93 vs 87 Octane
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Tuned
Joined: Nov 2003
Posts: 454
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From: CT
93 vs 87 Octane
I have always used 87 octane, but had this crazy theory that when towing heavy loads, it might actually make sense to use 93?
If there is a knock sensor on both banks, timing will be retarted if knock is detected, resulting in less power.
so....as "my" theory goes, if you can avoid knock by using 93, there won't be a chance of knock and always get the most available power.
This may be a reach, but towing a 8000# 5th wheel with a 5.4, every little but of power helps.
Thoughts?
If there is a knock sensor on both banks, timing will be retarted if knock is detected, resulting in less power.
so....as "my" theory goes, if you can avoid knock by using 93, there won't be a chance of knock and always get the most available power.
This may be a reach, but towing a 8000# 5th wheel with a 5.4, every little but of power helps.
Thoughts?
Tuned
Joined: Jun 2015
Posts: 344
Likes: 7
Doesn't make any difference other than draining your wallet.
Octane is just a combustion inhibitor, so higher octane tolerates higher temps before thermally combusting (due to compression) before the spark plug ignites it. The reason high horsepower engines use high octane is because they have much higher compression ratios than our 5.4's. Their air fuel mixture is compressed a lot more, which then heats up the mixture more than in our pickups before the spark plug fires. High octane prevents the high compression engines from igniting until the spark plug ignites the mixture at the correct time.
Octane is just a combustion inhibitor, so higher octane tolerates higher temps before thermally combusting (due to compression) before the spark plug ignites it. The reason high horsepower engines use high octane is because they have much higher compression ratios than our 5.4's. Their air fuel mixture is compressed a lot more, which then heats up the mixture more than in our pickups before the spark plug fires. High octane prevents the high compression engines from igniting until the spark plug ignites the mixture at the correct time.
Fleet Mechanic
Joined: Dec 2021
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I have always used 87 octane, but had this crazy theory that when towing heavy loads, it might actually make sense to use 93?
If there is a knock sensor on both banks, timing will be retarted if knock is detected, resulting in less power.
so....as "my" theory goes, if you can avoid knock by using 93, there won't be a chance of knock and always get the most available power.
This may be a reach, but towing a 8000# 5th wheel with a 5.4, every little but of power helps.
Thoughts?
If there is a knock sensor on both banks, timing will be retarted if knock is detected, resulting in less power.
so....as "my" theory goes, if you can avoid knock by using 93, there won't be a chance of knock and always get the most available power.
This may be a reach, but towing a 8000# 5th wheel with a 5.4, every little but of power helps.
Thoughts?
Ive tested my gasoline trucks for this many times. I tow 15-16k almost daily. Aside from really hot days 90+ degrees F I never noticed any conditions where I would benefit from higher octane. On the very hot days and the engine really working the knock sensors were quite active and switching to 89 octane did help. In the owners manual it does suggest running a higher octane while towing for this reason. At the same time though without verifying you actually need a higher octane all you are doing is guessing and paying more for fuel.
Lead Driver
Joined: Feb 2022
Posts: 7,955
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Unless you get a tune to take advantage of the higher Octane, you are just wasting money, with the few exceptions stated above. The Ecoboost engines are designed to take full advantage of higher octane fuels and it is recommended to use higher octane when towing, where it is "suggested" to use on the Superduty. With the price of Premium being higher than diesel, you will wish you had the power of the diesel for that price.
FTE Leadership Emeritus
Joined: Sep 2000
Posts: 23,174
Likes: 1,678
From: Stephensville WI
You should consult your owners manual. For instance, the 2019 manual says you can use 87 octane with the 6.2L, or E85, but 91 octane should be used for "best overall vehicle and engine performance", then goes on to explain that the performance gain from premium fuel will be most noticeable in hot weather or while towing.
Lead Driver
Joined: Feb 2022
Posts: 7,955
Likes: 4,039
OP has a 5.4, which I believe would need a tune installed to be able to use the higher octane as the 5.4 doesn't have the hardware or programming to adjust to it's optimum use. A 5 Star tune should give him what he needs to get the most out of 93.
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