C
Captain Nemesis
Husqvarna ?
Husqvarna recommends not to use high octane petrol
- Thread starter pidgeon1
- Start date
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High octane fuels are more resistant to ignition, which sounds a bit curious - until we recognise that this prevents the phenomenon of pre ignition - (knocking) or 'pinking'. High compression engines require higher octane fuel to deliver optimum performance.
Modern engines have knock sensors that can detect the onset of pinking and fractionally ****** the ignition timing to compensate, courtesy of the engine ECU.
Conversely, low compression engines may not like high octane fuels and performance may be affected to some degree. Two stroke and four stroke side valve engines may fall into this category.
John
Modern engines have knock sensors that can detect the onset of pinking and fractionally ****** the ignition timing to compensate, courtesy of the engine ECU.
Conversely, low compression engines may not like high octane fuels and performance may be affected to some degree. Two stroke and four stroke side valve engines may fall into this category.
John
It's not just old cars. Many modern performance cars (VW Golf R, Audi "S" and "RS" models and plenty others) recommend 98+ Octane for full performance. Of course they can run on 95 but this will result in lower power output and lower MPG.
unless you have an accelerator pedal that you can press.
My car says "Vehicles with a petrol engine require the use of premium unleaded fuel, with a minimum octane rating of 95 RON. Using the correct fuel specification helps to maintain the vehicle's performance, fuel economy, and driveability.
If premium unleaded fuel is not available, use unleaded fuel with a lower octane rating, down to a minimum of 91 RON. Using lower octane rated fuel may reduce the engine's performance, increase fuel consumption, and cause an audible engine knock and other driveability problems."
I don't think I've been offered fuel unsuitable for my car anywhere n Europe.
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What a daft argument. Your thinking is decades behind. The manufacturers map the engine ECU to take advantage of the higher octane and the quoted horsepower is based on the use of this fuel. Engine power output is a function of fuel/air and timing or retardation - the accelerator merely controls the delivery of the output. It may surprise you to know that many cars have a sports button (or profiles, Audi for example have 4 modes in their S/RS models) that shifts the scaling of the accelerator so the output has nothing to do with how much you move your foot - more about the setting the car is using.
Your car requires 95 and at a push can run on 91 - your car is not every car. I was merely pointing out that there are many many modern performance vehicles where the manufacturer says you should run them on 98 or higher if you want the performance and economy (I've had several - they have a 98 sticker on the fuel cap). Your original statement suggested that only old non ECU equipped cars need high octane fuel. You're wrong.
But if you are driving on the road (not the racetrack) under normal conditions, you will never be using anything near 100% of nominal power.
What does it matter if you are driving at 60, using 16% of a available power, rather than at 60 using 14% of the maximum you might have had with a more expensive and polluting fuel.
Just as you will do if carrying a portly passenger rather than a thin one, or the weight of a full tank rather than a half-empty one, or driving on an incline rather than the flat, you, or your automated controls, will simply put your foot down an infinitesimal amount without even noticing.
That has nothing to do with your original argument and you know it. You're just trying to cover the fact you don't understand the topic.
Yes it does.
That's why I quoted you including your use of the word "if"
What will your car do if you put 95RON fuel in it?
Run at a lower power output and be less economical as I stated originally (and crucially require the ECU to intervene more often to reduce knock, hence the lower power output, this in itself is bad for the engine and is warned about in the owners manual - eg don't cane it when using lower octane fuel).
No it's not. Your original assertion was that only old vehicles without ECU require high octane fuel. Your statement about carrying a heavy person has no bearing on engine output either, yes it will affect fuel economy but a fat bloke doesn't cause engine knock.
It's clear you don't understand engine calibration and are now looking for an obtuse argument to back pedal. Do the OP a favour and leave it there, it's the garden section about a mower.
I think you mean "use marginally more fuel"
Bearing in mind the extra cost of your superduper petrol, this is not the same thing as "more economically"
Oh right I see, you're wrong so now you double down on the minutia of sentence construction. Where I'm from this is how people phrase such a statement - it's common to use "less than" rather than "fewer" also, so to coin another local phrase "bugger off".
Wrong.
My original comment alluded to the fact that a modern ECU can accomodate different octanes.
Which it can.
Even yours.
Why not just fill the 10 litre can with low octane fuel after you have filled your car with high octane fuel or are you in that much of a rush when buying fuel?
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