external wastegate size

[gazcuprablk]

thinking now of converting my internally gated gt3071 to an external wastegate as from what i have read on other threads it eliminates boost creep and saves me the hassle of getting an actuator bracket made up for the turbo eliminating other turbo upgrading problems in the future,

i have seen a few options of size's from tial with 38mm,44mm,46mm etc so does having a bigger one matter? (obviously it does but make me feel a bit better about myself lol) and what would be the difference between them all apart from the spring rate you chose?

 

[grahams81]

Are you getting boost creep with your setup atm ? if so whack the boost up then then your not pouring as much air down the wastegate

Most sizes of wastegates are predetermined by the size of the connection on the manifold. Have you got a tubular manifold ? if it's cast then it's gonna be difficult to run an external gate.
Wastegate sizing is dependant on how much Boost your gonna run, the more boost the less wastegate flow required, from what i've seen on here a 38mm Wastegate seems good.

My borg warner EFR can be ported on the wastegate to allow more flow for use on low boost application / big cc engines, not to sure if the garratt units can be ported i'm sure somebody will be along soon to chine in.
Also check the preload on your wastegate to as too much won't let the gate open far enough.
In the manual for mine it says 2mm of preload, thats shut the flap by hand and move the nut clostest to the canister up by 2mm then screw the other nut in to tighten.

 

[ibizacupra]

garrett can be ported, and should be on gt30 sized units imho..
As supplied GT3071/t25 will creep... Seems daft garrett sell it in this guise, but its what I have encountered a few times now.

External gates and hotsides work so much better on gt30 frame turbos