Fuel Test Report, the latest chapter

[Thorney]

A few members here may remember we've done some extensive fuel testing over the last few years, comparing different fuels, different performance fuels and such like. Well we've just completed the latest report where we wanted to answer a few more questions we had. Firstly we wanted to test forced induction engines as these are most likely to benefit from higher quality fuel and secondly we wanted to test fuel economy. The full report is here:

http://www.thorneymotorsport.co.uk/A4_Report.pdf

Bottom line?

Using higher quality fuel (we tested 95 octane against Tesco 99 octane) will pay for itself in terms of fuel economy even taking into account the higher pump cost and the extra power it generates is a nice bonus. Most interesting was the difference in fuel economy if you compare a standard car on 95 octane to a remapped car on 99 - nearly 50% improvement in fuel economy.

[tomTVR]

Thorney said:

Bottom line?

Thorney is sponsored by Tesco 99. A little convenient dont you think?

[Thorney]

Well its not like we hide it is it? Would be more suspcious if we didn't show that?

However I take the point, but remember what it is we do for a living, we basically remap cars to get more power for people (amongst other things) and the fact is that if a customer comes into our place exepcting x bhp increase if he is running on 95 octane fuel then our job is that much harder. If he comes in on decent fuel (T99 being one of them) then our job is easier and he leaves a happier customer likely getting more power than we quoted. There is nothing magnanimous in what we've done its purely selfish.

This test was basically to see if the extra power gains actually cost more and the answer is the opposite, remapping a car (in this case Astra VXR's) gives you a lot more power AND better fuel economy when compared to a standard car ran on 95 octane fuel.

[JJCW]

I found it very interesting - thanks for sharing it.

[bordseye]

very interesting - I'm not so cynical as to think that Tesco pay you to fiddle the figuresthough I'm sure they wopuldnt let you publish if the results were bad.

anyway, on the standard car, is the increase the result of the knock sensors detecting the higher octane fuel and reducing the ignition advance? if so would it also work on my lotus with the toyota 190bhp engine?

even more interested in the ecu mods to give the extra power. given that the vauxhall involved is a car where you would expect the maker to get the best power output he could, where does your increase come from? why dont vauxhall do what you do? or to put it another way, is there a price (say flexibility) to your changes.

[Thorney]

bordseye said:

very interesting - I'm not so cynical as to think that Tesco pay you to fiddle the figuresthough I'm sure they wopuldnt let you publish if the results were bad.

I can certainly answer that, no, whilst Greenergy (suppliers of the fuel to Tesco) have seen the report before it went out they have no right of veto or editorial whatsoever, they did however point out a few spelling mistakes which I think is fair. The first Tesco knew of this report was at about 12.48pm when I emailed it to a few journalists.

bordseye said:

anyway, on the standard car, is the increase the result of the knock sensors detecting the higher octane fuel and reducing the ignition advance? if so would it also work on my lotus with the toyota 190bhp engine?

Essentially yes, cars react differently of course, for our last testing we used an M3 (normally aspirated but very sophisticated engine management system), we chose the Astras this time as we wanted an FI car with essentially a less extensive ECU function, but yes the majority of the gains are explained via ignition timing.

bordseye said:

even more interested in the ecu mods to give the extra power. given that the vauxhall involved is a car where you would expect the maker to get the best power output he could, where does your increase come from? why dont vauxhall do what you do? or to put it another way, is there a price (say flexibility) to your changes.

Thats the perrenial question in the engine mapping World and the simple fact is that manufacturers are the Worlds finest at compromise, we just use up part of that safety factor. There are also numerous rules that a manufacturer has to adhere to and the aftermarket doesn't and finally cost, manufacturers have to look at model upgrades through the life of the model, the only difference between the first and secodn incarnation BMW One series diesel for example was a more powerful map on the second - all done by BWM.

[mmm-five]

I'm assuming my car - an E86 Z4MC - won't particularly benefit from a remap or Tesco fuel as it already runs on V-Power to get it's full 343PS/338HP anyway.

Plus I assume the cost of the remapping is not factored into the cost of using 98+ fuel?

[bordseye]

thanks for your reply - as it happens I had found your site and read there the more detailed answers you had already given.

as indicated I've got an elise 111r with the toyota engine. is there anything you can do with the ecu on that car or is it the case that the lotus software is encrypted. if it is, can the ecu be replaced by a completely seperate third party one?

[Thorney]

mmm-five said:

I'm assuming my car - an E86 Z4MC - won't particularly benefit from a remap or Tesco fuel as it already runs on V-Power to get it's full 343PS/338HP anyway.

Plus I assume the cost of the remapping is not factored into the cost of using 98+ fuel?

Quite the opposite, the Z4M has the same basic engine (there are some differences of course) as the E46 M3 and we get lovely power oput of those with remaps and exhausts (we race them). If you read your owners manual it says BMW recommend a minimum of 98ron fuel, it will happily run on 95 but you wont get full power, but yes, T99 is only slightly better than VPower (but its a lot cheaper).

[AngryS3Owner]

Was the test driver driving the remapped car driving like a total sissy? I fail to see how it can be better fuel economy when mapped unless it was running seriously rich from the factory?

[Thorney]

bordseye said:

thanks for your reply - as it happens I had found your site and read there the more detailed answers you had already given.

as indicated I've got an elise 111r with the toyota engine. is there anything you can do with the ecu on that car or is it the case that the lotus software is encrypted. if it is, can the ecu be replaced by a completely seperate third party one?

The Toyota engien in the Elise is known to be a difficult one to gain real power from due to the cam configuration and how the ECU controls that, there are all kinds of stories about Lotus 'locking ' the ECU etc but its possible. Its not a model we do a lot of though I'm afraid (we specialise in BMW and Vauxhall) but most models of car can benefit.

[mmm-five]

Thorney said:

mmm-five said:

I'm assuming my car - an E86 Z4MC - won't particularly benefit from a remap or Tesco fuel as it already runs on V-Power to get it's full 343PS/338HP anyway.

Plus I assume the cost of the remapping is not factored into the cost of using 98+ fuel?

Quite the opposite, the Z4M has the same basic engine (there are some differences of course) as the E46 M3 and we get lovely power oput of those with remaps and exhausts (we race them). If you read your owners manual it says BMW recommend a minimum of 98ron fuel, it will happily run on 95 but you wont get full power, but yes, T99 is only slightly better than VPower (but its a lot cheaper).

Thanks.

Better have a look where my nearest Tesco that sells 99RON is then - don't want to lose a single one of those horsepowers or torques.

Will have to think about chipping it as it's only got 10,000 miles on it so far, and want to see how it goes round Oulton & Anglesey before I think about getting more power out of it.

[youngsyr]

AngryS3Owner said:

Was the test driver driving the remapped car driving like a total sissy? I fail to see how it can be better fuel economy when mapped unless it was running seriously rich from the factory?

Forced induction cars tend to run comparatively rich from the factory. It gives them an added safety margin should crap fuel be put in, etc.

[AngryS3Owner]

I see your point, but I got my car remapped because I wanted it to go faster so don't see the point in driving around like a granny and when I do press on (as expected) the fuel consumption is worse.

I think it might be better than before at a steady 70-80mph, but couldn't tell you as I don't do that often enough.

[youngsyr]

AngryS3Owner said:

I see your point, but I got my car remapped because I wanted it to go faster so don't see the point in driving around like a granny and when I do press on (as expected) the fuel consumption is worse.

I think it might be better than before at a steady 70-80mph, but couldn't tell you as I don't do that often enough.

Then you should be happy that remapping a forced induction car to run leaner will make it produce more power (up to a point, obviously).

That's why FI cars respond so well to remapping - you can lean out the fueling and add timing to the stock maps in most FI cars.

[majordad]

Would a remap of my 04 Cayenne S 4.5 make a difference to fuel economy. I must use 95 ul , thats all we have here. And how can I get it done.

[Thorney]

Yep, gains aren't bad but I'll be honest we've not tested MPG on that model specifically. Best thing to do would be to drop me an email - [e-mail]

[Thorney]

Here it all is graphically:



Mapped Astra VXR run on both fuels.

[AngryS3Owner]

How did you ensure both cars were driven the same way?

[youngsyr]

Could you post up the unmapped car's graphs, please?