Everyone knows about the usual airbox mods done to Vauxhalls and other cars. You typically get an increase in noise and a very small increase in power. Those of you who have de-restricted an Ecotec engine in the same way will know that the air box contains more restrictions than say the C20XE did. Also, it makes sense that turbo engines have the most to gain from these mods. Well, the Z20LET is the first proper Ecotec turbo engine, so out of all the current Vauxhall engines, this possibly stands to gain the most out of doing this modification.
The inlet pipe from the grille to the airbox is very small and can be replaced by two larger pipes from a Vectra C. Also, there are two short and narrowing pipes inside the airbox, which can also be removed. With these simple mods done, more air should be able to flow through the assembly.
The difference this made to my car was very noticeable. There is a slight increase in induction noise, but not really an intrusive noise. When planting my foot, it feels like my turbo is spinning up quicker and the car surges forward with more urgency than before. If also feels like there is more power - maybe a few bhp or so. Not only that, but the car now continues to pull all the way to the limiter instead of flattening out just past 5000rpm.
The system can obviously flow more air due to its larger size and therefore is a great starting point when tuning this engine.
There will be a full article on how to do this modification appearing in the MIGClub members' area soon.