metoo

I have Tial 38mm wastegates running on spring pressure only. I have the large yellow (.7bar or 10.153psi) springs installed. Actual pressure (measured at the blowoff valve) max's out at 7.5psi. Is this typical? I've always used boost controllers in the past.

Speedy911

iTrader: (24)

I'm sure spring fatigue, wastegate placement, vacuum source, excessive turbo/exhaust back pressure, wastegate sizing, and many other factors can influence it.

Where is your wastegate boost source coming from?

If spool and power seems normal and it is consistently doing that, I wouldn't be too worried about it. You have three choices, shim it, get a bigger spring, or throw on a boost controller.

denmah

iTrader: (2)

sounds normal to me.

rotary1307cc

iTrader: (5)

Yup

What a spring will make is all about backpressure

Higher drive ratio the less boost, lower ratio the more boost a certain spring will make

metoo

Dang it! Tial shouldn't refer to there springs in PSI ratings then. They should simply state the spring rate or some other system of description if they want to keep the rate a secret. Technically, I just wasted money on the springs then. While the turbos were out, I put in the higher rated spring and uninstalled my electronic boost controller since I figured I would never increase the boost and an EBC is just one more thing to fail. Oh well, since the waste gates are such a pain to get to on my setup, I guess an MBC is in order.

Slowhawk

iTrader: (12)

Piping design/back pressure plays a big role on boost level out of the rated spring.

ajrothm

Tial springs are rated correctly.. Your porting on the gate port/turbine housing will skew the results big time.. Not to mention your exhaust system after the turbo (aka back pressure).

On my bike with a short dump pipe (no restriction), here is what I see win various Tial springs:

Small red, 5.8lb : 6.00 psi
Big yellow, 10.15lb : 8.8-9.2 psi
Big blue, 14.5lb : 14.5 psi

Logged boost on two different map sensors... Identical results.

cjmatt

iTrader: (4)

tial includes all of the springs so that you can fine tune for your setup.

metoo

Since there are so many apparent variables that effect the boost pressure, describing the spring by pressure is inaccurate, especially since they don't state the conditions of the rating. Like an engine that is rated at 300 bhp, a compound bow at 300fps IBO, or 4130 at 52ksi yield. There are stated conditions that go along with those numbers, which if recreated, same or similar data would result. Tial doesn't state the conditions, so they shouldn't use that method to describe the springs. That's my point.

For the engine: certain fuel type, power at the crank, no accessories, etc
For the Bow: 70lb draw weight, 30in draw, 350 grain arrow, ....
For the steel: annealed at 865 deg C

TiAL

actually we state the springs are rated at 1:1 back pressure