List Benefits of 91/93 Octane ?
- Thread starter ChrisD46
- Start date
My truck doesn't require 93, but makes more power on it.
I also prefer to run it when towing the camper around, especially in the summer time. I just prefer to err on the side of engine safety when things are hot.
DI/TPI/Twin Turbo engine.
Do I think running 87 will shorten the life of the engine? Not particularly, but as the miles pile on the ECU may need to make enough changes that the performance won't be the same. I usually run 89 when not towing.
I also prefer to run it when towing the camper around, especially in the summer time. I just prefer to err on the side of engine safety when things are hot.
DI/TPI/Twin Turbo engine.
Do I think running 87 will shorten the life of the engine? Not particularly, but as the miles pile on the ECU may need to make enough changes that the performance won't be the same. I usually run 89 when not towing.
While most cars can run 87, and are designed to do so, some make full rated horsepower using 91/93 if you read the fine print. This is due to the ECU (engine computer that runs the show) adjusting ignition timing (advance) to take advantage of the "slower" burning fuel. This creates more power in a higher compression/forced induction engine that could be prone to knock (pre-ignition). Conversely, that same process works when lower octane fuel is used, since the engine has sensors that detect that knock when it happens and will "pull" (retard) timing to protect the engine, resulting in less power.
I know for my Tiguan, it is rated for 87 and uses more advance when possible because I can check this thru monitoring. When it is really hot and humid outside, it reduces this advance, or pulls timing more often and seems sluggish. If I use 93 during this time, the timing is pulled less and the car is way more responsive. Normal use I don't see/feel much difference, only when I drive it harder and demand more from the engine does it really show up. Thats mine though, YMMV.
I know for my Tiguan, it is rated for 87 and uses more advance when possible because I can check this thru monitoring. When it is really hot and humid outside, it reduces this advance, or pulls timing more often and seems sluggish. If I use 93 during this time, the timing is pulled less and the car is way more responsive. Normal use I don't see/feel much difference, only when I drive it harder and demand more from the engine does it really show up. Thats mine though, YMMV.
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Propflux01
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Some engines, Like Turbos, are designed to make more power using higher octane gas. Have to set those aside for your question.
Standard engine, designed for 87 with no mention of using 89/91/93, etc. Then, as posted above, a big resounding "No".
Standard engine, designed for 87 with no mention of using 89/91/93, etc. Then, as posted above, a big resounding "No".
It makes your wallet lighter....
It has been said there are more cleaning agents with 91/93 then 87. We have see the posts here of a news station doing testing and that testing said there were more cleaning agents as per gas seller stating it too. I guess that would be #1.
My 2018 Hyundai Kona AWD 1.6T rbo car OEM was tuned was 87, and as it technically was not a true performance car, the tune and ECU was not adjustable for octane as say a 2022 Hyundai Kona N Series that has a 2 liter turbo and can adjust for it. With my current tune, I MUST use 93 octane. Which is because the HP/torque is increased with aggressive timing advancement.
My 2018 Hyundai Kona AWD 1.6T rbo car OEM was tuned was 87, and as it technically was not a true performance car, the tune and ECU was not adjustable for octane as say a 2022 Hyundai Kona N Series that has a 2 liter turbo and can adjust for it. With my current tune, I MUST use 93 octane. Which is because the HP/torque is increased with aggressive timing advancement.
Maybe some of you would benefit from reading this article. Higher Octane-rated gas doesn't "burn slower", instead, it is more resistant to premature ignition: https://www.innovatemotorsports.com/spark-timing-myths-debunked/
Back in the day of fixed tunes, it would have been (almost) true to say "A car made for 87 will not benefit from Preium"
But now with moderm engine management even engines listed as requiring only 87 have shown noticable power improvements on the dyno.
Anywhere from 5 to 14 hp.
Not huge but considering the thousands of dollars some people pay for an exhaust upgrade which may or may not only add 5-10 hp on the dyno, thats huge.
This is one of many tests done which shows in a vehicle rated for "regular" run with different grades of fuel.
The Octane rating used are European
to translate when they test for "98" that would be approx 93.5 Octane in the US
When they write "95" Octane thats approx 90.7 Octane in the US and when they post "92" Octane results this is what would in the US be somewhere beteen 88 and 89 Octane.
With an Opel (formerly known as "GM germany")
There are many many other tests out there to look at just like this one:
and here is one with a Miata:
Conclusion. The days of when a car was "factory tuned for X Octane" are over.
Modern engine managements constantly listen for microknock and retard timing and lean out the mix if they hear none with signifcant improvements with the higher Octane.
Now is it economical, given the sky high price difference bewteen regular and Premium?
Thats a seperate discussion altogether, but from aperformance aspect, yes there are repeatable, measurable non-trivial improvements going up in Octane.
Too many objectively controlled tests are out there to document this.
These 2 links above i found in only 2 minutes of searching.
There was an even better one a few years ago , also from Britain where they had compared multiple cars on regular, midrange and premium fuels.
Plenty of econoboxes mixed in.
Same external temps, same day tests and documented noticable performance differences as well.
I just cant find it now.
But now with moderm engine management even engines listed as requiring only 87 have shown noticable power improvements on the dyno.
Anywhere from 5 to 14 hp.
Not huge but considering the thousands of dollars some people pay for an exhaust upgrade which may or may not only add 5-10 hp on the dyno, thats huge.
This is one of many tests done which shows in a vehicle rated for "regular" run with different grades of fuel.
The Octane rating used are European
to translate when they test for "98" that would be approx 93.5 Octane in the US
When they write "95" Octane thats approx 90.7 Octane in the US and when they post "92" Octane results this is what would in the US be somewhere beteen 88 and 89 Octane.
With an Opel (formerly known as "GM germany")
There are many many other tests out there to look at just like this one:
and here is one with a Miata:
Conclusion. The days of when a car was "factory tuned for X Octane" are over.
Modern engine managements constantly listen for microknock and retard timing and lean out the mix if they hear none with signifcant improvements with the higher Octane.
Now is it economical, given the sky high price difference bewteen regular and Premium?
Thats a seperate discussion altogether, but from aperformance aspect, yes there are repeatable, measurable non-trivial improvements going up in Octane.
Too many objectively controlled tests are out there to document this.
These 2 links above i found in only 2 minutes of searching.
There was an even better one a few years ago , also from Britain where they had compared multiple cars on regular, midrange and premium fuels.
Plenty of econoboxes mixed in.
Same external temps, same day tests and documented noticable performance differences as well.
I just cant find it now.
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My Honda runs noticeably better on 93
Thats why the quotes were used around the word slower. Yes, it all has to do with resistance to self-ignition and flame front speed and how timing is critical to produce the most power without causing damage. Cylinder pressure, fuel mixture, injector width, air density, crank geometry and several other factors play into the equation, but without creating a super long and confusing reply, it's just easier to simplify terms. Mea culpa.
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I live in an area with very steep and long hills. I always run 93 in my 2017 All Track...MUCH better performance, no pinging. In the Passat, I run 89 and it seems to run well on that.
If the engine is designed to run on 87 - absolutely zero.
I tried this with the Tundra - no improvement in MPG, power, or anything else.
Running premium in an engine that doesn’t need it is a wallet flush, plain and simple.
I tried this with the Tundra - no improvement in MPG, power, or anything else.
Running premium in an engine that doesn’t need it is a wallet flush, plain and simple.
Our owner's manuals say 87 octane. This actually enhances the performance of my wallet.
I think this is demonstrably false, and even some owners manuals say you'll get better performance on 91/93.
My Odyssey and my Atlas noticeably pull timing on 87. Even my wife notices.
One reason higher MPG might be seen when running premium vs. regular is that some fuel vendors (Co-Op in my neck of the woods, and previously true for Shell) don't use ethanol in their premium option. Given that ethanol is less energy dense than gasoline, one might see better MPG with an E0 fuel, even if higher octane rating isn't the cause. Whether the math works out to support the higher cost of the premium fuel (it generally won't) is another conversation.
That's not to say nobody has ever shown higher MPG in a more apples-to-apples (same ethanol percentage, different octane rating) scenario.
That's not to say nobody has ever shown higher MPG in a more apples-to-apples (same ethanol percentage, different octane rating) scenario.
It is demonstrably true. I did several comparison runs.
It is not true for any of the turbocharge cars in my signature, but it is absolutely, verifiably, true for the normally aspirated V8 designed to run on 87.
I agree there is not enough benefit to use higher octane in a vehicle that does not specify it.
In case of your Toyota I suspect it doesn't have enough compression to make any measurable benefit. My Nissan's also do not, however Nissan suggested 89 octane in the last years they put the identical engine in the last of the body on frame pathfinders. Most speculate it was purely for Cafe.
My Toyota - 13:1 compression will show a mild increase in mpg but not enough to make $$ worth it. It shows no performance improvement because it doesn't have any performance, so multiply zero by whatever still zero.
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From what I’ve seen, if the engine can adjust the timing there is a 2% gain available and the gain is in the torque curve across the entire rpm range, meaning the resulting HP numbers are also in the range of 2%. If your knothole can detect that then by all means spend the extra money. 
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