This is a rather long post, but I really need some advice. I have some questions on putting an external wastegate on a set of twins for my 03, but I am external wastegate challenged and need some help understanding things. The twins I am looking at would be best suited as towing twins, but if I can plump in an external wastegate before I install them to keep backpressures in check and keep the small turbo from building too much boost, I think they may perform really well at 550hp. I have read through all the old posts and seen many pictures and diagrams on external gate installs, but I'm still a little confused on a few things.

First, the biggest obstacle is fitting an external gate in there. Most are using a spacer between the manifold and the secondary and mounting the gate to that. Is there something wrong with mounting the gate directly to the top of the manifold? Reason I ask is it does not appear I would have enough room left in the engine compartment to use a spacer. The only way I can get a gate in there would be to drill a hole in the top of an ATS 3-piece manifold and weld on some pipe. I guess I'm just curious why more people don't do this…..something I should be aware of here? Seems like less work than fabbing up spacers. Is it just that most don't want to hack a perfectly good ATS manifold?

Second, in regards to external gate operation, I assume that the exhaust gas pressure pushing up on the valve at the bottom is what opens the wastegate. The more pressure you have pushing up on the valve, the more the valve opens, hence the more exhaust gets bled off, correct? Most external wastegates have two air supply ports on the side of the actuator housing to feed boost pressure to the gate (or one on top and one on the side). The port closest to the top of the gate appears to be filling the actuator housing with pressure to keep the gate from opening too soon or keep it closed longer...this is how you tune the wastegate to your needs, correct? I am confused about what the air supply port on towards the bottom of the wastegates are used for. Can someone fill me in on that one?

Last, there are too many spring sizes available to choose from. Any recommendations on a good starting point. I see springs anywhere from 6lbs to 25lbs.

I would like to be able to limit backpressure to 50lbs at 60lbs of boost. I understand that I would want to bleed off as little exhaust as possible to get my desired results due to heat energy loss. Is that realistic or should I be happy with a 1 to 1 ratio at 60lbs of boost.

Any help would be greatly appreciated!

Brian

 

i need to know this too... someone pipe up!!!!

 

Hey Brian, I have since figured all of this out. My twins should be here by the 24th and I will start hacking them up to add the external gate. I'll plug it and get with and without numbers and let you know how they do.

(the other)Brian

 

AK RAM,

Who's twin's are you lookin' at? Are you keepin' the B-1? Keep me posted on your results.

Blake

 

I purchased a set of BD twins. The price I was offered was just too good to pass up. I have to tell ya, six months ago I would not have touched the BD twins with a 10 foot pole, and with BD's new pricing on them, I would not do it regardless if I had to pay that much for them. The performance that "forthcomingtwin" was seeing with his set the way they came right out of the box and the price I was able to get on them made me start an intensive research project. With almost no help from BD (don't know what their problem is), I have been able to put together an accurate, and rather surprising picture of their performance and shortcomings. I'm pretty sure that with as little as $350 extra, I can make these twins challenge some of the more expensive twin sets available….as long as your not shooting for cool EGTs at 700+hp as they do have a limit. More to come I'm sure. You would not believe what I paid for these if I told ya.

Brian

 

PM me

 

look in my photos gallery

 

AK,

I have an external welded onto the top of my ATS manifold and it works just fine like that. My only guess is that guys either don't want to customize their manifold or they don't know how or want/like to weld on cast iron. The spacer will work, but it's a waste of space IMO. You basically drill a hole in the top (really the bottom since it's flipped over) of the manifold, weld in a short section of pipe as a spacer, then the flange for the wastegate.

As for the operation of the gate, it uses an air pressure signal to push on the internal diaphragm. As you noted, the gates have two ports: one on the side, and one on top. The one on the side is the total boost port where you run a hose from your final boost location (between the exit of your top turbo and the intercooler). This is the port that will push the wastegate open when the boost exceeds the closing force of diaphragm. Exhaust gas will help push it open a little, but it won't open without this line. The closing force comes from both the spring and the addition of air into the top port on the WG. Adjustable springs are available for gassers so they can set their boost at 6, 8, 10, 14 lbs... or whatever. They don't need any more boost than that, so they just run the bottom line and forget it. In our case, we generally need more, and it's nice to be able to adjust it, so you run an air line to the top of the WG as well. On this line, however, you need to tap in an air pressure regulator (just like off an air compressor) to regulate how much boost goes to the top signal. If you have a 10 lb spring and 60 lbs of boost the gate will open once the boost in the bottom line goes over 10 lbs. With a 10 lb spring, 60 lbs of boost, and an adjustable regulator you can adjust the opening pressure from 10 lbs all the way up until it will never open. I would try to stay away from the light springs, however, because they can have a tendency to not close fully after some time.

John

 

Good info Banshee. Thanks. In regard to welding to cast iron, I assume there is nothing special about it and can be done with a standard MIG and steady hand, correct?

What brand and size wastegate are you running and how is it holding up? I don't want to be constantly having to rebuild/repair broken gates and from the reading I have done, it doesn't look like most of the gates available will withstand the EGTs we generate. Some of the gates I see the better known twin makers using have manufacturer specs of "Withstands up to 900*F." That doesn't give me a warm fuzzy inside. I'm thinking about a Pro-Gate 45mm that operates comfortably at 2000*F. It is spendy but should be problem free for life.

 

I am not sure about welding cast, but you could ask here....

http://www.hobartwelders.com/mboard/index.php?

 

not sure of the makeup of the casting of our exhaust manifold
but
standard mild steel wire doesnt usually combine well with cast iron, (cast steel another story)
I like to tig weld cast iron with either a nickel filler or Stainless filler
Ive had very good outcomes using this

 

I've been told that you can weld cast iron pretty easily using TIG. The trick is
1) preheat the manifold with a torch if you can
2) use the right filler (castweld works well, I'm told)
3) consider a flux as it may help reduce the oxides that cause problems. Protect your eyes if you use this flux.

I'm no welder, but I'm interested and hope to learn soon.

Justin

 

OK...with that said, I have a small flux core wire welder in my garage, but I was going to have a "professional" weld the pipe to the cast manifold. For the welders.....if I heat the manifold with a torch prior, would my flux core wire welder make a good enough stick to last?

 

no, the flux HOHN is talking about is for use with the oxy fuel process (not Tig or Mig) either brazing or welding the cast iron, which both are possible

do not use flux if you areTIG welding, it will mess up the whole process
use a nickel alloy rod (nickel 99 is a good choice made by Harris now owned by Lincoln) or a stainless alloy and 100%argon

but before you attempt welding this, I would call ATS and find out if it is cast steel (I doubt it) or cast iron , there is a major difference

if it is a high carbon cast iron your mig weld with steel wire will just crack off
(the flux core in your machine IS steel wire designed for use without covering gas or as a dual sheild)

if I remember right castweld is for oxy fuel process only

welding is my life, I teach it, I do it, and I would be happy to help with any info you need

yes, preheating is important, but not just heating the spot you are going to weld
it needs to be heated evenly over the entire peice or you will cause warpage and possible cracking
put it in a gas grill and get it as hot as the grill will go

 

They said it was cast iron and would be difficult to weld to. I guess that is why not many people do it. Recommendations? Well, Banshee is proof it can be done. I'm thinking drill, tap, and screw in a piece of threaded pipe. Do they make a 1.5" tap?