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Old 01 September 2005, 10:54   #31
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Someone i know has been running his diesel on almost 100% veg oil, purchased from Tesco (or wherever) for over a year and over 15,000 miles. It's caused no problems, appart from starting when cold. £5 worth of "real" diesel per tank of veg oil seams to solve this. Yes the car does smell a little of a chip shop, but it still goes just as well.
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Old 25 July 2006, 16:09   #32
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Octane is not a measurement of power. Octane ratings are a measurement of the fuel's ability to resist harmful engine knocking or pinging, ie pre-detonation. An engine that has 13.5:1 compression requires high octane fuel so that the air/fuel mixture does not spontaneously ignite (under heat/pressure) before the ignition system triggers the sparkplug to ignite the mixture. It is the high compression in the engine cylinders that make the increased power, not the higher octane fuel (which is required to avoid pre-detonation).

With that said, even though I beleive that there is no power gain to be had by running higher octane fuel than what is required by the engine, I do beleive that the higher octane fuels have a superior additive package and are worth running through your fuel system every once in a while.
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Old 27 July 2006, 17:59   #33
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This came straight from Tohatsu they didnít recommend me running anything other then reg unleaded in my TLDIís because of the extra ethanol used in the supper to up the octane and decrease emissions. Their comment was that the seals in the outboard are good to about 10% ethanol anything greater will start to dry out and crack the seals in the fuel system.
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Old 28 July 2006, 04:41   #34
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Petroleum

Apparently, is you use Optimax (from Shell) your engine will run cleaner, quicker and smoother.

I have tried and tested this theory in my Aunties EVO, I ran what was in the tank down to virtually empty and put a scores worth of Optimax in. We received lots of information when we plugged the ECU into the laptop -

1. 3.78% more MPG
2. 2.4.....% increase in accelaration
3. 1.68% temperature gain - Hotter engine

The list went on and on about how much the car had improved.

I then heard that a supermarket had a Super Unleaded which has a RON rating of 99%, for those that don't know, this is good.

We tested this aswell and got more increase, but the temperature gian was slightly less than the Optimax, the engine seemed to sound as if it were running more freely too.

I thouroughly recommend Tescos Super Unleaded
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Old 28 July 2006, 07:44   #35
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Quote:
Originally Posted by DaCosta
Apparently, is you use Optimax (from Shell) your engine will run cleaner, quicker and smoother.

I have tried and tested this theory in my Aunties EVO, I ran what was in the tank down to virtually empty and put a scores worth of Optimax in. We received lots of information when we plugged the ECU into the laptop -

1. 3.78% more MPG
2. 2.4.....% increase in accelaration
3. 1.68% temperature gain - Hotter engine

The list went on and on about how much the car had improved.

I then heard that a supermarket had a Super Unleaded which has a RON rating of 99%, for those that don't know, this is good.

We tested this aswell and got more increase, but the temperature gian was slightly less than the Optimax, the engine seemed to sound as if it were running more freely too.

I thouroughly recommend Tescos Super Unleaded

It is not 99% - it is the octane rating. Not bad but only just better than the old 4 star. They used to sell 5 star petrol in this country which was I think 105 octane - during WWII spitfires ran on 150 octane!!!
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Old 28 July 2006, 08:16   #36
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Fuel additives

Thanks for correcting me.

What about fuel additives?

There are some additives out there, that thicken the fuel up. The best time to fill up is in the cold too, as the fuel is thicker and you get more for your money as it expands when it gets warmer. Learnt that off Top Gear!!
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Old 28 July 2006, 10:13   #37
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Quote:
Originally Posted by DaCosta
Thanks for correcting me.

What about fuel additives?

There are some additives out there, that thicken the fuel up. The best time to fill up is in the cold too, as the fuel is thicker and you get more for your money as it expands when it gets warmer. Learnt that off Top Gear!!
But I can't get enough in my tank in February to last me through the summer
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Old 28 July 2006, 15:08   #38
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Quote:
Originally Posted by DaCosta
Thanks for correcting me.

What about fuel additives?

There are some additives out there, that thicken the fuel up. The best time to fill up is in the cold too, as the fuel is thicker and you get more for your money as it expands when it gets warmer. Learnt that off Top Gear!!
There are various octane boosters out there - methanol and nitromethane help or even acetone(nail varnisher remover) but you have to be careful and often the engine needs the timing adjusted to take real advantage of it.
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Old 28 July 2006, 23:59   #39
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Quote:
Originally Posted by Donnie144
This came straight from Tohatsu they didnít recommend me running anything other then reg unleaded in my TLDIís because of the extra ethanol used in the supper to up the octane and decrease emissions. Their comment was that the seals in the outboard are good to about 10% ethanol anything greater will start to dry out and crack the seals in the fuel system.
There are a number of different ways to up the octane rating of gas. Ethanol is one (ignites at a higher temp than pure gas); however, it's primary purpose for being in gas in the US is as an oxygenator. Oxygenated fuels burn more completely, reducing visible pollution.

A while back, the gas companies had the US gov't require MTBE as an oxygenator, which raised gas prices by about 15 cents a gallon for the added production costs. When they were about to be sued for MTBE polluting groundwater, they agreed to change to ethanol, but it would cost about 15 cents a gallon to stop putting MTBE in, and a bit more to start blending ethanol. All the while, the big oil companies were turning record profits. Go figure.

Higher octane fuels in most engines will not release more energy than lower octane fuels. As someone said above, they are harder to ignite, so have less of a tendency to detonate (pinging, knocking, dieseling, etc.) Most high performance engines will require it due to higher compression ratios. Engines that run very lean may also, due to higher heat levels. Normal engines may see a very slight change in power output due to changes in detonation timing, but it generally will not be large enough to detect without dyno'ing the engine.

The opposite, however, is very bad. Running low octane fuel in an engine designed for high octane will cause pre-ignition, which will prematurely wear valves, pistons, rods; pretty much all moving parts in the motor.

jky
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