another cheap and easy way to improve the boost hold and response time of your factory turbo is to re-tension the often rusty wastegate adjuster.

the factory wastegate arm is not often not tensioned tight enough to give a strong seal on the wastegate, the more gas that slips past the wastegate during spool, the longer it will take to spool. plus boost controllers struggle to maintain a constant pressure when the wastegate arm is able to move around to freely.

since these wastegate arms are often overlooked during simple maintenance, plus with most GC8's running TD04 turbos over 12 years old, its probably something you should do anyway.

first thing to do is get the turbo exposed, while cold- spray some CRC or similar on the 10mm nut to loosen the rust, crack the nut and wind all the way up.



next, remove the circlip and lift off the arm, tighten the end piece all the way then stretch back over the wastegate arm, reattach the circlip and tighten the 10mm locking nut back against the end peice.

the waste gate arm should now be significantly reduced in travel, not such a problem for cars running boost controllers, although on an unmodified car, depending if you have headers, you may boost spike.



but lets say you dont have a TD04, something like a VF series, these wastegates cannot be adjusted, so often you need to consider aftermarket alternatives, these raise the standard 0.8bar wastegate to around 1 or 1.2bar and allow much greater resolution in boost control, these though- cost more then $10.

the alternative is to help the standard wastegate actuator with an external spring,

first thing to do is weld a small washer or hook to the wastgate arm,



next is to stretch a small heavy tension spring from the actuator to the washer.



in this example, we raised the wastegate pressure from 0.8bar to 1.7bar, you can obviously pick a weaker spring if you dont want to go so high...

similiarly, you can do this on a TD04 without the need for welding.



end result is your turbo will spool faster, will hold boost longer, your boost control doesnt need to work as hard.

you will however need to replace the spring eventually, the heat from the turbo will weaken it over time.

usual disclaimer, if you dont know what you are doing, dont do it.

otherwise, enjoy!

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Long live the WRC