Fuel efficiency remapping

Scania_Man

Leaving aside the standard options of increasing fuel efficiency (tyres at correct pressure, no roof racks/minimum luggage, not filling the fuel tank fully, not using air con etc as well as the obvious reading of the road and driving sensibly!) I have been advised that I can increase fuel economy by approx 10 to 15% by getting a remap.

When doing 20,000 miles plus per year this could amount to a rather significant saving which would more than cover the cost of the work. It will result in a power increase from about 125 to 155hp all apparently well within the manufacturers safe limits on the engine and parts.

All sounds too good to be true and to an extent it is - neither my currently any other insurer I have contacted is willing to insure. I'm a licence holder of about 10 years no points no claims and am in late 20s and was shocked to discover they're not trying to stick a few hundred on but instead flatly saying no.

I was recommended a company specialising in 'modified' cars that after contacting wouldn't quote for my annual mileage!

Surely I'm not the only one who's ever tried to actually get insurance for this on an otherwise run of the mill car. I'm not a boy racer trying to make it 300hp with exhausts the size of a small sewer belching clouds of black smoke out! Just seeking a minimal power increase for long term fuel savings.

Anyone had similar experience or found a reasonable insurer? Also are there different categories of remapping? Is there a performance orientated one vs a fuel saving orientated one?

Seems strange to have something that can be legally carried out by specialists but then not be able to insure it for the road!

forgotmyname

No issues with mine, join clubs/forums for your make/model of car and see who they use for their insurance. Quite often they have an insurer who sponsors the site or advertises on it. Mine just asked for the code off the club site which is given in their advertising thread.

It may save you fuel, but you will have more power and your likely to use more power and even more fuel.

Not strange to legall modify a vehicle and then not be able to insure it. Years ago the place i worked at stuck a 3.5 litre rover V8 engine into a MK2 escort van 1300cc to 3500cc. Passed the MOT with no issues, but insurers had other idea's.

Driven around on trade insurance before selling to a customer who offered enough money at the right time. No idea if they got it insured?

AdrianC

Scania_Man wrote: »

...I have been advised that I can increase fuel economy by approx 10 to 15% by getting a remap.

Lemme guess... by the people selling the remaps?

Look, it's very simple. Manufacturers spend a huge amount of time, effort and money on maximising the efficiency of their vehicles. Fuel economy sells. So does it really make sense that a remap from some random small outfit could be SO much more efficient?

Joe_Horner

AdrianC wrote: »

Look, it's very simple. Manufacturers spend a huge amount of time, effort and money on maximising the efficiency of their vehicles. Fuel economy sells. So does it really make sense that a remap from some random small outfit could be SO much more efficient?

It can, but only if your driving style is suitable or you're prepared to modify your driving to suit.

Essentially, a good remap will provide extra torque at lower revs which allows you to hold higher gears for longer but you only really benefit if you're prepared to potter around with a very light foot to take advantage. Start pressing the loud pedal and the extra power will drink more.

Manufacturers set things up for "average drivers" and for specific fuel consumption test which specify speeds and rates of acceleration. Outside those conditions their maps are often less than ideal. Which is why no-one ever gets what the makers claim,

AdrianC

Joe_Horner wrote: »

Essentially, a good remap will provide extra torque at lower revs which allows you to hold higher gears for longer but you only really benefit if you're prepared to potter around with a very light foot to take advantage.

Fuel maps are massively complicated things, with a myriad of data points taking into account revs, load, throttle position, manifold vac (on a petrol), etc etc etc... So if it's so easy to remap a specific portion of that map, why don't the manufacturers do that to start with?

If the low rev, high load, low throttle portion of the map can be improved so easily... why isn't that portion optimised to start with? It's independent of other sections of the map...

Gloomendoom

Scania_Man wrote: »

Seems strange to have something that can be legally carried out by specialists but then not be able to insure it for the road!

You can insure it. Your choice of insurers will be more limited and you may have to pay more. All the cars I have are modified in some way and I have no problem insuring them.

If you are looking to save money, keep the car stock.

I have used specialist brokers such as Adrian Flux and Chris Knott. I have one car insured with LV direct and the other through Flux (can remember the insurer)

Gloomendoom

AdrianC wrote: »

Fuel maps are massively complicated things, with a myriad of data points taking into account revs, load, throttle position, manifold vac (on a petrol), etc etc etc... So if it's so easy to remap a specific portion of that map, why don't the manufacturers do that to start with?]

Because they have to produce a map that will work reliably with every engine that comes off the production line and in all territories that the car is likely to be used. They may also be trying to meet specific fuel consumption or emission targets.

If you narrow down the parameters, you can start to optimise the map to suit the requirements of a specific engine or user.

AdrianC

Gloomendoom wrote: »

Because they have to produce a map that will work reliably with every engine that comes off the production line and in all territories that the car is likely to be used. They may also be trying to meet specific fuel consumption or emission targets.

Indeed...

If you narrow down the parameters, you can start to optimise the map to suit the requirements of a specific engine or user.

Because, of course, every single remap is developed, bespoke, on a rolling road with that individual user's driving habits logged and analysed in-depth.

Anyway, a sizable proportion of engine management now is adaptive to driving styles.

Gloomendoom

AdrianC wrote: »

Indeed...

Because, of course, every single remap is developed, bespoke, on a rolling road with that individual user's driving habits logged and analysed in-depth.

I suspect that you know that is not the case. A map tailored to a specific engine and driving style is the ideal and perfectly possible but will usually involve a lot of dyno time and road testing so costs considerably more than a generic remap. A generic remap is less likely to get the absolute best out of an individual engine but will usually produce worthwhile and noticeable results. The downside of both is that improvements in one area may result in poorer performance in others. The car may be undrivable in a Siberian winter, for example.

Edit: I would add that I have been fiddling around with tuning boxes and remaps for a few years now and have never seen a genuine improvement in economy in my own vehicles or those of others that I have spoken to. Power, on the other hand, is different matter.

AdrianC

Gloomendoom wrote: »

The downside of both is that improvements in one area may result in poorer performance in others. The car may be undrivable in a Siberian winter, for example.

If only manufacturers thought to put ambient temperature as one of the factors the map takes into account...

Oh, wait. They do.

Gloomendoom

AdrianC wrote: »

If only manufacturers thought to put ambient temperature as one of the factors the map takes into account...

Oh, wait. They do.

I'm not sure what point you are trying to make.

That generic or custom remapping makes no difference to the the way an engine performs?

The manufacturer's map may take ambient temperature (for example) into consideration but the values may conflict with the revised parameters of the remap.