Hello, I have spent many weeks looking through posts here as well as other forums and just wanted to ask the groups experience on my issue of not being able to control boost.
Setup is a 392" windsor, 9:1 comp, blow thru E85, Forced Inductions Borg 88/100, 1 3/4" primary headers into 2 1/2" fully divorced T6 1.32 flange, into 5" downpipe, using twin 40mm jgs gates. With the 5-6lb spring, boost continues to climb, I have not let it go past 17psi, however it would I believe.
Several reliable sources have told me twin 40s should be more than enough to control the boost at or close to spring pressure.
I just would like to know if anyone is running similar setup successfully? Or is my wastegate placement possibly the issue?
I have attached a few photos of them.
I am trying to decide do I attempt to modify the wastegate placement to make the 40s work, or buy 50s or even 60s?
Thank you for your time and any thoughts.
Blessings,
Doug #ad
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Welcome, Doug!

How are controlling the gates? Direct pressure from compressor to bottom port?
Have you done any testing on backpressure?

From the pictures it appears the left (drivers) bank is not getting "priority" to the gate. Meaning, it's more convenient for the exhaust gas to flow right past the WG than to make that turn and exit. I think if you set up a couple pressure gauge ports and logged or carefully monitored it you would see and BP delta between the two banks. Meaning the right bank is getting vented and the left bank is still driving the turbine.

I would definitely do more testing before I started cutting up that beautiful hot side plumbing. Test BP on both banks, test flow out of both gates, test gate actuation on the bench, etc. If you have a GoPro camera, maybe put some tape over both outlets and run it up on a gate and watch to see if they both blow out the tape.

 

Thank you for the reply!
I have the gates controlled from a -4an line from compressor housing to lower ports on the gates.
I have not done any testing on back pressure, however the tape idea is a great one.
I was just thinking of the gopro idea this evening, as I do have one.
I have had gates off, disassembled and greased, and air checked them both on the bench.
I will look into doing some BP checks on both banks if I do not come up with anything.
The other idea was to "triangulate" the opening on the 90 degree gate port by cutting piece of pipe in half and grafting it over the outside radius, effectively giving that gate more volume hopefully.
Thanks again!

 

The rear gate looks fine,the front not so. You are basically trying to control with one gate. The front gate needs to moved to the outside of the bend, like the rear gate.

 

Wg placement needs to be moved. Those gates should be able to control boost without a problem.

 

It looks like you can get a good location and still keep location close to the same and keep the same dump exit.

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What do you use to check back pressure?

Would you bother doing that or just work to get more flow to that front gate?

I dont have much room to move gate over for a straight shot off that curve. That's why I was hoping to "oval" the opening for that gate. Even though it wouldnt be a straight shot, it should gather more volume, you think?
My wg dump is out the front fender, so was really hoping to not disturb it. I had this system made, and will have to pay to have this done, so I'm trying to find the most cost effective solution.
Already hurts doing it twice!
Thank you!

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What I was trying to show in my little drawing was to turn the WG 45*-ish and run a new stub pipe from the outside of the bend to the WG. Then make up some new pipe from the WG to reconnect in to the existing WG dump.

I also think your idea of a shroud inlet would probably work. Just make it broad enough that it gets into the curve so the flow will want to go to the WG instead of passing it as it does now.

Lastly, we are going to need you to start a build thread on this Hot Rod. The first round of pics had me intrigued, and now i'm overboard with it. I want to see more of that car!!!!

 

IMO you need to move the angle of both pipes feeding the wgs. You want the air to feed in easily.

 

Yes, ideally I would love to turn it 45*, just not sure if I will have space to do that, plus I figured it would be easier (less $) if he didnt have to touch the exit side of wg.

Thanks, car is a 68 mercury montego, was given to me by my neighbor in 1988 when I was 15, and was my 1st car.
It is back half, 4 link, full size tubs, strut towers cut out of front with coil overs. I ran a procharger F1R for years with same bennett engine. Switched to turbo and just trying to sort it all out.

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I don't like the placement. Twin 40's should get it done, but need to be placed better to do it imo.

 

How is your tune ign timing wise?

 

Furthermore, do you guys think shrouding what I have is worth the effort? Meaning in yours opinions do you believe it will fix my issue?
Or should I put my $ and efforts to installing larger gates in the same spots?
My fab guy believes we will be wasting our time trying to make the twin 40s work?
I appreciate all the feedback!

 

Dist locked at 32* using btm to pull down to 20* under boost. I know it's a bit low on timing, but I'm being conservative until I figure out the boost control.
I know overly retarded timing can overrun the gates, but I dont think 20* is retarded enough to cause an issue, do you?

 

I'm with Disney, move that gate. Here is a crappy photoshop to illustrate. I don't even think you need to 45 it.

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If you can read my doodle you should be able to keep the wastegate angle exactly as it is, patch the old hole and move the gate inline with that bend. Minimal work.

 

Thank you, I dont have that much room to move gate up as it will get into the radiator and hoses, but may be able to compromise some with angles.

 

I think twin 40's is more than enough WG, you just have to fix the plumbing to them. And really, it looks like it's just the one.

 

Just rolling into it easy, boost creeps to 17psi before I lift. Not sure how far it would climb...

 

40's should be enough....

i have a mild 496 (around 500 hp NA as a guess), with twin jgs 40's.....i can take the springs out and only be around 2-3 psi.....springs in around 7.....no fancy flow priority scheme, wastegate entrance 90* to flow ......old school twin T72 turbos with Q trim turbine wheels and 0.96 A/R housings.....will make 7 psi at 3000 rpm with a manual trans in any gear .....so definitely no oversized turbines here

Try taking the wastegate springs out and see what it does.....maybe you got the incorrect spring in the gates or something goofy with the pressure signal line plumbing.....this will at least show if the wastegates/flow path are adequate.

I certainly agree with the others....if starting from scratch....having wastegate flow priority strategy would be beneficial....but i think it will work unless something really goofy is going on (fitting not machined all the way, fab guy didnt cut hole to merge pipe, wastegate assembled incorrectly/stuck, etc)

 

Thanks for the response. I redid my signal lines to wastegate with 1/4" rubber hose and 5/16" T fittings, and verified I was getting proper boost signal to gates, no real difference.
Also taped ends of exhaust and blew the tape off both exhausts. I am going to remove exhausts from wastegate next to see if that may be a restriction. They are 1 3/4" and about 2' long with small bends in them. I read where someone had an issue with the wastegate exhaust impeding flow, so its worth a try!