External wastegate. Exhaust manifold or O2 housing?

[Shane2GSX]

I like it on the o2 housing on a mitsu turbine turbo, if running the stock 2g manifold, the top heatshield is still in place and makes it look someone stock, as seen by the pics posted by gsxtacy.

Only con is no more AC right? The A/C fan has to be removed? Was that the only thing you had to sacrifice. Nothing else had to be removed/moved? It looks awfully close to alternator, belt vicinity.

Can someone confirm/deny this?? I may be going with one on the O2 housing, but A/C is a must for me. I'll be using a Punishment O2 w/38mm Tial.

 

[DSMunknown]

Cost aside you ask?

Please...my setup was a DONE DEAL External Wastegate with atmospheric dump, that cost less than $250 of my hard earned washingtons total....

$250 in the real world will barely buy you a 38mm Tial WG alone, much less the custom o2sensor housing.

Not everyone has custom fabrication resources either I know...go with the best solution for your situation.

Yeah, that wasn't quite the "reply" I was hoping for...

 

[definitiveno]

I believe that from the collector off the manny is the best place for an external wastegate. Once gasses reach the inside of the turbo I think the importance of an undisrupted flow across the turbine is essential for quick spool and top end hp.

 

[cfisher]

I went with the o2 housing from RNR. $250 shipped, 3" which connected right to my 3" turboback. I can run 10psi - 25psi without any boost creep or spikes. I have friends with the manifold mounted gates on the center collector and they have had great success as well. I wanted a 3" o2 housing anyway so the extra $50 for the wg flange was no big deal. I removed the fan as well and I have no problems running my A/C. The other fan takes over the duty but I do have overheating issues with the A/C on hot summer days after my FMIC install which is another story.

 

[pitbull419]

I know some turbos act different under different conditions.
Does anybody think there could be difference's depending on the turbo i go with?

 

[tbTalonES94]

turbo differences when it comes to wastegate control? The turbo really shouldn't matter as long as you put all contributing factors in. Saying boost level, flow, etc.

As long as the wastegate is placed properly, and the turbine housing can flow properly...boost should be controlled correctly no matter what the turbo is.

 

[ILLiCliPSE]

Its been said a few times in this thread already, but Id have to say the worst place to mount an external wastegate is on the #1 runner. What if you need to dump more than 25% of the exhaust to control boost? I guess its ok if you dont need to, but that would just turn me away from it immedietely, and it has. Reading this thread also got my thinking that an o2 housing mount wouldnt be the best either. (Insert member name here) said that the stock wastegate hole is I think 31mm. So now that exhaust gas has to pass through a 31mm space, THEN a 38mm space...it bottle-necks. Probably not the best. I would go with a 38mm off of the collector of the manifold.

 

[tbTalonES94]

It's obvious the collector is the best place to have a wastegate ran from. It's just not always the easiest option especially with a stock ex. mani. The o2 housing is a good place, all you have to do is bore out the waste gate hole in the turbine housing. You don't need a flapper to cover it so boring it out shouldn't be a problem.

 

[pitbull419]

I think im going to go with the manifold mount.
Off the collector.
Now on to picking the set turbo/manifold/wastegate setup.
I was thinking a punishment tubular header w 38 mm tial and a gt35r turbo.
Sound good?

 

[tbTalonES94]

that sounds good, what are your power goals? DD, road race, drag, etc.?

 

[DSMunknown]

I would go with a 38mm off of the collector of the manifold.

Yeah, I will concur that this is the "ideal" location to have a WG extension pipe, but it also depends on what angle the pipe is at in relation to the four runners. As I have said before in regards to the external 'gate placement, you want symmetry. You do not want a pipe extension to be 90 degrees in relation to the runners (or even worse, a larger angle).

The vast majority of the OEM-style exhaust manifolds offered to us (whether that be the 1G/2G/Evo III/FP designs) take a 90 degree turn anyways, so branching off a pipe at the 90 degree turn would be the ideal.

Here is a quick photo reference of what I'm talking about (and no, this particular manifold is not offered for DSMs). In this photo, you see that there is a WG flange at the collector. However, the flange is roughly about 90 degrees in relation to the four runners. I would rather see something like what is in red:

You must be logged in to view this image or video.

Hopefully within a fair amount of time, I will send out an Evo III manifold to a shop of my choice and have something similar in place in the end. I realize there are special considerations when asking a shop to work with cast manifolds and asking them to make an extension that will be reliable, resistant to cracking, and effective. But hopefully it won't be too big of an issue.

It's obvious the collector is the best place to have a wastegate ran from. It's just not always the easiest option especially with a stock ex. mani.

If you can find a shop that is willing to work with cast manifolds, and (hopefully) who will support their work, then you're good to go. It might be a little expensive (you'll have to ask around), but I think it would be well worth the effort in the end. ShaneGSX says Punishment is willing to do something similar for him. You can read about it here.

The o2 housing is a good place, all you have to do is bore out the waste gate hole in the turbine housing. You don't need a flapper to cover it so boring it out shouldn't be a problem.

Others have also said this, but I don't understand why anyone would want extra gases escaping past the turbine wheel without being able to account for the loss. You've put good money into an external 'gate, and you're looking for the best performance possible. Why would you want to waste the exhaust gases by giving them another route to escape past the turbine wheel? Either you want the gases to help turn the turbine wheel, or you want them to go through the external 'gate - nothing else. Unless you want slower spool (perhaps for traction) I don't see why people would leave the internal WG hole unplugged.

 

[TSG59_Steve]

http://www.punishment-racing.com/tialss38mmo2.jpg

I'm looking into this one... is this what ^^^you, unknown^^^ are talking about losing performance?

 

[pitbull419]

daily driver but something i can take to the track for fun.
My current dd runs high 11 so i know i can do it.
My problem now is i have never dealt with turbos that arent mitsu flanged.
Do you guys know of any turbos that are t/3 t/4 flanged but use a stock o2 housing pattern
Im aiming for high 10's so i will need a decent size turbo.
I will ###### want to improve later so it cant be maxed while running 10's
Any ideas

 

[tbTalonES94]

bullseye makes a turbine housing with a t3 inlet and stock mitsu o2 housing bolt-pattern, i'd just go full t3 though. It's better, and you always have the option to upgrade the turbine housing without having to change your exhaust components.


DSMunknown-
what do you mean extra gases escaping past the turbine wheel without accounting for something? It's controlling boost. No matter what the exhaust gases have to pass through the waste gate before the turbine wheel. Wether it's at the #1 runner, the collector, or in the turbine housing right before the wheel....the gases are style by-passing the turbine to control spin hence controlling boost. Why do you think FP designed their turbine housing with a waste gate outlet right before the turbine wheel. Same concept. Simply put the exhaust gases have to by-pass the turbine wheel in order to control boost, it doesn't matter when or where they are expelled..just as long as it is before the turbine wheel. Now obviously certain placements are going to be more efficient and worthwhile, but there is no problem with having the waste gate on the o2 housing. If everything flows correctly, it is just as effective as having it mounted on the collector and I can't see how it would abrupt flow to the turbine anymore then a collector mounted gate.

 

[DSMunknown]

http://www.punishment-racing.com/tialss38mmo2.jpg

I'm looking into this one... is this what ^^^you, unknown^^^ are talking about losing performance?

I'm not sure what you're asking. I am not prepared to say that one will see performance differences on the dyno or wherever. I am concerned here with the ease of flow from the manifold runners to the wastegate. I am trying to illustrate the importance of removing unwanted exhaust gases from the collector in the most efficient way possible (in practical terms).

daily driver but something i can take to the track for fun.
My current dd runs high 11 so i know i can do it.
My problem now is i have never dealt with turbos that arent mitsu flanged.
Do you guys know of any turbos that are t/3 t/4 flanged but use a stock o2 housing pattern
Im aiming for high 10's so i will need a decent size turbo.
I will ###### want to improve later so it cant be maxed while running 10's
Any ideas

Dude, you've already started a thread here about your question. Wait patiently or PM a trustworthy member if your question is a pressing one.

 

[DSMunknown]

DSMunknown-
what do you mean extra gases escaping past the turbine wheel without accounting for something? It's controlling boost.

Yes, but as I've already said, one has purchased an external 'gate for a reason. You said it yourself, "controlling boost." You want to control and channel the gases, not let them escape without doing something productive.

In very simplistic terms, and in strict relation to what has been discussed already about the exhaust gases and their relation to an external wastegate, the exhaust gases are productive in two ways.

• They pass by the turbine wheel and rotate it
• They go pass the waste gate and assist in controlling boost and not letting the turbine wheel spin too fast

So letting the gases do something other than those two things is unproductive IMHO.

No matter what the exhaust gases have to pass through the waste gate before the turbine wheel.

That's right. But it's important where the gases are taking this second route.

Wether it's at the #1 runner, the collector, or in the turbine housing right before the wheel....the gases are style by-passing the turbine to control spin hence controlling boost. Why do you think FP designed their turbine housing with a waste gate outlet right before the turbine wheel. Same concept.

It's already been discussed that the Number 1 runner is definately not the ideal placement for an external 'gate. I would rather see an O2 mounted 'gate instead of the former.

Simply put the exhaust gases have to by-pass the turbine wheel in order to control boost, it doesn't matter when or where they are expelled..just as long as it is before the turbine wheel.

Couldn't disagree with you more.

Now obviously certain placements are going to be more efficient and worthwhile, but there is no problem with having the waste gate on the o2 housing. If everything flows correctly, it is just as effective as having it mounted on the collector and I can't see how it would abrupt flow to the turbine anymore then a collector mounted gate.

I don't have much to say to that, just that we differ in opinions. The only thing I will say is that having the exit hole (going to the external WG) in close proximity to the turbine outlet is not ideal in my mind. There is a lot that's happening in-and-around the turbine housing and the O2 housing - complicating this with wasted exhaust gases only makes turbulence and other things more of an issue. Taking the excess exhaust gases out of the equation nice-n-early is ideal.

 

[tbTalonES94]

I think we may have gotten ideas mixed around here. I think you thought I meant leaving the waste gate hole on the turbine housing open while have the actual external gate located elsewhere. If that is what you thought I meant, i'm sorry it may have seemed like that but that is not what i was saying. That would produce severly slow spool characteristics and more then likely poor boost control.

Yes the #1 runner is not the best place to put the gate, we have established this, but I was pointing out no matter where you put the gate as long as it's before the turbine wheel it's doing it's job expelling gases to control boost. Now that doesn't mean any location before the turbine wheel will efficiently or effectively control the boost at all. You are correct in saying the placement is key and I thought that's what I was stating.

I just don't see how you feel that running a waste gate off the o2 housing wouldn't be efficient. The gases are still expelled before they hit the turbine wheel. If your worried about abnormal flow because of the gases taking a different route before the turbine wheel then look at the collector mounted idea. It is the same thing, and depending on the manifold not that much further then the internal flapper area. You have to look at the exhaust as "pressure" in the manifold/turbo and the gas is going to take the easiest route. I don't think it's going to make much difference in flow characteristics (when we are talking about power and efficient boost control) between the collector mounted and properly flowing o2 mounted location.

I don't mean to stir up any arguments and I'm surely not telling you are wrong. Just a friendly information/theory cross.

 

[DSMunknown]

I think we may have gotten ideas mixed around here. I think you thought I meant leaving the waste gate hole on the turbine housing open while have the actual external gate located elsewhere. If that is what you thought I meant, i'm sorry it may have seemed like that but that is not what i was saying. That would produce severly slow spool characteristics and more then likely poor boost control.

Thanks for the clarification. Yeah, now I see you're starting to agree with me.

Yes the #1 runner is not the best place to put the gate, we have established this, but I was pointing out no matter where you put the gate as long as it's before the turbine wheel it's doing it's job expelling gases to control boost. Now that doesn't mean any location before the turbine wheel will efficiently or effectively control the boost at all. You are correct in saying the placement is key and I thought that's what I was stating.

Now I see you're on the same page as me. As you said before, "it doesn't matter when or where they are expelled..just as long as it is before the turbine wheel" and I think this is where you lost me (or lost yourself, however you want to look at it).

I just don't see how you feel that running a waste gate off the o2 housing wouldn't be efficient.

That's not what I'm saying. An external WG off the O2 housing will generally be more efficient and effective than an internal WG. What I am arguing is that an O2 mounted external WG will not be as effective or efficient as a properly placed external WG on the exhaust manifold collector.

I'm sure for the average tuner, it may not matter much, and may not be able to tell the difference between the two. And perhaps this would be even more difficult to test. But I will still maintain that the one (the one I've been arguing for) is beneficial than the other.

The gases are still expelled before they hit the turbine wheel. If your worried about abnormal flow because of the gases taking a different route before the turbine wheel then look at the collector mounted idea. It is the same thing, and depending on the manifold not that much further then the internal flapper area. You have to look at the exhaust as "pressure" in the manifold/turbo and the gas is going to take the easiest route. I don't think it's going to make much difference in flow characteristics (when we are talking about power and efficient boost control) between the collector mounted and properly flowing o2 mounted location.

I do understand the exhaust gases as "pressure."

I also will agree with you about the gases taking the easiest route (out) possible. But I also believe exhaust gases will take the quickest route (out) possible. Thus, when there is a appropriate passage before the turbine housing, the gases will make a smoother transition past/around the turbine wheel. The smoother the better. Obviously, there are going to be instances where turbulence and such are unavoidable, and I also account for that.

I believe it will make a difference in flow characteristics. Perhaps the difference is small or marginal, but I will contest that there will be a difference.

I don't mean to stir up any arguments and I'm surely not telling you are wrong. Just a friendly information/theory cross.

No hard feelings taken. I love these type of discussions.

 

[EclipseSH21]

DSMUnknown, i'm on thje same page with you here. I have an internally gated 20G, which creeps horribly, but i don't wanna shell out cash for a proper tubular mani with the WG off of the colletor, and rigging something up off of the #1 runner seemed such a backass way to do it....so I was gonna go with 02, but what I really want is something like you're proposing.

To help answer some of the questions in this thread, it's not that o2 mounted gates and #1 runner mounted gates aren't functional, they are just ineffcient. Essentially a WG diverts exhaust flow away from the turbine wheel, and to do this most efficiently, the path of least resistance is the best, its simple fluid dynamics. This path of least resistance is at the front of the collector, where gases are flowing directly at, before having to take a 90 degree turn out of the runners into the turbine housing. The gas is litterally being rammed right into the wall of the collector. That is where the flange should be. Also, this is most efficient for exhaust flow if dumped to the atmosphere, as this would create the least disturbance within the exhaust flow, as when closed, it will flow like stock. Unfortunatly, the use of a pipe to the gate does create some turbulence, but within the limits of the stock manifold and the underhood layout of most DSM's, the perfect setup is hard to attain. If someone could retrofit the manifolds for a WG flange like DSMunknown has sketched up, I think it would not only be a huge seller, but the most cost effective way of efficient boost control.

I'm subscribing to this thread, i want to see where this goes.

 

[tbTalonES94]

Well basically we both have the same ideas, just worded differently. It's like beating around the bush with words. I am in agreement with everything you say...and I do agree 100% that the collector mounted waste gate would be more ideal then the o2 housing mounted gate. The only thing I was pointing out is that the o2 mounted gate will do it's job controlling the boost perfectly if everything is flowing right.

I guess we just kind of started an argument on some mis-calculated wording. Ah well, good talk

i guess *cliff notes* from what we've argued:

1. #1 runner placement is crap (but still gets the job done)
2. o2 mounted gate will do it's job very well, easier to make work when stock parts are used
3. manifold collector location of the gate is the 100% best place to locate the waste gate for both boost control and flow.

i think that covers it?

 

[definitiveno]

at you guys. You guys type alot so it's hard to back track and find where the error's were made. Made me laugh though.

 

[pitbull419]

Ya thanks for all the info guys.
Tbtalones94 i would love to go all the way t3 but then i would have to weld up something to go from the turbo to my down pipe i dont have access to a welder at the moment.On top of that the machine shop around here is a joke they didnt even know how to measure the step of a flywheel let alone resurface it.By the way if anybody wants to buy a machine shop and all there tools its up for sale rite now.I cant guess why tho

 

[dsm-onster]

I have to disagree w/ the 'tapping on the number 1 runner is crap' point of view.

The goal of the wastegate is to lower pressure on the turbine blades.

If exhaust runner 1 is evacuated of a large number of molecules, then why and how should the pressure not go down. And not equally so w/ tapping at anyother place? If you tap where all the runners are equidistant from the oriface, the All the molecules would be clammering to get out of the opening. Not but so much mass can flow througha certain oriface at a certain pressure and temperature. If its all number one runner particles or a smaller portion of all the runner particles, how does that not lower the pressure equally. The blade sees all the particles otherwise. So what if the particles have to take strange trips to get to the oriface. It doesn't matter if they even get out of the oriface. All that matters is that the number of moles present in the model decreases so that pressure decreases. P=nRT/V. "n" is the number of moles in the system. Lowering the number of moles by one coefficient DIRECTLY lowers the pressure P by the same coefficient. So what if all that is left is number 2, 3, and 4 runner molecules running into the turbine wheel. That's 25% less pressure on the wheel! It is not likely that there will be only number 1 runner particles not going to the turbine anyway. It's still easier to travel to the oriface than to the turbine whether or not they evacuate. Each particle that is inclined to trave in such a direction cannot strike the turbine blades OR strikes the blades at a severly less momentum and consequently the total work done on the wheel is significantly diminished.

Tapping at the number one runner of a currently owned exhaust manifold is comparativey cheap. It's using the laws of thermodynamics to save you money. No gas will fail to depressurise into intake runner 1, if there's a large unrestricted oriface present there.

Also, when the pressure suddenly drops in exhaust runner 1, the body of molecules (from all the other runners) expands. This expansion lowers temperature in the model rapidly. Remember P=nRT/V. This "T" is the total "T". degrees celcius + 273.15 Kelvin. So not such a drastic coefficient. Nevertheless, this is another addition to the loss in pressure across the turbine blades.

 

[tbTalonES94]

Your correct in form of mathematics. You forgot though that the exhaust comes out in pulses through each cylinder. Not every cylinder is expelling exhaust gases at the same time. So while #1 cylinder is expelling gas..to others aren't. You also have to realize that when the gate opens, pressure has to equilize accross the exhaust manifold. The other 3 runners are going to try and back-track to the waste gate, which would cause as you can imagine serious turbulance.

We've already stated undoubtably that the gate on the #1 runner will work, and will control boost. It just doesn't do it as efficient and ideal as a collector mounted gate or o2 housing mounted gate.

Simply put...the best place for a waste gate hands down is where ALL cylinders are feeding into it. Go look at any really well designed exhaust manifold for any turbo application. If it has been researched and developed to add power and work right...the gate is ran off the collector...NOT the #1 runner. It is a cheap way of controlling boost and that is it. Yes it works, yes it's cheap, and no it is not efficient.

 

[dsm-onster]

This is a great discussion btw

Your correct in form of mathematics. You forgot though that the exhaust comes out in pulses through each cylinder.

Hmmm, I would think that to accept that the exhaust "wind" coming out in pulses means that there would be zero turbulance. Say a pulse goes through runner 1. When the gate opens, the gasses follow a predictable (non-entropic) path. When a pulse goes through runner 2, it travels to the collector. It has a choice either to go to the wastegate (since there is very little flow fromrunner 1 being the exhaust flows in pulses) or to the turbine wheel. I can see how the runner mounted wastegate can cause turbulance when first cracking open (I.E., in the middle of a pulse). But after that one pulse, the flow is much like electricity. The majority of it follows the easiest path to most pressure differential.

We've already stated undoubtably that the gate on the #1 runner will work, and will control boost. It just doesn't do it as efficient and ideal as a collector mounted gate or o2 housing mounted gate.

I know. I'm just throwing in my 2 cents. It doesn't make sense to me theoretically that the collector mount is significantly superior.