Super Unleaded & Tesco 99 Ron

Guest · Aug 20, 2006

Quick question, how quickly does it take the ECU on the boxster to adjust between having been run on 95 Ron to running on Super Unleaded?

I always told that the Vectra VXR had a self learning ECU and after 2 tanks you could feel the difference.

Secondly has anyone run their car on this Teco 99 Ron Super Unleaded? If so have you found any benefit? A lot of people on Pistonheads seam to think it has really benefited their cars (not necessarily Porsches) performance wise. We don't Optimax locally so that isn't an Option and I have never felt any benefit from BP Ultimate and the cost difference to me is not justifiable.

daro911 · Aug 20, 2006

ORIGINAL: CatherineJ

I have never felt any benefit from BP Ultimate and the cost difference to me is not justifiable.

Unless you are doing track days or are concerned that your 0-100's are not 0.00000000001 secs slower

I think the biggest gains to be felt will be in the profits of the petrolium company of your choosing [

]

Mark_Bennett · Aug 20, 2006

Something else to consider is that many owners have reported that they get better milage from the 98/99 octane fuels.
So it costs more initally, but can actually work out cheaper.

sawood12 · Aug 20, 2006

It might take 2 tankfulls of fuel to fully flush out the old 95 RON fuel but until then you'll have a mix that will effectively be somewhere between 95 and 97 (or 98) RON which your ECU will adjust to immedialtely in real time through sensing knock. Tesco 99 RON is pointless as I believe the Boxster ECU cannot see more than 98 RON so unless you have your ECU re-programmed to be able to use the extra 1 RON you're wasting your money.

BrianJ · Aug 20, 2006

Except that round here Tesco 99 is currently 96.9p whilst Optimax is 107.9!

daro911 · Aug 20, 2006

ORIGINAL: Mark Bennett

Something else to consider is that many owners have reported that they get better milage from the 98/99 octane fuels.
So it costs more initally, but can actually work out cheaper.

Whilst this may or may not be true ( and in my Porsche I use only Optimax in the hope of better mpg = extra 5p per litre) most people are mainly concerned with the extra oooomph and in that regard I think they are wasting there money IMO [&o]

Richard_Hamilton · Aug 20, 2006

I used to notice a big difference when Optimax/Ultimate on my Impreza Turbo compared with 95 RON, but I haven't noticed anything significant when I have had to fill up with 95 RON in the 911 when 98 hasn't been available.

Guest · Aug 20, 2006

ORIGINAL: BrianJ

Except that round here Tesco 99 is currently 96.9p whilst Optimax is 107.9!

Yes that is the sort of cost difference we have down here in Wiltshire. I have to say I have never seen any benefit from Optimax and I never felt it was worth the 24 mile round trip to fill up with it.

Black80XSA · Aug 20, 2006

I always get roughly 10% more mpg and sharper throttle response from Optimax over Shell 95 unleaded - well worth the 6% difference in cost IMO.

As for Tesco 99 - i used it once after Optimax - i got 3mpg less on the 200 mile journey home compared to the outward journey on Optimax. I ersonally think Tesco is a waste of time, but then there are also reports of BP Ultimate not doing what it says on the tin [8|]

Remember the 987 is meant to run on 98RON, with 95 RON allowable but not optimal

Mark_Bennett · Aug 20, 2006

ORIGINAL: Black80XSA

Remember the 987 is meant to run on 98RON, with 95 RON allowable but not optimal

And the 986 [

]

craig johnson · Aug 20, 2006

But has anyone tried (or seen) the BP 102 RON that was demo'd at Goodwood? Claims to give even more performance and they were using it on a 996 Turbo to show an extra 10% power over super.

Personally happy with 95 RON in the 964, others dont seem to make a difference but agree my old Impreza Turbo did take a shine to the Optimax and heard similar.

Do you reckon different cars respond better to different types/suppliers of petrol instead of the octane ratings? Heard supermarkets cut certain additivies to keep the prices low or is this an urban myth?

Cheers

Craig

Richard_Hamilton · Aug 20, 2006

And Shell are launching their new V-Power 100 octane at the end of this month I believe.

http://www.porscheclubgbforum.com/fb.asp?m=224265

engineerjim · Aug 20, 2006

I have used Tesco 99 once and could detect no discernible difference. As a matter of choice I do try and steer clear of supermarket petrol if I can as I am not convinced that it has all the detergents and other drops of juice that keep an engine's inside clean, irrespective of price.

As an aside, two years ago we had a motoring holiday in Italy where it is difficult, even on motorways, to find anything but 95 and I couldn't detect any difference in performance on the Autostrada dash on the way down to that on the way back two weeks later.

sawood12 · Aug 20, 2006

Turbo charged cars can make better use of the extra octane from a performance perspective due to the higher temps involved and the better knock resistance of higher octane fuels. I think the performance gains in N/A cars is less noticeable but you should notice slightly better fuel economy, but ultimately it depends upon how you drive the car. If you've a heavy right foot your fuel economy will suffer irrespective of what fuel you use. People I know in the states who rack up serious miles on the freeways swear by higher octane fuels for significantly better fuel economy - granted they have a much wider gap in octane options so the difference between the lower and upper range is much more than the 2/3 RON we have in this country (not counting Tesco 99 and BP 102 as very few if any cars have ECU's that can utilise the RON's above 98).

There is a school of thought that says even if you only ever use 98 RON you will not quite have 98 RON in your tank due to dilution of the fuel by water and other fuels in the distribution network so in threory by using 99 or 102 RON fuel you are guaranteeing you have at least 98 RON in your tank therefore your ECU can push the ignition to the max.

THX911 · Aug 21, 2006

I have found Tesco 99 to give much less MPG on my 986S when used in the city compared to Optimax or even Shell 95 with no extra performance or response; on the Motorway all seems to give pretty much the same MPG... Optimax gives the best city miles. However, Tesco 99, on my brother's Honda Accord Type-R (Japanese import), is like rocket fuel and apparently it is the case with the other Japanese performance cars too i.e. Impreza, Evo, etc...

V-Power RON 100 outside Germany (well, at least I can confirm in France) is just RON 98 (like Optimax here); so I hope we are getting Germany RON 100 rather than a re-branding of Optimax to V-Power as apparently Britain is the only country left (?) that still calls it Optimax.

I was speaking to one of the ex-OPC engineers (now a Porsche Specialist) on the fuel ECU mapping and he assured me that the modern cars ECU are far more sophisticated and as Sawood12 mentioned they adjust in real time rather than having to wait for 2-3 tank fulls...

Also, another interesting thing he mentioned, (and which is the main reason I use Optimax i.e. I assume the additives keep the engine clean and healthy): well, he has worked on several Porsches engines on which the owners have claimed that they have only used high octane fuels like Optimax, BP Ultimate and he has not yet seen the internal deposits of any such engines to be different from all the other engines...

Guest · Aug 21, 2006

ORIGINAL: THX911

I have found Tesco 99 to give much less MPG on my 986S when used in the city compared to Optimax or even Shell 95 with no extra performance or response; on the Motorway all seems to give pretty much the same MPG... Optimax gives the best city miles. However, Tesco 99, on my brother's Honda Accord Type-R (Japanese import), is like rocket fuel and apparently it is the case with the other Japanese performance cars too i.e. Impreza, Evo, etc...

Apparently this is because Tesco 99 contains approx 5% ethanol which helps boost the octane rating - the downside being a drop in fuel economy. I noticed the drop in motorway MPG on my GT3 too so I stick to Optimax which it seems to like.

Steve

Carl.Young · Aug 21, 2006

ORIGINAL: THX911

I have found Tesco 99 to give much less MPG on my 986S when used in the city compared to Optimax or even Shell 95 with no extra performance or response;

Same experience here. I've also found my 986S seems to run a little more smoothly on Optimax. My missus Focus ST seems to prefer Optimax too.

Steve Brookes · Aug 21, 2006

I use 97+ octane fuels because I notice the engine feels more laboured when normal unleaded is in the tank. I would not say that the car is faster or more economical on higher octane fuel (in fact the latter is about the same from my calculations). It just feels better with the good stuff in[

].

Regarding the 102 RON, at £2.50 per litre I'll be giving it a miss [8D]

Gordon Attar · Aug 21, 2006

If your car was designed for 98 RON but will use 95 RON and adjust the knock/timing, then you should use the 98 RON as I've been advised that ultimately you can cause damage if you use 95 RON extensively not really worth the risk with the potential engine issues that can occur in the more modern cars, it may be contributing!!.
You should find that the 98 RON works better if you like to put your foot down. In my 993 Turbo I could feel some engine hesitation (knocking) on full acceleration also my fuel consumption improved by 2mpg(17 to 19) with Optimax so its more cost effective, I dont have ready access to Tesco's but it sounds like its an ideal track day fuel.
When I had my 964 which was designed for 95 RON I couldnt notice any difference in fuel consumption or performance just the price.
The other thing to bear in mind is seeming fuel degrading if in the forecourt or in your own tank for more than a month! so use a petrol station that is reasonably busy and dont fill your tank up if you dont use a tank full in a month!!

daro911 · Aug 22, 2006

BP's announced that it will expand the availability of its 102 octane grade fuel, following a successful initial trial earlier this year.

The "˜handmade' BP Ultimate 102 Unleaded's formulation meets exactly the same specifications used in Formula 1 and the World Rally Championships, according to BP, and the decision to target a further 30 sites follows extremely positive reaction from customers after the fuel was introduced at six locations in April this year.

This octane level is, reckons BP, the highest octane available on any UK forecourt, while remaining road-legal. 102 is crystal clear, and is less than 0.1 per cent benzene. This makes it the only automotive petrol available not classed as carcinogenic, and it's also unique in containing a high performance "˜bio-component' which works to reduce greenhouse gas emissions -- that's according to the BP press office.

BP Ultimate 102 is intended for the growing numbers of highly tuned, high performance cars available, and for use on track days or for race testing.

The price of the fuel, at £2.42 per litre, reflects its advanced components and small-batch production at BP's Speciality Fuels Technology Centre.

Product manager Paul Beckwith said: "This fuel was developed to satisfy the need for an extreme high performance fuel that's easily available to private motor sporting enthusiasts. People who invest in supercar-engineering naturally want to fill up with similarly advanced fuel, which has all the properties of the fuels used at the pinnacle of motor sport."