Chris recently brought this stunning Caterham 420R and got in contact as he felt it was missing the roar of a set of throttle bodies and wanted more power.

420R Throttle Body Conversion:

All 420’s are powered by the 2.0L Ford Duratec engine. Unlike the Caterham 360, the 420 and 420R comes with a set of uprated camshafts and springs & retainers as standard from Caterham so a throttle body conversion is not invasive and a relatively straight forward job. Chris also loves a track day so part of the brief was to try and keep the noise down as much as possible.

We offer throttle body conversions for the 420 in three variants; the first is with everything is kept under the bonnet including the air filter (SV / wide chassis only). The second option is aimed at maximum power output and is supplied with longer trumpets and an air filter which exits the bonnet. Our third option which Chris opted for is suited to track day enthusiasts which still has longer trumpets, but enclosed within a carbon fibre air box to try and dampen the noise.

Caterham 420R Throttle Body Kit Instillation:

Once the tuning package was agreed, it was time to get the throttle bodies installed. We start by removing the stock plenum, fuel rail and throttle cable. The throttle bodies are then assembled off the car (which includes the Throttle Linkage and injectors but without the air horns) and are bolted into place. We then move onto the fuel system and start by installing the injector blanking caps in the cylinder head. We also have fuel line adaptors made specifically for this conversion which allow the Jenvey fuel rail to easily connect to the 420’s original fuel system which makes this part of the job very simple. As part of the kit, a new Throttle Position Sensor and Fuel Injectors are supplied so the wiring is modified and these components are installed and plugged in. The Air Filter Black plate is the measured, cut and installed along with the Jenvey Air Horns and followed by the carbon air box. The stock air temperature sensor is retained so this is also installed into the air filter back plate. Further measurements are then taken and the bonnet is cut to suit the airbox. We then hook up the throttle cable, balance the Throttle Bodies and we are ready for start-up!

Throttle Body Components:

Here at Northampton Motorsport, we understand that some Caterham owners prefer to work on their own cars. As well as the drive in and out service that we have detailed above, we also offer this kit as parts only enabling customers to install their own kits. In these cases, we are still happy to offer engine calibration but we are unable to confirm whether we are able to calibrate the stock MBE ECU without seeing the car. Please see our web listings for details and pricing on the kits or contact us for installation and mapping costs.

All of our Caterham tuning packages are developed and tested in house by drawing on over 20 years’ experience of engine tuning and ECU calibration. They consist of high quality Motorsport products from the worlds leading manufactures. With the exception of the fuel injectors (made in Germany), all of the components of this kit are made in the UK.

Engine Calibration:

Now that this Caterham 420R Throttle Body kit has been installed, the car needed to have the Engine Control Unit recalibrated to suit the modifications. The standard Caterham MBE ECU is encrypted and cannot be accessed without the correct software. Northampton Motorsport can in most cases access these locked ECU’s and in this case, we were able to tune the stock MBE 9A4 ECU.

We saw gains across the entire rev range with the best gains found in the midrange. After calibration, we saw 224.8bhp and 163.8lb/ft peak power. If you look at the rolling road graph at the bottom of this page, the black lines are prior to installation and tuning with the red lines after. Chris’s 420R still had its original catalyst and we best have seen using the carbon air box is 227.1bhp and 167.2lb/ft with a de-cat.