[longbedGTs]

I'm trying to figure the best spring to use. Im running 26psi, but their chart only goes to 21.
http://www.tialmedia.com/documents/MVRspc.png
I've tried the springs recommended for 20psi, but it seems awfully stiff. I don't want to overboost and pop a HG because the springs were too stiff to open the WG, so should I start small and work my way up to 26lbs? Any tips on external gates? This is my first one...TIA

[stott]

you don't necessarily have to have the exactly correct spring on your wastegate, it just needs to be lower than or equal to what boost you want to run.

if you want to run higher boost than the spring is rated for, you just need to also run a manual boost controller.

also, the reason the spring seems awfully stiff, is because 20psi is a **** ton of boost

[tangerine]

Lets see, if you have 8 to 1 CR and you have 18lbs of boost, it's like having a 17.8 CR and you want to run 26lbs of boost, good chance you'll do more than just blow a head gasket. Maybe not you can see why they don't recommend going above 20 lbs of boost.

[longbedGTs]

^^ Maybe I'm misunderstanding you, but are you saying that they don't recommend going over 20psi with this gate? Im at 26psi now on an internal gate and haven't had any problems with headgaskets(current HG is 3+ yrs old)...so Im not sure where you get that anything above 20psi will eat a HG. :confused:
Ok, so compression ratio figures into the equation then? The WG came with about 7 springs...

[stott]

put in a spring rated for less psi than what you want the turbo to run at. use a manual boost controller and boost gauge to get correct boost. not really anything else to it.

[Stinger]

Originally posted by stott:
put in a spring rated for less psi than what you want the turbo to run at. use a manual boost controller and boost gauge to get correct boost. not really anything else to it.

This.

And don't worry about the tangent above that. While it is typically difficult to run over 22-23psi on pump gas successfully, there are far too many factors involved to make blanket statements about boost limits. Furthermore, effective compression ratios aren't calculated like he stated they are (and certainly have nothing to do with wg spring selection).

[DaveBob1]

The Tial website has a diagram How to hook up the manual boost control valve. I prefer the 7 lb spring myself. I'm running the tial 38mm and with the bleed off valve I am able to control steady 26 psi. That's with torco mixed to 100 octane and 26 deg. advance. Of course Your results will depend on Your combo, and tune