external gates and spring/PSI levels

**slide86** · 02-07-2006, 07:07 PM

howdy all.

not sure if this has been covered before....anyways, im building an engine for a customer at home. (CA18DET). he was looking at various gates to use.

we came up with a few, one is a 3.6 PSI (30mm) and the other is 5 PSI (45mm, i think). Now, im pretty sure thats not how much boost it will hold......how do i work out the max amount of boost these will be able to hold?

the turbo will probably be a smaller garret item or a vg30. he is undecided yet. i am just unsure of the exact way to determine the boost level. ill be using a boost controller on the car also.

thanks for the help, hope its not a confusing post....

**30psi 4agte** · 02-07-2006, 08:09 PM

The spring pressure is where the gate will opemn at with no form of boost control ( bleed or electronic boost solenoid) hooked up.

The optimum is to have a spring pressure closest to the amount of boost you plan to run this will enable a minium amount of wastegate creep.
You will beable to run higher boost than the 5 psi but it will need to be bleed off the air to the gate.

I.e i run a spring pressure of 16 psi so that i can control a boost of 30 psi with minium creep.
The only down side to this is that i can only run a minium boost of 16 psi.--- what a shame

**slide86** · 02-07-2006, 08:14 PM

so you would want to have the spring pressure at bout half the boost level you want to run. ie 7psi spring for 15psi??

are the wastegates able to be pulled apart for a different spring to be fitted?

**30psi 4agte** · 02-07-2006, 08:22 PM

to be honest i dont know exactly how you work the spring pressure side of things out .

When i ordered my gate i told the bloke about how much boost i run. and he said i will need a spring of 16 psi or i will not beable to maintain steady boost at 30 psi even with EBC

I had originally planned to run a 13 psi spring so i can run that as my low boost setting but that was no go !!

As a rough rule the half max boost pressure is the spring you will need. I think

Almost all the gates i have seen are able to be fitted with different springs. Its fairly easy to change them

**Joshstix** · 03-07-2006, 08:42 AM

The amount of boost that a specific external gate spring will allow to be held is not a static number either. This is dependant on the amount of pressure in the turbo manifold as well. Pressure in the manifold acts to push the wastegate open helping the boost pressure on the diaphram to open the gate earlier.

In my setup I am running a .58AR turbine housing so manifold pressure gets up a bit, this makes my supposed 1 bar spring open at ~10psi.

**go_the_datt** · 03-07-2006, 09:45 AM

30psi are you running an internal wategate or external?

**emp?** · 03-07-2006, 11:05 AM

I bought a hks 7psi spring for my wastegate and gets to 25psi no worrys on the boost controller, im still working out if i want to put the 20psi spring back in

**30psi 4agte** · 03-07-2006, 10:18 PM

Originally Posted by go_the_datt

30psi are you running an internal wategate or external?

im using a external gate. However i was using a internal gate on my old t60-1 turbo. With a competition waste gate actuator from garret. I also use electronic boost controlled through the ECU. With this old setup i managed to get a flat line boost at 30 psi NO CREEP AT ALL !!!

So if anyone says it cant be done with an internal gate they are wrong

**30psi 4agte** · 03-07-2006, 10:21 PM

Originally Posted by emp?

I bought a hks 7psi spring for my wastegate and gets to 25psi no worrys on the boost controller, im still working out if i want to put the 20psi spring back in

What is the boost like does it creep much??

**sebatron** · 03-07-2006, 10:26 PM

where can one acquire a wastegate spring for a t2*?

**30psi 4agte** · 03-07-2006, 10:49 PM

T2 or T25 / 28 ??? either way you can get wastegate actuators from any turbo shop. it may require custom munts though. --- mine did.

I ended up cutting the rod cutting a thread onto it ( to make it adjustable) and making my own rod up .

**30psi 4agte** · 13-04-2007, 01:05 AM

thought id dig this thread up as i have been having trouble with boost creep on my gate.

I do have electronic boost control but im more concerned about the gates std ability to control boost.

IE with the EBC bypassed and the line hooked directly from the inlet manifold to the gate , my boost will creep from 16 psi to almost 20.

Now you would think that being a tial gate that it would hold 16 psi on the spring with no problem........ but it doesnt.

Im not sure what to do about this. I run a decent 7mm line to the gate so it as a decent amount of air to push the gate open but ...... no go.

Im thinking of changing the spring to a softer one and then controling the creep with the EBC and then bleeding it back up to the 16 psi.

This will wpork but isnt the way i should have to go about things

Anyone else had probs with boost creeping up on an external gate ????

**chris davey** · 13-04-2007, 08:27 AM

I am not sure what psi my spring is rated at but it always runs 15psi minimum. Mine doesn't creep but I do notice small fluctuations on the microtech datalogs. I can't see it on the boost guage or dyno logs though and apparently the MT MAP sensor is VERY sensitive.

So what has changed since before? It used to hold 16psi all the way right?

**Joshstix** · 13-04-2007, 10:09 AM

The usual cause for boost creap on an external gate in my experience is not having it merge with the exhaust flow in the manifold nicely. If the exhaust gas has to make a turn to get out the wastegate it reduces the effectiveness of the gate.

**30psi 4agte** · 13-04-2007, 06:50 PM

Originally Posted by chris davey

So what has changed since before? It used to hold 16psi all the way right?

Nah nothing has changed. Its the first ime it has really run and been tested.

Josh : I do think you have some merrit in your post. But the thing is i know of a fair few cars that have their gate setup the same as mine with no probs..... So that leads me to look else where.
You are prob right though ........ Its sort of what i think too.