"Y" boost line orfice, what size hole?

[Gmachine]

I'm having a boost creep problem and someone said that the GM orfice hole was too small at one point and it could be drilled larger. Mine now is .050 IN big. Just wondering how much larger I should go, or if this was OK.

Thanks in advance!

Ryan

 

[salvageV6]

I think the .050" is correct and normal.

The others were made small about .032" or so.

 

[Two Lane]

Originally posted by Gmachine
I'm having a boost creep problem and someone said that the GM orfice hole was too small at one point and it could be drilled larger.

Mine now is .050 IN big.

Thanks in advance!

Ryan

That's what you want for your TR!

 

[John Craig]

.050" is the size it should be. If you enlarge it, you remove the
ability of the computer to control the boost. What is the model of your turbo? Which line is the orfice in? How much boost are you trying run?

 

[Slow91z]

Originally posted by John Craig
.050" is the size it should be. If you enlarge it, you remove the
ability of the computer to control the boost. What is the model of your turbo? Which line is the orfice in? How much boost are you trying run?

How does it take that away??? the wastegate it still hooked up, I thought it would still control, but less??? Not trying to argue or anything, just confused and ignorant.

 

[NCTURBOS]

Ryan,

Actually the .050" and under units are the ones known to be bad about boost creep. What you want to do is open it to .059" and that should fix the problem, as long as that is the reason for the boost creep to begin with.

I just happened to find my paperwork from GM Partech when I was going back and forth with them about it. GM has revised these multiple times.

If you buy one new from GM you need to look at the sticker taped to the hose. It will have a 4-digit code that refers to what revision orifice is in it.


K.

 

[tcgn]

Y fitting orifice

My boost spikes to 24# and settles to 19/20#.So I wanted to eliminate the spike.I ran a hose fromt turbo to actuator to see what the wastegate is set at.It is set at 14#.So I use the ATR Y-fitting that came with the downpipe.The orifice was alot smaller than stock.I installed it and WOT.WOW,it went to 30# and I heard my engine knock for that 1 second before I let off.
So I enlarge the orifice with a 1/16" drill(.0625") and the boost goes to 18# and settles at 14#.Now I reinstall back the stock for now.Next time I will find a bit I size smaller than 1/16" for my experiment.Need another Y-fitting first.

 

[OKTurbo]

Why not just get one of these....don't have to rely on getting the right one from the dealer.

http://secure.johnsperformance.com/images/large/large-orifice.jpg

 

[Two Lane]

Originally posted by OKTurbo
Why not just get one of these....don't have to rely on getting the right one from the dealer.

http://secure.johnsperformance.com/images/large/large-orifice.jpg

Only $4.95

 

[tcgn]

Y-FITTING

Thanks OK TURBO.I`ll order one.

 

[tcgn]

Y-FITTING

Thanks OK TURBO.I`ll order one.

 

[NCTURBOS]

Re: Y-FITTING

Originally posted by tcgn
Thanks OK TURBO.I`ll order one.

Just remember that if you have a "Y" with an orifice that is too small from GM you still need to enlarge it or remove it when you install John's orifice. Otherwise you will still have the problem, 'cause you have not changed the size of the smallest hole.


K.

 

[YLDMAN]

Originally posted by Gmachine
I'm having a boost creep problem and someone said that the GM orfice hole was too small at one point and it could be drilled larger. Mine now is .050 IN big. Just wondering how much larger I should go, or if this was OK.

Thanks in advance!

Ryan

I was told by a guy who has worked on these for 30 years .052 drill bit is correct. It was very hard to find a bit that size. Found one at ACE.

 

[OKTurbo]

Here's a hint if you know a welder. The nozzle cleaning reams/tool thingy's they use to clean out their welding guns work great for re-sizing a Y orifice. They come in enough small sizes...one is .050" dia. Quick fix for a too-small Y if you have one of these cleaner tools.

This is what we did on a friend's car and it worked just fine. Your local Farm&Ranch supply will probably have these in the welding section.

Good Luck,
John

 

[Two Lane]

Good advice, OK Turbo

(Tractor Supply has them also.)

 

[tcgn]

modifying Y-fitting orifice

I decided to drill out my original .050 orifice to .052 bit and same boost spike result.Now I use a .055 drill bit and boost now spikes to 23#.I went too much on the first Y-fitting(.0625")causing lower boost levels.Just wondering should I use the next size up (.059")?
Don`t want the boost drop too low.I want the spike to 22# max.
Has anyone tried the .059" size?

 

[scottyb]

tcgn, what were your results or other attempts?