SMART ForFour Tuning

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The ForFour is a good project car to execute. We see lots of DIY modders wasting money on their ForFour doing the wrong mods and then having to start over. Follow our advice to avoid making the common mistakes

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Engine tuning Transmission tuning Care care Intake & exhaust mods Improve handling Forums

Our aim in ForFour engine tuning should be to increase peak power and Torque at the top end.

ForFour make good sleepers if you debadge them and fit the most powerful engine mods and handling mods you can !

Sadly with smaller engine sizes you are wasting your time spending money on modifications, so if this applies to you get yourself an engine swap then apply the following mods.

Engine tuning mods.

The following performance parts are usually carried out by our members, decide how far you want to push your car before you start.

Getting the right uprated parts for your planned usage of the car is a time and money saver. Stage 3 motor sport mods just don't work well on the road hard to control in slow traffic.

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Guide to the Best Tuning Mods & Upgrades

  1. Mods that Remove a Restriction

    If the intake or exhaust are restricted in any way this will have an impact on your cars performance, so use an induction kit/filter upgrade and better flowing exhaust whenever your tuning creates a flow restriction.

  2. Mods that Improve Handling

    Braking, Suspension and general alignment of the suspension components is vital for any tuning project even before you start increasing power.

  3. Fit Stronger Parts

    Tuned cars will show up weaknesses, typically in the turbochargers, clutch and internal engine components. Whilst most engines can cope with mild tuning mods, TorqueCars recommend that you upgrade the internal components before these weak spots manifest themselves.

  4. ECU Tunes & Remapping

    While some cars can be easily remapped, others may require piggyback ECU's or aftermarket ECU's but this is the most vital step of your tuning project as it fully releases the power from all of your mods and upgrades. Expect 10-20% on NASP engines and 30-40% on turbocharged units.

  5. More Power Needs More Fuel & Air

    Every tuning project will aim to increase the air supply, but fuel supply is just as vital and will need to match the air the engine can utilise. Fuel to Air ratio is vital so upgrade the fuel pump & injectors. Also you can look to perform head mods (flowing and porting), bigger valves, fast road cams and forced induction upgrades to improve fuel.

Stages of Tune

Stage 1 mods: Suspension upgrade (drop 30-40mm), Lighter flywheel, Panel air filter, Remap, Alloy wheels, Sports exhaust.

Stage 2 mods: Fast road cam, Ported and polished head, Power/Sport clutch, fuel pump upgrades, high flow fuel injector.

Stage 3 mods: Adding or upgrading forced induction (turbo/supercharger), Sports gearbox, Competition cam, Engine balancing, Internal engine upgrades (pistons/head/valves).

Peak power is nice in motorsport but for a daily driven car you need a long power band and perhaps extending the rev range.

The point of our guides is to give a brief overview of car tuning mods and point you in the right direction, our forum is where you can ask for more detailed advice and tips on your tuning project, the best performance modifications and all aspects of modding cars.One of the biggest mechanical motorsport upgrades you can do on your NASP engine is to fit a fast road camshaft .

It maximises the intake and exhaust flow and increases the power if done right. Ideally you'd add other mods and finish up with a performance chip. TorqueCars would caution you not to go with a competition cam as this upsets the engines idling and general town driving characteristics.

You will need to ensure that the engine is not starved of fuel so will need to ramp up the fuelling.

If you find you experience flat spots and surges after your mods you should check the fuelling and try a higher octane fuel as well. Improving the injectors is another beneficial modification and will deliver sufficient fuel.

Uprate the fuel pump to cope with the extra fuel requirements of your tuned ForFours uprated injectors.

Intake and Exhaust Tuning.

Now we move on to the intake and exhaust and ensure proper flow through the engine. Air induction kits only help to boost performance if the air intake is restricted! Adding an induction kit to most stock engines will see NO LOW END POWER GAIN AT ALL. If you have heavily modified your engine and it's need for air INCREASES DRAMATICALLY then an induction kit is the answer and will help remove this restriction.

Maximum power gains come from a full induction kit with a cold air feed on heavily tuned engines, this can be sited within an air box but a panel filter should suffice for most applications. TorqueCars suggest you use a panel air filter as these are easy to clean and maintain and generally perform better than paper ones.

Sports exhausts equal out the flow of gases through the engine. But if your exhaust is too large, ie: over 2.5 inches bore, you will lose a great deal of the exhaust flow rate and end up lacking power and torque.

Head work including a gas flow (ported and polished) and 3 or 5 angle valve job will really help to release the potential of the engine. When you start tuning your ForFour you will discover that the standard clutch starts to suffer so get an uprated clutch. The best mods in our experience for your ForFour are a remap especially on a turbo, a fast road camshaft and sports exhaust, with a good air intake.

Turbo engines are just asking to be Upgraded. You will see large power gains on most modern turbocharged cars including diesels making a remap one of the most cost effective and large modifications for your money.

We've also come across some owners playing with twincharged applications and making some impressively high power hikes.

The most phenomenal power gains for NASP engines usually involve the addition of forced induction. Superchargers are often easier to add than turbos. It is harder to map a turbo as the boost builds exponentially with rpm.

It is more straightforward to map a supercharger because the boost is correlating to engine speed on a linear curve. Adding forced induction will often require a lower compression ratio or water injection.

Handling/Suspension upgrades

Handling modifications are the thing most do first for the ForFour.

If you set the toe out to 1 to 2 degrees on the front, and add a tiny bit of negative camber then cornering will substantially be enhanced.

Drop the car by as much as 26mm - 35 mm and fit modified stiffer dampers, bigger drops will need other modifications in most instances.

Alloy wheel upgrades.

Alloy wheels will help the brake cooling and are usually less heavy than the steel ones. Get a good directional tread pattern tyre to improve your handling and help improve traction on your ForFour. Please note although they can look cool on the ForFour large alloys will actually decrease your performance. The larger you go the lower your acceleration will be - this to the change in your effective final drive ratio.

Due to this we would advise sticking to a maximum wheel size of 15 inches, although we know some of our members have fitted larger wheels with no problems.

There is a more updated version of this SMART ForFour Tuning article on TorqueCars.com.

For more information on Tuning your car please join us in our friendly forum where you can discuss ForFour options in more detail with our ForFour owners. It would also be worth reading our unbiased SMART tuning articles to get a full grasp of the benefits and drawbacks of each modification.

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