Now of course to create more power we need to suck in more air which means we need to burn more fuel! This is why we made this page to show our injector recommendations for injectors for different era’s of 1.8T engines.
Now adding bigger injectors won’t increase power on their own. They will only help unlock more power if the current injectors can not supply enough fuel to meet the desired AFR (air fuel ratio) set by the tuner. Fitting big injectors to a stock car WILL NOT create more power and we recommend the stock injectors are left in place until the day of mapping and are switched onsite before mapping the car.
Now there are a lot of different 1.8T engine codes out there and there are a lot of small variances. But we are gonna to split them in to 3 basic groups. Now these will not include ALL the 1.8T engines out there but it gives you a good idea.
Early Me3.8 ECU cars such as the <98 Golf and A3 – AGU etc
These cars used 205cc injectors. They are quite small and will struggle to push past even 220bhp. Its common to upgrade to Vauxhall Calibra C20LET yellows which are 306cc and should be good for around 250bhp or Saab reds which are 346cc and are good for about 280bhp. When changing injectors in the AGU Me3.8 ECU, its far easier to scale injectors in with the mapping with a larger sized MAF housing due to the structure of the ECU and how it works. When upgrading injectors or pushing past the limits of the stock AGU MAF sensor, we recommend the MK3 VR6 OBD2 2.75 housing fitted with your original AGU MAF sensor element. This gives a larger diameter tube to allow the ECU to correctly see the volume of air passing over the MAF sensor
Me7.1/7.5 cars – ARZ, AUM, AUQ etc
These cars most commonly use the Bosch 315cc injector. These max out around 240bhp so are normally sufficient at a normal stage 2 setup. But a very good setup may the larger injectors from the K04 cars found below which are a direct fit. The added bonus to fitting these injectors from factory vehicles is all of the relevant mapping data such as KRKTE, TVUB and other map data is all available, which means that the injectors will be perfectly scaled in if your tuner copies over the relevant fuelling maps during tuning. This leads to low fuel trims and a good cold/hot start, something which many tuners struggle with when fitting larger, non-oem, injectors.
Me7.9 and k04 equipped cars. – BAM, AMK, APX, APY
All the K04 equipped cars came with 386cc injectors from the factory and are good for around 280bhp.
Common upgrades for the Me7 cars include the Bosch 550cc injectors which are normally used when going for a K03 or K04 hybrid and will support around 350bhp. The next step up are Bosch 630cc injectors which will support upwards of 400bhp
We recommend you avoid the green giant injectors as the spray pattern doesn’t suit our engine’s. Since our engines have 3 inlet valves, its important to find a injector with the right spray pattern to ensure even fuel distribution across all 3 of the inlet valves. Another injector we recommend to avoid is the Siemens ‘Deka’ injectors. These have a poor linear voltage response which often leads to a lot of idle misfires or rough running. However, its always best to speak to your chosen tuner who will be doing the mapping and seek their advice on what injectors they are comfortable using and are suitable for your power goals and hardware fitted.