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Dawes and Needle Valve

876 Views 4 Replies 4 Participants Last post by  Chaz
Hi all I have a GU series2 automatic just fitted dawes and needle valve all works well. What i noticed is the boost comes on quite fast as it shifts through gears boost can climb to 15or16 psi at about 1800-2500rpm using about 1/4to1/2 throttle but dose not peek over 18psi before droping back to about 10psi .The qusetion is this okay/normal if not do i adjust the dawes valve or the needle valve? If i adjust the needle valve do i close it a bit or do i open it a bit? Can this rapid boost do any danage?
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welcome to the forum mate

the dawes valve will set your boost level. screwing it all the way in will see your vehicle make the most boost possible. safety wise you dont want your maximum boost to be anything over 15 or 16psi.

to answer your question no it is not normal, that is a very fast spool rate, which you possibly already know. to keep things nice and safe you want a very linear boost curve i.e 6psi @1500rpm, 10psi @2000 and your max psi @3000. this rapid boost will do damage over time yes. your needle valve will adjust your spool rate (how fast you make boost). from what i have read if you have setup these valves correctly, have the needle valve all the way closed on idle and then slowly open it so the vnt arm moves off its stop. it should take you about 3 or 4 goes ( it took me about 150000000) but patience paid off and fingers crossed i have got it right.

i have only just installed these myself and still very much a novice, but have been helped out muchly by doing a bit of a search as there is plenty of info to go around.

good luck mate.
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Thanks Chuckles
I set the dawes vavle at 18psi using an air supply from a compressor regulator and master guage into the pressure side i will change that abit, to slow the spool rate do open the needle valve or do you close it ?

ps new to nissan patrols only had it for 6 weeks
Thanks Chuckles
I set the dawes vavle at 18psi using an air supply from a compressor regulator and master guage into the pressure side i will change that abit, to slow the spool rate do open the needle valve or do you close it ?

ps new to nissan patrols only had it for 6 weeks
Hi John,
You need to open the needle valve a bit more to slow the spool rate.
Hi John,

Chuckles has good advice on setting up the needle valve. 18psi is too high unless you’re doing 4000rpm. Set your Dawes valve to 15psi below 3000rpm and you won’t have any safety mode issues. The boost curve is done this way to achieve 16psi at 3600rpm which is where the ZD30 makes maximum power. If you are not sure about it, read the bottom of THIS page.
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