External Wastegate Springrates

[warringtonjack]

Hi guys, I'm just trying to clue myself up a bit on wastegates. Is there a finite amount that a boost controller can alter the spring pressure within an external wastegate? i.e. I know that the spring rate should be less than your target boost pressure, but is there a maximum boost pressure you can obtain from a spring?

 

[tonyrally]

it shouldnt mater tbh the spring presure is allways overcome by the boost presure.

 

[warringtonjack]

it shouldnt mater tbh the spring presure is allways overcome by the boost presure.

I thought that, but what's the point in buying uprated spring rates then?

 

[wrc]

To hold the wastegate shut on high boost applications.

 

[warringtonjack]

To hold the wastegate shut on high boost applications.

So there is a maximum that the boost controller can change the pressure from the standard spring pressure?



*Note to self* - Must go away and learn how a boost controller works. Hehe.

 

[stumo]

So there is a maximum that the boost controller can change the pressure from the standard spring pressure?



*Note to self* - Must go away and learn how a boost controller works. Hehe.

Max boost depends on how the wastegate is setup.

if you have it setup like a single port wastegate (with a single pipe to it) then max boost depends on spring pressure.

If it's setup correctly (dual port...two pipes going to the wastegate) then you can have a light spring and almost any boost you like (within reason)

How it's setup depends on what boost controller you use.

 

[tonyrally]

but no wastegate chatter

 

[stumo]

i couldn't give a flying f how it sounds, just want it to work....

 

[warringtonjack]

If it's setup correctly (dual port...two pipes going to the wastegate) then you can have a light spring and almost any boost you like (within reason)

Hey stumo

I've seen a few comments on various internet forums suggesting that 2 times spring pressure is a 'safe' limit to stick to, with any more than that potentially causing issues (early spring opening, delayed boost, overstressed turbo) related to insufficient exhaust back pressure. I'm just wondering because I think I've got a 7psi spring, and struggling to get any more than 1.4/1.5Bar, so essentially running 3 times the spring pressure. My boost is also coming in later than I would have hoped.

 

[stumo]

Hey stumo

I've seen a few comments on various internet forums suggesting that 2 times spring pressure is a 'safe' limit to stick to, with any more than that potentially causing issues (early spring opening, delayed boost, overstressed turbo) related to insufficient exhaust back pressure. I'm just wondering because I think I've got a 7psi spring, and struggling to get any more than 1.4/1.5Bar, so essentially running 3 times the spring pressure. My boost is also coming in later than I would have hoped.

How do you have the wastegate piped up? single pipe to it or two?
What boost controller are you using?

late boost can be anything from cam timing to a restricted exhaust

 

[williams]

if its a blitz controller it works off % of your actuator pressure, most you can run is 150 or 200%, cant remember.

thats why after 2 blitz boots controllers i went for an avcr.

 

[stumo]

Are you running an external wastegate or an internal one with an aftermarket actuator?

My guess is the latter, either way it sounds like you're only using one pipe on the gate/actuator ( i don't know if the blitz can run two pipes, to either side of the diaphragm)

I'll assume you're using a single pipe on the actuator (as most normal turbo cars would), in that case trying to get anywhere near your required boost with the spring you've got installed isn't really the ideal thing to do and it'll give you problems.

 

[red reading]

if you are running external or dual port actuators you pipe the boost controller in to put pressure on the spring not bleed air off, if done like this you can use a 7 psi spring and run 2 bar plus.

 

[warringtonjack]

I'm running a 3076 with an XSPower external wastegate on the manifold branch, with a 3" front exit. Screamer is recirced into the exhaust, just prior to a small silencer. Boost controller is a Gizzmo MS-IBC. I'm assuming it's plumbed in with 2 pipes. I take it the 2 pipes put equal pressure across the 2 ports of the wastegate to 'equalise' the pressure so the spring shouldnt open?

 

[williams]

could it not be the xs power wastegate? xs power arent really known for thier quality.

 

[warringtonjack]

could it not be the xs power wastegate? xs power arent really known for thier quality.

But what can they really get wrong? Poor seal along the diaphragm? I'll have to find out if anyone has got a spare around me that I can swap to try out.

Thanks for all comments. : )

 

[stumo]

I'm assuming it's plumbed in with 2 pipes

that could be your problem....together with the XS wastegate.

Double check the way it's been plumbed in and check that the XS is sealing properly.