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This fortwo started out, many moons ago, as a standard 2002 599cc mk6 Passion City Coupé (as they were called back then).

We're going to skip taking you through the early days as the bar has been considerably raised, due to the fact a lot of knowledge is now in the public domain from web sites exactly like this one. The early modifications are now everyday items and totally uninteresting by today's standards.

Within the smart world, modification has always been a very big thing. Back in 2003 when the car was purchased, there was very little in the way of off-the-shelf products available. Anything more than a set of wheels, remap or air filter had to be developed; this is where we really started here at FQ101, working on our own.

This Ferrari red fortwo was our project car; if a modification was being tested, generally it was on this car during a set period to ensure correct operation.

This fortwo's big power jump was produced in 2005 when a Brabus engine was fitted from a 699cc G2 car. We stripped and cleaned the whole unit, finishing it in the same Ferrari red paint for that special touch.

The engine itself is a direct fit if just swapping the block and head, the standard 45kw gearbox was left behind and blue Brabus injectors were fitted to compliment the existing Smart Tune remap.

On fitting a bigger turbo, the car required a new exhaust as the 45kw unit has a smaller inlet and different stud pattern on the exhaust site of the charger.

Below are two pictures of the turbo chargers inlets, starting with the new bigger turbo.

The EGR valve was blocked off and removed at the pipe. As the pre-2003 cars never had this feature, this was quite simply dumped.

The car was tested and GPS verified at 117mph in the middle of summer which is quite a result in a fortwo. Most owners we've spoken to inflate their figures, guessing their top speed at the pub rather than real world testing.

Towards the end of 2006, we were becoming itchy when it came to modding, as people were coming too close with modded Roadsters (with very little done) so it was time to raise the bar again.

After sitting down and looking at dyno plots, it become clear that we just couldn't get the power down off the line in the older G1 fortwo even with the Brabus power plant; a G2 conversion was now on the cards.

The car was absolutely stripped to the core including all cables and wiring looms. Everything was removed from both the interior and exterior to leave this poor smart carcass open to the next stage of the plan.

The car was then fitted with a Roadster engine wiring harness, a 2004 G2 cabin and a front ESP loom. Later we were hit with a spell of realisation that the rest of the car's electronics system and hydraulics are totally different as nothing mated up under the car.

This is precisely the problem with a project like this: we were in uncharted territory as no one had attempted this type of conversion before. We were left to work it out alone with no literature to look at for reference.

We had budgeted a month of our time on this project which had now just tripled; we were feeling disheartened to say the very least and at the point of no return.

We pushed on and continued to fit the car's new wiring loom and as we started to replace sensors one-by-one, things started to come together.

The ECU, SAM unit and gearbox fitted were from a G2 Passion so these should produce 61bhp standard (without mods). This would give us more ground to play with regards to mapping (already having 10bhp from the old 51bhp unit).

One of the main objectives for this conversion was the quicker gear changes and the addition of 'sports start' so the G2 two-stage pedal was added.

A cheap wrecked roadster came up through someone we knew. Without delay we were there trying to salvage any parts that could be used for the conversion.

We left there with a 80bhp Roadster gearbox, SAM unit, ECU, keys, speedo head and pods. As we had a G2 block installed, these parts could give us the Roadster's 80bhp base rather than the 61bhp from a G2 Passion.

Off came the 45kW G2 box (that we'd only fitted days before) and on with the 60kW unit combined with a Brabus clutch and flywheel.

After connecting the sensors and control units, we turned the key just one 'click' and we had signs of life. Our enthusiasm was restored.

Our next hurdle was the ESP and ABS system. With the exception of front flexy hoses and calipers, the G2 has a completely new brake system with regards to hydraulics. It become apparent that major work was required to get everything working, including:


  • New ESP / ABS unit.
  • Master cylinder.
  • G2 pedal box.
  • All new metal brake lines front to rear.
  • ESP loom from SAM to control unit.
  • Fabricating a control unit mount as they mount differently to the old units.
  • Additional lines needed to be added to the back wheels for the addition of the ESP's independent four wheel braking.


What we did find interesting is the fact smart increased the size of the brake lines from the master cylinder to the ABS pump from 3/16 to 5/8.

Once the brakes were bled and the speedo head connected, the car was carefully taken out for a little drive to ensure that everything functioned as it should and, after a few teething problems, sure enough it did.

We were happy with the results so moved on to the fit and finish of the car, a totally custom mount was made to house the roadster speedo head. This, of course, was a necessity of the conversion to obtain the correct speed reading as we were using the full 60kW Roadster gearbox.

The first prototype was developed (pictured below in white). After a few revisions to the seating angle, the unit was re-made and shown below finished in black.

In addition to the speedo conversion we looked at adding the Roadster pod gauges. These just didn't look right anywhere in the cabin due to their small size, so we fabricated mounts for them to fit flush into the roof lining (just above the rear view mirror) where they could be seen with just a glance.

While we had the car stripped out we took the opportunity to fit a Brabus Roadster paddle steering wheel and the sound upgrade bass bins.

Just when we think it's done and it's running well we discover that the fuel gauge is actually reading wrong. After investigating the problem, we traced it to the sender unit that is combined with the fuel pump into one unit. There was no alternative, we ordered the item from smart and swapped the arm and float assembly from the old fortwo unit so it would read correctly.

After lots of testing we were faster than every 80bhp Roadster just on weight so we decided to up the game yet again. Several hundreds of pounds were spent on the following mods to bring the power right up to make the car a complete handful:

  • 4 Bar fuel pressure regulator.
  • Mocal silicone intercooler pipes.
  • Modified Pipercross Viper induction kit from a Ford Focus (this was alot bigger than the smart designed kit).
  • Big Performance camshaft.
  • Mocal front mount oil cooler (for extra oil capacity).
  • mk1 fuel rail and IAT sensor.
  • 74kw Brabus roadster TIK.
  • Throttle body butterfly modification.
  • De-catted stainless steel exhaust.
  • 60kw yellow injectors (had a better spray pattern than the Brabus blues).
  • Brabus charge cooler unit with a custom front mounted radiator unit, combined with large high flow pump for extra, more stable, water holding capacity.


The picture below showing the installation of the oil cooler and charge cooler radiators; the second picture is displaying our charge cooler's high flow pump with our custom mounts and rubber supports.

This combination of performance parts in addition to the existing selection and new management system obviously boosted the car's performance way above what we were looking for. However, there is always room for improvement and seeing as the car was only running as the standard 80bhp with mods there was definitely a lot of room for improvement.

Ian at Big Performance talked about mapping the car when we were building it so I took him up on his offer. To get the map right that suited the car's extensive modifications it took most of the day. By about 3pm he cracked it and we had a car that was boosting to 1.4 bar (1.5 on overboost) that pulled hard in every single gear without any flat spots. This also allowed the car to accelerate off the new 120mph speedo with ease.

Now, with the car on Schmidt Space alloy wheels and Eibach suspension, it handled pretty well but not quite good enough. We removed and replaced the whole setup for a complete Brabus Widestar kit (including the huge arches), with 17's on the rear and 16's on the front. The car sat perfectly on its new 40mm lower springs. These Brabus Monoblock alloys wheels were custom finished in BMW M5 black chrome to darken them right down.

We dynoed the car in January 2007 at Red Dot Racing in Watford with a result we were all happy with: 119bhp but more importantly a huge 117ft lbs of torque.

The smart was run twice as they thought there was an error as the graph showed such a powerful line so quickly and torque to match the power. Its quite possible to get over 100bhp in a smart now with the right combination of modifications but getting the torque figure to match is almost impossible. As of today the car is still unrivalled.