turbo line orifice question

[jeff1234]

All, what is the correct orifice size for a stock "85" turbo wastegate line. Also, what effect does enlarging or reducing the opening have on the rate at which boost happens.

[4 l-bodies]

Jeff the resrictor allowed for a slight temporary overboost for a few couple seconds on the T1's IIRC, 9PSI then it drops to 7 PSI after a couple seconds. It was either yellow or red restrictor. A smaller restrictor will allow for more temporary overboost. Removing the restrictor will make for rock steady boost control. If you have an adjustable wastegate rod, you can tighten (or make smaller) the rod to put more preload on the wastegate flapper to increase part throttle boost. The T1log style large can actuators used a slightly stiffer spring than the smaller 87-88 actuators. The later smaller actuators were also prone to getting tired with age resulting in actuator blowing open when it was supposed to be closed.
Todd

[jeff1234]

Hey there 4 L-bodies. I didn't think anyone was going to answer, thanks. Jackson suggested I use a .030 wire feed welder tip, inline as a restrictor. That's what I have in now but I was wondering if any tuning could be accomplished by changing restrictor size. I have the large can waste gate actuator and a grainger valve so I can set my boost where I want it. Have you run your boost line both with and without? If so, what differences did you notice.
thanks, jeff

[4 l-bodies]

Hey there 4 L-bodies. I didn't think anyone was going to answer, thanks. Jackson suggested I use a .030 wire feed welder tip, inline as a restrictor. That's what I have in now but I was wondering if any tuning could be accomplished by changing restrictor size. I have the large can waste gate actuator and a grainger valve so I can set my boost where I want it. Have you run your boost line both with and without? If so, what differences did you notice.
thanks, jeff

Removing the restrictor will make for rock steady boost control.

With no temp overboost.^^^^^

Jeff if your running a g-valve you really don't need a restrictor in place. The g-valve is the restrictor. I don't run a g-valve on my 85 GLHT log car. I use a solenoid with an adjustable bleed for a low-hi boost control. Been that way for 25+ years, long, long before calibrations were available.
Todd

[jeff1234]

Todd, thanks for the info, I will remove mine, I noticed the overboost at 18 psi finally settling to 15 psi and wondered why it did that. Now I know. Hats off to your 25+ years of playing with these things. That type of commitment working with these difficult cars when you could have chosen rear wheel drive V8's is commendable. I have been at it since 2006 and it has been a trying experience. Slowly but surely I am winning and I can tell you that I am getting pretty good at taking them apart and putting them back together again, lots of practice. LOL