Please explain external WG spring sizes to me!!

[99gst_racer]

I recently purchased a Tial 38mm WG and I have it plumbed off of my #1 runner on my ported 2G manifold. I will be running a dual stage BC with my low setting on 14 PSI and my high setting on 19 (or so) PSI. How in the hell do I determine what spring my WG needs to have in it?? Please school me on wastegate springs!!!

 

[kilurv8]

Wastegate springs are pretty easy to understand.

If you want to run 14psi as your absolute lowest boost, then you need a .9 bar. The wastegate spring rate is the absolute minimum amount of boost you will be able to run. For example, if you want to run 1 bar 14.5 psi, you put in the 1 bar spring. If you connect a vacuum line up to the side wastegate port with no boost controller, you will run 14.5 psi. The thing to remember is that boost controllers typically can only run 2 times the spring pressure. So if you want a max boost of 2.5 bar, then you would have to run at least 1.25 bar spring inorder to achieve your desired pressure. This would be any combination of large and small tial springs since the largest pressure you can get is 1 bar large spring. a 1.25 bar spring combination would leave you running a minimum boost of 17.8 psi.

Make sense?

 

[PaleDSM]

Great explanation.

 

[99gst_racer]

kilurv8 - Dude, you are the man. I completely understand now. One more question though. How do I know what spring mine came with? Is there anyway to tell?

Thanks a ton. -Paul-

 

[99gst_racer]

Actually, I just spoke with SBR (thats where I got it from) and Mark said the base spring they come with is a .9 bar. Should be perfect for me. Thanks again for your help.

 

[Mirage2LTurbo]

I have no problems running a stable 38psi with only a 1bar spring.

 

[kilurv8]

I have no problems running a stable 38psi with only a 1bar spring.

Well I did say most boost controllers. Which boost controller do you use that allows that? My Joe P and my EVC EZ will only allow 2 times the spring pressure.

 

[Mirage2LTurbo]

Well I did say most boost controllers. Which boost controller do you use that allows that? My Joe P and my EVC EZ will only allow 2 times the spring pressure.

It's being controlled by my Autronic. It won't allow you?

 

[kilurv8]

Not that it wont allow me, it just isn't capable of it. If I use my AEM for boost control, I am sure I would be able too, but most people dont have that option.

 

[Mirage2LTurbo]

Not that it wont allow me, it just isn't capable of it. If I use my AEM for boost control, I am sure I would be able too, but most people dont have that option.

How is it not capable of it? All's any boost controller does is open a valve at a desired set point.