V power

[chrishewett]

I filled up on sunday morning for the trip to Donnington park at the shell station and found myself at the new V power pump. I had never noticed much difference using Optimax and was therefore amazed that the car seemed to have so much more go. I mean it really did seem to be much more responsive, picked up quicker and generally had more ooumph. I have no reason to promote shell but I am interested to know if anyone else has any comments after using it.
I await your feedback.
Chris

[stuartgb100]

Chris,

When I asked about this, Shell said that with the old Optimax, they would only say it was at least 98 rating.

for V Plus they guarantee a min 99 rating.

Does this make the diference, and give value to the price hike ..... ?

Regards,
Stuart

[Tintin]

Does this make the diference, and give value to the price hike ..... ?

I'd be most tempted to say no. Higher octane rating fuel will only have an effect if the engine specs are altered, at least in terms of the ignition advance curve and only if the engine was operated rather close to knocking before. A real benefit would only be available if the degree of efficiency would be altered and this would mean a higher CR, different carb jetting and ignition timing.

An engine is designed and tuned to operate safely with a minimum octane rating and exceeding this rating only adds to the safety factor. The amount of energy stored in the fuel has nothing to do with octane rating and is pretty much the same for all pump fuels. At least the ambient pressure and temperature and thus density of the air would have a bigger effect on the power output of an engine.

V-Power is a marketing tool for a lot of engines apart from very modern engine management systems which have the ability to adopt to such high octane ratings.



Tim

[Dave_Newcastle]

Whatever the brand on the pump, and the claimed octane rating I believe that much of the petrol we have in the UK is not of the same quality as is available on the continent - certainly my car has always sounded sweeter and performed better on french fuel. I for one will look forward to the prospect of trying the new shell fuel and seeing if there is a difference.

Taking up the point on what octane rating was/is optimax - there is no information given on the pumps and I have asked several times at filling stations and have not ever been able to find anyone who knew. Does anyone here know?
How much is the V power??

[tdafforn]

Just gone through the Shell website.
No real info, just lots of corporate blurb and a picture of a cleaner exhaust valve..
Tim

[Dave_Newcastle]

On topic - report below claims better performance than optimax or bp ultimate from tesco 99

http://www.pistonheads.com/gassing/topi ... 7&t=302977

[Tintin]

On topic - report below claims better performance than optimax or bp ultimate from tesco 99

http://www.pistonheads.com/gassing/topi ... 7&t=302977

They report 8hp on a BMW M3 equipped with a modern ECU which features a knock sensor. This ECU does exactly what I referred to: It adapts the engine characteristics (ignition and fuel timing) to the fuel. This is a far more advanced setup than a (pair of) carb and a dizzy.

BTW: The octane rating does _not_ tell the amount of octane in the fuel, it's just a comparison number to a laboratory value. The pump fuel simply features the same knock characteristics in the lab as a mixture of Octane and Heptane (IIRC) and the Octane Number is the percentage (for RON).
One of the posty on that page gets this wrong.



Tim

[M100]

You won't find me using it. I'd sooner walk on broken glass/crawl over hot coals/chop off my b*llocks with a rusty knife than use any Shell product!

The Octane of F1 fuel by the way has to be within the range 95 - 102 RON and greater than 85 MON. There is no specified energy content limit.

[chrishewett]

Come along Martin dont sit on the fence, tell us how you really feel about shell. It wont do you any good to keep it bottled up!

[M100]

Chris

I've vented my anger with Shell a few times on various Lotus lists and a few times down the pub. I could repeat it again but with some other strife I've got at the moment it would only get me more wound up which is the last thing I need.

[denicholls2]

It's unlikely you would see a difference in performance just from the fuel, unless your system is currently over-advanced for the fuel it is using. Then the difference might be large (but you'd be knocking on your old fuel.)

With the Twincam at stock compression ratios, octane isn't as much of a factor as it is for those of us, say with Europa-Renault engines, running at 10.5:1 or better. The same would be true of high-compression Twincams. We can tell the difference, but only when we advance our dizzys to gain better power within our "knock curve". I can attest that the greater advance supported by higher octane in this case results in a DRAMATIC power increase on a Renault engine, power that is unavailable without dangerous detonation at lower octane.

But you need to modify your advance to gain a real benefit, assuming you are properly tuned for the fuel you were using before.

As to energy content, for economy it is in fact what matters. My Sienna has a knock sensor and VVT, plus other wizardry I'm sure. I had the opportunity last week while in the midwest, where regular unleaded is more expensive than "mid-grade", a higher-octane fuel with lower energy content (due to ethanol being added), to see if the higher octane of the ethanol fuel (and resulting better automatic advance) made up in any way for the lower energy content of the ethanol blend.

The Sienna (AKA Behemoth) gets about 500 miles out of a tank of regular unleaded 87 octane RON, around 25 MPG. Running on 89 octane mid-grade, I lost about 50 miles range (10%) per tankful. So, the low compression (8.5:1) engine's happiness with low octane resulted in no benefit in terms of economy, and the five cent per gallon savings (about 2%) was not an actual savings because of the lower energy content. 240 horsepower underfoot means performance isn't a big issue at any octane with this beast, so no gains there.

My results differed substantially from those presented in a local commercial for the ethanol blend, where lower MPG was acknowledged but slightly more than covered by the lower fuel cost.

-- Doug Nicholls, 54/1822 Ma~