What to check to reduce MPG?

mercutio · Post by **mercutio** » Thu May 03, 2012 1:47 pm

here you go

Fixed: Graham

mercutio · Post by **mercutio** » Thu May 03, 2012 1:47 pm

dont know how to embed sorry

Post by **indigolemon** » Thu May 03, 2012 1:49 pm

mercutio wrote:dont know how to embed sorry

For Youtube just paste the link man, don't worry about the tags - the site works it out automatically.

skinny · Post by **skinny** » Thu May 03, 2012 5:41 pm

as someone who's job it is to run vehicle fleet trials to look at differentiating between fuels that are robust enough to stand up in a court of law, i can say that pretty much everything in that video is complete bollocks

it's basically an italian tune-up probably using a high detergent additive pack.

you'd basically get the same effect from filling up with a tank of Shell or BP super unleaded (or maybe just stick in some of that injector cleaner stuff, not that we're supposed to recommend them) and doing a load of full throttle accels over the tank. it's a genuine way to improve long term fuel economy but terra-clean is just snake oil, same as most of that stuff.

mercutio · Post by **mercutio** » Thu May 03, 2012 6:11 pm

they did a before and after on a gas analyzer and there was a huge improvement

skinny · Post by **skinny** » Thu May 03, 2012 8:53 pm

Going through some of the things that are crap:

Higher octane fuel produces no more carbon deposit than lower octane, even if it doesn't have more detergent (which generally it does)

Deposits are formed on the *intake* valve, not the exhaust

Fractionalising the molecule is a nonsense statement. They might be saying that they are using more saturates (Aliphatics as they call them) which make up about 60% of gasoline but I can't make out if they are actually putting different fuel in...

Columbic fractionation is more bollocks than the L - casei immunitas in my yoghurt. Fuel molecules are not electrically charged. If they were, then if the carbon that enters the combustion chamber is positively charged as he claims, the molecules would be repelled from each other, not attracted to each other. Also, molecules of carbon do not enter the combustion chamber - carbonaceous deposits are created in areas of quench in the combustion chamber.

High exhaust temps (from a thrashing) will 'decarbonise' your O2 sensor and cat. you don't need terraclean for that!

The gas analyser does not tell you how much power you are making. That's what the dyno is for. Also, proper exhaust emissions analysis requires a non leak connection at the exhaust to the analyser so that you can capture the tailpipe HC's, CO, CO2, NOx and O2 - they don't seem to have this. They made no claims based on the exhaust emissions data, apart from him saying you got a more efficient burn.

Injectors do not fire randomly! At least they shouldn't...!! Pulsewidth doesn't really change unless the injectors are massively clogged and the lambda is out but its very unlikely to be that bad.

the graph they put up of what was presumably the O2 output, the 'after' doesn't look very different to the 'before' - they just chose to show a smaller part of the range!! They were also talking about injector flow when showing those graphs, and didn't mention O2 output (even tho it was printed on the graphs) which was a bit misleading.

on the 'decel' test, they talk about combustion balance - showing slight variation before and much more uniform after terraclean... this is completely meaningless!! the graphs are also rubbish and seem to show that on the dirty engine, when they snap the throttle shut the lambda sensor reads lean for a while, whereas on the clean engine, it reads rich straight away. However, even with instant fuel cut off, you'll still read very rich immediately on throttle shut, and this would be more exaggerated in a clean engine, so the wrong way round to what they seem to be showing.

bristol_bb4 · Post by **bristol_bb4** » Thu May 03, 2012 8:55 pm

skinny wrote:Deposits are formed on the *intake* valve, not the exhaust

really???

skinny · Post by **skinny** » Thu May 03, 2012 9:01 pm

Yep, on a standard pfi engine, the injectors spray fuel on the back of the intake valve, and the shitty bits in fuel cause gums and lacquers that build up to form deposits on the relatively cool surface. The recirculation of crankcase (oil) vapours also contribute massively to deposits.

IVD's is a very common acronym in engine design - stands for inlet valve deposits

The gas speed as it exits the combustion chamber is much higher than intake so nothing is hanging around to cling to the back of the valve, and also the exhaust valve is so much hotter its much more difficult to get deposits to format on it as they immediately burn off.

littlefeller · Post by **littlefeller** » Thu May 03, 2012 10:55 pm

Ammo wrote:Results are in with a few Vtec blasts

367miles on 51.88L = 32.16MPG

Costs 19.92 pence per mile

32mpg, thats an improvement, so what have you changed?

yep i saw wheeler dealer too, its new and not really here in the uk and yes it does lower the emitions

Post by **Ammo** » Thu May 03, 2012 11:02 pm

Valve clearances, oil, changed to OEM air filter

Or other factors which although didn't reduce MPG but have changed my driving style

Ebay manifold and downpipe
UKDM CAT
Quiet Janspeed cat back exhaust

I no long get any bangs and pops from the exhaust so I pootle along rather than 3rd gear at 40mph and backing off for loads of pops and bangs

Car feels a lot smoother, but boring though, but it's saving me money lol

And as at the mo I'm £190 out of pocket for unpaid mileage, kinda glad it's not double that