Hope i'm not opening myself up to ridicule here but here goes

Noticed when filling up the other day (on a complete aside it was in east ardsley and there was a gorgeous blue scoob (sti I think) filling up too) anyway, back to my qestion

The fller caps says 98RON fuel only

Done quite a bit of research on google etc looking to see if there are any substantial gains from using this fuel (depends what you read as to what people say) but what are the impacts of not using it?? Do you guys and gals all fill up at the super pump?

Had a search but couldn't find the answer so any info would be great

Rich

 

I only use tesco 99 or shell vpower
I believe with a higher rating fuel it will burn more efficiently, less wear and tear on engine and possibility of more mpg.
I have previously used normal unleaded or 97 but have noticed that the drive isn't as smooth and sometimes feels sluggish plus i get about 20-30 miles less per tank.
Stick with the higher 99 rating in my opinion

 

just had mine mapped to tesco 99 mine seems more hesitant with anything else in,more sluggish.

 

The ECU is supposed to "learn" what fuel is being used and will adjust ignition timing accordingly, therefore changing how your engine responds.
I only use tesco 99 or Shell V-power

 

As above me but mine was done to Vpower....

Doesn't seem to like much else either....

 

Same as above but mines on Vpower

 

don't know what happened there

 

Stuttering now, theres no hope

 

If its an imported Impreza it will have to run on higher octane fuel because Japanese fuel is generally a better quality (our v-power, super unleaded etc is their standard fuel) and putting our normal fuel in will cause the engine to 'knock' severely causing serious damage.

I have to use super unleaded as mine hasn't been mapped for standard UK fuel (thankfully, that would mean a major loss in power)

If your car is a UK car but has say a prodrive map on it then the sticker will indicate what octane rating the engine has been mapped to and that rating or better will have to be used. I have some cases that case mapped on V-Power 97 RON don't respond well to Tesco 99 RON for some reason so be careful.

 

Landy. It took a bit of searching, but this article from EVO magazine has everything you need.

EVO 087 - January 2006

Petrol Wars; WOULD YOU, SHOULD YOU?

Tesco has just released the highest octane pump fuel you can buy. But is it any good? Does it really matter what petrol you put in your car? Is it worth paying the extra for a premium brand, high-octane unleaded such as BP Ultimate or Shell Optimax, or will your car perform just as well on regular, considerably cheaper 95-octane unleaded? Newly launched Tesco Super Unleaded 99 Octane could offer the best of both performance and value.

To find out, we rolling-road tested a total of eight petrols in two cars. Four were regular 95-octane unleaded - Shell, BP, Tesco and ASDA. Three were super unleaded - BP Ultimate (97 octane), Shell Optimax (98 octane) and Tesco Super Unleaded (99 octane), the highest octane pump fuel available in the UK. Our final petrol was Sunoco GT race fuel, a 105-octane brew that can be purchased - at vast expense - in 25-litre cans and which we have included principally to see where the upper limit of each of our test cars' adaptability lies.

Test mule one is a 2500-mile-old Volkswagen Golf GTi - 2-litre, light-pressure turbo, four-cylinder engine, six-speed manual gearbox, front-wheel drive. Test mule two is a 9300-mile-old BMW M5 - 5-litre naturally aspirated V10, seven-speed automated manual, rear-wheel drive. Both manufacturers recommend the cars are run on 98-octane petrol but say that 95 is acceptable if 98 is not available. Both have adaptive engine management systems that should be able to detect between various fuel grades and adjust to make the most of the fuel in the tank.

All UK pump fuel conforms to British Standards, BS EN 228 for 95¬octane unleaded, BS 7800 for higher octanes (including Sunoco GT), so a car configured to use either should have no issues using any petrol purchased at any UK service station. What we wanted to discover was whether there was a measurable difference in power and torque between our eight fuels and also whether there was any perceivable difference in the performance - smoothness, throttle response, low-down urge, top-end zing.

The Dyno Dynamics rolling road at Silverstone-based WRC Technologies produces representative flywheel figures using proven correction factors for transmission losses. The readings are also corrected for ambient temperature, pressure and humidity. All fuel was purchased at filling stations within a 40-mile radius of Silverstone. To ensure minimal contamination between batches, each test car was run until its onboard computer showed a range of 3 miles or less, filled with 10 litres or more of the test fuel, then run down to a range of 3 miles or less again and filled with 20 litres or more of the same fuel. To allow the car to adapt to the fuel, it was then driven hard, allowed to stand overnight, cold-started, driven hard again, and then tested on the rolling road dyno. Any perceived variation in drivability and power and torque delivery was noted.

So, is there a real difference between regular and high-octane unleaded, or between branded and supermarket petrol? Read on ...

ANALYSING THE RESULTS

There were surprises, the first being that on all fuels both cars performed beyond their makers' claims. Against a quoted 197bhp, the Golf gave a best of 212bhp (+8 per cent) and against a quoted 501 bhp the M5 gave a best of 534bhp (+ 7 per cent).

More astoundingly, on pump fuel the Golf's torque peaked at over 250lb ft, 20 per cent up on VW's claim, and gave a minimum of almost 220lb ft. It would seem that German car makers' claims are rather conservative.

The second surprise was that it didn't seem to matter what fuel the MS was running, the spread of power and torque figures being very small. We look into this in greater detail on page 127.

Happily, the Golf showed a clear distinction between the eight fuels - and they delivered tangible differences on the road, too.

THE MANAGEMENT- HOW THE GTi ADAPTS TO THE FUELS

Any engine's output depends in part on ignition timing - the number of crank degrees after the piston has reached the top of its compression stroke (a.k.a top dead centre) that the spark fires. The greater the retardation, the lower the peak combustion pressure and the lower the output. Trouble is, if you combine advanced (near-TDC) timing with a high compression ratio, you hit the knock limit - the point at which the mixture explodes rather than just burning very quickly. The result is 'pinking' which can soon result in a holed piston.

There are two ways of operating close to the knock limit (therefore at the highest possible efficiency and output) without putting the pistons at risk. The first is to run an engine on the bench and determine its knock limit at various speeds and loads, Then you can set the ignition timing of production engines to remain below this (by mapping it into the management electronics).

The second way is actually to sense when the engine is approaching the knock limit. A big advantage of this approach is that it works, and maintains maximum engine efficiency, more or less regardless of fuel RON - it is 'adaptive'. It will even guard against the detonation-provoking effect of combustion chamber deposits in a 'dirty' engine.

In turn, there are (at least) two ways of doing this. Most common is to use one or more knock sensors - highly sensitive accelerometers attached to the cylinder head, which can 'feel' the changes in pressure pattern which mean knocking is close. Signals to the management unit then call for the ignition timing to be retarded. The GTi uses two knock sensors for this purpose. JD

THE M5 - TOO CLEVER?

The MS has arguably the most sophisticated engine management system in production and should, therefore, be able to distinguish between the weakest and strongest performing fuels as suggested by the Golf, but in our hands it didn't. BMW GB tested the car on its own Sun/MAHA rolling road and claimed to see 501.5bhp on a regular 95 and 515.5bhp on Shell Optimax but we didn't see any appreciable difference between any of the fuels. The power and torque traces for all our sample fuels are so close that they are effectively the same. Take the torque curves (below) - at 4500rpm there is just 10lb ft between best and worst, or less than 3 per cent - an amount that would be, and was, undetectable on the road,

BMW GB was as baffled as we were, particularly as the factory recommends that the MS is run on a diet of 98 octane. Like the Golf, the MS performed beyond its maker's claims, even on the 'weakest' fuel as determined by the Golf (our best figure was 534bhp, on BP Ultimate). We wondered if the M5's sophisticated engine management was adhering to an upper torque limit, set by some component either in the engine or the drivetrain, thus pegging all the tested fuels to the same level. If this is the case, our guess would be that the SMG paddle-shift manual gearbox is the weak link. Select maximum power and the fastest shift speed allowed and the first-to-second upshift hits home with a neck-jolting thump that can't do the drivetrain much good.

Perhaps an example of the V10 producing close to, or less than, the quoted 50lbhp and 3831b ft would have shown the anticipated gains on the higher octane fuels. Without finding one, we can't say, but in our hands this well-run-in M5 went just as well with its tank filled with the lowliest 95 as with I05-octane race fuel.


HOW THE M5 ADAPTS

BMW employs a sophisticated alternative to regular knock sensors - it uses the spark plugs themselves as sensors. Even before the spark happens, as the voltage builds up, the air in the electrode gap 'ionises' - its physics change to allow a current to pass through it. With the latest and fastest electronics, the rate at which ionisation takes place can be sensed - the resistance of the air between the electrodes can be measured. As the knock limit is approached, ionisation is faster. By detecting and measuring this, the engine can be kept just below the limit. Because of its accuracy and speed of response, it allows the M5's V10 to be run even closer to the limit than the Golf's turbocharged 'four', and thus at even higher efficiency. Its big drawback, needless to say, is cost. ..

Note, however, that there is a limit to any (naturally aspirated) engine's output. If it can run at its most advanced ignition timing without knocking, then the mean combustion pressure (BMEP) is determined almost entirely by the compression ratio. That's why old, low- compression engines - assuming they can tolerate lead-free petrol - are more than happy to run on 95 octane, and in many cases on 91 octane (known as 'regular grade gasoline' in the US). Using higher-octane in these engines would be a total waste.

The fuels tested:

SHELL 95

Price paid 91,9p/litre
Max power 205bhp @ 5600rpm
Max torque 234lb It @ 2650rpm

Rated slightly below BP 95 because although it's power-peak was 1 bhp higher, BP delivered significantly stronger torque throughout the low and mid-range. Driver notes: 'Definitely seemed to be lacking an edge after Ultimate. [Fuels were not tested in a set pattern; Shell 95 was tried after BP Ultimate.] Delivery seems softer, there's less punch from low down and less response in the higher gears too.'

BP 95

Price paid 89.9p/litre
Max power 204bhp @ 5600rpm
Max torque 242lb ft @ 2300-3100rpm

A consistent performance. Lots of low-end torque, which is sustained until beyond 3500rpm, Fades a little further up the rev-range but still stronger than Shell 95 right up to 5000rpm, Driver notes [tried after Tesco 99]: 'Not as punchy and there's much less manic flashing of the traction control light. Foot to the floor more often out of corners - doesn't spin its front tyres up as much. Still felt quick though.'

Supermarket 95 - What you’re buying.

Supermarket 95-octane couldn't be included in the final results for the reason that supply is not consistent, so testing a batch would merely be a snap-shot. A spokesperson for ASDA, which sells unleaded at just 85p per litre, told us that it draws fuel from no fewer than seven suppliers, including Esso, Texaco and BP. Tesco is similar, although 200 of its 380 filling stations stock a part bio-ethanol unleaded 95 octane which, like Tesco 99, is supplied exclusively by Greenergy. These are in the south east and a small area in the north west. For the rest, as with ASDA, it's a bit of a lottery as to what you get. Out of curiosity, we did test 95 from our local ASDA [Corby] and Tesco stores in Northampton and Wellingborough which, according to a spokesperson, might have been bio-ethanol as these branches do get it 'but not 100 per cent of the time', The ASDA fuel [which we were told was drawn from an Esso depot] was storming stuff and a match for BP 95, Tesco 95 was on the pace power-wise but up to 30lb ft down on torque.

SHELL OPTIMAX

Price paid 95.9p/litre
Max power 209bhp @ 5500rpm
Max torque 242lb It @ 2500-2900rpm

Shows useful gains compared with Shell 95. Compared with other higher octane fuels, it's on a par with Tesco 99 low down but lacks its mid¬range [and that of BP Ultimate) with torque fading slightly earlier. Driver notes [tried after 1st batch of BP Ultimate): 'The Golf suddenly discovers a top end - you want to rev it right to the red line. Of all the fuels, the GTi felt the crispest and most fun to drive on this. It would be my choice.'

Tesco 99

Price paid 93.9p/litre
Max power 212bhp @ 5500rpm
Max torque 242lb ft @ 2400-3500rpm

Highest octane rating of the pump fuels didn't quite give the top results. Massive gains over our sample of Tesco 95. Doesn't deliver like BP Ultimate low down but then gets ever closer before matching its power and staying stronger for longer, A fine result, and it's part bio-ethanol. Driver notes [after Shell Optimax]: 'Mega mid-range but feels a little laboured to the redline. Somehow less clean feeling, sound was less positive, too.

BP ULTIMATE

Price paid 100.9p/litre
Max power 212bhp @ 5300rpm
Max torque 252lb ft @ 2400-2500rpm

Level-pegged with Tesco 99 on peak bhp but significantly out-performed it and every other pump fuel in terms of torque [and even matched the race fuel into the mid-range!. Very strong right from the off and stays ahead of the others right up to 5000rpm, Driver notes [tried after a 95]: 'Explosive low down - really quick on boost and sharp response, too, Woolly top end, though - the last 1000rpm is a struggle. Strange'

SUNOCO RACE FUEL

Price paid 352,5p/litre
Max power 218bhp @ 5200rpm
Max torque 248lb It @ 2500-2800rpm

Mixes it with BP Ultimate initially, but beyond 3500rpm it's well clear of the pump fuels, as expected. Storms to highest peak power, though the flat topped curve suggests it's capped. So costly, only justifiable in a race car (with a high compression ratio], where a second a lap is a lifetime. Driver notes [tried after 2nd batch of BP Ultimate): 'Felt like it kicked hard low down and then kicked again at about 4000rpm, when it just took off.'

 

Oh my good god Alan!

 

I think it makes very little difference when the weather is cold, I just put a tank full of Morrisons own in and she's flying, NO PROBLEMS.

But higher octane is a safety net when the ambient temperatures are high.

DunxC

 

by crikey!!! all i know is if i fill up on cheapo supermarket fuel, my car pops and bangs its way round (and not in the good sense) and it runs out reaaaally quick too, so its BP or shell for me (plus they are the closest stations! i'm sooo lazy!)

 

My ecu is probably more powerful than this ancient laptop I'm using !

LOL

 

Cheers all

and thanks for that Alan, will have a proper read through tomorrow

I think to be safe i'll start using a higher ron fuel as mine has had the PPP kit done

Had a quick read but way too depressed after getting back from watching bradford lose to St Helens AGAIN!!!!! to take it in

 

Mine seems to run better when it's colder. The damp, cool, dense air really helps the intercooler keep the charge temp down and feed the Turbo some decent dense air....

I use Shell SUL a lot of the time and can't find too much of a difference between Shell. MY car does not like BP...... the EVO test seems to backup the fact that freshly changed petrol is a good as something of higher octane that's been there for a while....

However she does like Tesco 99 as I do feel a difference with that one... and I get a few more MPG too...

 

we had a stage before mapping where we used the octane booster stuff with normal asda fuel, if i remember rightly it didnt seem to run as well.....

So its V Power for us.....

but im sure the husband will be along to correct me once he's home....

 

i just use the stuff that total xcellium stuff. its expensive, but the juice station is only 200 yards away... the car runs fine on it, and thats ron 97.... have noticed that she did run slightly betta on shell vpower, but the nearest garage for me is cas!!!! i dunt think it makes a differance what you put in it to be honest....

 

I've just filled her up with total xcellium too and now i'm a much poorer man £1.11/Litre!!

not even sure where the nearest shell garage to stanley is??

 

Sainsbury's super unleaded will be as good.

Don't loose sight that if you put 95 RON in, then you WILL loose power compared to 97 or even 99 and you will most likely loose some MPG.

I got badgered () into dropping mine on to the Scoobyclinic rollers when I only had 95 RON in.. It developed 299.7 and wasn't happy at the higher revs. With 97 in, it developed 320/335 on the Powerstation rollers.

 

But 95 % of the time you're stuck in traffic or sticking to the speed limits....

I would obviously fill up with V-Power for Blyton, etc., but for chugging to work at 40/30 mph it seems overkill. We would all be running on methanol if all that mattered were BHP figures...

IMO

DunxC

 

No mate... good point. But I'm only jammed for a fraction of my driving time and I usually like to give it some beans as often as I can... and play with the odd M3, Porsche, Chav etc when I can, then at least 97 is a must.

 

All good points well made

My initial question was more around what damage it cause not using it (the the sticker in my petrol cap says 98ron fuel only) but getting the sense that its more about the power loss than the major mechanical implications which is good.

I'll just sell a kidney and stick to the 97 ron total xcellium for now as i'm within a mile of easily buying that

 

You'll have to reduce the alcohol intake if you sell a kidney....

What are they fetching now ?

DunxC

P.S. Alan, you're lucky I can barely beat my cycling time in a Scoob, bloody traffic....

 

Very good point....I'll sell one of our lasses, sure she'll be fine with one

 

correct me if i'm wrong but isn't sainsburys petrol the same as BP?
Making the super unleaded BP ultimate but at a cheaper price.
I regulary see BP tankers filling the pumps at colton

 

No ! Her's will be in better nick (probably !) buy some bits for the car with the extra...

LOL

 

Not sure Si. Is Sainsbury's 97 actually BP Ultimate?

Damn cool if it is....

Landy... on that topic..

The Research Octane Number or RON is a measure of how good a petrol is at resisting engine knock and is not a measure ofhow 'powerful' a fuel is. If your manual recommends 98 RON, then 95 RON can be used with a slight loss of power under heavy driving conditions (eg heavily loaded, high revs), the power loss is due to the engine management system adjusting to avoid engine knock and thus potential damage.

This is true if that if you use 99, 100 or 102 fuels, then heavy use (which is the way the majority of Scoob owners will drive - especially on runs, trackdays or rolling road sessions) will mean the engine management has to retard less, thus giving you more power and better driveability.

If you do run your car and drive in the high rev range, then higher RON will be more 'efficient'. I'm no mechanic, but the computer having to cut back to prevent knock must mean that something bad is happening in the first place.... If you drive like 'Miss Daisy' or like Dunx stuck in traffic, then 95 will be fine. But if you drive hard every now and again, then 97+ will be needed or the engine will be constantly powering down to prevent damage......

 

Cheers Alan

you put that in words even i could understand

I don't consider myself a good driver but defo like a little blast when safe and legal to do so :-)

 

Amen to that.....