How to find the right octane

[moranor@axis]

the amount of octane you need is determined by many factors making it almost impossible to say what octane you need without testing under your specific driving conditions...

once you have the right octane level adding more will NOT improve anything by adding more and it just cost you more on fuel...

obviously copious amounts of data logging will be the best way to find out what octane you need for your car but its not practical for most people...

the easiest way to determine what octane boost you need is to monitor your fuel consumption...

simplest way to do this on most of our cars is to reset your trip computer at at every fill up... you need to do this for two fill ups minimum to get a good baseline... you can set the baseline with octane boost as long as you use the same boost level over two tanks...

once you have a baseline you can add octane boost at the next fillup... a reduction in fuel consumption on the tank with octane boost will mean your engine needs it to run an optimum you can then experiment by adding more or less boost in your next tank till you find what level your car likes...

 

[abmi0000]

You're spot on Moranor.

I used the 3RON (also NF) on my car first and the detonation went away immediately but there wasn't much of a fuel saving which could also be because I was testing the new founded option to reduce my pinking :grin:

I jumped straight to 6RON and my car appears to be somewhat better on consumption at the moment. I only do it when I have spare cash since this is a costly exercise when using 5-6 tanks of fuel per month.

I will try and drive decently again with 3RON as this needs to be determined, ito effeciency.

Thanks for the post :thumb:

 

[Whacko]

3 Ron on half a tank works just right for me :rollsmile:

 

[abmi0000]

3 Ron on half a tank works just right for me :rollsmile:

Always wondered about this. Will it push it up by more than 3 points if used with less fuel?

 

[Whacko]

3 Ron on half a tank works just right for me :rollsmile:

Always wondered about this. Will it push it up by more than 3 points if used with less fuel?

I worked it out, it raises the octane to between 97 and 98, 3 ron is supposed to raise 50 litres by 3 ron, but test show that this is not really the case, and by test data I would estimate the above increase. The M has a 13:1 compression ratio and with the mods it does make a noticeable difference in performance, but not really sure about consumption, I have a heavy foot by default. But you have to use at least a tank before you really notice the difference as the ECU is adaptive, does not run an optimized map immediately.

 

[abmi0000]

3 Ron on half a tank works just right for me :rollsmile:

Always wondered about this. Will it push it up by more than 3 points if used with less fuel?

I worked it out, it raises the octane to between 97 and 98, 3 ron is supposed to raise 50 litres by 3 ron, but test show that this is not really the case, and by test data I would estimate the above increase. The M has a 13:1 compression ratio and with the mods it does make a noticeable difference in performance, but not really sure about consumption, I have a heavy foot by default. But you have to use at least a tank before you really notice the difference as the ECU is adaptive, does not run an optimized map immediately.

So in your opinion, would it be beneficial to collect logs without any octane boosters before a remap? My view is that if it collects data with proper octane before remapping with one of the tuners the car will perform poorly when running off pump fuel, whilst possibly causing serious detonation.

Not sure if this is the case, but I am assuming so.

 

[Whacko]

3 Ron on half a tank works just right for me :rollsmile:

Always wondered about this. Will it push it up by more than 3 points if used with less fuel?

I worked it out, it raises the octane to between 97 and 98, 3 ron is supposed to raise 50 litres by 3 ron, but test show that this is not really the case, and by test data I would estimate the above increase. The M has a 13:1 compression ratio and with the mods it does make a noticeable difference in performance, but not really sure about consumption, I have a heavy foot by default. But you have to use at least a tank before you really notice the difference as the ECU is adaptive, does not run an optimized map immediately.

So in your opinion, would it be beneficial to collect logs without any octane boosters before a remap? My view is that if it collects data with proper octane before remapping with one of the tuners the car will perform poorly when running off pump fuel, whilst possibly causing serious detonation.

Not sure if this is the case, but I am assuming so.

Absolutely, but you got to b careful with the remap, depends on how it effects your torque curve, you could end up with higher consumption regardless of the octane rating being higher.

 

[abmi0000]

3 Ron on half a tank works just right for me :rollsmile:

Always wondered about this. Will it push it up by more than 3 points if used with less fuel?

I worked it out, it raises the octane to between 97 and 98, 3 ron is supposed to raise 50 litres by 3 ron, but test show that this is not really the case, and by test data I would estimate the above increase. The M has a 13:1 compression ratio and with the mods it does make a noticeable difference in performance, but not really sure about consumption, I have a heavy foot by default. But you have to use at least a tank before you really notice the difference as the ECU is adaptive, does not run an optimized map immediately.

So in your opinion, would it be beneficial to collect logs without any octane boosters before a remap? My view is that if it collects data with proper octane before remapping with one of the tuners the car will perform poorly when running off pump fuel, whilst possibly causing serious detonation.

Not sure if this is the case, but I am assuming so.

Absolutely, but you got to b careful with the remap, depends on how it effects your torque curve, you could end up with higher consumption regardless of the octane rating being higher.

This would only be the case IF the torque band is moved further up in the rev range, not so?

 

[Whacko]

Always wondered about this. Will it push it up by more than 3 points if used with less fuel?

I worked it out, it raises the octane to between 97 and 98, 3 ron is supposed to raise 50 litres by 3 ron, but test show that this is not really the case, and by test data I would estimate the above increase. The M has a 13:1 compression ratio and with the mods it does make a noticeable difference in performance, but not really sure about consumption, I have a heavy foot by default. But you have to use at least a tank before you really notice the difference as the ECU is adaptive, does not run an optimized map immediately.

So in your opinion, would it be beneficial to collect logs without any octane boosters before a remap? My view is that if it collects data with proper octane before remapping with one of the tuners the car will perform poorly when running off pump fuel, whilst possibly causing serious detonation.

Not sure if this is the case, but I am assuming so.

Absolutely, but you got to b careful with the remap, depends on how it effects your torque curve, you could end up with higher consumption regardless of the octane rating being higher.

This would only be the case IF the torque band is moved further up in the rev range, not so?

Yes

 

[moranor@axis]

the chemistry is not that simple... if you add half you dont get half the Ron increase

Eg:

NF 5 ron and 6 ron are both 300ml so obviously a different formulation is needed to get up to 6ron

the only boost that has mixing instructions for different levels is the ULTRA RACE FUEL that comes in one 1l

when mixed with:

20l = 10ron
40l = 8ron
60l = 6ron

if you mix less in your tank you get ?ron :rollsmile: could work best for you car, but i worry that you might end up with an uneven mix in your tank... i dont know enough about the chemistry to know for sure what effect mixing less boost in has on the fuel...

 

[Whacko]

the chemistry is not that simple... if you add half you dont get half the Ron increase

Eg:

NF 5 ron and 6 ron are both 300ml so obviously a different formulation is needed to get up to 6ron

the only boost that has mixing instructions for different levels is the ULTRA RACE FUEL that comes in one 1l

when mixed with:

20l = 10ron
40l = 8ron
60l = 6ron

if you mix less in your tank you get ?ron :rollsmile: could work best for you car, but i worry that you might end up with an uneven mix in your tank... i dont know enough about the chemistry to know for sure what effect mixing less boost in has on the fuel...

The way I do it is I treat roughly 30 litres with 3 RON, don't forget the fuel in the tank has already been treated, so on a top up of +-30 litres I add one full bottle of 3 RON. If the tank is almost empty, I add 2 bottles.

 

[abmi0000]

the chemistry is not that simple... if you add half you dont get half the Ron increase

Eg:

NF 5 ron and 6 ron are both 300ml so obviously a different formulation is needed to get up to 6ron

the only boost that has mixing instructions for different levels is the ULTRA RACE FUEL that comes in one 1l

when mixed with:

20l = 10ron
40l = 8ron
60l = 6ron

if you mix less in your tank you get ?ron :rollsmile: could work best for you car, but i worry that you might end up with an uneven mix in your tank... i dont know enough about the chemistry to know for sure what effect mixing less boost in has on the fuel...

The way I do it is I treat roughly 30 litres with 3 RON, don't forget the fuel in the tank has already been treated, so on a top up of +-30 litres I add one full bottle of 3 RON. If the tank is almost empty, I add 2 bottles.

I somehow doubt that adding 2 x 3RON bottles will give you anything more than 3 point increase.

 

[Whacko]

the chemistry is not that simple... if you add half you dont get half the Ron increase

Eg:

NF 5 ron and 6 ron are both 300ml so obviously a different formulation is needed to get up to 6ron

the only boost that has mixing instructions for different levels is the ULTRA RACE FUEL that comes in one 1l

when mixed with:

20l = 10ron
40l = 8ron
60l = 6ron

if you mix less in your tank you get ?ron :rollsmile: could work best for you car, but i worry that you might end up with an uneven mix in your tank... i dont know enough about the chemistry to know for sure what effect mixing less boost in has on the fuel...

The way I do it is I treat roughly 30 litres with 3 RON, don't forget the fuel in the tank has already been treated, so on a top up of +-30 litres I add one full bottle of 3 RON. If the tank is almost empty, I add 2 bottles.

I somehow doubt that adding 2 x 3RON bottles will give you anything more than 3 point increase.

You are right again, remember we have 95 octane on the coast. So my estimate falls between two and three points.

 

[abmi0000]

You are right again, remember we have 95 octane on the coast. So my estimate falls between two and three points.

We have 95 here too but it just happens to be k@k :grin:

 

[moranor@axis]

the chemistry is not that simple... if you add half you dont get half the Ron increase

Eg:

NF 5 ron and 6 ron are both 300ml so obviously a different formulation is needed to get up to 6ron

the only boost that has mixing instructions for different levels is the ULTRA RACE FUEL that comes in one 1l

when mixed with:

20l = 10ron
40l = 8ron
60l = 6ron

if you mix less in your tank you get ?ron :rollsmile: could work best for you car, but i worry that you might end up with an uneven mix in your tank... i dont know enough about the chemistry to know for sure what effect mixing less boost in has on the fuel...

The way I do it is I treat roughly 30 litres with 3 RON, don't forget the fuel in the tank has already been treated, so on a top up of +-30 litres I add one full bottle of 3 RON. If the tank is almost empty, I add 2 bottles.

so you trying to make about 5 Ron from 3 Ron boost?

whatever Ron you ending up with might be right for your car but you might also want to try some 5 Ron its only R5 more expensive than two bottles of 3 Ron at my prices...

Im not convince that two bottles of 3 Ron will make 5 Ron if put in 60l like you doing because they are different formulations:

3 Ron is 200ml and treats 50l
5 Ron is 300ml and treats 60l

if they were the same formulation there would be a ratio between how much is mixed per L and how much Ron you get

 

[Whacko]

the chemistry is not that simple... if you add half you dont get half the Ron increase

Eg:

NF 5 ron and 6 ron are both 300ml so obviously a different formulation is needed to get up to 6ron

the only boost that has mixing instructions for different levels is the ULTRA RACE FUEL that comes in one 1l

when mixed with:

20l = 10ron
40l = 8ron
60l = 6ron

if you mix less in your tank you get ?ron :rollsmile: could work best for you car, but i worry that you might end up with an uneven mix in your tank... i dont know enough about the chemistry to know for sure what effect mixing less boost in has on the fuel...

The way I do it is I treat roughly 30 litres with 3 RON, don't forget the fuel in the tank has already been treated, so on a top up of +-30 litres I add one full bottle of 3 RON. If the tank is almost empty, I add 2 bottles.

so you trying to make about 5 Ron from 3 Ron boost?

whatever Ron you ending up with might be right for your car but you might also want to try some 5 Ron its only R5 more expensive than two bottles of 3 Ron at my prices...

Im not convince that two bottles of 3 Ron will make 5 Ron if put in 60l like you doing because they are different formulations:

3 Ron is 200ml and treats 50l
5 Ron is 300ml and treats 60l

if they were the same formulation there would be a ratio between how much is mixed per L and how much Ron you get

I have even tried 6RON, couldn't notice any difference on my test strip 800M I get 240 either way. In fact with the 6RON she seemed a bit more sluggish, I think it was an overkill.

 

[abmi0000]

the chemistry is not that simple... if you add half you dont get half the Ron increase

Eg:

NF 5 ron and 6 ron are both 300ml so obviously a different formulation is needed to get up to 6ron

the only boost that has mixing instructions for different levels is the ULTRA RACE FUEL that comes in one 1l

when mixed with:

20l = 10ron
40l = 8ron
60l = 6ron

if you mix less in your tank you get ?ron :rollsmile: could work best for you car, but i worry that you might end up with an uneven mix in your tank... i dont know enough about the chemistry to know for sure what effect mixing less boost in has on the fuel...

The way I do it is I treat roughly 30 litres with 3 RON, don't forget the fuel in the tank has already been treated, so on a top up of +-30 litres I add one full bottle of 3 RON. If the tank is almost empty, I add 2 bottles.

so you trying to make about 5 Ron from 3 Ron boost?

whatever Ron you ending up with might be right for your car but you might also want to try some 5 Ron its only R5 more expensive than two bottles of 3 Ron at my prices...

Im not convince that two bottles of 3 Ron will make 5 Ron if put in 60l like you doing because they are different formulations:

3 Ron is 200ml and treats 50l
5 Ron is 300ml and treats 60l

if they were the same formulation there would be a ratio between how much is mixed per L and how much Ron you get

I have even tried 6RON, couldn't notice any difference on my test strip 800M I get 240 either way. In fact with the 6RON she seemed a bit more sluggish, I think it was an overkill.

If you're running at 13:1 and found zero benefit, then I have clearly wasted my money on 6RON whilst my motor runs at 10.5:1 (I think) :bangdesk:

 

[moranor@axis]

looking at just static compression does not tell the full story because you timing will change the actual compression ratio thats how cars adjust to higher octane

Whacko you probably right because more octane means less energy in the fuel... how octane makes power is is allows you to use more of the power in the fuel... so once you have the right octane adding more will decrease performance...

this is why alot of top drag teams will run different octane depending on track conditions to give then the edge...

 

[Whacko]

looking at just static compression does not tell the full story because you timing will change the actual compression ratio thats how cars adjust to higher octane

Whacko you probably right because more octane means less energy in the fuel... how octane makes power is is allows you to use more of the power in the fuel... so once you have the right octane adding more will decrease performance...

this is why alot of top drag teams will run different octane depending on track conditions to give then the edge...

Too high an octane boost results in weak ignition of fuel, octane boost is really just to prevent pre ignition of fuel on higher compression engines (detonation), and obviously a very slight margin of less calorific value per litre, but the latter is so small, it's insignificant.

---

the chemistry is not that simple... if you add half you dont get half the Ron increase

Eg:

NF 5 ron and 6 ron are both 300ml so obviously a different formulation is needed to get up to 6ron

the only boost that has mixing instructions for different levels is the ULTRA RACE FUEL that comes in one 1l

when mixed with:

20l = 10ron
40l = 8ron
60l = 6ron

if you mix less in your tank you get ?ron :rollsmile: could work best for you car, but i worry that you might end up with an uneven mix in your tank... i dont know enough about the chemistry to know for sure what effect mixing less boost in has on the fuel...

The way I do it is I treat roughly 30 litres with 3 RON, don't forget the fuel in the tank has already been treated, so on a top up of +-30 litres I add one full bottle of 3 RON. If the tank is almost empty, I add 2 bottles.

so you trying to make about 5 Ron from 3 Ron boost?

whatever Ron you ending up with might be right for your car but you might also want to try some 5 Ron its only R5 more expensive than two bottles of 3 Ron at my prices...

Im not convince that two bottles of 3 Ron will make 5 Ron if put in 60l like you doing because they are different formulations:

3 Ron is 200ml and treats 50l
5 Ron is 300ml and treats 60l

if they were the same formulation there would be a ratio between how much is mixed per L and how much Ron you get

I have even tried 6RON, couldn't notice any difference on my test strip 800M I get 240 either way. In fact with the 6RON she seemed a bit more sluggish, I think it was an overkill.

If you're running at 13:1 and found zero benefit, then I have clearly wasted my money on 6RON whilst my motor runs at 10.5:1 (I think) :bangdesk:

I think you will benefit on 10.5:1 with 3 RON but maybe not on the same scale. Best would be to do before and after on a dyno.

 

[moranor@axis]

im not saying that a 13:1 engine will need less octane than a 10.5:1 but it just might depending on the dynamic compression and how the engine is setup... static compression ratio is just one indicator...

this kind of makes my point though because this shiz gets complicated fast... so the easiest way is just to monitor fuel consumption