--- In [email protected], "Bru Peckett" <[EMAIL PROTECTED]> wrote: > > Colin wrote .. > > > As an advocate for Ultimate it probably takes several tankfulls to > > clean the > > system out. As I said before it costs 5% more but on long runs I get > > 10% > > better fuel Consumption. My daughter who has my old Mk1 Zafira and only > > does > > short school runs gets to the point where its lumpy starting. I buy her > > a > > tankfull of Ultimate and it improves quite quickly. I've a friend who > > caravans and he always fills up with Ultimate when he caravans, reckons > > he > > can feel the difference. Hate to sound like a BP advert but reckon its > > worth > > the money. Apparently it also has a higher Cetane number (cue Ron) > > which > > means you get more bang for the money. > > Well, as an employee of BP I'm supposed to persuade people to switch to the > stuff so I entirely agree with everything you say!!! > > [Can I have a pay rise now please boss?] > > Bru
I hope not - that bit about the Cetane number is just wrong. The cetane number describes how easily the fuel will ignite in the cylinder, the higher the number the easier it will ignite. This is important because the longer it takes to ignite the more fuel is in the cylinder before it ignites so when it all goes off at once you get a very rapid pressure rise in the cylinder creating a worse diesel knock. We are talking about microseconds here and I honestly can not see a low cetane number causing any problems for a well designed diesel heater. The "advanced" diesel fuels may well have a higher cetane number and that will make the engine feel far smoother and run quieter. I could argue that it would make the combustion process more of a constant pressure one so MIGHT produce a more sustained "push" on the piston I suspect the reality in our marine engines with more or less fixed injection timing is rather different. I know the TVU van appeared to drive differently when I was forced to put some of the BP stuff into it. Tony Brooks
