different types of fuel in a gti?

[speedynz]

Rhyso, you're right about the cars, standard Golf GTI and a BMW M5.

The Golf showed great gains, the M5 not so great. Forced induction cars always appear to respond better to high octane fuel than normally aspirated ones.

The cars were tested over a number of days as it took in road driving impressions and the dyno runs. The process of getting different fuels in and out was lengthy and there may well have been different atmospheric conditions outside of the controlled dyno run coditions, this is unavoidable but unless there is a huge difference in ambient tempreature or barometric pressure then the power delivery differences and ultimate figurative discrepancy would be negligible anyway.

[Teutonic_Tamer]

I stated it wasn't statistically correct, because from memory, they never had a "control" car, nor did they use a "control" fuel.  They didn't list the full atmospheric conditions for each dyno run, and I don't remember them even being done at the same time (though I could be wrong).

if i remember correctly they used a Golf GTI and a BWM 5 series petrol (could be wrong on that one) but do you mean in that they should have used 2 GTI's, one with standard 95 ron and the other using the super unleaded stuff?

Both were put on the dyno at the same time

For a "control", a whole host of things need carrying out.  Batch certified and sealed fuels should be used, ECUs should be reset to default, reverse batch runs (ie, standard 95, then shell, then tesco, then BP, etc - and then run in a reverse sequence).  All fuel lines should be purged, and then run for a set period on the "base fuel", before using another fuel, etc, etc.

True "controled" tests like that are an absolute nightmare, and whilst many of the control procedures can be omitted for non-scientific tests such as magazine reports - it is very easy to see how results can be "squewed" on favour of a certain "preferred" fuel.  The test that Fifth Gear did was probably one of the worst examples of squewed testing.

[speedynz]

TT, as you stated, true "controlled" tests are an absolute nightmare and no, EVO did not go to these lengths. They ran the cars on forecourt fuel, took each batch down to 3 miles left in tank on the trip computer, ran 10 litres of the new batch through, again took it down to 3 miles left to run then put another 20 litres in before running that batch through on the road and on the dyno.

Not as scientific as you might like but enough to show clear performance differences between the fuels.

As I said before I'll mail you the entire article if you like, it makes good reading.

[Teutonic_Tamer]

TT, as you stated, true "controlled" tests are an absolute nightmare and no, EVO did not go to these lengths. They ran the cars on forecourt fuel, took each batch down to 3 miles left in tank on the trip computer, ran 10 litres of the new batch through, again took it down to 3 miles left to run then put another 20 litres in before running that batch through on the road and on the dyno.

          

That is grossly inadequate!  Absolutely no question that that test is grossly flawed.  Firstly, relying on the cars own trip computer is completely in-excusable.  I would think that every single car owner with half an ounce of common sense knows that trip computers should NOT be relied on, as they are well know to give inaccurate readings.  Because of this, the testers didn't have a clue how much of the previous jungle juice was left in the tank!  The fact they "tried" to flush with 10 litres is a very poor and feeble attempt, as they clearly knew the need to avoid cross contamination, but would have failed miserably.

Finally, the final 20 litres used for the actual "test" - again, woefully inadequate.  That could be used up in 60-70 road miles, and the fact it was also used for the dyno run too - well that would probably leave about 30 road miles for a "butt dyno" assessment!  This is clearly NOT long enough for the ECU to properly adapt to the requirements of the particular fuels used.

Was there any indication that they reset the ECUs back to default settings?

Not as scientific as you might like but enough to show clear performance differences between the fuels.

I'm sorry, but I have to strongly disagree.  It seems that there was absolutely no way it could show any differences, never mind clear differences between fuels!

It is simply a case of journalism at its' very worse, and it would seem the most appropriate place for this particular article would be to hang it on the nail in the outside "dunny" !!!

My own gut feeling is that EVO were trying to, or had recently succeded in securing major advertsing revenue from BP. 

As I said before I'll mail you the entire article if you like, it makes good reading.

Can you not scan it, and then e-mail it to me?

[Teutonic_Tamer]

Staying on this theme, a couple more contradictary "tests".

This one http://fifthgear.five.tv/jsp/5gmain.jsp?lnk=601&featureid=143 from Fifth Gear shows that Shell Optimax is better than BP Ultimate.  However, Optimax has been superceeded by the even higher octane V-Power, and the Fifth Gear test still has some major "omissions" in its' published data.

However, this one http://www.thorneymotorsport.co.uk/gcs_article.php?artid=64&typelink=http%3A%2F%2Fwww.thorneymotorsport.co.uk%2Fgcs_article.php%3Ftype%3DNews%26subtitle%3D0%26title%3D0%26text%3D0%26toc%3D1 is probably one of the best published fuel tests.  Thorney clearly understand the need for transparency in their testing methods, and are not after "sensationalist" headlines which journalists rely on.  Nor do they have to "bow" to commercial revenue streams from heavy handed advertisers.  Again, the Optimax used has been superceeded, but it clearly shows that Tesco 99 is the best fuel available.

[speedynz]

TT, I hoped for a little more from you.

Jesus, I thought that I was cynical but not any more!!!!

The car's trip computers were used only as a guide, the first batch of fuel was flushed and another greater quantity added, no it wasn't 100% pure but I bet it was very close to it and certainly close enough to make a clear difference between fuels.

EVO gave BP a good hard kicking during the test as well as mentioning the positive aspects of it's fuels. Your assumptions that BP had just secured a major advertising contract from EVO are baseless and purely speculative.

Yes, the article is flawed from a highly pure scientific perspective but it also makes very good sense and as I said before if you take off your cynical gown, step back and absorb the content then you'll understand that this is a fair and unbiased report carried out in a manner conducive enough for you to make your own judgements.

Don't condone this article until you've read it.

Sorry TT, I can't scan it but my offer of posting it to you remains.

[Rhyso]

in that issue wasn't there a load of Shell Optimax advertising?   

I seem to remember one issue where that was the case..........