remap for mpg?

russellbridge

russellbridge

A2OC Donor
Is it possible to re-map the engine for better economy? Given that my A2 looks like it's staying with us for some years to come (helped by the fact Skipton Auto's are only a few miles away), a £250 remap to give, say, an extra 5mpg would pay for itself in just over a year at today's diesel prices, given that I'm currently doing 20k miles per year.

£1.40/ltr (£6.36/gallon!) @ 51mpg over 20,000 miles = £2493 / yr on diesel
£1.40/ltr @ 56mpg over 20,000 miles = £2270 / yr on diesel

(51mpg is my average over the past 10 months, all calculated brim to brim, mostly short journeys, mostly 4-up + child seats, potties etc, tyres all at 36psi, 16" SE wheels with 185/50 quality tyres, standard 75 engine)

ps didn't know whether to post this in 'chipping and tuning' or 'fuels' - mods pls move if you think appropriate

Russ
 
russellbridge said:
Is it possible to re-map the engine for better economy? Given that my A2 looks like it's staying with us for some years to come (helped by the fact Skipton Auto's are only a few miles away), a £250 remap to give, say, an extra 5mpg would pay for itself in just over a year at today's diesel prices, given that I'm currently doing 20k miles per year.

£1.40/ltr (£6.36/gallon!) @ 51mpg over 20,000 miles = £2493 / yr on diesel
£1.40/ltr @ 56mpg over 20,000 miles = £2270 / yr on diesel

(51mpg is my average over the past 10 months, all calculated brim to brim, mostly short journeys, mostly 4-up + child seats, potties etc, tyres all at 36psi, 16" SE wheels with 185/50 quality tyres, standard 75 engine)

ps didn't know whether to post this in 'chipping and tuning' or 'fuels' - mods pls move if you think appropriate

Russ
Click to expand...

Hi Russ, a remap would give you better MPG. Stealth Racing is the place, see Vince he does a great job.

Cheers

Mark
 
It depends on your short journeys as mine gas been remapped and if i use it for work 3.5 miles round trip drinks the stuff but on average its mid 50's and long trips I've had 72. But a remap does more than give you better mpg's it transforms the drive of the TDi

Phil
 
You will probably notice a small improvement in MPG (say 1-2MPG) with a remap anyway becuase the increase in torque will enable you to drive in a more fuel-efficient manner (higher gears earlier, less full throttle etc).

If you're serious on the improving MPG route though there are are several other steps you can take, all of which have been explored on the forum.

Do a search for "aero mods" - there are some small additional aero bits you can buy and easily retrofit which were standard fitment on the ultra-frugal 1.2TDi (never sold in the UK) which will probably see you good for an extra 1-2MPG.

Do you do much motorway driving? If you do, you could also consider the "5th gear mod" (again do a search, but make sure you've got 3-4 hours to spare on reading the thread!). This is a simple cog-swap for the existing 5th gear ratio - gives you a longer 5th gear, dropping RPMs at 70MPH by about 400RPM compared to stock gearing. In combination with a remap (to maintain driveability) this would also give you a boost of 4-5 MPG (and also makes driving on m-ways a bit more comfortable as general noise/vibration levels are reduced).

I've done all of the above and am now seeing a genuine all-time average of 60MPG (I do 300miles a week but a mixture of urban, a-road and motorway driving so a real mixed cycle), with my best brim-to-brim being 69MPG on mostly motorway.

Food for thought for you there!
 
Thanks for the quick replies chaps. I'm an avid reader of the A2OC forums so I'm aware of the aero mods, longer 5th gear etc. I don't neccesarily need any more power as I'm driving as eco as possible everywhere at the moment (which in itself is pushing around town driving up to about 54mpg), the question was more - can the remap be done to favour lower fuel consumption rather than power?
(the aero mods will be going on at the next service btw)
Cheers
Russ
 
The question is already answered! More power (as in torque) will help sustain higher gears longer, however the aero mods will not be much use in town driving. Another significant factor is low rolling resistance tyres, they really do make a difference. Overall though it all depends on how much you want to spend versus the gains/savings etc. The 5th gear mod combined with a remap simply make the cars so much more enjoyable and reduce engine wear etc. However the remap, aero and 5th gear mods will be @ £6/700 if memory serves me correctly. For me it was worth it but that equates to 14 tanks of diesel and for me 12 weeks driving, 20-25% of the annual fuel bill.
 
A very good point on tyres, get low-rolling resistance ones when you next change them. You could also consider going for a narrower tyre width too as that will physically create less drag and give better MPG - one thing I noticed was how much easier it was to get >65MPG during the winter when I had 155/65/15s on - markedly narrower than 195s and even though winter rubber is physically more sticky, my MPGs went up vs the summer rubber. Ok I was probably driving a bit more slowly too, but it all plays a part.
 
Cheers ulp. Sorry my original question was badly worded, but you understood what I meant! It was: if a standard remap gets more power from the same amount of petrol, could an 'eco' remap use less fuel for the same power? If it means that the engine thinks it's being under-fuelled then it's obviously a non-starter.
Russ
 
russellbridge said:
Cheers ulp. Sorry my original question was badly worded, but you understood what I meant! It was: if a standard remap gets more power from the same amount of petrol, could an 'eco' remap use less fuel for the same power? If it means that the engine thinks it's being under-fuelled then it's obviously a non-starter.
Russ
Click to expand...

I see you own a TDi. Like most modern diesels the injection timing runs retarded to optimise emissions. A remap can advance the timing which increases engine efficiency. Its worth talking to Vince at Stealth Racing for advice in a custom 'economy' remap.

Cheers Spike
 
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