Effect of 93 octane

[RalphVa]

You F-150 drivers will want to read this: Is Premium Gas Worth It? We Test High Octane on 4 Popular Vehicles

It's the only vehicle where 93 octane was a big improvement over 87 octane. On the BMW, the 87 octane was better.

On my own tests in the MX-5, I've settled on 89 (probably more nearly 90) octane for it. Think the owners manual recommends 91.

Ralph

 

[2LaneCruzer]

You F-150 drivers will want to read this: Is Premium Gas Worth It? We Test High Octane on 4 Popular Vehicles

It's the only vehicle where 93 octane was a big improvement over 87 octane. On the BMW, the 87 octane was better.

On my own tests in the MX-5, I've settled on 89 (probably more nearly 90) octane for it. Think the owners manual recommends 91.

Ralph

I use it in everything I own (CX5; F150; 60 Impala, mowers, saws, blower, etc.) and never buy anything with ethanol in it unless it's an emergency.

 

[KennyG]

I read that article but it left me uncertain about the benefits for my truck. The article says they tested a 450 HP F-150. That would be a Raptor, not the approximately 375 HP engine I have in mine. I think it is likely that the Raptor benefits more from premium fuel than the regular 3.5 Ecoboost, but I haven't experimented to find out.

 

[dalola]

Any of the Ecoboost engines will respond incredibly well to higher octane fuel, due to boost management. Ford left lots of margin in their tuning tables to account for a range of fuel qualities.

This is partly why performance tunes are so popular (& effective) on the EB engines. Lot's of untapped potential if you tune for high octane fuel.

I have been running a 93 octane performance tune (Livernois) on my 2.7 F150 for a couple years now, and it's insane the difference. The 2.7 was already a potent little engine, but with a tune it's in performance car territory. In good weather conditions, I can run high 12's very consistently with my truck, in 4x4 mode, low 13's in 2x4. The magic of good fuel & lots of boost.

 

[fatjay]

From my understanding, higher octane is the resistance to explode. Low compression engines require lower octane, high compression engines require higher octane to prevent detonation before the spark plug ignites when the piston hits top dead center. My supercharged jaguar, being supercharged, requires 93 octane because it's a high compression engine. My hummer h2, which is a regular old gm 6 liter v8, is fine with 87 because it's a low compression engine.

 

[skipmarcy]

I also use premium non-ethanol in all of my gas engines, large & small. Have for over 45 years. My small engines can sit for 6 months or better and ALL of them start easily if there are no other mechanical issues. My last weedeater was 19 hard-years old and still had the original carb on it when I tossed it for compression loss. The higher octane isn't the key here, it's the additive package premium fuels receive. I use no additives or stabilizers with my gasoline - they're already in there. I DO use additives in my diesel fuel for my truck and tractor.

 

[MossRoad]

From my understanding, higher octane is the resistance to explode. Low compression engines require lower octane, high compression engines require higher octane to prevent detonation before the spark plug ignites when the piston hits top dead center. My supercharged jaguar, being supercharged, requires 93 octane because it's a high compression engine. My hummer h2, which is a regular old gm 6 liter v8, is fine with 87 because it's a low compression engine.

Our 2013 Impala has 11.5:1 compression and runs on 87 octane.

It's all about the computers now.

 

[bunyip]

Woonder why we are diffferent, only see 91, 98 and E10.

 

[Gary Fowler]

All the studies I have ever read including car owner manuals say that it is a waste of money and could actually be detrimental to the engine to use any higher octane than what the OEM recommends. This does not include engines that have been made into dragsters by highly modifying them like dalola did to his truck.
If the engine is designed to run on 87 and has not been modified, then use 87 but if it is a high performance engine like you find on high priced luxury cars that require 93 then using lower grade gas could definitely harm the engine.

I am not in my 20's (some folks like my 50 year old son who just bought a Hellcat take longer to grow up) and I no longer need to show off my manhood with a high performance car so I dont own anything that requires more than 87 octane including lawnmowers, chainsaws and motorcycles.

 

[dodge man]

I have also read you get a benefit in the F150 both the eco-boost and the 5.0 of using higher octane and even E85. The problem is does it offset the cost? Does slightly more power and slightly better fuel mileage offset the cost? I doubt it.

I couldn't read the article either, it just took me to the top of the page. I'm guessing you have to subscribe. What engine did the Charger have?

 

[MossRoad]

You F-150 drivers will want to read this: Is Premium Gas Worth It? We Test High Octane on 4 Popular Vehicles

It's the only vehicle where 93 octane was a big improvement over 87 octane. On the BMW, the 87 octane was better.

On my own tests in the MX-5, I've settled on 89 (probably more nearly 90) octane for it. Think the owners manual recommends 91.

Ralph

Initially, one would think that means the higher octane fuel has more power, but it doesn't.

In reality, it just detonates later, allowing the computer to alter the timing, which produces more power.

 

[snymat68]

Our 2013 Impala has 11.5:1 compression and runs on 87 octane.

It's all about the computers now.

As does my 2013 Camaro with the same compression ratio. BUT it runs BETTER on 93. Why? Because, just like you said, computers.
ECU's have lookup tables and will ****** the timing automatically to prevent predetonation if the knock sensors detect it.
Yes, my car will run just fine on the 87 (the manual even says so), but the 93 lets the engine perform to its full potential.

 

[MossRoad]

As does my 2013 Camaro with the same compression ratio. BUT it runs BETTER on 93. Why? Because, just like you said, computers.
ECU's have lookup tables and will ****** the timing automatically to prevent predetonation if the knock sensors detect it.
Yes, my car will run just fine on the 87 (the manual even says so), but the 93 lets the engine perform to its full potential.

Yes, I believe we have the same engine. Good luck with that. I drive it pretty hard. The cam shaft phasers malfunctioned and snapped the camshafts around 100,000, which ate the engine. Replaced with a junkyard engine with 58,000. I really like the way that engine revs. More like a motorcycle than cars of the past. But I do not think it's as durable as the 3800 series II that we had in the 2000 Impala. Too many moving parts, sensors, etc.... It does get very good MPG. Quite impressive to get 31MPG in a 4 door sedan cruising down the road at 75MPH with the RPMS around 1700.

 

[dodge man]

I own a 2010 Challenger I have a tuner for it with which I bumped up the timing and leaned out the fuel based on a dyno tune. With that you can record data to a laptop and view it latter. You can choose what you can record to the laptop, and you realize what all the different things the computer in a car looks at. Two of them that were critical were called short term knock ****** and long term knock ******. The short term is not a big deal, the engine is just pulling timing briefly based on feed back from the knock sensors. The long term knock ****** is bad. Say you are running 85 octane and really need 93. If you keep getting timing pulled at certain rpms and conditions, the computer will store that info and that timing will be pulled from then on until a computer reset. I don't know if all car and trucks have a similar system or not, but running to low of an octane all the time could have negative performance issues. Around here 87 octane is as low as it goes but I know in Colorado, 85 is available.

 

[snymat68]

Yes, I believe we have the same engine. Good luck with that. I drive it pretty hard. The cam shaft phasers malfunctioned and snapped the camshafts around 100,000, which ate the engine. Replaced with a junkyard engine with 58,000. I really like the way that engine revs. More like a motorcycle than cars of the past. But I do not think it's as durable as the 3800 series II that we had in the 2000 Impala. Too many moving parts, sensors, etc.... It does get very good MPG. Quite impressive to get 31MPG in a 4 door sedan cruising down the road at 75MPH with the RPMS around 1700.

I'm somewhere around 102k on mine. I've used it for drag racing, autocross, and don't baby it as my daily driver year round. (Knock on wood) So far so good. Hopefully it holds out because I plan to have it at least another 5 years!

 

[oosik]

It's very simple. The 6.4 liter engine in my Taco Wagon will produce 410hp with the recommended 89 octane fuel. That's what I use. I've got 9800 miles on the truck and get 18+ mpg. I'm very happy.

 

[KennyG]

Woonder why we are diffferent, only see 91, 98 and E10.

I think the rest of the world uses a different method of reporting octane rating. There is research octane and motor octane. The US uses an average of the two and most everyone else uses research octane. No surprise there.

 

[MossRoad]

I'm somewhere around 102k on mine. I've used it for drag racing, autocross, and don't baby it as my daily driver year round. (Knock on wood) So far so good. Hopefully it holds out because I plan to have it at least another 5 years!

Stick or auto? We have auto. I dislike the way it interacts with the slow timing of the throttle-by-wire. I step on the gas pedal, nothing happens, so my brain says "step harder', but in that instant of brain-to-foot time, the throttle catches up with my initial step, and it ends up pushing it too far, the car accelerates faster than you want, and it jerks your neck. I know there's some tunes out there that can clean that up. Just deciding if I want to go that route.

 

[wheelbuilder]

I've tracked the mileage and has octane on my current car (an 09 Subaru Legacy) over 10 years. I've used 87, 89, and 91 octane (the 91 is ethanol free). My data from that shows the car gets about 3 mpg better mileage do the the 91 than the 87 and the 89 is about 1 mpg better than the 87.
Lately, I've been buying the ethanol free 91 octane for the mileage. Its about a wash cost wise between the different octane and the extra distance I can drive.

The service manual says this engine has 10.7:1 compression. It must ****** the timing pretty hard to get away with 87. I don't think an old v8 could run well with that compression and octane.

 

[RalphVa]

From my understanding, higher octane is the resistance to explode. Low compression engines require lower octane, high compression engines require higher octane to prevent detonation before the spark plug ignites when the piston hits top dead center. My supercharged jaguar, being supercharged, requires 93 octane because it's a high compression engine. My hummer h2, which is a regular old gm 6 liter v8, is fine with 87 because it's a low compression engine.

Not true about low/high compression engines. The Mazda 3's engines (2.0 and 2.5) are about 13/1 compression ratio and run 87 octane. These are the "Skyactive" engines. Mazda is expected to soon come out with an even higher compression ratio gasoline engine that uses no spark plugs. They're in testing. Think the bugaboo with higher compression, like the 17 to 20ish for diesels, is the generation of more NOX in the exhaust. This starts being a problem somewhere past 13/1.

The Mx5's 2.0 engine, on the other hand, is tuned for 91 octane because of its valve/ignition timing, but it'll run on anything from 87 to 93 octane.

Ralph