagree on it being a waste of money. In my opinion, its waste of money.

Disagree + Agree...sounds like a political statement?

~ Pete


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[dustinm]

I have been running 87 in my 6.2 (not towing with it) as the price for premium has escalated higher than diesel. With the lower octane I have managed a new MPG high score on the display (33.5 for last 25 miles, 29.5 last 50). When I go to tow again I will def fill up back up with 91. But whats to say we are getting 91 out of the hose? Esp when there is only 1 hose for three fuel grades. I know they dont dedicate a truck for each fuel either.

[69 Post Sedan]

Originally Posted by dustinm

I have been running 87 in my 6.2 (not towing with it) as the price for premium has escalated higher than diesel. With the lower octane I have managed a new MPG high score on the display (33.5 for last 25 miles, 29.5 last 50). When I go to tow again I will def fill up back up with 91. But whats to say we are getting 91 out of the hose? Esp when there is only 1 hose for three fuel grades. I know they dont dedicate a truck for each fuel either.

Is it possible that the engine timing is backed off with the lower octane and the result is better fuel mileage? Although power will be down in that scenario also.

On a side note, I’ve gotten 28.5 on a 25 mile average.

Kurt

[southernfriedcj]

Originally Posted by wheelhop

Get a diesel and lower your octane!

This.

Get a Cummins tow pig and never look back.

[69 Post Sedan]

Originally Posted by southernfriedcj

This.

Get a Cummins tow pig and never look back.

I only pull my trailer 3 or 4 times a year. I can’t justify the extra money
PLUS the maintenance on a diesel. My 6.2 suits me well....

Kurt

[dustinm]

Originally Posted by 69 Post Sedan

Is it possible that the engine timing is backed off with the lower octane and the result is better fuel mileage? Although power will be down in that scenario also.

On a side note, I’ve gotten 28.5 on a 25 mile average.

Kurt

I think the load is light enough, that it isnt detonating and is able to keep the higher timing table.