<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ALL IMPORT &raquo;</TD></TR><TR><TD CLASS="quote">i have a percision 67/76 on my b18 using a neukin ram horn mani. with a 38mmtial wast gate. trying to just run 15lbs for right now & with a 10lbs spring it wont even hold that. it slows down the spool but the higher u rev the boost goes up. im thinking of cutting off the pipe comming off the mani & putting a 46mm on. i would think that would hold up?</TD></TR></TABLE>

You have a big turbo on a street car, a bigger wastegate is required. If you have any more question please feel free to MSG ME

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by D@nnY &raquo;</TD></TR><TR><TD CLASS="quote"> if you have a 48mm gat and cant hold anything less then 22 psi the diaphram is ripped inside the gate</TD></TR></TABLE>


the wastegate is perfectly fine. its a high horsepower car, with a large turbo, and everything on the car flows extremely well. i dont care if you have a 100mm wastegate.....if the manifold design doesnt allow for the exhaust to get to the wastegate easily, then its not going to get there.

 

I'm not arguing with you. But you need to verify root cause of the problem. Do you know what the valve lift is? If it isn' lifting, then of course it'll creep.

But just walk me through some logic here real quick. If flow pathing is the issue with the manifold, and exhaust gas doesn't want to make a 90 deg turn out of the manifold and into the WG, how the hell is a 46 mm gate going to fix that?

If a 46 mm gate fixes his issue, then either his other WG wasn't lifting, or his gate wasn't big enough. Which, in either case has nothing to do with the design of the mani.

 

I think it has to do with pressure differential across the wg. You're already dealing with an instance where there's limited flow to the gate. The less pressure differential there is, the less air is going to make that turn. A bigger gate will flow more, allowing more of a pressure differential at the outlet of the manifold. Now, a 38mm would work fine, if there was more flow into the gate.

We're all saying the same thing, it's related to the flow of the gate. Now, when people are saying 38, 44, etc. we're referring to a specific gate for the most part. The gate flows what it does. Synapse is saying that the valve diameter does not tell the whole story, and that is correct, but it's not something that's adjustable with the wastegates we're talking about.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Synapse &raquo;</TD></TR><TR><TD CLASS="quote">

If a 46 mm gate fixes his issue, then either his other WG wasn't lifting, or his gate wasn't big enough. Which, in either case has nothing to do with the design of the mani.</TD></TR></TABLE>

If u look at the pics he posted, u can clearly see a lot of material blocking the flow. After he trimmed all the material, It should help him a lot. 46mm wg is also going to hold low boost better.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Turbocivic94 &raquo;</TD></TR><TR><TD CLASS="quote">If u look at the pics he posted, u can clearly see a lot of material blocking the flow. After he trimmed all the material, It should help him a lot. 46mm wg is also going to hold low boost better.</TD></TR></TABLE>

Oh hooey. That little bit of material isn't the issue. The issue is hes using a dinky little WG with on a turbo setup that requires a larger WG to increase flow since the exhaust really doesn't want to leave via the WG. Think about it. These manifolds are turbine priority. He has a big turbine which is consuming most of the exhaust as he is only running 15psi. Then the manifold's pressure itself is probably in the 15-20psi range. Then you have to figure exhaust velocity is pretty darn high. So you have a relatively low pressure with air moving at a high speed, and you expect it to want to leave out of a 38mm hole? Com'on kids, common sense here. Bigger WG fixes this issue. Whether its using two WGs or one big one it fixes the issue.

Also, I can't really see any issue with the Neukin manifold's construction as far as causing the boost creep. If anything its his fault for not letting you know right off the bat that the 38mm wouldn't do the trick. Other companies might tell you this so you won't have this kind of issue.

 

I understand what u r saying. I had this problem a long time ago with another manifold company. I bored out the hole bigger and boost creep was gone. As I said earlier that bigger wg also would take care the problem.

 

Agreed, then your situation was an issue of restriction that produced the creep. Wanna know another source of flow restriction, a valve not lifting.

Everyone's on the right track. The only thing I don't get is why someone won't take 5 minutes to take apart the 38 mm gate and eliminate that as even an issue, instead of making assumptions.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Synapse &raquo;</TD></TR><TR><TD CLASS="quote">

Everyone's on the right track. The only thing I don't get is why someone won't take 5 minutes to take apart the 38 mm gate and eliminate that as even an issue, instead of making assumptions.</TD></TR></TABLE>

Because this isn't the first time it's happened. I've personally seen it happen over 20 times. It's not a bad gate...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tony1 &raquo;</TD></TR><TR><TD CLASS="quote">I think it has to do with pressure differential across the wg. You're already dealing with an instance where there's limited flow to the gate. The less pressure differential there is, the less air is going to make that turn. A bigger gate will flow more, allowing more of a pressure differential at the outlet of the manifold. Now, a 38mm would work fine, if there was more flow into the gate.
</TD></TR></TABLE>

Are you saying that a bigger gate will increase the pressure differential across the gate? Correct me if I'm wrong, but the ex mani pressure is the same, the turbo is the same, ex mani is the same and last I checked, the pressure of the air we breath after the gate is the same. How do you propose a bigger gate will increase differential pressure? If anything it will drop it, and lower the backpressure when the WG is open, which you say produces creep. A bigger gate will increase flow capacity so you're basically working on the principal of maximum flow for a given cross section. Unless what your saying is that at higher ex gas Mach numbers bigger gates will increase the backpressure?????

If the mani is the issue because the ex gas can't make a 90 deg turn to flow out, then following your logic, he should be able to run with that hole open to atmosphere and still make 22 psi of boost, right?

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tony1 &raquo;</TD></TR><TR><TD CLASS="quote">

Because this isn't the first time it's happened. I've personally seen it happen over 20 times. It's not a bad gate...</TD></TR></TABLE>

Maybe all those "38 mm" gates are flawed in design from the get go. Poorly engineered spring rates, galling valve guides, wrong durometer diaphragm, whatever.


Modified by Synapse at 9:31 PM 8/10/2006

 

Ok, you have a straw and a 2" pipe, both feeding off of a tube with 20psi in it. There is a cap at the end of each one. You uncap each one. The straw can only flow so much, so there will be pressure at the inlet side of the valve, as the valve can't flow enough. Now at the 2" pipe, it flows a lot more, enough to maintain low pressure at the inlet side of the valve. It makes sense in my head anyways. Just like an intercooler that's too small, there's a pressure drop across it because the air backs up at the inlet. Maybe i'm wrong, but that's how i see it.


As far as the 38mm gate being designed bad, that's not what was at question. You said take it apart and check it, insinuating something is wrong with it that's fixable. This isn't about how much a gate with a 38mm valve can flow in theory, it's specifically about a 38mm Tial wastegate...

 

get a larger gate.

I have a Neukin, and it crept on a tial 38 BAD. I rewelded a 44m flange and holds boost PERFECT

 

Ok lets think about this scenerio in man's world.

If you have a 2" weiner, its hard to hit the G Spot vs 12" weiner would hit the spot nice.

So in most cases bigger is better.

Bigger wg would help the gases.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tony1 &raquo;</TD></TR><TR><TD CLASS="quote">Ok, you have a straw and a 2" pipe, both feeding off of a tube with 20psi in it. There is a cap at the end of each one. You uncap each one. The straw can only flow so much, so there will be pressure at the inlet side of the valve, as the valve can't flow enough. Now at the 2" pipe, it flows a lot more, enough to maintain low pressure at the inlet side of the valve. It makes sense in my head anyways. Just like an intercooler that's too small, there's a pressure drop across it because the air backs up at the inlet. Maybe i'm wrong, but that's how i see it.</TD></TR></TABLE>

A small (flow limited)intercooler will actually produce more pressure before the intercooler. Since it is backing up, air is compressing, raising the pressure, thereby raising the temp. On the other side of the IC, the air has been drastically cooled. The air is denser in charge since it is cooler, less volume, less pressure, the result is a massive pressure drop.

Pressure differential (delta P) in this scenario is= ex mani pressure - Air pressure after the WG

The straw will have a higher Delta P since it can't flow the ex gas so it backs up and produces pressure. The 2" pipe will not have backup and will flow the gas, so there is a smaller Delta P.


<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tony1 &raquo;</TD></TR><TR><TD CLASS="quote">This isn't about how much a gate with a 38mm valve can flow in theory, it's specifically about a 38mm Tial wastegate...</TD></TR></TABLE>

I agree with you, but people keep hammering how it is the Neukin Mani that is at fault here. And if it really is due to the design, there's no way this guy could produce this result, no matter how big a gate you go, this would've still been creepin:

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by wade &raquo;</TD></TR><TR><TD CLASS="quote">
I have a Neukin, and it crept on a tial 38 BAD. I rewelded a 44m flange and holds boost PERFECT</TD></TR></TABLE>

 

The 2 situations i've seen with neukin manifolds both had 44mm tial gates, that's what i was referring to. It's obvious that he is not porting the hole for the wastegate to fit up very well at the collector. There were 2 pics of his manifolds on this post, 1 was alot worse than the other, so you can see why some people might have a problem and some not. One of my situations was having a problem holding boost past 7k with an sc61, not many people have this problem with sc61's.


A small intercooler has a "pressure drop" because it can't flow enough and the air backs up, causing more pressure at the inlet than the outlet. A bigger ic will have less pressure drop because of the increased cross sectional area of the hot flow side. There might be a small pressure drop because of air temp, but the general "pressure drop" we're talking about when dealing with intercoolers is not because of the temp. drop, but because it can't flow enough.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tony1 &raquo;</TD></TR><TR><TD CLASS="quote">
A small intercooler has a "pressure drop" because it can't flow enough and the air backs up, causing more pressure at the inlet than the outlet. </TD></TR></TABLE>

I agree, another variable besides temp is what you point out above, artificially high pre IC pressure due to lack of flow. Same turbo shaft speed, inlet temp, piping, etc, higher pressure pre-ic with a flow limited IC vs a free flowing IC.

 

huh.

This thread went from manifold build issues, to IC pressure drop.

interesting.

 

the problem is the manifold, with the crap over the wastegate hole it created a "scavaging" effect. therefore if the manifold pressure at the turbo will be higher than in the wastegate tube, therefore you have boost creep. When everyody welded a bigger wg tube on they done a better job than was on it before. If you would have just cleaned up the mani before changing wastegates it probably would have fixed it.

 

I like all your theorys. This is better than most stuff on here

 

go dame it took 20 min to read uo to this point

well i understand i might of cleand it up & it might of worked . but not really that turbo makes to much volume for that 38 to keep up at low boost.

everything is finished. i will be putting it all back together tommorow starting it up. & if thiers time some dyno runs.

if u look at both wasgates 38 46 the outlets are basically the same size, but inlet it 3/8 bigger but more importnatly the chamber is way bigger alowing more exaust to flow by the valve, thats where the gain is. after studying thats where i see most restriction, along with not porting things. witch i ported the flang side also
ill post pics tomorow of the flange comleted & everything else hpoing ti all goes good

hey bryson tell your boy to lay of the royds

 

That issue was taken care of about 3 months ago, wastegate holes are 44mm as compared to the 38mm as some people where saying they had problems with. We would make a 38mm hole for a 38mm gate and 44mm hole for 44mm gates but now all are 44mm. Our race manifold has a 54mm hole/elbow for high hp. Given that elbows are 42mmID and straight pipe is about 41mmID the 44mm hole is larger then the pipe that everyone uses. The loss of 2-3mm diameter does result in like 14% less of a hole for air to flow but other issues could be to blam too. So yes the 38mm hole in some of the collectors could cause a problem on some cars in some situations.

 

well its all good it seems to be holding boost at 14lbs even runnig a 10lbs spring so were good.

 

[QUOTE=tony1As far as the 38mm gate being designed bad, that's not what was at question. You said take it apart and check it, insinuating something is wrong with it that's fixable. This isn't about how much a gate with a 38mm valve can flow in theory, it's specifically about a 38mm Tial wastegate...[/QUOTE]

Question for you on the 38mm Tial? With High Whp applications I have heard that some prefer the smaller gate such as the Tial 38mm and it will operate fine at higher boost levels. I have my 38mm from my previous setup. Mon. I'm getting hatch retuned with a Gt35R .63A/R w/ Inline Pro Log mani, Tial 38mm WG, and 2.5 Downpipe. On my pump gas runs do you think I am going to run into issues holding boost around 15psi?

 

you should be fine

 

thats what 2 of my buddy run u should be fine,
its just my turbo really isnt designed to run lower than 20.
aslo ill have pics today been to buisy.
Noooooooooooo more chrome rims