I've always tried to run 95 octane in my TJ Magnas, believing that you get a little extra oomph from the engine and better fuel economy from the denser fuel. Well, it seems I've been fooling myself and the only "denser" thing is my brain.

Watch this Canadian consumer affairs program for a full technical comparison:

https://www.youtube.com/watch?v=FPPkPAbzwbU

I've always tried to run 95 octane in my TJ Magnas, believing that you get a little extra oomph from the engine and better fuel economy from the denser fuel. Well, it seems I've been fooling myself and the only "denser" thing is my brain.

Watch this Canadian consumer affairs program for a full technical comparison:

https://www.youtube.com/watch?v=FPPkPAbzwbU

Over time I've tried them all including the 100 Shell had. I've never been able to tell the difference. As for economy, never been able to justify the the price difference and doubt you'd be ahead in the end. I use E10 and it would not surprise me lower economy but at 95 RON it was far cheaper than using premium in a car with 95RON min.

So these engines are ok to run on E10? There's so much urban myth out there and even the so called "experts" cant agree on the benefits/downsides of the stuff that I've generally steered clear of it.

My TJ has run exclusively on E10 for the last 5 years without problems. It's 95 octane and always a few cents cheaper. What's not to like?

Well I'm always up for saving a few $ when I can so I'll give it a try. Although the major chains don't seem to carry it? I mostly see it at 7/11's and United servos, but correct me if I'm wrong...

Octane rating and energy density are two different things.

Just because E10 has a higher octane rating than regular unleaded 91, does not mean you will get better performance. You will get significantly less km from a tank of E10.

Octane rating and energy density are two different things.

Just because E10 has a higher octane rating than regular unleaded 91, does not mean you will get better performance. You will get significantly less km from a tank of E10.

Well if that's the case will the cars' trip computer pick it up in terms of the l/100km & range functions?

I've always been under the impression that since the Magna does not have a knock sensor it is not able to capitalise on the higher octane ratings of 95 and 98 RON, therefore there should be no (or little) performance enhancement from using it. Having said that, I do get more range from a tank of 98 than a tank of standard unleaded, but not enough to justify the extra cost. I alternate between standard and premium for its cleansing additives, though I understand that the cleansers are not equivalent to a proper fuel system cleanout and gunge will still build up over time.

I've always put Shell 91 in mine since the day I got it, runs smooth no issues

Well if that's the case will the cars' trip computer pick it up in terms of the l/100km & range functions?

Oxygen sensor tells the ECU about fuel ratio, and adjusts fuel pulses at the injectors to get the right fuel:air ratio.
ECU works out the fuel consumption from the number and duration of fuel pulses.
E85 can't be used in the Magna because it is too corrosive on the standard fuel system and the ECU can't extend the injector pulses long enough to get the right fuel:air ratio.

Short answer: YES. Accuracy of trip meter doesn't depend on fuel octane rating.

The O2 sensor measures the oxygen content of the exhaust and that"s taken (by the ecu) as a reading of how rich or lean the exhaust is. The ecu then decides how long the injectors shoul be open. IOW it assumes things ... eg, if one injector is responsible for an overly rich exhaust all injectors are held responsible but adjusting all to compenmsate leads to ... ?

read : http://www.jaguarfuelinjectorservice.com/02%20sensors%20and%20injectors.htm

"...remember what the O2 sensor is reading. It is reading O2 exhaust content. Injectors (therefore cylinders) #1 and #2 are still underfueled. As a result of their underfueling, the O2 exhaust content still reads a lean overall mixture, as there is still unburned O2 present in the exhaust, from underfueling of cylinders 1 and 2. The ECU continues to increase injector pulse width, until the O2 exhaust content reaches the level that says stoichiometric level is achieved. That is when cylinders 1 and 2 are at stochiometric.Injectors 3 thru 6 become irelevant, as their O2 exhaust content has reached the 0.1 to 0.3 % O2 content, and regardless how much additional fuel is added to #3 thru 6, no additional O2 will be burned, as there is no more available. Unfortunately, at this point, cylinders 3 thru 6 are now overfueled.

So, the "actual" end result of fueling is..."

etc

"...remember what the O2 sensor is reading. It is reading O2 exhaust content. Injectors (therefore cylinders) #1 and #2 are still underfueled. As a result of their underfueling, the O2 exhaust content still reads a lean overall mixture, as there is still unburned O2 present in the exhaust, from underfueling of cylinders 1 and 2. The ECU continues to increase injector pulse width, until the O2 exhaust content reaches the level that says stoichiometric level is achieved. That is when cylinders 1 and 2 are at stochiometric.Injectors 3 thru 6 become irelevant, as their O2 exhaust content has reached the 0.1 to 0.3 % O2 content, and regardless how much additional fuel is added to #3 thru 6, no additional O2 will be burned, as there is no more available. Unfortunately, at this point, cylinders 3 thru 6 are now overfueled. "

Jesus wept...

E85 can't be used in the Magna because it is too corrosive on the standard fuel system and the ECU can't extend the injector pulses long enough to get the right fuel:air ratio.

You sure about that? That's the first I've heard of this.
I personally know of a few magnas running E85 fuel with E85 definitions flashed into the factory ECU & with requisite changes to fuel system & injectors etc so it can run the stuff.

You sure about that? That's the first I've heard of this.
I personally know of a few magnas running E85 fuel with E85 definitions flashed into the factory ECU & with requisite changes to fuel system & injectors etc so it can run the stuff.

Proves my point - E85 can't be run on a standard Magna like E10 can. Read my post again, I think you read something I didn't write!

Meh!

The Magna V6 is too dumb to use anything except the fuel it was designed for unless you modify it. (Although better fuel and oil will make a cleaner engine and retain near to new specs)

It doesn't have a knock sensor so it can't advance the spark to use higher octane fuel, It doesn't have variable valve timing to allow a change in mixture to adjust the engine performance between economy and power, it doesn't have an ECU that has been set up for any other fuel than petrol. (unless you own an LPG car)

Like me you will notice putting high octane fuel in does make the car get up and go better, but the economy isn't changed - maybe lower as you get on the loud pedal more :-)

So E10 - it's cheaper - but you won't go as far as the engine isn't injected with as much long chain fuel and the O2 sensor will richen up the injectors - I did the math and it needs to be 8 - 10 cents/L cheaper to make sense....

E85 - better get a tow hitch - you'll need a tanker....

95 or 98 or 100 octane - It Goes better, right up the next refuel - in 5 minutes..... But I blew the doors off that V6 Dunnydoor.....

I used to use E10 from my local, now i make a bit more effort to go out of the way to a cheaper fuel station where they have regular 91 for cheaper than e10 from caltex.
Since changing away from e10 i have picked up 70-90kms per tank on distance.
If i drove grandpa spec everywhere i dont see why 91 couldnt get me close to 650-700kms a tank.
e10 wont even come close and the pittance savings isnt worth it.
That and i like driving 'sportingly'

no hard evidence yet, i have all my fuel usage recorded on an excel spreadhseet, but i havent been capturing/inputting the new fuel yet.
It'll be interesting to see over a space of time exactly how it compares.

"Since changing away from e10 i have picked up 70-90kms per tank on distance."


I've always used 95 as a minimum since I've had the car (2001) and have always got around 550- 600km out of a tank around town and 800 or over on the highway. I believe, as stated above, that the energy density of the fuel is responsible.

Energy density of petrol is 46.4
Energy density of E10 is 43.5

FROM: https://en.wikipedia.org/wiki/Energy_density

So the energy in 100% petrol is 1.066 that of E10. You can in theory expect a 6.6% increase in km/L with 100% petrol when compared to E10.

A full tank of 70L at 10Km/L on petrol will get you 700 Km, on E10 that would be 10.66L/100 km and a lesser range of 656 Km.

Conclusion: Difference of Km to a tank would definitely be noticeable.

EDIT: pure ethanol is only 30, so E85 (energy density of 33) would probably give you a fuel consumption of 15L/100km if you are getting 10L/100 km on petrol. No wonder the injectors wouldn't keep up on a standard car!

I think I have just convinced myself to stop using E10. lol

Proves my point - E85 can't be run on a standard Magna like E10 can. Read my post again, I think you read something I didn't write!

Meh!

No you did write it, you said there are two things stopping you when in actual fact there really is only one thing stopping you from running E85 in your car and that is the ECU not having a flex fuel sensor. E85 corroding fuel lines, rubber seals, or fuel tanks is complete BS. Maybe for 1970's cars. It is a warning that had to be put out there when first developed because there were cars out there that were really old, still are a few, as well as some car manufacturers use crap seals in their cars (GM).

Technically even E10 isn't going to run perfectly in your car because when you're accelerating it's using the open loop fuel maps, which are technically telling it to dump in less fuel than what you need to when running on E10 (due to less energy density in the fuel than standard 91/95/98). Closed loop however (when you're cruising around) the ECU will dump some more in and get the values closer to stoichiometric / lambda 1.0 based on readings from the o2 sensor.

So is E10 going to damage your car? No. The energy density values are close enough that even if you are running lean on open loop you will not have any issues because the 1. standard open loop maps are set very rich and 2. the higher octane and cooling values of ethanol will ensure your car will not detonate.

Proves my point - E85 can't be run on a standard Magna like E10 can. Read my post again, I think you read something I didn't write!

Meh!

Ok so you were meaning standard for both ECU & Fuel system. Thanks for clarifying, You see? That's why I asked the question!!
E85 ECU definition flash was something I am considering for my car, that's all.
I thought there might have been something you knew that I didn't.

Fair enough.
Just the flash would do, if the ethanol doesn't affect the components of the fuel system, but you run the risk of too lean a mixture if you hit the maximum duty cycle of the standard injectors trying to keep the fuel:air ratio right under some driving conditions.

Fair enough.
Just the flash would do, if the ethanol doesn't affect the components of the fuel system, but you run the risk of too lean a mixture if you hit the maximum duty cycle of the standard injectors trying to keep the fuel:air ratio right under some driving conditions.

Yes, it's not good peaking out the injectors. But they only reach 65-70% at full throttle in high RPM on any standard 3.5l. The magna injectors have a huge safety zone.

If you are running several mods (cams or charger) you should have bigger injectors anyway.