Tesco Momentum vs. Shell V-Power

[jondkent]

Tried Momentum for the first time a few weeks ago, car certainly seemed to like it. Even my passenger noticed the difference in the way it shifted and my wallet has noticed the difference as well. Sticking to it me thinks.

[350matt]

where some folks have had issues running high octane I'd strongly suspect that this has been where the fuel is basically old and de-natured

as high octane goes off more quickly than 95 and as most folks don't bother with paying the extra for high octane, so on a forecourt in a less affluent area it just sits in the tank and goes stale
then comes along Mr rexi and pumps it in gleefully getting 3 year old jollop instead of something fresh from the refinery

[manuRx8]

Some sums, for reference.

Compared to petrol (I'm assuming pure octane) pure ethanol has:
- 12% higher density
- 30% lower calorific value
- 40% lower stoichiometric ratio (9:1 rather than 14.7:1)
- 113 octane rating
- 12% less carbon dioxide emissions

These values mean that your tank of pure ethanol will:
- take you only 68% of the distance that petrol will take you. (Or have 32% worse mpg, if you prefer. If you get 20mpg on petrol you will get 13.6mpg on pure ethanol)
- Produce 18% more power.
- Require a fuel pump and injectors that can flow 49% more fuel.
- Will permit more aggressive compression ratio / boost / timing, further increasing the potential power.

When going for E85 the most important design change is to specify a high flow fuel pump, and larger injectors, and then tune the fuel flow tables appropriately. If you don't then the mixture goes lean at high speeds and loads, then things go bang....

Of course, it is not advisable to use pure ethanol, nor even E85 in our cars. It would be necessary to change many components and readjust the PCM.

Most of the studies that I have read recommend E10 or at most E20 and Mazda recommends not to go beyond E10; because the components of our gasoline circuit, the rubber seals of the housings, etc. they are designed so that those proportions of alcohol do not harm them.

With E10 and from the measurements of the Lambda probe, the PCM can adjust the injection to stay within the stoichiometric ratio. With greater proportions of alcohol, the maps would have to be modified.
This capacity of adjustment of the PCM, makes that hardly notice loss of power; certainly with E10 there is a slight increase in consumption (in my car I have only measured an increase of 1.6%) but I think it is compensated with some of the other benefits.

In my case, what decided me to try the E10 mixture was the ability of the alcohol to slowly remove carbon deposits and prevent the formation of others. But I also discovered other advantages that most people do not know:

• When using mixtures between 10% and 20% ethanol the intake temperature decreases considerably (due to the higher latent heat of vaporization compared to gasoline) which can also cause a significant increase in the volumetric efficiency of the engine.

• I have already mentioned that it reduces pollution (especially CO and HC) but also, by increasing the ethanol content, the exhaust temperature tends to decrease, which is directly related to the combustion temperature, where at lower temperatures the formation of NOX will be lower.

• The engines run at many revolutions per minute, but not all cycles are the same, in some it releases a lot of energy and is used efficiently and in others it does not. One way to decrease this variability is to add additives to the gasoline to make it burn faster and, precisely, it is proven that ethanol achieves a faster combustion and helps to solve this problem.

[350matt]

you will also find it harder and harder to get petrol that is ethanol free these days
as lot a companies are adding up to 10% without mentioning anything on the pump and I think tesco 99 has a higher ethanol content than V power

the biggest issue when running a reasonable percentage of ethanol is the large variability and quality of the fuel
this is why on something that is setup to run the corn juice you have a ethanol meter that can detect the percentage mix and adjust the fuelling appropiatly
Bentleys for example and most top end VAG cars run one of these and if you convert over to E85 usually one of these sensors will form part of the 'flex-fuel' kit if its been done correctly

as E85 is usually more like E70 by the time its at the pumps for any length of time

[delta0]

Isn’t 5% the limit otherwise it has to be called E10?

Also Vpower and Momentum are both limited to 5% max

[geofftl1000r]

Isn’t 5% the limit otherwise it has to be called E10?

Also Vpower and Momentum are both limited to 5% max

Sorry to wake up a sleeping thread but......

When I lived in Ealing my nearest fuelling hole was a Shell garage but it made the bike run crap so I used a different place a few miles away. Well someone decided the place that sold the nice fuel needed to be refurbished so closed it down for a few weeks. Well I had to put up with the Shell fuel for a while. I emailed Shell to find out if there was any corn juice in the fuel and they confirmed that in the south they used 10% ethanol.

I changed my route to work just to get fuel from non-shell garages.
My previous bike didn't mind so much but slowly lost the ability to rev. I found out that the fuel pump housing had a hidden filter and it was clogged with black crap. Almost as if something had been eating away the rubber fuel line. That bike was filled nearly exclusively on Shell fuel.

[350matt]

on some 90's BMW's they have issues with ethanol fuels rotting out out the petrol tank.....

however I've not heard of any problems with Jap manufacturer's

[warpc0il]

Most modern fuels, and especially the premium brands, include solvents and detergents "designed to keep your engine clean".

The problem is that these can also soften and dislodge dirt and gum that has been minding its own business on the inside wall of the tank and pipework.

This muck drops into the fuel and then starts blocking filters, pumps and jets.

This phenomena isn't new, I wrote an article that got printed in Motorcycle Trader magazine back in 1992, when this problem first hit, but it does come in cycles as the level of active additives is increased in steps and muck that has withstood previous attacks can't hang on any longer.

[geofftl1000r]

The bike that had the blocked filter I had owned from new and was only 3 years old.
My new bike has had it's filter changed once as it's documented on the forums of bikes having trouble with fuelling due to partially blocked filters. Only really brought this up after watching the YouTube video of that RX8 being mapped and it was decided to replace the fuel pump as it seemed to be running out of juice over 7k rpm. Sounded just like the issue with all 3 of my bikes!.
Now wondering if I should change filters on the cars.

[warpc0il]

The problem with old (previously stable) muck being released by more aggressive fuels can also apply to the storage tanks at filling stations.

My Father worked at Gilbarco (manufacturers of fuel pumps) and their called-out rates for pump filters would jump every couple of years, as new fuels would release old muck from inside the tanks.

He always recommended not to fill-up at a station that had the tanker on-site, as the action of filling the tanks would also stir up the muck that was settled at the bottom of the tanks, better to let this settle back down again to avoid picking up a dose. Of course, you'd never know if the tanker just left 5 minutes before you arrived...