GTD - Standard or performance diesel??

[monkeyhanger]

You'd need a few tankfuls of V-power to drive it to the point you'd be confident it makes a mpg difference, if it does at all.

If you look at Shell's own website, V-power Nitro in either Petrol oor Diesel variants is marketed at keeping your engine clean, which leads to efficiency gains, rather than making out that it's more potent and gains in mpg will be seen directly. Fuel tech across the board has come on so much in the past 10 years, even basic diesel is very clean, so are there any significant build-ups in the engine of a recent car for V-power to be cleaning?

[monkeyhanger]

Semi off topic, my GTI will probably be getting Tesco 99.  I've heard that gives the best improvements in power and efficiency when coupled to a variable cam time capable engine...

Bill, what's the GTI set up for? If it's set up for RON95 you might not see appreciable gains in using RON 98/99. If it's set up for 98/99 but capable of running 95 then you'll see those gains.

I was under the impression from previous brochures that 2.0TSI on MK5 and MK6 were set up for RON98 but were capable of running RON95 when higher octane fuels weren't available. On the current brochure it would seem that recommended fuel for GTI is RON95, with ability to use higher octane fuel. Variable timing allows it to use both, but preference of the engine seems to be an unknown at this stage. Anyone tried both for a few tanks each and conveyed the results yet?

[Bill_the_Bear]

I really don't know what I'm talking about...

However, I read that the variable cam timing and height allows the engine to adjust to the higher octane and use less fuel giving you improved mpg.  The test I read about showed best gains with Tesco 99 and specifically said you need the variable cams to take advantage of it.

Like I say this is not my area of expertise.

[p3asa]

good video to explain octane http://www.youtube.com/watch?v=D9nhXNarFdg

[ajmoir36]

I have 57k on the clock now no problems as such and it used to be run on Shell fuel as I thought it was better and it might be I am no expert, but when it became 3p more a litre I figured that's not worth it. (1000 miles a week). 73mpg was on my normal 28 mile trip to work in the morning, I think I have perfected the route really. Its a mix of 30/40 to 70 for a few miles then the remaining journey at 50/40/30. I have to admit it probably very hard to find any diesel that's not 5% bio these days and the majority are probably all 7% by now. They certainly don't advertise it that well. Most it states a particular BS standard on the pump somewhere.

[Bill_the_Bear]

good video to explain octane http://www.youtube.com/watch?v=D9nhXNarFdg

Nice.  Unless you change the compression ratio you'll not notice a difference with higher octane.  So if I've got this right the variable cam timing will adjust the compression ratio and the variable cam height will adjust the mixture (guessing that second part?) so the ECU can make use of the higher octane to reduce the amount of fuel needed and increase the mpg?  Not sure how the ECU will know how to do this though.  Anyone confirm/deny this?

[Hawaii-Five-O]

good video to explain octane http://www.youtube.com/watch?v=D9nhXNarFdg

Fascinating video that p3asa I learnt a lot watching it and now clearly understand what the octane rating means. I also learnt something about compression ratios too.

Basically if your engine is rated to 95 RON then there is absolutely now reason to put anything higher into your tank. You might as well burn money.

Cheers matey

[Agreeable Slick]

Knock sensors, cam postion sensors, sensors, sensors.... etc.

Basically it detects pre ignition and will either retard/advance the timing on the engine so that it can stop damage from the fuel pre ignition. So valves will either open sooner (retard) or later (advance) thus mixture has more / less time to be burnt fully. The other thing is that it will meter the fuel required as well so higher octane = more bang per mg, so less will be injected into the cylinder on each compression stroke.

[Bill_the_Bear]

Knock sensors, cam postion sensors, sensors, sensors.... etc.

Basically it detects pre ignition and will either retard/advance the timing on the engine so that it can stop damage from the fuel pre ignition. So valves will either open sooner (retard) or later (advance) thus mixture has more / less time to be burnt fully. The other thing is that it will meter the fuel required as well so higher octane = more bang per mg, so less will be injected into the cylinder on each compression stroke.

Cheers AG!

[Ricepop]

good video to explain octane http://www.youtube.com/watch?v=D9nhXNarFdg

Nice.  Unless you change the compression ratio you'll not notice a difference with higher octane.  So if I've got this right the variable cam timing will adjust the compression ratio and the variable cam height will adjust the mixture (guessing that second part?) so the ECU can make use of the higher octane to reduce the amount of fuel needed and increase the mpg?  Not sure how the ECU will know how to do this though.  Anyone confirm/deny this?

Variable valve timing has nothing to do with compression ratio. Valve timing is when the valves open in relation to the piston position, Compression ratio is the difference between the volume of the cylinder at bottom dead centre compared to top dead centre. They will not effect each other.

I always use Morrison's diesel and never have a problem with it. If you think there is a difference you are kidding yourself.

Save some money and buy the cheapest fuel it all comes from the same place.