External Wastegate questions

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Cnp22

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I'm sure this has been answered a time or 2 but I haven't found the answered to my questions.

I'll start with the problem. I'm spraying my truck, A LOT, and after about a year of lots of spray it finally popped the head gasket one hot summer night (the bottle pressure was finally high enough I matter). Now I'm in the market for a external wastegate to bleed off my drive pressure/boost to about 50-60psi. This will be welded on to a stock ported 12v manifold.
Now my questions:
What gate is everyone using?
What is everyone doing to keep 50-60psi? Manual controller?
What's the best spot to weld it on the manifold? Middle over the divider? Front half? Or back half?

Thanks in advance for the help.*nx*
 
I would say that the middle over the divider is the best place, and unless you grind out the divider, it's really the only place.

That being said, welding onto cast isn't something I think you want to do. Especially something that holds pressure and cycles crazy amounts of heat. You'd probably be better off surfacing a section on a mill, drilling/tapping some holes, and making a wastegate mount that you can bolt on. That still sounds like a pain in the ass to get it from leaking, but you wouldn't get cracks and potentially a wastegate flying off the manifold at that point.
 
Cast iron gets welded all the time. A novice welder isn't going to weld to it successfully however, but Ni55 or Ni99 with properly preheat, proper heat control, proper post heat and peening can make a sound weld that'll live just find with that wastegate. It's done all the time.
 
whitneyj said:
Cast iron gets welded all the time. A novice welder isn't going to weld to it successfully however, but Ni55 or Ni99 with properly preheat, proper heat control, proper post heat and peening can make a sound weld that'll live just find with that wastegate. It's done all the time.
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Hmm, I wouldn't feel comfortable with it. I did weld up a poorly placed thermocouple hole before with no adverse effects, but I've seen the cast crack past the welds a ton of times.

Post up some examples that have survived the test of time and beating like spraying it would cause.
 
CorneliusRox said:
Hmm, I wouldn't feel comfortable with it. I did weld up a poorly placed thermocouple hole before with no adverse effects, but I've seen the cast crack past the welds a ton of times.

Post up some examples that have survived the test of time and beating like spraying it would cause.
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I don't have any examples, just experience with welding and too much time on the interwebz wishing my truck ran :D

If the weld cracked then there wasn't enough parent material welded. Deeper and wider bevel with multiple passes would be required then.

Most of the time I see cracks from welding on cast it's because there was already a crack there from a too aggressive heat cycle, such as too much heat or improper post heat/peening, and the heat cycles just walked the crack along the weld. Also the rod that's used. I've seen guys just MIG with 70K tensile strength wire and be fine, 60 or 70 series rod used ect, but Ni rod is really the best rod for the dollar. There are FAR better rods out there but get ready to spend $100 a pound.

Just my $0.02 with the welding experience I have, but then I'm not a welder by trade.
 
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I was kinda thinking the middle and split the divider as well just going to drill/grind it down so it splits evenly and has good flow.

As far as the welding cast goes one of my best friends welds cast all the time on the stuff he builds 1000+ gas stuff that is street driven. It holds up nicely all in how you preheat and post heat it mostly.
 
I'm running a 44mm Godspeed an eBay one. was to cheap to buy quality gate. Built a homemade undivided t3 to t4i adaptor to run my hx52. Been running it for 2 years. The clamps suck the come with other than that it hold up pretty good no problems.
 
montser633 said:
I'm running a 44mm Godspeed an eBay one. was to cheap to buy quality gate. Built a homemade undivided t3 to t4i adaptor to run my hx52. Been running it for 2 years. The clamps suck the come with other than that it hold up pretty good no problems.
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How are you gating over 20psi?
 
Cnp22 said:
How are you gating over 20psi?
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Boost reference line. You need xx spring tension and xx boost, for example 5lb spring and 5 lbs of boost you'll need more than 10lbs of drive pressure to open the gate. Another example 50lbs of boost and 12 lbs spring you'll need at least 62psi of drive pressure to open the gate that's how a friend explained it to me.
 
montser633 said:
Boost reference line. You need xx spring tension and xx boost, for example 5lb spring and 5 lbs of boost you'll need more than 10lbs of drive pressure to open the gate. Another example 50lbs of boost and 12 lbs spring you'll need at least 62psi of drive pressure to open the gate that's how a friend explained it to me.
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Gotcha, so a manual boost controller on top of the gate with a boost gauge showing what I'm sending to the gate? So say I want 60psi of drive pressure I could use a 15lb spring and send 45lbs of boost on top of the gate?
 
Ideally you want 1:1 ratio drive pressure to boost. I don't know to use a external gate to its fullest potential. Mine came with a 12lb spring believe I used a boost reference to the top and a regulated/ needle valve to control the bottom to change opening pressure with boost pressure. My external gate has a top and bottom hook up. With out a drive pressure gauge it's hard to know.
 
montser633 said:
Ideally you want 1:1 ratio drive pressure to boost. I don't know to use a external gate to its fullest potential. Mine came with a 12lb spring believe I used a boost reference to the top and a regulated/ needle valve to control the bottom to change opening pressure with boost pressure. My external gate has a top and bottom hook up. With out a drive pressure gauge it's hard to know.
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Cool thanks for the help man! I have the same god speed gate on my 03 turbo gas truck. I'll order another and give it a shot. You have any pics of your set up?

My plan is to run a boost reference line to a needle valve, to a T off the 2 ends of the T one go to the gate and the other go to a gauge so I know how much boost I'm sending to the gate. Then I plan on tapping the tube running to the gate for a drive pressure gauge.
 
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