Effects of undivided ext. gate spacer on divided manifold & turbine housing

Hurley

Hurley

BLAKLUNG
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Apr 27, 2008
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I have recently purchased a used E.D. external gate setup with the 1" thick T4 spacer; the divider had been cut out (I'm assuming it was used in conjunction with an undivided turbine housing). After installing on my truck ( PDI t4 manifold, 66/74 with the divided .91 housing) I am experiencing spool times that are a minimum of twice as long as before the install; no other modifications were made during this install.

I am currently running the gate with spring pressure only, and am seeing 40psi max boost, which is what I was intending to set it at anyway; as well I can hear the gate opening at that pressure.


Is the undivided spacer plate hurting the performance? Or is the gate cracking ever so slightly enough to delay the building of boost pressure?
 
^so you are saying that the divider being removed is killing my performance?
 
My main point is that at current state it's regulating boost to 40psi when it lights, which is where I want it to be for now.
 
Hurley said:
My main point is that at current state it's regulating boost to 40psi when it lights, which is where I want it to be for now.
Click to expand...

I see what you're saying but if you add more spring and drive to the top port if you all of the sudden notice decreased spool time or regain your spool time than you just identified the waste gate creeping open as the cause of your spool time loss. You will have to adjust the gate accordingly to keep from creeping open and still regulate to 40psi if you find creep is your issue.

Or as suggested earlier you could block the gate exhaust although I don't know what you'd use to do that off the top of my head.

Good luck.
 
I'm thinking the larger manifold plus the divider missing is killing spool from a pulse perspective.
 
^I'm wondering that myself.


I've access to a cnc Plaz, probably just cut a disc and install wih the v-band clamp to test via that method.

Sooo drive pressure to the top port raises the 'crack pressure' but doesnt substantially raise the overall boost pressure limit? (i'm imagining in my head how the operation would be simulated)



Edit: I was originally intending to run boost to bottom port and 'throttled boost' to top port, via intarweb searches on tuning.
 
Hurley said:
I've access to a cnc Plaz, probably just cut a disc and install wih the v-band clamp.

Sooo drive pressure to the top port raises the 'crack pressure' but doesnt substantially raise the overall boost pressure limit? (i'm imagining in my head how the operation would be simulated)
Click to expand...

Cool deal!

You could use less spring and more drive pressure possibly if you found the gate was creeping open, drive being there to aid in keeping gate from creeping open and less spring to offset the resistance gained by now introducing drive to the top port. Or possibly more spring then you have and balance drive to the top and boost to the bottom etc etc. The only way to find out is to fool around with it trying all the possible combinations.
 
Joesixpack said:
I'm thinking the larger manifold plus the divider missing is killing spool from a pulse perspective.
Click to expand...


The larger manifold will not decrease spool time unless it is more restrictive. Contrary to popular belief increased volume in an exhaust manifold does not directly correlate to slower spool.
Having said that I wouldn't be the least bit surprised that lack of divider is a major contributor, but I would also look at the gate as other members suggested.
 
full pull said:
I think when he said cracking he ment the gate is opening a little bit.
Click to expand...


indeed, cracking as in the wastegate opening ever so slightly.



Nick, I'm starting to better understand where you are headed with the topic, and honestly I have been adamently against putting any level of drive pressure to the gate for fear of clogging & maintenance. It seems to me that I could do the same thing with boost, no? with the understanding that boost would be slightly lower or equal to drive (or is there some relationship there I am missing)
 
Hurley said:
I have recently purchased a used E.D. external gate setup with the 1" thick T4 spacer; the divider had been cut out (I'm assuming it was used in conjunction with an undivided turbine housing). After installing on my truck ( PDI t4 manifold, 66/74 with the divided .91 housing) I am experiencing spool times that are a minimum of twice as long as before the install; no other modifications were made during this install.

I am currently running the gate with spring pressure only, and am seeing 40psi max boost, which is what I was intending to set it at anyway; as well I can hear the gate opening at that pressure.


Is the undivided spacer plate hurting the performance? Or is the gate cracking ever so slightly enough to delay the building of boost pressure?
Click to expand...

when I was testing the gate, with just spring pressure the gate was starting to open arround 20 psi and was fully open by 30psi.
 
Hurley said:
indeed, cracking as in the wastegate opening ever so slightly.



Nick, I'm starting to better understand where you are headed with the topic, and honestly I have been adamently against putting any level of drive pressure to the gate for fear of clogging & maintenance. It seems to me that I could do the same thing with boost, no? with the understanding that boost would be slightly lower or equal to drive (or is there some relationship there I am missing)
Click to expand...

I was totally in the same boat given these nasty ole diesels and their soot producing exhaust fumes make a mess of things. Thing is though drive will be ahead of boost; therefore, do a better job of pressing down against the valve at the same time (for all practical purposes) as the drive is acting to press against the face of the valve and lift it. The gate is setup to take the abuse so i'd just go ahead and use drive. Worse case is you have to clean it if you want to change it or what have you.

I used to run mine with drive to the top and regulated boost to the bottom. I never tried anything other than the stiffest or 2nd stiffest spring option available (memory is a bit cloudy) but had issues with oscilation like that. I think drive to both the bottom and top with the bottom being regulated would've been the way to go given you're dealing with the same pressure rise on both sides and it's easier to regulate it that way. Boost and drive aren't 1 to 1 across the boost curve is my thinking.

Again, with these things I really think you have to try some different setups to get what you want. The goals being to: 1) eliminate any creeping open of the valve prior to when you want it to open; and 2) open at the boost level you want it to open (or ratio where drive pressure gets much above 1.2 times boost pressure) and maintain that boost level until you let out of the throttle.
 
94 12valve said:
when I was testing the gate, with just spring pressure the gate was starting to open arround 20 psi and was fully open by 30psi.
Click to expand...

interesting - with both springs, I assume? I got antsy and installed it without using your test setup :D I love the thing, regardless!


Nick, I'm glad you took some time to spell that out.


Also, what are you guys using to lubricate the o-rings on the piston?
 
You could use one of these to cap it off and see if it makes a difference. I know others with the gate setup like you have it, have seen it creep open as they are building boost.

MSC Item Detail
 
PASSENGER said:
The larger manifold will not decrease spool time unless it is more restrictive. Contrary to popular belief increased volume in an exhaust manifold does not directly correlate to slower spool.
Having said that I wouldn't be the least bit surprised that lack of divider is a major contributor, but I would also look at the gate as other members suggested.
Click to expand...

Try a header manifold and get back to me on that. All the extra volume kills pulse energy.

The easy check is to cap the gate.

I'm interested how it turns out.
 
The only problem is the missing divider. Weld one in, and then have it milled off flush. I am pretty sure this will solve your problem.

IIRC, there was a 2.8 truck, he purchased a new @t$ manifold and removed the divider for "better flow." Immediatley began having spool up problems and snuffing out on the big end. Wend back to the old setup with the divider, and it came back to life. The culprit wasn't the manifold, but how they removed the divider.
 
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