Premium ULP

[Scott63]

Question can i run 91 ULP in my Maloo, I am not concerned with loss of power, just a query

[stumps57L]

Ping ping ping

[daskip]

Ping ping ping

constructive :goodjob:

if its an emergency and thats all thats around at the time it wont hurt to much but on a long term basis i wouldnt

[SS_ute]

I personally wouldnt touch it with a 10ft pole.

The one time i had to use 91 was in Hay on my way across country and they didnt have 98 or 95 fuel.
I think that was the most stressful drive of my life. When i got to my destination we ended up dumping the fuel just to be safe.

If you drive your car like a 80yr old lady i cant see there being any huge risk to the engine but for the sake of a few $$$ why take chances?

[Groboz]

This might be a stupid question.... but would adding a bottle of octane boost help if 91 was all you could fill up with?

[VX2VESS]

what year is it should have dual spark tables?

is it tuned?

[planetdavo]

If it's stock tuned it can handle it.
If it's aftermarket tuned they often push the envelope well toward 98 octane, so it usually wont like 91 at all.

[R863]

Question can i run 91 ULP in my Maloo, I am not concerned with loss of power, just a query

If it is stock of course you can,I have a new E3 R8 and even it states you can run 91 RON in it but recommends Premium. It also states you can run E10 which is around 93 RON but you won't get you as far on a tank due to the way it burns in the chamber, had it explained to me once by a techo at the refinery but it went over my head because he spoke too quick. I drive a fuel tanker for a living and can tell you that 95 Ron is the most popular fuel at the minute.

[pah]

If it's stock tuned it can handle it.
If it's aftermarket tuned they often push the envelope well toward 98 octane, so it usually wont like 91 at all.

Hi Davo,

Yes I've heard that. In fact, it always puzzled me as to why a car with DUAL spark tables would ping on 91 RON. My research indicates that some tuners put the same hotrod tune into BOTH tables!! OUCH?? When the knock sensors tell the PCM to jump to the 91 RON spark table, it finds the same tune and continues to ping.

I bought a tune from Daniel (Chipmaster) and never had any problems with pinging on E10 or 95 RON. His tune also IMPROVED fuel economy on the open road and around town. I invariably use Shell V-Power because it gives me better fuel economy (and I am comparing V-Power to other 98 RON fuels here. That's why I don't bother with 91 RON. It STUFFS fuel economy! It has to - it contains ethanol! Any perceived E10 cost savings are offset by the loss of economy. Do your own fuel checks. I suspect you will find similar results.



PAH

[swingtan]

Clarification time.....


In stock form, the car WILL ping, a bit for a short time, then less as the ECM learns. The ECM uses the knock detection to move the commanded spark down to the low spark table. No ping = no learning so it would stay on the high table. You may not hear the pinging, but it will be occuring.
In stock form, if it's E10 compatible, run that way before running 91. E10 is a much better fuel than 91 and if sourced from a bigger servo, has a high chance of retaining a higher than stated octane rating. If it's post 2006 then E10 is a great option as this ECM handles the fuel very well.
Adding octane boost will help, but it's not an ideal solution. It's certainly not a cost effective one.
Tuning the ECM/PCM should have little impact on the sbility to ru 91, as long as the tune is done correctly there should be sufficient room between the high and low tables to cater for the change in fuel types. If the high table is on a knife edge for knock using 98, then it's set too high already.


You would need to look at why you want to run 91 in the car and think about the options you have. If you are haeding to remote locations, most will still have 95 RON or possibly E10. If you are doing it to save money on fuel, then you might find that running E10 is a much better alternative.

Simon.

[iloveholden]

Can someone explain what "ping" is and how i can identify it?

I'm running 95 in my ute atm because it was close to empty and the shell servo didnt have 98. Otherwise next tank will be 98 :)

Do people really see a difference in mileage when using 98 compared to 91?

[daskip]

Can someone explain what "ping" is and how i can identify it?

I'm running 95 in my ute atm because it was close to empty and the shell servo didnt have 98. Otherwise next tank will be 98 :)

Do people really see a difference in mileage when using 98 compared to 91?

ping = pre detonation

fuel igniting before spark plug fires

http://en.wikipedia.org/wiki/Engine_knocking#Pre-ignition

[Space Pope]

If you're stuck you can run a reduced octane like 91 til you can gas up with a 95 or 98 BUT don't be stomping at the loud pedal (the ECU will probably pull out a bunch of spark and timing if you try anyway but you'll definitely be inviting more conditions for pinging to occur...'specially on a hot day).

[swingtan]

Can someone explain what "ping" is and how i can identify it?

I'm running 95 in my ute atm because it was close to empty and the shell servo didnt have 98. Otherwise next tank will be 98 :)

Do people really see a difference in mileage when using 98 compared to 91?

As daskip says, "pinging" is pre-detonation of the intake charge. What that basically means is that the cylinder pressures are rising faster than the engine can actually use in pushing the piston down the bore.

Normally, the intake charge is ignited prior to the piston reaching Top dead Centre, (TDC) to allow it time to fully ignite, the aim is to reach peak cylinder pressure just after the piston reaches TDC giving it the biggest "push" down the bore. If the peak pressures are reached with the piston still rising in the bore, the effect is that the expanding gases try to stop the piston from rising, which is obviously a bad thing.

You can identify it if it gets bad enough by listening to the motor under load. You will hear loud "click" noises which indicate pre-detonation. Sometimes it's referred to as "pinking" as it sounds like the work "pink". The easiest way to learn what it sounds like is to listen to many Korean/Japanese cars take off on a hot day. A lot of them detonate badly in this situation.

Differences in mileage is a pretty open ended question. I can speak from experience though for my car. When I returned from holidays in Eden, I filled with 95 at the Caltex there and drove to Bairnsdale towing a pretty heavy trailer. At Bainsdale I filled with 98 at the Shell and the difference in driving was significant. The car had much more power when cruising, requiring less throttle input. Less throttle means less fuel, so it used less. That is an extreme case though. Obviously, if a car is tuned for a specific fuel, it runs better on that fuel. The best mileage I've done on the Eden trip was a couple of years ago when V-Power Racing was available.

The next question though is, of course, is the price difference worth it? That's even harder to quantify, but my view has always been that if you are concerned with "value for money" then you should run E10. that is probably the best "value for money" fuel on the market, though it may require a tune tweak to get the most out of it.

Simon.

[SirNemesis]

I fail to see why a HSV owner would even consider this. The car is designed for 95 octane minimum, and it really isn't that much more expensive. If you can afford a HSV, you can afford a few dollars worth of petrol.

[theco]

Tried them all. My L76 runs best on 95 E10.:)

[pah]

Can someone explain what "ping" is and how i can identify it?

I'm running 95 in my ute atm because it was close to empty and the shell servo didnt have 98. Otherwise next tank will be 98 :)

Do people really see a difference in mileage when using 98 compared to 91?

Hi ILH,

You've probably heard cars pinging. It often happens when a manual car (most noticable pre PCM cars) is driven up a hill in a gear that is too high. The engine is under lots of load and it can be heard rattling. I think the term pinging is meant to describe the noise the engine makes. As Swingtan says, pinging damages engines so it's the last thing we want!

I agree with the E10 ethanol comments. I think it was Burma who made a big deal of their ETHANOL ENHANCED petrol years ago. I think they advertised it as 95 RON? Ethanol does a good job of keeping the fuel system clean as it's corrosive. Car makes who addapt their cars to burn E10 no doubt change components so they will cope with ethanol's corrosive nature. Does ethanol burn hotter in the engine and is this an issue?

Even though E10 is around 95 RON, I still use 98 RON because E10 stuffs economy. The price advantage is not as good as it looks at the bowser.

Check out this article: http://en.wikipedia.org/wiki/Engine_knocking

And do a Google Image Search on engine pinging. You might get some pics of engine damage. I did a Google Image Search on Twisted Pair (phone cable). I got a picture of Paris Hilton and Brittany Spears.

And YES! The worry is that pinging cannot always be heard. I had my XR6T tuned. I picked up pinging driving up-hill next to a concrete lane divider with my driver's window down. I needed the concrete wall to bounce the pinging noise in through the open driver's window. I got that fixed pronto. Different tuner this time. Thanks Spiro at Autotech!



PAH

[J_VZUTE]

for the sake of a few $$$ why take chances?

Spot on... for the extra few bucks at the pump, its worth it. Specially if you've got a nice car, why put dodgey fuel in it? Its not a 89 corolla..

[HYMEY]

e10 is fine i would not run the 91 in that engine. I have tuned engines specifically to run 91, it is very sensitive to detonation ie rise in IAT or just add 1 more degree timing and they knock there guts out, it is not forgiving. 95 isn't so bad. e10 is a good thing will keep your tank clean too.

[theco]

Tried them all. My L76 runs best on 95 E10.:)

.....and most economical.

[OMR346]

I fail to see why a HSV owner would even consider this. The car is designed for 95 octane minimum, and it really isn't that much more expensive. If you can afford a HSV, you can afford a few dollars worth of petrol.

VS HSV, $5k??? Or even VT HSV (with LS1), $10k??? Just becuase it is HSV, deosnt mean it is expensive.

In saying that though, i only ever run 98ron in my cars. Ive even told the misses if i find out she has run anything but in her car, ill sell it lol.

[R863]

If it is stock of course you can,I have a new E3 R8 and even it states you can run 91 RON in it but recommends Premium. It also states you can run E10 which is around 93 RON but you won't get you as far on a tank due to the way it burns in the chamber, had it explained to me once by a techo at the refinery but it went over my head because he spoke too quick. I drive a fuel tanker for a living and can tell you that 95 Ron is the most popular fuel at the minute.

Just becareful as all premium fuels are not the same, I cart mainly Shell fuel and it has an additive called "NEMO" in it which is a valve anti wearing lubricant and is injected into Shell's premium fuels when loading, this is why it is dearer to buy than say 7/11 premium fuel which is still loaded out of the Shell terminals but has no "NEMO"additive injected while loading. A lot of BP fuel is now imported from the Phillipines so that leaves Caltex Vortex or Shell V Power that I prefer to use, but this is just my opinion only.

[steve_t]

Just becareful as all premium fuels are not the same, I cart mainly Shell fuel and it has an additive called "NEMO" in it which is a valve anti wearing lubricant and is injected into Shell's premium fuels when loading, this is why it is dearer to buy than say 7/11 premium fuel which is still loaded out of the Shell terminals but has no "NEMO"additive injected while loading. A lot of BP fuel is now imported from the Phillipines so that leaves Caltex Vortex or Shell V Power that I prefer to use, but this is just my opinion only.

I thought all fuel companies had additive packages with different names but essenstially the same thing. Nemo just sounds like marketing hype. What makes Shell's Nemo additive better than Techron by Caltex, or the other fuels?

[pah]

Just becareful as all premium fuels are not the same, I cart mainly Shell fuel and it has an additive called "NEMO" in it which is a valve anti wearing lubricant and is injected into Shell's premium fuels when loading, this is why it is dearer to buy than say 7/11 premium fuel which is still loaded out of the Shell terminals but has no "NEMO"additive injected while loading. A lot of BP fuel is now imported from the Phillipines so that leaves Caltex Vortex or Shell V Power that I prefer to use, but this is just my opinion only.

Thanks for the info R863.

I suspected that there's something different about Shell. My VY SV* gave better economy on V-Power. Ditto for my XR6T. On the other hand, my Kwaka ZRX1200 does not like it too much. Too many tanks and it starts farting. This problem was much worse with Optimax. The bike shop told me not to run Optimax in the Kwaka. I switched to anything else and the problem disappeared. It can stand V-Power but I have to run a tank or two of BP Ultimate every now and again to avoid what feels like fouled plugs. As I say, this has only a problem with the bike and Optimax. The cars love V-Power.




PAH

[R863]

I thought all fuel companies had additive packages with different names but essenstially the same thing. Nemo just sounds like marketing hype. What makes Shell's Nemo additive better than Techron by Caltex, or the other fuels?

You need to read my post correctly, I said I use Caltex Vortex and Shell V power, but will not use Bogas (no name caltex fuel) or 7/11 (no name shell fuel) because they have no additives, or BP fuel because I never know where it comes from at the moment.
There is no maketing hype from Shell as the tanker driver is the only one that can see the fuel has "NEMO" in it not the general public as it is noted as part of the load authority.
Take this information on board if you like or just foget it, I don't get involved in forum slanging matches I'm only here to pass on information in return for what I get from this great forum.

[R863]

Thanks for the info R863.

I suspected that there's something different about Shell. My VY SV* gave better economy on V-Power. Ditto for my XR6T. On the other hand, my Kwaka ZRX1200 does not like it too much. Too many tanks and it starts farting. This problem was much worse with Optimax. The bike shop told me not to run Optimax in the Kwaka. I switched to anything else and the problem disappeared. It can stand V-Power but I have to run a tank or two of BP Ultimate every now and again to avoid what feels like fouled plugs. As I say, this has only a problem with the bike and Optimax. The cars love V-Power.




PAH

You are correct, I have had Ducati's in recent years and was told by the chemist at the refinery not to run V Power in them as it is too oily and has something to do with the way it is refined (can't remember what he told me at the time). V Power and Optimax is one of the same it's just Optimax is the old name but you may still find a blue Optimax marker on the service station driveway but it will only be V Power in the tank.
I used to use Caltex Vortex 98 and BP Ultimate 98 in my bikes but have given the BP fuel away for the bike as it mostly comes in by ship from the Phillipines.

[steve_t]

You need to read my post correctly, I said I use Caltex Vortex and Shell V power, but will not use Bogas (no name caltex fuel) or 7/11 (no name shell fuel) because they have no additives, or BP fuel because I never know where it comes from at the moment.
There is no maketing hype from Shell as the tanker driver is the only one that can see the fuel has "NEMO" in it not the general public as it is noted as part of the load authority.
Take this information on board if you like or just foget it, I don't get involved in forum slanging matches I'm only here to pass on information in return for what I get from this great forum.

Errr.... OK. I wasn't having a go at you :confused: I was asking what Shell say the advantages of the Nemo additive are. Obviously, if only the tanker driver knows that the fuel has Nemo in it, then there's no marketing of it at all. And I was under the understanding that all fuels have additive packages but if there are fuels available with no additives, I'm happy to be corrected. Sorry if you thought I was 'slanging' you

[VL Executive]

Question can i run 91 ULP in my Maloo, I am not concerned with loss of power, just a query

The original question sort of tells me that fuel prices, Which are going up, are starting to bite again. :(

Todays Courier mail said $1.50 pl for is likely again soon.

[A PSYCHO]

VS HSV, $5k??? Or even VT HSV (with LS1), $10k??? Just becuase it is HSV, deosnt mean it is expensive.

In saying that though, i only ever run 98ron in my cars. Ive even told the misses if i find out she has run anything but in her car, ill sell it lol.

what planet are you on? Try more like $13K and up for the VT.

I have only ever ran 98.

[OMR346]

what planet are you on? Try more like $13K and up for the VT.

I have only ever ran 98.

Says the fool who doesnt know how to barter if his life depended on it lol

The cheapest VT HSV LS1 on Carsales at the moment (that i have seen) is $11.5k. And there are a fair few 5Ltr VT HSV's under $10k.

[iloveholden]

As daskip says, "pinging" is pre-detonation of the intake charge. What that basically means is that the cylinder pressures are rising faster than the engine can actually use in pushing the piston down the bore.

Normally, the intake charge is ignited prior to the piston reaching Top dead Centre, (TDC) to allow it time to fully ignite, the aim is to reach peak cylinder pressure just after the piston reaches TDC giving it the biggest "push" down the bore. If the peak pressures are reached with the piston still rising in the bore, the effect is that the expanding gases try to stop the piston from rising, which is obviously a bad thing.

You can identify it if it gets bad enough by listening to the motor under load. You will hear loud "click" noises which indicate pre-detonation. Sometimes it's referred to as "pinking" as it sounds like the work "pink". The easiest way to learn what it sounds like is to listen to many Korean/Japanese cars take off on a hot day. A lot of them detonate badly in this situation.

Differences in mileage is a pretty open ended question. I can speak from experience though for my car. When I returned from holidays in Eden, I filled with 95 at the Caltex there and drove to Bairnsdale towing a pretty heavy trailer. At Bainsdale I filled with 98 at the Shell and the difference in driving was significant. The car had much more power when cruising, requiring less throttle input. Less throttle means less fuel, so it used less. That is an extreme case though. Obviously, if a car is tuned for a specific fuel, it runs better on that fuel. The best mileage I've done on the Eden trip was a couple of years ago when V-Power Racing was available.

The next question though is, of course, is the price difference worth it? That's even harder to quantify, but my view has always been that if you are concerned with "value for money" then you should run E10. that is probably the best "value for money" fuel on the market, though it may require a tune tweak to get the most out of it.

Simon.


Hi ILH,

You've probably heard cars pinging. It often happens when a manual car (most noticable pre PCM cars) is driven up a hill in a gear that is too high. The engine is under lots of load and it can be heard rattling. I think the term pinging is meant to describe the noise the engine makes. As Swingtan says, pinging damages engines so it's the last thing we want!

I agree with the E10 ethanol comments. I think it was Burma who made a big deal of their ETHANOL ENHANCED petrol years ago. I think they advertised it as 95 RON? Ethanol does a good job of keeping the fuel system clean as it's corrosive. Car makes who addapt their cars to burn E10 no doubt change components so they will cope with ethanol's corrosive nature. Does ethanol burn hotter in the engine and is this an issue?

Even though E10 is around 95 RON, I still use 98 RON because E10 stuffs economy. The price advantage is not as good as it looks at the bowser.

Check out this article: http://en.wikipedia.org/wiki/Engine_knocking

And do a Google Image Search on engine pinging. You might get some pics of engine damage. I did a Google Image Search on Twisted Pair (phone cable). I got a picture of Paris Hilton and Brittany Spears.

And YES! The worry is that pinging cannot always be heard. I had my XR6T tuned. I picked up pinging driving up-hill next to a concrete lane divider with my driver's window down. I needed the concrete wall to bounce the pinging noise in through the open driver's window. I got that fixed pronto. Different tuner this time. Thanks Spiro at Autotech!



PAH

Thanks so much. :)

[michaels1v8]

I've got a vx ss with mail order mafless. No problems on regular, premium or premium 98 during regular driving and negliable difference in economy. Standard tune i imagine should be ok unless otherwise specified. . I only ever drive ordinary on standard and have only used it out of necessity. . If demanding any kind of performance out of the car i always run premium 98 . . Its just added safety against leaning out

[swingtan]

If demanding any kind of performance out of the car i always run premium 98 . . Its just added safety against leaning out

Actually, no it's not. the actual Air/Fuel Ratio will not change one bit (well, not enough to make any difference). The 'protection' is against pre-detonation and nothing more. Some may be thinking "Hey, but premium unleaded is a denser fuel, so it should run richer." The thing is that the O2 trims will see this "denser fuel" and adjust for it. So the over all fueling will be no different. If the car is tuned correctly (IMO, talking about cars regularly driven on the street), you should be able to use any fuel and still put your foot to the floor and not have it rattle its self to death. All bar one factory Holden has dual spark tables and they should be used to cater for any fuel differences. To lock a daily driver to only use 98 is not going to help if you want to go for a holiday to a place that has no 98...

Now is probably a good time to also mention how the knock sensors work. Believe it or not, the knock sensors are not there to detect knocking or pinging. *pause for effect*. they are there to detect The onset of pre-detonation. It's a big difference and needs to be understood. If your engine pings loud enough for you to hear it, then the ECM has well and truly lost control of the combustion process. It's already missed the chance to prevent the knock and thus protect the engine. Instead, the knock sensors "listen" to the cylinders when they fire and the ECM determines when the sound matches the onset of a pre-detonation event. It hen pulls timing to prevent actual knock from occurring. Knock Retard (KR)is not a bad thing to have occurring and the vast majority of people would have no idea if/when it occurs. It's the ECM protecting the motor, ideally though, with known good fuel, there should be no KR occurring either. When running 98, I might get an occasional occurrence of KR, usually on throttle movement. But if running 95 and towing the trailer, I get a lot more. I don't hear any pinging, but I can see it in the log files as the ECM pulls timing due to the increased load and the lower quality fuel. I'm not worried about it, it's the way it should be.

Simon.

Simon.

[pah]

Using E10, my SV8's economy dropped into the high 14's or maybe 15L / 100 kms around Sydney. Using 98 RON Shell V-Power, it ran in the high 12's or mid 13's around town.

I was very happy with fuel economy in the high 12's or mid 13's around Sydney. Fuel economy improved to these levels after a Mail Order Tune from Chipmaster. I was obviously not flogging the car. Open road economy was great too. Always in the low 8's on the Hume. Multi lanes means the car is on cruise and not throttle for overtaking.



PAH

[steve_t]

With these dual spark tables from factory, is one set for 91 and the other for 98? What's the scope of adjustment within each table? eg using 95

[IJ.]

The bigger danger is from prolonged incipient detonation you can't hear it and it's doing damage in the background...

[aus_07]

so does this mean after a tune for 98, you can still run normal unleaded if 98 wasn't available - but be light on the throttle and you shouldn't have any drama's? since the tune i've always run BP ultimate, but have always wondered what if i was in a remote area and only normal unleaded was available...

[Scott63]

I fail to see why a HSV owner would even consider this. The car is designed for 95 octane minimum, and it really isn't that much more expensive. If you can afford a HSV, you can afford a few dollars worth of petrol.

Mate - It just a question - I read that you can run 91, MY INTENTIONS are to run 98.

[swingtan]

With these dual spark tables from factory, is one set for 91 and the other for 98? What's the scope of adjustment within each table? eg using 95

Basically, yes. There is a "low spark" table and a "high spark" table. The ECM will, by default, use the high spark table. If it detects knock occurring, it blends the two tables to reduce the commanded spark. the more knock there is, the more it "learns" toward the low table.

The scope of adjustment is pretty much anything. The tables are a 3D plot of airflow vs RPM and the commanded spark values can be anything from say 50' retard to 50' advance. Normally though there difference between the high and low tables is somewhere between 20' to 0' depending on what part of the table you are in. The type of fuel means nothing to the tables, only the detected knock amount.



The bigger danger is from prolonged incipient detonation you can't hear it and it's doing damage in the background...

Partially correct. A couple of big hits from detonation can lunch a motor totally. Continued "incipient pre-detonation" will probably compress the top ring lands and damage bearing, but it won't blow the motor instantly. It will over time though.


so does this mean after a tune for 98, you can still run normal unleaded if 98 wasn't available - but be light on the throttle and you shouldn't have any drama's? since the tune i've always run BP ultimate, but have always wondered what if i was in a remote area and only normal unleaded was available...

After a good tune for 98, you should still be able to run 91, with no risk to the motor. You should not "need" to be light on the throttle, but trying to race won't help at all. Remembering you have 91 in the tanks and taking it easy is always advisable. Stock tunes are capable of running 98 and 91, but are not optimised. If you optimise the tune for 98, you must expect that running 91 will not be the best option, however it should not prevent you from running 91.

Simon.

[aus_07]

Thanks for clearing that up Simon.

[Vulture]

Simon, if your vehicle spends some time disconnected from power, does it lose the learning on the spark tables that had occurred previously? Cheers.

[swingtan]

Any form of ECM reset will clear learned data. This includes fuel trims, octance scaler (the high low learning) and idle control, possibly other data as well.

Simon

[woffty12]

Yeh mate for the sake of 4-5 bucks go 95 -98 oct not worth the risk...

[steve_t]

Basically, yes. There is a "low spark" table and a "high spark" table. The ECM will, by default, use the high spark table. If it detects knock occurring, it blends the two tables to reduce the commanded spark. the more knock there is, the more it "learns" toward the low table.

The scope of adjustment is pretty much anything. The tables are a 3D plot of airflow vs RPM and the commanded spark values can be anything from say 50' retard to 50' advance. Normally though there difference between the high and low tables is somewhere between 20' to 0' depending on what part of the table you are in. The type of fuel means nothing to the tables, only the detected knock amount.




Partially correct. A couple of big hits from detonation can lunch a motor totally. Continued "incipient pre-detonation" will probably compress the top ring lands and damage bearing, but it won't blow the motor instantly. It will over time though.



After a good tune for 98, you should still be able to run 91, with no risk to the motor. You should not "need" to be light on the throttle, but trying to race won't help at all. Remembering you have 91 in the tanks and taking it easy is always advisable. Stock tunes are capable of running 98 and 91, but are not optimised. If you optimise the tune for 98, you must expect that running 91 will not be the best option, however it should not prevent you from running 91.

Simon.

Cheers Simon. You're the man :goodjob:

[SAMCRO]

I fail to see why a HSV owner would even consider this. The car is designed for 95 octane minimum, and it really isn't that much more expensive. If you can afford a HSV, you can afford a few dollars worth of petrol.


Maybe they can't coz they already spent too much mula.. :rofl::rofl::rofl:

[SAMCRO]

It's funny how we all spend at least $ 10-20 a day on unnecessary items or on a pack of cigarets, but can't bear extra $5 when refuelling.. You ain't gonna get nowhere with extra 4 litres of 91 shyte, but to your mechanic :rofl::rofl:
Honestly, don't kid yourself mate.Just put proper juice in there, she deserves it.. :goodjob:

[A PSYCHO]

It's funny how we all spend at least $ 10-20 a day on unnecessary items or on a pack of cigarets, but can't bear extra $5 when refuelling.. You ain't gonna get nowhere with extra 4 litres of 91 shyte, but to your mechanic :rofl::rofl:
Honestly, don't kid yourself mate.Just put proper juice in there, she deserves it.. :goodjob:

although he said he intends to put good fuel in it, this should still be reiterated IMO. To serve as 'food for thought' if nothing else for anyone on here.

I hit an all new high for petrol on saturday night myself at a whopping $1.57c/L but you do what you have to do i guess.

[IJ.]

Basically, yes. There is a "low spark" table and a "high spark" table. The ECM will, by default, use the high spark table. If it detects knock occurring, it blends the two tables to reduce the commanded spark. the more knock there is, the more it "learns" toward the low table.

The scope of adjustment is pretty much anything. The tables are a 3D plot of airflow vs RPM and the commanded spark values can be anything from say 50' retard to 50' advance. Normally though there difference between the high and low tables is somewhere between 20' to 0' depending on what part of the table you are in. The type of fuel means nothing to the tables, only the detected knock amount.




Partially correct. A couple of big hits from detonation can lunch a motor totally. Continued "incipient pre-detonation" will probably compress the top ring lands and damage bearing, but it won't blow the motor instantly. It will over time though.



After a good tune for 98, you should still be able to run 91, with no risk to the motor. You should not "need" to be light on the throttle, but trying to race won't help at all. Remembering you have 91 in the tanks and taking it easy is always advisable. Stock tunes are capable of running 98 and 91, but are not optimised. If you optimise the tune for 98, you must expect that running 91 will not be the best option, however it should not prevent you from running 91.

Simon.

I was commenting on the thread starters original question Simon, while the low octane may run ok, over time it's doing damage that can't be heard or defended against, anyone with half a brain will back off if they rattle the engine badly but if you don't hear the rattle you have NFI it's slowly hurting itself... :(

Whenever I'm on the dyno I wear a pair of electric ears, first time was an eye opener...

[Thorpey]

Its funny as i dont generally comment on any of the fuel threads ,although i do read them. i guess this one has just tipped me over the edge. people on car forums be it here or GMH Torana, HSV forum ect ask the same questions about saving a few bucks by running 91 over 98. If you are reading this you are clearly an enthusiest or u would be lookin at something else so why for the love of god would for a few measly bucks run 91? You tight fisted f*&ks! Try running it on bio diesel. I suppose u guys running 91 wash your car with washing up detergent to and use a cut off piece of ya ole denim jeans to dry it off?? Oh i hear Woolies has a sale on black & Gold engine oil for $1 for a 25litre drum ! Do it ! I seriously hope i dont ever buy a second hand HSV off any of these kind of people. BTW throwing in $25 of 98 or 95 in with your 91 is better than a kick in the rear but its still subgrade. If you love your car treat it so or hand it on to someone who will. Dont get upset as its only my opinion.

[steve_t]

Dont get upset...

Right back at ya :jester:

[michaels1v8]

Its funny as i dont generally comment on any of the fuel threads ,although i do read them. i guess this one has just tipped me over the edge. people on car forums be it here or GMH Torana, HSV forum ect ask the same questions about saving a few bucks by running 91 over 98. If you are reading this you are clearly an enthusiest or u would be lookin at something else so why for the love of god would for a few measly bucks run 91? You tight fisted f*&ks! Try running it on bio diesel. I suppose u guys running 91 wash your car with washing up detergent to and use a cut off piece of ya ole denim jeans to dry it off?? Oh i hear Woolies has a sale on black & Gold engine oil for $1 for a 25litre drum ! Do it ! I seriously hope i dont ever buy a second hand HSV off any of these kind of people. BTW throwing in $25 of 98 or 95 in with your 91 is better than a kick in the rear but its still subgrade. If you love your car treat it so or hand it on to someone who will. Dont get upset as its only my opinion.

Why buy a second hand HSV? You tight fisted f*&k! :stick:

I think most here are talking about running on 91 in pretty dire situations (i.e. When premium is unavailable). Also, I never touch the premium in country roadside service stations because chances are that Premium is not commonly bought in a place like that and could be very old fuel.

I'd rather use 91 because that is what the majority of people stopping will buy so fuel turnover should ensure a fresher batch and less crap built up in their tank (I hope).

Nobody is talking about feeding their car a 91ron diet all day everyday, so sleep easy tonight and rest assured we enthusiasts arent all tight fisted f*&ks :)