Hi all,
This post isn't so much a question but more a statement after reading various posts on this subject.
Firstly a bit of background info on the car!
I have recently bought a 2003 1.8T AUQ 180 which had various engine mods on it.
I didn't like the way these mods had been done so i put the engine back to standard and started again, an arse about face way of doing things i know but for peace of mind i thought this was best.
The engine is now sitting with a performance filter in standard air box, N249 bypass and N75 bypass using MBC.
After reading various forum threads (not just on here) about bypassing the N75 and how it is a bad idea i decided to go ahead and do the mod anyway.
A lot of people have said that this is a sure fire way of detonating the engine... i agree, however this is only the case if you are stupid and decide to turn the boost right up.
I have found that by bypassing the N75 and installing a MBC and keeping the boost turned right down i actually have a smoother application of power from the turbo rather than a sharper punch when the N95 is running the show.
For those people deciding to try and introduce an MBC to get more boost from the engine id advise against it, not only do you risk damaging the engine if something fails but also you probably won't get the gains your looking for.
The reason you probably won't get the gains you want is due to the fact that if you don't upgrade your actuator the standard spring is probably going release at its set pressure, around 7-8psi i believe!?!
You can adjust your actuator by re-tensioning the spring by adjusting the tread on the push rod but this is not advised. By adjusting the tread and giving the spring more tension you can get a few extra psi, however depending on the way your engines ECU is set up you may run in to limp mode if you over boost.
If you turn your MBC right up and don't adjust your actuator you'll probably get a boost spike before your boost then drops back down to whatever your actuator spring is set at.
For anyone wanting to get more gains, spend the money and do the job properly. ECU upgrades, larger intercoolers and upgraded pipes, upgraded turbos and actuators... you name it you can do it... if you have the money. Just don skimp and do things the easy way, it'll only end up costing you in the long run
