Tuning for stingy people - MPG tuning.

Tuning for economy. With the rising price of fuel one question we frequently get asked is how do we tune a car for maximum economy. Short of getting the family to push the car everywhere there is only a little that can be done to improve fuel economy. Get you makers stats out and work out if you are getting the right fuel consumption to start with. (Your driving habits and use of air conditioning may also be partly to blame so take the diving boot of the right foot and affix a helium balloon.)

First off we need to rid ourselves of problem areas that can rob us of fuel economy. You need a good strong spark to ensure that the engine burns the fuel effectively. Clean plugs are an essential, all leads and hi-tension electrics need to be in perfect working order. The fuel system also needs to be in tip top condition. Over time on injection engines the injectors - the little nozzles that spray the fuel into the engine become silted up and instead of spraying a fine mist of fuel into the combustion chamber which would burn very well it squirts a jet of fuel which sits in the bottom of the cylinder and much fuel is wasted.

Tyre pressures should also be checked as a 10psi drop in just one tyre can rob you of 4 mpg!!! This gets even worse if all 4 tyres should be under inflated. Are all of the sensors (temp, airflow, Lambda, idle speed etc) working correctly. Less obvious but important none the less is to check the hoses in the engine bay for air loss - vacuum loss can cause high idling and other combustion issues. You also need to ensure that the air filter is in good condition. Now moving on to the tuning tips. When making a car more powerful you lose fuel economy so the reverse is also true - less power means more economy.

Things we do to make our cars faster can also be reversed to get economy. Fitting a smaller bore exhaust. Restricting the air intake. Decreasing fuel pressure. Basically if you reverse the power tips you will have found economy tips! Taking the theory a little further - the hotter the intake air the less oxygen it carries and the less fuel will be burnt as the fuel to oxygen mix is carefully maintained.

Putting a warm air feed to take air from behind the radiator or better still just under the branches of the exhaust manifold you will do much to increase fuel economy. You probably notice that your car is a few MPG better off in the Summer compared to the middle of winter but the car seems much faster and more responsive in the Winter. This is due to the air intake temperature and the fact that the engine is running a little hotter. Hotter engines are more efficient and just raising the thermostatic valve that controls the cooling system by a couple of degrees can improve fuel consumption.

On cars with a couple of cooling fans in them you can wire one up to a switch which you manually throw if you see the temperature of the engine rising. Re mapping the ECU is possible and on turbo models a fairly substantial fuel saving can be had but few people actually ask for an economy remap - some companies offer remaps which give better economy at low revs and more power at higher revs but this seems to balance out as we tend to enjoy the power bit regularly. In the middle of winter drivers often mask part of the radiator which ensures the car gets up to operating temperature as quickly as possible this is best done with a heavy grade foil but you must always leave the area behind the fan free otherwise the car will overheat and if it does you will kill the engine.

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