Don't think anyone is disagreeing?
Nope because you made the blanket statement that all engines will return more MPG if they are capable of using higher octane?
Because the majority of your posts are open ended one liners
Premium fuels. Hidden benefit
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It effect the flow into the combustion chamber. The end
Its not the end though. How about carry on your train of thought and back up any conclusions?
Welcome to post 19.
When did I say that? I said if the engine can benefit from high octane it will get higher mpg
All engines are capable of using high octane fuel!
I thought we established that the pictures refer to a apecific indirect injection engine that hasn't been used in any cars since 2010?
Care to show pictures of premium fuel doing the same for direct injection engines? Assuming we can base everything on how things look.
All the Shell literature also always refer to improvements in port injection engines.
https://www.youtube.com/watch?v=4WPfLnVuQyM
Not disputing the cleaning effects in port injection engines. Disputing the actual benefit (engine manufacturers are aware there will be some carbon buildup which reaches an equilibrium, DPFs, EGRs etc. all have some build up as well which can't be helped). Assuming I concede that for a second anyway.
Are we saying the benefits these pictures are showing are not what you will see with DI engines? Yes?
What do the pictures above tell me about my direct injection engine? Something not being witchcraft or something, You told me to look at them.
Actually a lot of manufacturers are now switching to a duel injection system (VAG, Subaru, Ford and others). It's not to prevent build up of carbon, though. It's actually to meet Euro 6 and above emissions regs. Direct injection is more efficient, but it's very dirty indeed compared to port injection. Newer dual injection systems use direct injection to stabilise idle and at full load, and port injection the rest of the time. The fact this gives the inlet valves a good wash and clean is just a happy side effect.
Simon, I understood the spirit of your post and I agree with it. Carbon deposits even on DI vehicles (injectors etc) will rob combustion efficiency and even affect the air:fuel rate by absorbing fuel from the mixture. Keeping injectors clean is no bad thing, and for the small extra cost compared to everything else you pay for in running a car, it'd be daft not to use the best you can really.
My car returns around 10% better MPG on 99 RON, but it was designed for such fuel. @Armageus you said a car might provide more power rather than better economy on high octane / premium fuel, but surely to a degree they're interchangeable? You either make full use of the benefits (e.g. ignition advance) and gain more power than on 95 RON because you planted your right foot, or you used it to gain MPG by getting the same power as before but with less throttle?
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I was curious about this and found a copy of the E46 M3 manual for the USA model which has 333BHP. Compared to the UK one (343BHP), the manual says that the engine is designed to be run on 91 octane premium unleaded fuel. The UK/EU manual says it is designed to run on 98 octane. There are no physical differences between S54 engine in either market otherwise.
Does the octane of fuel differ between Europe and USA then? Or is this how BMW met the regulations for the US market by adjusting the ECU for 91 octane vs the EU version's 98, and thus resulting in 10HP difference?
Does the octane of fuel differ between Europe and USA then? Or is this how BMW met the regulations for the US market by adjusting the ECU for 91 octane vs the EU version's 98, and thus resulting in 10HP difference?
The mapping will be different to make use of the different fuels. Petrol in the US tends to be lower quality in places.
But also, manufacturers have been known to fudge official figures to get lower tax bands etc
In the US they use AKI (anti knock index), sometimes called PON (pump octane number) which is worked out with RON x MON / 2. Roughly:
86-87 AKI (91-92 RON) for regular
89-90 (94-95) for mid-grade (European Premium)
90-94 (RON 95-99) for premium unleaded or E10 (Super in Europe)
Ah that makes sense. So largely not much difference then with conversion considered.
Probably right, but it's not helped by literally every piece of written material using one or the other I know mine made 337.7hp on dyno,
Probably right, but it's not helped by literally every piece of written material using one or the other
I know mine made 337.7hp on dyno,