RUNNING ON 95 RON UNLEADED
- Thread starter Sandeep
- Start date
Of course it will run on 95 - in fact you try finding 98 in places like Italy, Corsica etc... [&o]
It is designed to run on 98, and will back off the timing automatically to adjust for the faster burning 95 fuel - so not causing problems. You lose a little performance however, but I'd defy anyone to notice.
Having said that, I always use 98 unless forced otherwise. [
]
By the way, most report better economy as a side benefit of running 98.
It is designed to run on 98, and will back off the timing automatically to adjust for the faster burning 95 fuel - so not causing problems. You lose a little performance however, but I'd defy anyone to notice.
Having said that, I always use 98 unless forced otherwise. [
]By the way, most report better economy as a side benefit of running 98.
engineerjim
New member
Mark
98 was widely available in Italy this summer. It has just been introduced by Agip so look out for blue pumps
Regards
Jim
98 was widely available in Italy this summer. It has just been introduced by Agip so look out for blue pumps
Regards
Jim
Good to know [8D]
Thanks [
]
ORIGINAL: THX911
...and the extra additive in the higher RON fuel like V-Power, BP Ultimate must be good for your engine in the long run...
Something to ask your local MP: why is fuel tax the same on higher RON fuel, if it burns cleaner and gives better mileage [
I noticed when I was in France that the "premium" for using 97/98 Octane fuels was only a few euro cents, so presumably there is no tax difference on the higher octane fuel on the continent
Pete
Dapster
New member
Interestingly the Audi Centre in the Docklands told me that they fuel all their cars on 95 including the RS models. Presumeably this is because they only have responsibility for the cars for 3 - 6 warranty covered months at most....
I'd imagine engine longevity is more likely related to following a correct warm up procedure and the use of good oils rather than the choice of fuel.
I'd imagine engine longevity is more likely related to following a correct warm up procedure and the use of good oils rather than the choice of fuel.
[Devils advocate coat on]
Engine longevity.......has anyone known a 986/996 to have problems due to unsympathetic treatment of their engines?
I, like most others on here, make sure I don't rev the car past 4k until the coolant is at full running temp and then wait a few minutes for the oil to warm up before I rev it any more. I always use at least 97RON fuels, almost always Optimax, occassionaly Tesco 99Ron.
However, apart from anecdotal(?) evidence of higher MPG/BHP when using these fuels, and general guilt when not warming up the engine correctly, what evidence is there to support this expensive and cautious behaviour? Wouldn't these engines pack up/need a rebuild, long before the effects of this kind of misuse ever emerge?
According to Porsche's own figures, us owners tend to sell our cars every 18 months. During any 18 month period of ownership, what percentage of the owners will ever feel the effects of misuse during the car's lifetime? What percentage of these cars is owned by people who have no idea about these precautionary measures? Are their cars worth any less or are less desireable? If so based on what evidence?
[Devils advocate coat on]
Engine longevity.......has anyone known a 986/996 to have problems due to unsympathetic treatment of their engines?
I, like most others on here, make sure I don't rev the car past 4k until the coolant is at full running temp and then wait a few minutes for the oil to warm up before I rev it any more. I always use at least 97RON fuels, almost always Optimax, occassionaly Tesco 99Ron.
However, apart from anecdotal(?) evidence of higher MPG/BHP when using these fuels, and general guilt when not warming up the engine correctly, what evidence is there to support this expensive and cautious behaviour? Wouldn't these engines pack up/need a rebuild, long before the effects of this kind of misuse ever emerge?
According to Porsche's own figures, us owners tend to sell our cars every 18 months. During any 18 month period of ownership, what percentage of the owners will ever feel the effects of misuse during the car's lifetime? What percentage of these cars is owned by people who have no idea about these precautionary measures? Are their cars worth any less or are less desireable? If so based on what evidence?
[Devils advocate coat on]
This is a lively debate on the Impreza web sites and seems to be due to running 95 ron in older imported Jap cars set to run on 99/100 with their ECU's unable to retard timing enough. Many an import STi has melted a pistion on its boxer engine.
Modern cars are designed to run to the knock limit of the fuel in use, so as long as the fuel is within the range of the ECU, then there is no more damage running on 95 as against 98. I imagine that the Porsche ECU is more than capable of retarding enough.
Some power will be lost as the ECU adjusts
Modern cars are designed to run to the knock limit of the fuel in use, so as long as the fuel is within the range of the ECU, then there is no more damage running on 95 as against 98. I imagine that the Porsche ECU is more than capable of retarding enough.
Some power will be lost as the ECU adjusts
bryno
New member
Anorak on:
There are a few sources of heat from a nomally aspirated unning engine, primarily the actual combustion process, and exhaust gas temperature. Secondary from internal friction in bearings and other moving parts (pistons). The heat of combustion is removed by the coolant normally water and them transferd to atmosphere by the radiator. The heat from friction effects in bearings is transfered to the lubricant i.e the oil and in most engines removed to the air by surface contact with the crankcase or in more sophisitcated high perfomance engines the oil temperature is reduced in a cooler whether oil to air or even oil to water.
With the majority of the heat energy wasted in an engine coming from the combustion process and transfered to the coolant the coolant temperature always gets to "running temperature" before the oil temperature.
The oil as well as lubricating also removes heat from bearings caused by fricition, this is not any metal to metal friction (rare in a well maintained engine) but the friction between the oil and the bearuing surfaces as they are in contact under pressure not just from the oil pump but especially from combustion pressures on the main and big ends with a substantial component from all other bearings especailly any thrust bearings. The oil temperature will thus rise as the engine begins to work, the substantial heat imput going into the coolant with the important but secondary heat input into the oil from the bearings.
I would concur with Rodney's running regime of not using maximum revs and thus higher power outputs until the oil temperature is up and the bearings have reached their designed working tolerances.
If you have a car with oil & water temperature gauges you will notice this effect. When working an engine hard say on a track day you will see the oil temperature rise to levels not seen on normal road driving.
Anorak off:
Regards
Bryn Owen
Boxster Register
Technical Assistant.
There are a few sources of heat from a nomally aspirated unning engine, primarily the actual combustion process, and exhaust gas temperature. Secondary from internal friction in bearings and other moving parts (pistons). The heat of combustion is removed by the coolant normally water and them transferd to atmosphere by the radiator. The heat from friction effects in bearings is transfered to the lubricant i.e the oil and in most engines removed to the air by surface contact with the crankcase or in more sophisitcated high perfomance engines the oil temperature is reduced in a cooler whether oil to air or even oil to water.
With the majority of the heat energy wasted in an engine coming from the combustion process and transfered to the coolant the coolant temperature always gets to "running temperature" before the oil temperature.
The oil as well as lubricating also removes heat from bearings caused by fricition, this is not any metal to metal friction (rare in a well maintained engine) but the friction between the oil and the bearuing surfaces as they are in contact under pressure not just from the oil pump but especially from combustion pressures on the main and big ends with a substantial component from all other bearings especailly any thrust bearings. The oil temperature will thus rise as the engine begins to work, the substantial heat imput going into the coolant with the important but secondary heat input into the oil from the bearings.
I would concur with Rodney's running regime of not using maximum revs and thus higher power outputs until the oil temperature is up and the bearings have reached their designed working tolerances.
If you have a car with oil & water temperature gauges you will notice this effect. When working an engine hard say on a track day you will see the oil temperature rise to levels not seen on normal road driving.
Anorak off:
Regards
Bryn Owen
Boxster Register
Technical Assistant.
sawood12
New member
Actually you'd be surprised as to how long your oil takes to get upto temp. You can't use how long it takes for your heater to start blowing warm air as an indicaion. Unless you have an oil temp gauge you should allow a good 10 mins to assusme your oil is fully upto temp. Once upto temp then you cannot abuse modern engines. They all have rev limiters now so you can't over rev them and they are usually set to safe levels so you'll have a good 1000rpm margin there.
In terms of 95 vs 98 RON fuel - so long as your ECU can run both then there is no detremental effect to your engine. The reason why higher octane fuels will either give you more power or better fuel economy (you can only have one, not both) is because a higher octane fuel allows the fuel air mixtrure to be compressed more (i.e. delayed spark) meaning more energy will be released once the mix is combusted which means more torque. You can either use the extra torque to change gear earlier, hence benefit from the better fuel economy, or you can just enjoy the extra performance. In reality you might struggle to notice the difference through the seat of your pants but the laws of chemistry dictate that running 98 RON will give you more energy per bang than 95RON.
Unfortunately due to the petrol distribution network when you buy 95 RON you are getting something less than 95 RON by the time it gets to the pump. This is due to dilution of the petrol with contaminants (water, oils, other chemicals etc). So one reason for using higher octane fuels is to guarantee that you do actually have at least 95 RON in your tank.
In terms of 95 vs 98 RON fuel - so long as your ECU can run both then there is no detremental effect to your engine. The reason why higher octane fuels will either give you more power or better fuel economy (you can only have one, not both) is because a higher octane fuel allows the fuel air mixtrure to be compressed more (i.e. delayed spark) meaning more energy will be released once the mix is combusted which means more torque. You can either use the extra torque to change gear earlier, hence benefit from the better fuel economy, or you can just enjoy the extra performance. In reality you might struggle to notice the difference through the seat of your pants but the laws of chemistry dictate that running 98 RON will give you more energy per bang than 95RON.
Unfortunately due to the petrol distribution network when you buy 95 RON you are getting something less than 95 RON by the time it gets to the pump. This is due to dilution of the petrol with contaminants (water, oils, other chemicals etc). So one reason for using higher octane fuels is to guarantee that you do actually have at least 95 RON in your tank.
GOOFY
New member
I myself would run on 98 Ron as the engine compression is designed for this fuel. From my experience tuning early Beetle engines I remember that you could compensate for low octane by retarding the ignition - the point at which the spark occurs. This is now achieved automatically by the ECU in modern engines - called anti knock. However I remember the downside was that you risked burnt out valves - as the ignition occured later, the exhaust gases were hotter on leaving the combustion chamber, (having not done enough "work" in the combustion chamber as ignited later by the time the exhaust valves begin to open). By using lower octane you are not using the engine at it's peak efficiency - hence the lower mpg.
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