Tesco Petrol - Momentum or not?

[Dieselman]

The same applies to the Tesco Momentum fuel which is typically rated at a higher RON than V power (I think the TMS test showed it was around 100 RON i.e. above the spec of 99 whereas Shell V Power is typically 98+) T

Surely, that should have reduced the tendency for pre-ignition, not increased it, which contradicts R.Sendouts post.

 

[SHAUNE55]

I use Tesco momentum and whether it's in my mind is debatable but I'd swear My car prefers it, and believe me I hate giving Cameron and his cronies more pocket money to spend.
As stated in another post we have knock sensors and adaptive ECU's, and with a higher RON this allows the timing to be advanced. (I think).

 

[camerafodder]

Tesco fuel = Donkey piss.
Not as bad as BP though beleive it or not.

Shell comes out on top I wont put anything else in my Nissan.
Had to use BP in an emergency once and could not beleive the amount of det I got. I had to drive like Miss Daisy till I found a shell staion where I brim filled it to dilute it as much as possible.

The problem people are having is that you make these statements without qualifying them.

This forum has a lot of very knowledgeable people in its midst so when you make sweeping statements like these they are genuinely interested to learn your reasoning. Why not share your knowledge and add to the collective understanding of us all?

 

[Simon_M]

Tesco 99 for me...

 

[SHAUNE55]

I had to drive like Miss Daisy till I found a shell staion where I brim filled it to dilute it as much as possible.

I thought Miss Daisy had a chauffeur.

 

[Apial]

I try to avoid Tesco for everything. They announce price cuts that giveth with one hand and taketh away with the other. They move into small market towns and undercut the opposition until they force their closure, and once they have a local monopoly they put their prices up and expand on to the next town.

Slowly we are being ring fenced by Tesco stores in every direction with increasing little choice but to have to shop with them.

In the larger branches of Tesco, buying fuel is a truly awful experience of slow moving lines of queueing traffic caused by a profit seeking reduction on manpower at the tills.

 

[Mike Walker]

I try to avoid Tesco for everything. They announce price cuts that giveth with one hand and taketh away with the other. They move into small market towns and undercut the opposition until they force their closure, and once they have a local monopoly they put their prices up and expand on to the next town.

Slowly we are being ring fenced by Tesco stores in every direction with increasing little choice but to have to shop with them.

In the larger branches of Tesco, buying fuel is a truly awful experience of slow moving lines of queueing traffic caused by a profit seeking reduction on manpower at the tills.

I bought my petrol at 6.15am on Monday morning and all pumps were free with no queing. Lady at the till was very pleasant as well so an enjoyable experience:bannana:
it's all about timing

 

[scillyisles]

Surely, that should have reduced the tendency for pre-ignition, not increased it, which contradicts R.Sendouts post.

R.Sendout's post was rather general and non specific in that he said that all Tesco fuel was donkey p--ss. The comment he made about getting "Det" in his Nissan was related to BP fuel which he considers worse than Tesco fuel.
He is entitled to his opinion - I disagree with regard to Tesco Momentum 99 which in at least two tests I have read is considered one of the best fuels available on the UK market. It is closely followed in both these tests by Shell V Power. I use both these fuels extensively in my fleet of cars and the tests findings seem to be backed up by my personal experiences.
Higher RON/MON equals less of a tendency to pre-detonate (sometimes known as pinking or knocking) and is entierly consistent with the post I made.

 

[scillyisles]

I thought their tests showed for most cars there wasn't an increase of performance, but for some highly tuned, typically turbocharged ones, there was as the knock sensor could advance the timing and increase boost.

The tests I am referriing to were the tests done by Evo magazine which AFAIK tested a number of cars of which the Golf GTI was one and the BMW M3 was another. In both these cars the best fuel from an economy and performance perspective was Tesco Momentum 99 very closely followed by Shell V Power.
THE Thorney Motorsport test compared AIRC a Vauxhall Astra or such like plus an M3 CSL. Again the best fuel was Tesco 99 with Shell V Power being a close second.
The What CAR test link posted seems to talk about a VW Polo (no details of engine spec or technology) and lacks any real detail.
Clearly not all cars have the engine technology to adjust the ecu/mapping to take advantage of the fuels and in these cars, the use of higher octane fuel would be of limited benefit. My guess would be that the Polo would fall into this category which seems consistent with the What Car test.

 

[Apial]

I bought my petrol at 6.15am on Monday morning and all pumps were free with no queing. Lady at the till was very pleasant as well so an enjoyable experience:bannana:
it's all about timing

At 6.15am I was having tucked up in a nice warm bed with still hours to go until my wake up time. I don't want to have to get fuel at that unearthly hour when I can go to a BP or a Total anytime I want and not have to worry about the queue. I prefer my timing to yours.

 

[markjay]

This is a topic often debated in forums and indeed I saw tests that showed some BHP gain for Subarus and Evos but not so for more mundane vehicles.

Modern vehicles do indeed have a knock sensor, the idea is to advance the ignition as much as possible (leaving longer time for the fuel to burn and thus achieving more complete burn), but not too much to generate 'pinking' or 'pinging'. Indeed in the olden days we use to turn the distributor around followed by a low-rev test drive until the car just pinked under acceleration, then turn the distributor a smidgen back, secure the bolt and leave it there.

The reason high-Octane fuel can have the spark at an earlier stage, is that it is 'purer' in the sense that it has less unwanted foreign molecules which ignite quickly and cause a rapid and uncontrollable burn process. So you can ignite it earlier and it will burn slowly and fully in a controlled manner, which is what you want really.

So yes, if you use higher Octane fuel the ECU will advance the ignition to allow the burn process to start earlier, and therefore the engine will burn the fuel in a more complete way (i.e. more CO2 and less CO), producing more energy. This process is essentially identical to manual distributor tuning of days of old, albeit done 'on the run' by the ECU.

This additional energy could manifest itself in the guise of additional power, or better fuel consumption. So higher-Octane fuel is always better for your engine.

Said that... the benefit in many cases is marginal. The extra power achieved in non-tuned cars is negligible, and the fuel saving is more than offset by the higher purchase price.

So the science is sound, but it does not always have practical application. It's better fuel, but for many motorist it may not be worth the extra cost.

As for me, as said in an earlier posts, I use only Shell V-Power, not because of the Octane but because of the detergents - very important in my opinion if like me you do low annual mileage and many short trips.