High Octane or not to High Octane
- Thread starter MovingShadow
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jra3d
Well-known member
This evening it starts!
Have put V-Power in both the Twingo and the Megane from new and the same goes for the Mrs Twingo as well.
All cars by law have to be able to run on 95RON fuel but a lot of tuned engines are designed to run on 98RON+ so I've always fuelled mine with V-Power (plus I live round the corner from a Shell petrol station lol).
I can recall guys on MeganeSport.net running their car on supermarket 95RON fuel and their cars going into 'limp mode'. Also for the minimal driving and petrol I pay out for, I've no reason not to opt for the better stuff.
All cars by law have to be able to run on 95RON fuel but a lot of tuned engines are designed to run on 98RON+ so I've always fuelled mine with V-Power (plus I live round the corner from a Shell petrol station lol).
I can recall guys on MeganeSport.net running their car on supermarket 95RON fuel and their cars going into 'limp mode'. Also for the minimal driving and petrol I pay out for, I've no reason not to opt for the better stuff.
jra3d
Well-known member
Mmm the smell of power when you fill it up always smells good 
jra3d
Well-known member
No idea they seem to vary in tank length!
decbolton":1n8micle said:haha
I'm guessing that the Octane rating of V-Power (98) and rating of Tesco 99 which is 99RON (obviously lol) are genuine. But what Shell claim from their fuel is that it has other additives that are good for your engine where as I don't think Tesco pride their 99 fuel with any additives.
I'd personally consider Tesco 99 as the budget high octane fuel! lol
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waitey
Well-known member
Dumb question but does getting a remap say on 98shell mean the engine afterwards will only work best with 98 and if you put standard fuel in it will run rough?
Can't remember where I heard this think it was on the forum somewhere.
Only asking as was contemplating remapping my twingo when I want abit more 'oomph'.
Can't remember where I heard this think it was on the forum somewhere.
Only asking as was contemplating remapping my twingo when I want abit more 'oomph'.
I'm no expert but as far as I know, that is correct. For example a lot of Jap cars are mapped to run 100RON+ as higher octane fuels are readily available in Japan. I've heard that quite a few imports will require fuel additives to bring up the octane rating.
Effectively if you have you car mapped to make the most of 98RON fuel then you'd ideally need to keep putting that fuel in.
Effectively if you have you car mapped to make the most of 98RON fuel then you'd ideally need to keep putting that fuel in.
Is that a turbo of some kind like a TDI? Only reason I ask is because a turbo engine get's much better gains from a re-map. For example a Megane 225 will see 260bhp from a re-map but if you re-map a Clio 172 for example you probably won't really see even 10bhp.
TwingoConvert
Member
If the 133vvt engine has only one engine map available and no knock sensors fitted (and I've not read anything definitive yet in the handbook or elsewhere-please tell me otherwise) then the engine is not able to detect higher octane fuels in order to take advantage of the higher compression that they allow, and that means you are wasting your money.
Many high performance engines eg M series beemers and mitsubaru 2.0 turbos can do this, but, Im not sure the humble 1.6 renault unit is that sophisticated.
Many high performance engines eg M series beemers and mitsubaru 2.0 turbos can do this, but, Im not sure the humble 1.6 renault unit is that sophisticated.
jra3d
Well-known member
TwingoConvert that's quiet interesting, didn't know any of that!
TwingoConvert
Member
I don't want to get too technical here, but trying to keep it simple, 95/98/100 etc octane fuels all have the same energy content, it does not follow that higher octane fuels are more 'powerful'.
Additives in the fuel (used to be lead) prevent the fuel detonating as it is compressed (as it does in a diesel engine), the more you can compress the fuel/air mixture will determine the power released, however it will also get much hotter as you compress it. The ignition will spark later in the cycle to take advantage of the higher compression.
If the ignition is fixed for 95ron fuel then the compression is fixed at that point and using 98 or higher is pointless. If the engine is enabled to detect the higher octane fuel it will delay the spark (ignition timing) to suit, giving extra power.
If the engine is designed to run 98 or higher fuel and does not have a knock sensor, then using 95 fuel and driving hard will damage the engine as the fuel will detonate while the piston is still rising, and before the spark plug fires.
Even in an engine that is able to adjust it's timing, I doubt the economy gains would outweigh the extra cost of the fuel!
Hope that helps!
Additives in the fuel (used to be lead) prevent the fuel detonating as it is compressed (as it does in a diesel engine), the more you can compress the fuel/air mixture will determine the power released, however it will also get much hotter as you compress it. The ignition will spark later in the cycle to take advantage of the higher compression.
If the ignition is fixed for 95ron fuel then the compression is fixed at that point and using 98 or higher is pointless. If the engine is enabled to detect the higher octane fuel it will delay the spark (ignition timing) to suit, giving extra power.
If the engine is designed to run 98 or higher fuel and does not have a knock sensor, then using 95 fuel and driving hard will damage the engine as the fuel will detonate while the piston is still rising, and before the spark plug fires.
Even in an engine that is able to adjust it's timing, I doubt the economy gains would outweigh the extra cost of the fuel!
Hope that helps!
jra3d
Well-known member
Makes sense and really interesting!
Matt
Well-known member
You'll notice on the petrol cap of the Twingo that Renault have recommended 95. I honestly don't notice any differences when using 98/99 and I run it for about 4/5 tanks.
If the price difference isn't much at whatever station im filling up in then I'll go for super because I'm won over by the "better for your engine" marketing malarky but I've no idea whether it makes any difference really.
Anyway, Renault recommend 95 so that's what I tend to go for. Don't think that's it's a poverty fuel or will give you less performance.
If the price difference isn't much at whatever station im filling up in then I'll go for super because I'm won over by the "better for your engine" marketing malarky but I've no idea whether it makes any difference really.
Anyway, Renault recommend 95 so that's what I tend to go for. Don't think that's it's a poverty fuel or will give you less performance.
Timbob955
New member
"The ignition will spark later in the cycle to take advantage of the higher compression."
Sorry folks but I've got to put my 2p in here. When you run 98RON fulel the ignition timing is actually more advanced (earlier in the cycle) than with 95. This means you get a longer burn duration and more complete combustion of the fuel, hence more power. Nearly all modern engines have knock sensors to compensate for the wide range of fuel qualities seen around the world which means you can run the engine as efficiently as possible no matter what the fuel type.
Knock sensors are normally bolted to the side of the block and 'listen' for knock (vibration). When knock is detected the engine management system will retard the ignition timing until it stops and then advance the timing again until it starts again. Manufacturers will normally map the ignition/fuelling to suit 98RON because any decent knock system will be able to compensate for the differences seen with 95.
If you drive steadily you should see better MPG with 98, I got an extra 30 miles out of a tank and so now only run 98.
Hope this helps!
Sorry folks but I've got to put my 2p in here. When you run 98RON fulel the ignition timing is actually more advanced (earlier in the cycle) than with 95. This means you get a longer burn duration and more complete combustion of the fuel, hence more power. Nearly all modern engines have knock sensors to compensate for the wide range of fuel qualities seen around the world which means you can run the engine as efficiently as possible no matter what the fuel type.
Knock sensors are normally bolted to the side of the block and 'listen' for knock (vibration). When knock is detected the engine management system will retard the ignition timing until it stops and then advance the timing again until it starts again. Manufacturers will normally map the ignition/fuelling to suit 98RON because any decent knock system will be able to compensate for the differences seen with 95.
If you drive steadily you should see better MPG with 98, I got an extra 30 miles out of a tank and so now only run 98.
Hope this helps!
TwingoConvert
Member
If it has additional detergents that possibly clean the fuel injectors etc it may be better, but that is unrelated to the octane rating (RON) and nearly all fuels contain detergents nowadays anyway.
Those of us who remember the "Formula Shell" debacle during the late 80's where shell fuels were proven to be damaging inlet valves on many cars, may treat these unverifiable claims by fuel companies with a big pinch of salt...!
Those of us who remember the "Formula Shell" debacle during the late 80's where shell fuels were proven to be damaging inlet valves on many cars, may treat these unverifiable claims by fuel companies with a big pinch of salt...!
TwingoConvert
Member
This explains it better than I can! Basically, the question we all would like answered is; can the 1.6vvt motor adapt it's settings to properly take account of high octane fuel?!
https://oldeloohuis.com/octane3.html
https://oldeloohuis.com/octane3.html
singlespeed
Well-known member
I'm not 100% sure if the RS133 can learn and addapt to different fuels. I know my old Toyota MR2 could as there was a noticable difference when going from 95-98 and back. It was more noticable going from 98 to 95, where it would be rough and lifeless for the first 10-20 miles then it would have remapped itself to compensate. Also, disconnecting the battery would mean it defaulted back to it's base map and needed to re-learn and adapt the base map to suit whichever fuel is in.TwingoConvert":awu0kubf said:
With the Twingo, theres no noticable roughness when going from 98 to 95 and I know that disconnecting the battery on the RS doesn't make any difference (however any adaptation could be stored in non volatile memory).
I had my remap done on 95 as 98 isn't always avaliable in some areas up here
MovingShadow
Well-known member
Matt":r031k5l7 said:
On the inside of my fuel cap it recommends 95 as well as 98