Shell V-Power is here - Comments?

[Ian W]

http://www.shell.com/home/Framework?siteId=uk-en&FC2=/uk-en/html/iwgen/news_and_library/press_releases/2006/zzz_lhn.html&FC3=/uk-en/html/iwgen/news_and_library/press_releases/2006/v_power_launch_2308.html

........and don't forget to run your car for at least as long as it takes to clear the fuel lines of the old stuff that was there - then, and only then, to reset your DMEs. (Negative battery terminal disconnected for at least an hour to be sure). You will need to reset your radio codes etc. so don't forget!

This stuff is finally high-octane enough to allow the engines in all our cars to work as intended. Wonder if the feedback will match the claims?

Ian W

 

[Mark_Bennett]

No need to re-set, the car constantly adjusts using the knock-sensor.[]

 

[sailor]

Unless it is close to Optimax prices, forget it.Wont make a noticeable difference unless you drive a smaller-capacity, highly tuned motor, such as my BBR-tuned 205GTI. Waste of money for a Porsche owner.

JohnC
993turbo

 

[John Ware]

Planned to fill up with Optimax yesterday somewhere down-route. Got there to find they only had V-power or mild so put in a tank full of V-power at 99.9p a squirt. Retraced my steps back home at pretty much the same rate and got an extra 0.5 mpg compared to Optimax. She seemed a bit more torquey and significantly smoother and I got a marginally snarlier sound (non-sports exhaust on a 3.4).

To be honest, I'd rather pay slightly less for Optimax as I tend to get somewhere between 2 and 3 mpg extra compared to mild and the difference from V-power is negligible. What you need to hear is whether it makes a difference to a TT or a GT3.

 

[Guest]

Read in the latest Evo magazine that Shell will charge a premium of approx 7p per litre over their 95 ron fuel. Given that Tesco 99 tends to be (in south Cheshire at least) the same price or slightly cheaper than Shell's 95 fuel I can't see any reason to switch to V Power.

 

[Ess_Three]

ORIGINAL: sailor

Unless it is close to Optimax prices, forget it.Wont make a noticeable difference unless you drive a smaller-capacity, highly tuned motor, such as my BBR-tuned 205GTI. Waste of money for a Porsche owner.

JohnC
993turbo

Interesting you say that...
I can tell no difference in performance or economy using standard 95 octane, Shell Optimax or BP Ultimate in my C4S.
I've tried and tried but just can't detect any differences on the road....although the dyno suggests it makes more power on Optimax over the rest.

On my well tweaked Golf GTI (2.0 16v NA), it needs the higher octane stuff due to me pushing the limits on ignition timing...and I can tell the difference between standard 95 (shouldn't use), Ultimate and Optimax - it feels nicer to drive on Ultimate but makes more power on the dyno with Optimax.

Strange....

 

[sailor]

Maybe not so strange, Ess_ Three.
We are not talking of large octane jumps.With, say, a 2litre highly-tuned motor, the driver is going to detect changes in power-delivery etc because there is less of it overall compared with, say, my 450bhp beast.
Reckon only a pro-racer could note any change in my case.

JohnC
993turboX50

 

[Ess_Three]

I guess you're right John.
If you can feel something missing when you loose 10BHP by running a tuned 2.0 NA engine on lower fuel than it's mapped for...I would have thought that you'd have detected a different feel to how the 996 drives in similar circumstances, what with it's higher compression ratio and more advanced engine management.

I see what you are saying about the relative power though...you could probably loose 50 BHP on yours and not really notice it.

I'll give V-Power a try...and see if I can feel any difference....

Glen.

 

[Fidgits]

ORIGINAL: Ess_Three

ORIGINAL: sailor

Unless it is close to Optimax prices, forget it.Wont make a noticeable difference unless you drive a smaller-capacity, highly tuned motor, such as my BBR-tuned 205GTI. Waste of money for a Porsche owner.

JohnC
993turbo

Interesting you say that...
I can tell no difference in performance or economy using standard 95 octane, Shell Optimax or BP Ultimate in my C4S.
I've tried and tried but just can't detect any differences on the road....although the dyno suggests it makes more power on Optimax over the rest.

On my well tweaked Golf GTI (2.0 16v NA), it needs the higher octane stuff due to me pushing the limits on ignition timing...and I can tell the difference between standard 95 (shouldn't use), Ultimate and Optimax - it feels nicer to drive on Ultimate but makes more power on the dyno with Optimax.

Strange....

So you can run a 996 on standard unleaded?

 

[Mark_Bennett]

ORIGINAL: Fidgits

So you can run a 996 on standard unleaded?

You can - but it will retard the ignition to compensate for the lower octane rating.
Performance will not be optimal (whether you can tell the difference is debatable - as you can see! [])

 

[dave10ken]

Just returned from deepest wales in my Rouse Sport Cosworth. After several attemps to obtain fuel with an octain rating over 95, I came upon a filling station selling V-Max. What a diference. the car was much more responsive, and definately felt more poverful. Cant wait to try it in my 996,

 

[Ian W]

Having run on V-Power for a week now (and 3 tanks full) I can confirm it does make a difference. If you do not reset your DME (sorry Mark) then you will not notice any immediate difference or 'wow' factor - it takes some time to adapt and the improvement comes gradually. If you do reset the DME, you will notice any improvement immediately. I've found there is more torque around 2000rpm, less of a flat spot between 2-3000rpm (where the troque curve goes flat if you look at the factory plots) and more oomph and smoothness above 4000rpm. The differences are not huge but immediately noticeable and very obvious. I've also found an improvement in fuel economy - I averaged 27.5 mpg from Manchester to London and back whilst not exactly going slowly!!!! Better than I've ever got before on the same run whilst going at a similar pace (by about 1.5 mpg).

Ian

 

[lazza]

Fascinating how different cars behave differently. We all know our cars and if we feel a difference with different fuels, then there is one!

I know that different cars we have owned over the years of the same basic model (two Boxsters for instance) always behaved differently - some better than others. Must be all to do with the build tolerances - DISCUSS[]

Lazza

 

[THX911]

Something related to read but the tests were done before the launch of V-Power:
http://www.pistonheads.com/news/default.asp?storyId=14919

 

[NIL98]

Obviously my turn for the dumb question but ......

can someone explain the DME reset please. How and why.

 

[Grant]

ORIGINAL: NIL98
Obviously my turn for the dumb question but ......
can someone explain the DME reset please. How and why.

The engine managment learns driving style & selects a suitable map according to your usual demands, it also reads fuel quality & tinkers with the timing (etc) accordingly to balance peformance/economy/knock etc.
The thing is most of us aren't 100% sure how quickly the system adapts on Porsches, some claim it is instant, others that it takes a fair amount of time. So will the first tank of 99 RON fuel benefit you after running on 95 previously?
If you disconnect the battery for a fair while (MAKE SURE YOU TURN THE ALARM OFF THOUGH, preferably with the key!!!) it re-sets the system & the engine is set to default maps & learns again from the off!!

On my 996TT I had a daily drive that involved lots of slow traffic & there is no doubt that over time it's pick-up got much more sluggish, the light bulb moment came for me when it came back from the OPC after a minor visit, it's performance was sensationally better the OPC explained why.

So I can confirm 100% that the re-set works to adjust the "learned map" but I'm not sure about fuel quality, i always thought this adapted far quicker & would give virtually instant benefits!!

 

[Ian W]

DME ( Digital Motor Electronics or some German equivalent?) is the electronic brain that controls the fuelling and ignition timing of your engine. The Bosch unit used in the 996 is extremely sophisticated and in addition to containing maps that determine the amount of fuel that is delivered / timing of the spark at various loads and rpm also includes many features that allow the system to adapt to certain variables that could otherwise cause harm to the motor.

The inclusion of these safety systems allows the manufacturer to program the base settings very close to an imaginary 'ideal' (cold air, at optimum humidity, at known pressure, using laboratory grade fuel). In the real world, these 'ideal' conditions are rarely met and if the engine designers released a vehicle with these settings - but no way of compensating for any variance - the engine would quickly destroy itself as soon as it was asked to operate with hot air and / or at low pressure and / or with sub-standard fuel.

Historically, before the advent of so-called 'adaptive' engine management systems, the designers used settings some way off the ideal (to allow for the variables described above and engines almost always performed below their optimum level. With the advent of adaptive systems, the engineers could use optimum settings as a starting point and then program-in a way of backing-off those setings if the ideals are not being met. As an aside, this is why there are very few gains to be made by chip-tuning modern-day naturally aspirated engines: the manufacturers base settings are usually so close to optimal for the engine under ideal conditions that there is frankly nothing more to achieve. In the old days the conservative settings used could often be improved upon if the owner made sure the engine was used only in close-to-optimum conditions.

One of the adaptive systems used in the Bosch DME is knock control. If an engine uses the optimal settings with a fuel that is less than ideal (in other words of lower 'octane' than it was designed for) that mixture can detonate (causing a knocking sound, hence the terminology) in the cylinder rather than burning the mixture progressively. What the knock control does is sense the onset of possible detonation and back-off the ignition timing to prevent it. Backing off the ignition timing from the optimal values reduces engine performance but prevents engine destruction. The DME also logs recurrent knock sensor activity (if the timing has to be backed off again and again) and eventually stores the ignition retard value as a semi-permanent value that is always applied to the base settings. Most DMEs also richen the fuel mixture (beyond that which gives best power) under these conditions as richer mixtures burn cooler and further prevent detonation.

If you then fill up with higher grade fuel, the settings stored for the poor fuel are in the DME's memory. Over a period of time and miles, the DME will log the fact that the knock sensor has not detected any detonation or near-detonation throughout the engines rev and load range (as better fuel is capable of accommdating settings closer to the optimal base rather than the one's corrected for the poor quality fuel). It will then begin a process of bringing the timing forward until potential detonation is sensed again and the new values will be stored.

To be able to do a 'back-to-back' comparison, resetting the DME (in essence, re-booting the computer that controls engine management) willl immediately clear all previously stored correction values so there is very little time required for adaptation to the new fuel to occur. The knock sensors immediately back-off the timing by any required amount and those new values are eventually stored in the DME as required.

To reset the engine management computer (DME) simply disconnect the negative battery terminal for about an hour (to let everything fully discharge). You must have the ignition key in the 'on' position when you disconnect the battery lead (BUT THE ENGINE MUST NOT BE RUNNING) or the alarm will go off. When you re-connect, you will need to re-enter your radio code (do you have it?) and reset any settings in your trip computer if fitted.

Looking forward to hearing the results you achieve.

Ian

 

[PaulHere]

When I fill up my 180,000+ mile two litre 924 with Shell Optimax I notice a power increase and the engine is quieter as well.

 

[ian996]

Just another point i heard the other day - V-Power is going to replace Optimax in the coming months as Shell's premium fuel. Price seems to be the same as Optimax from what i have seen so should be good news to those who use Optimax anyway....

 

[THX911]

ORIGINAL: ian996

Just another point i heard the other day - V-Power is going to replace Optimax in the coming months as Shell's premium fuel. Price seems to be the same as Optimax from what i have seen so should be good news to those who use Optimax anyway....

I thought this was a complete change over last month all over UK rather than slowly replacing Optimax over the coming months? So far all the Shell stations I have passed in the South East have all changed. I have already received my V-Power Club card which replaces the Optimax card.