Petrol - good or bad

[bird]

I'm just interested in people's thoughts here.

Forever, I've used the better patrols such as optimax or v-power. This is also what the car was mapped on. The other day, I was running out of petrol and had no real choice but to put some cheaper petrol in from Morrisons (only £10).

 

I noticed absolutely no difference at all in the way the car drove. So I'm wondering what people's thoughts are on using the cheaper fuels and whether it 'really' makes a difference or every day use.

 

For info, it's a jap car.

 

Thanks,

Lee

[groover]

I only noticed slightly better fuel consumption, ie on a long run more efficient, but general day to day, diddly :thumbup1:

[RichardS]

Having a UK spec car, I normally use "regular" unleaded anyway..... Although more for loyalty points, I stick with BP or Shell, as opposed to any other brand of fuel.

 

I have used V-Power and Ultimate fuels - but like you say, there's little noticeable difference most of the time. But I do think my Zed runs better on the higher octane fuels on those odd occasions in summertime, when we get very hot weather. Say 26+ degrees....?

 

Same with the Merc and Land Rover - neither car runs any different on "super" varieties; but for the occasional higher MPG between fill-ups.

[bird]

I guess UK cars should be taken out of the equation a little as they're meant to run on the lower grade petrol.

I guess the ultimate question here is... Should I pay 99p for petrol at morrisons or asda etc or should I pay £1.13 or whatever for v-power.

[nicjwin]

Might be worth reading Honest John for his views . If your knock sensor is working cheap fuel can be managed .

[ashleydc]

If you have to use lower octane fuel to get you home, then I wouldn't use full boost. You're increasing the risk of detonation and engine damage if your car was mapped for better quality fuel.

[bird]

To be honest, it's rare than I really put my foot down to be honest. But this is the kind of thing I want to know.

 

So are we sure I'd get detonation from using worth fuel just because it was mapped when on v-power? Wheres Noz when you need him

[TheRealNips]

I did an experiment with my NA Z for 2 months. I only put V-power in my tank for 2 months (I wanted to make sure the tank and engine had been flushed out of normal petrol) Most of my mileage was driving the 8 miles to work and 8 miles back, due to the nature of my job, sometimes that was at 4.30am, sometimes at 11.30am, so I had clear runs and got stuck in traffic. I also had a couple of long motorway journeys and a few times I went for a drive just because I felt like "unleashing the beast". Now heres the things, I noticed NO difference in performance and according to my car app, I lost 10-20MPG by using more expensive petrol... So for the moment im back to cheap petrol (tescos) for another couple of months to double check...

[dutchgold92]

We only have E95 anyway...

[Gaz 300]

I always use BP Ultimate in my Z. No Shell petrol garages in N.I. or I would use the V max. It will keep your engine cleaner, give better mpg and better performance. Plus all Jap imports are set up for the higher grade fuel. If you use a lower grade petrol you might not notice any difference straight away but over time you will harm your engine imo.

 

http://www.moneysupermarket.com/car-insurance/blog/is-it-worth-paying-more-for-premium-unleaded/

[ashleydc]

If you map a turbocharged engine to run on higher octane fuel it will make significantly more power than on regular octane fuel. If you then run the engine that is mapped for high octane fuel on lower octane fuel, it won't necessarily make less power, it's just more likely to go bang. How much more likely depends on how 'aggressively' it is mapped. Only Noel could answer that one.

Modern cars are more sophisticated and are able to alter ignition timing etc to make the most of whatever fuel they're using.

[JaiKai]

Always used the premium fuel on all my zeds unless I get stuck and have no choice.

 

And it was my understanding that the lower octane fuel was bad for the injectors or something.

[Gaz 300]

JAE 2015 I was able to get a fill of V max and you always meet the best super cars at a Shell petrol station :biggrin:

 

 

 

 

 

[Akita]

Noel, noel, noel, we seek your wise words.

[JaiKai]

I remember pulling up at a garage just after leaving JAE last year and it was queued with jap cars trying to fill up in Kettering but

the pumps were empty and we all got stuck trying to get back out.

 

JAE 2015 I was able to get a fill of V max and you always meet the best super cars at a Shell petrol station :biggrin:

 

 

 

 

 

[takemetothepub]

If you've upped the boost then yeah, run the higher octane stuff. If you're running stock there is really no need to.

 

I've always got less MPG and no extra performance from higher octane, for every day car use it's a gimik that has no real world advantages. Sure in a lab environment it proves otherwise, but out on the roads is where it counts.

[Mondo]

A higher octane rating reduces the chance of knock on an FI engine. It's as simple as that.

 

I personally would only use Morrisons' fuel in an absolute emergency, and even then I'd put super unleaded in asap afterwards.

 

As your Zed is rumoured to be around the 500bhp mark, Bird... stop being so cheap and use the right stuff!! :tt2:

[AndrewG]

I guess UK cars should be taken out of the equation a little as they're meant to run on the lower grade petrol.

 

How many UK cars are still running stock boost though?

 

For the number of miles a year I do the difference in cost is not significant and I always use V-Power.

[Mondo]

This thread is right up there with ones like "I'm ok to use DieYung DitchFinder tyres on my Zed, right?" and "Cheap oil's all I need in my highly-tuned VG30, yeah?" :lol:

[JaiKai]

For those of us that don't understand the knock effect I found this nice bit of reading

 

When a spark plug fires, it does not cause an instantaneous explosion of the entire cylinder's charge of fuel and air.

The spark actually lights off a small kernel of air-and-fuel mixture near the plug. From there, a flame front expands in every

direction, gradually igniting the rest of the air and fuel. This takes some time, as much as 60 degrees of crankshaft rotation.

 

Meanwhile, the air-and-fuel mixture that the flame front has not yet reached is experiencing huge increases in pressure and

temperature. If any part of this air-and-fuel mixture gets heated and squeezed enough, it will explode spontaneously, even

before the flame front ignites. This self-ignition is called detonation, or the dreaded "knock."

 

Now for the chemistry lesson: Oil is a hydrocarbon fuel, meaning the individual molecules contain carbon and hydrogen atoms

chained together. Modern gasoline is blended according to various recipes, the active ingredients for which include about 200

different hydrocarbons, each with a spine of between 4 and 12 carbon atoms. One of them, isooctane, consists of 8 carbon

and 18 hydrogen atoms (C8H18) and is exceptionally resistant to exploding spontaneously when exposed to the heat and

pressure found inside a typical combustion chamber. Another, n-heptane (C7H16) is highly susceptible to such self-ignition.

 

These two compounds are therefore used to rate the knock resistance of all gasoline blends. A gasoline recipe that resists knock

the way a mixture of 87-percent isooctane and 13-percent n-heptane would is rated at 87. Racing fuels with octane ratings over

100 resist self-ignition even better than pure isooctane. The octane ratings for regular-grade fuel range from 85 to 87, midgrades

are rated 88 to 90, and 91 and higher is premium.

 

Mind you, premium fuel does not necessarily pack more energy content than does regular. Rather, it allows more aggressive engine

designs and calibrations that can extract more power from each gallon of gasoline.

 

An engine's tendency to knock is influenced most by its compression ratio, although combustion-chamber design also has a large effect.

 

A higher ratio extracts more power during the expansion stroke, but it also creates higher cylinder pressures and temperatures, which

tend to induce knock. In supercharged engines boost pressure behaves the same way.

 

That's why the highest-performance engines require higher-octane fuel.

 

If you feed such an engine a fuel with insufficient octane, it will knock. Since it is impossible, for now, to change an engine's compression

ratio, the only solution is to retard the ignition timing (or reduce boost pressure). Conversely, in some engines designed for regular fuel,

you can advance the timing if you burn premium, but whether this will yield additional power varies from engine to engine.

 

Knock sensors are used in virtually all new GM, Ford, European, and Japanese cars, and most DaimlerChrysler vehicles built today.

 

According to Gottfried Schiller, director of powertrain engineering at Bosch, these block-mounted sensors-one or two of them on most

engines and about the size of a quarter-work like tiny seismometers that measure vibration patterns throughout the block to identify

knock in any cylinder. Relying on these sensors, the engine controller can keep each cylinder's spark timing advanced right to the hairy

edge of knock, providing peak efficiency on any fuel and preventing the damage that knock can do to an engine. But, noted Schiller,

only a few vehicles calibrated for regular fuel can advance timing beyond their nominal ideal setting when burning premium.

[coopd]

I only ever use V-Power... Hate it when I end up having to use another petrol station

[coopd]

This thread is right up there with ones like "I'm ok to use DieYung DitchFinder tyres on my Zed, right?" and "Cheap oil's all I need in my highly-tuned VG30, yeah?" :lol:

 

Also, "I'm ok to buy a cheap ebay Chinese MAF aren't I??" :lol:

[phutumsch]

For the last 2 or 3 years i have only ever used the 99 octane Momentum from Tescos, i make a bee line for it, it just makes me feel a bit better.

 

Yes it's more money but for 1500 miles a year it aint gonna break the bank, the 3 years before it was the 95's from mainly Morrissons - never noticed any difference at all whatever octane i use.

[bird]

A higher octane rating reduces the chance of knock on an FI engine. It's as simple as that.

 

I personally would only use Morrisons' fuel in an absolute emergency, and even then I'd put super unleaded in asap afterwards.

 

As your Zed is rumoured to be around the 500bhp mark, Bird... stop being so cheap and use the right stuff!! :tt2:

 

 

Erm... It's over that at the wheels!

 

 

 

 

How many UK cars are still running stock boost though?

 

For the number of miles a year I do the difference in cost is not significant and I always use V-Power.

 

Good call andrew.

[bird]

It was the first time I've ever put the lower grade fuel in the zed in all the years of ownership so o was just curious about the advantages/disadvantages as it seems to make no difference in the few miles ive drove since.