Nameless Downpipe: Official 5th Gen GT Install Thread

[GTEASER]

I obtained Swannee's DP this past weekend when I flew down to LA for his wedding. It is currently being shipped home to me. Couldn't really take it on the plane, TSA might think that the intermediate pipe was some sort of grenade launcher. Perhaps this weekend I can get detailed pics and measurements of both the original DP design, and the GB DP design, side by side.

[jojorios]

Has anyone brought this up to Nameless' attention?

[Sm00veM00ve]

I think we're kind of waiting for the final results to come in for the people who have installed and had issues. Fahr Side has also brought up some pretty great info as always (small housings harder to control boost, porting common solution, etc.). I think it would be the smarter decision to wait and get the outstanding issues solved and then compile the information, then draw up and email. Probably not a great idea to have an email filled with lots of frustration/emotion without having as much evidence as we can, plus I think GTeaser will be heading the action regarding emailing/contacting nameless so we don't have a bunch of people emailing them with complaints etc.

 

I should know if cutting that lip off the inside of the downpipe solves my OB issues by June 2nd, though I'm still hoping for another cancellation this week.

[jojorios]

I agree, but maybe they should just be made aware of the thread so they can also see how progress goes? And being aware of the issues, maybe they may be inclined to do some type of extra testing now, and since they are still selling these currently with possibly a design flaw?

[GTEASER]

I think we're kind of waiting for the final results to come in for the people who have installed and had issues. Fahr Side has also brought up some pretty great info as always (small housings harder to control boost, porting common solution, etc.). I think it would be the smarter decision to wait and get the outstanding issues solved and then compile the information, then draw up and email. Probably not a great idea to have an email filled with lots of frustration/emotion without having as much evidence as we can, plus I think GTeaser will be heading the action regarding emailing/contacting nameless so we don't have a bunch of people emailing them with complaints etc.

 

I should know if cutting that lip off the inside of the downpipe solves my OB issues by June 2nd, though I'm still hoping for another cancellation this week.

 

 

However you modify the DP, please please please provide pictures.

[GTEASER]

I agree, but maybe they should just be made aware of the thread so they can also see how progress goes? And being aware of the issues, maybe they may be inclined to do some type of extra testing now, and since they are still selling these currently with possibly a design flaw?

 

I agree, but let me think about it for a little while and go back and research what they said about why they changed the design. I still have the original email chain between myself and them but I haven't looked at it in almost a year. And let me get the other DP so we can make a direct comparision with measurements.

[GTEASER]

I also don't want them jumping the gun to start defending their product. I think we have a better chance of recourse if we can prove something prior to engaging them.

[laopadak]

My tuning is scheduled for 11-June. Will be installing the nameless DP, Racer TMIC, piping and Turbosmart BOV. Plan on using OEM turbo bolts, gasket and push the DP head to the front as much as possible (suggested by Nameless somewhere in this thread).

 

 

I'm hopeful because another local member (Colorado) had success with the same parts / tuner with no overboost. Holding steady at 19PSI max. I think the high altitude, stock mid and cat-back will help.

 

 

If there's a mod that's required, hopefully we can learn within the next week or so. Will keep everyone posted.

[Sm00veM00ve]

I may not be able to have a picture of the inside of the DP and where they cut, but when I go to hopefully pick the car up, I'll show them a picture of the lip part from a picture in this thread to confirm that's all they did. It would be a different story if I had the car and was taking everything off again myself but it's still at the shop. I'll confirm (if the car is good to go) that the overboost issues he encountered was due to the flapper hitting the inside lip of the DP and that they only cut that lip piece off to solve the issue, if they did anything else I'll get the details from them.

 

And that was exactly what I was trying to say GT, rather go in with sources to back up a claim rather than rely on emotions which probably won't get us anywhere any quicker.

[cww516]

How much was the flapper interfering with the pipe by? Just wondering if the problem could be solved using a thicker (or more likely, second) gasket and a healthy dose of high-temp RTV rather than trimming the pipe. I kinda have this thing where I don't like to modify anything in case I need to revert back, so maybe I'm just over-complicating things. I have pins plugged into the connector on the power supply I use for my 3D printer, despite the fact that I'll never ever use that PSU with a computer.

 

My guess (for what little it's worth, but everyone else has one, so I'll join in) is that the downpipe just flows too well for our tiny little wastegate to handle, and that the folks who don't have issues may be right on the hairy edge. The quick way to test this would be to tack a stainless fender washer to the inside of the pipe upstream of the cat to restrict flow- if you had overboost issues before and that cures it, there's your problem. The angle of the wastegate pipe where it intersects the turbine pipe will factor in, but with as little of a bend as there was and where it's located (partway through the 3"elbow), I'm not convinced that's the issue. My assumption is that there's a lot more flow going through the turbine at a higher velocity than there is through the wastegate, so the turbine flow will suck that wastegate flow right out of the wastegate pipe (Bernoulli principle, think carburetor). It'll be plenty turbulent where the streams intersect, but more turbulence would mean more back-pressure throughout the system (not just to the wastegate), and more back-pressure means less risk of overboost, so that geometry isn't necessarily a bad thing. Runs a little contrary to what fahr_side said, but considering I'd rather be unemployed than do computational fluid dynamics all day, take this with a grain of salt.

[ripstik]

.... but considering I'd rather be unemployed than do computational fluid dynamics all day, take this with a grain of salt.

Dude CFD is where its at tho, how people figured out carburetors without it is freakin mind blowing to me.

[GTEASER]

how people figured out carburetors without it is freakin mind blowing to me.

 

math.

[jackal8788]

Dude CFD is where its at tho, how people figured out carburetors without it is freakin mind blowing to me.

 

Bernoulli my friend

 

Can't tell you how frequently I use Bernoulli's Equation in venturi design. Note that I said 'use' though. Deriving it, best left to minds brighter than my own.

[cww516]

Bernoulli plus a LOT of guess-and-check would be my guess. Gotta get those tables of empirical values somewhere...

 

 

Don't get me wrong, CFD and FEA are fantastic tools, but my experience with FEA mainly consisted of me staring at my computer all night on my 22nd birthday. Set parameters, hit the go button, wait, get garbage results, lather, rinse, repeat. I prefer to limit the things I work on to objects I can hit with a hammer or throw across a room (or could after they're built), so things like programming and computational analysis aren't usually my favorites.

[laopadak]

You guys are speaking Chinese to me...I'm in sales and am still trying to figure out how the flux capacitor works and that's like from 30 years ago!

[ChrisCrash]

I shouldve finished college.

[jackal8788]

Dude CFD is where its at tho, how people figured out carburetors without it is freakin mind blowing to me.

 

Bernoulli plus a LOT of guess-and-check would be my guess. Gotta get those tables of empirical values somewhere...

 

 

Don't get me wrong, CFD and FEA are fantastic tools, but my experience with FEA mainly consisted of me staring at my computer all night on my 22nd birthday. Set parameters, hit the go button, wait, get garbage results, lather, rinse, repeat. I prefer to limit the things I work on to objects I can hit with a hammer or throw across a room (or could after they're built), so things like programming and computational analysis aren't usually my favorites.

 

Early on it was more back-and-forth testing, analyzing, and refining the mathematical models. Now I've gotten to the point where I can usually estimate the fudge factors (discharge coefficient, correction factor, etc.) close enough to make parts that do what they need to. You know, for government work...

[FLlegacy]

The issue with your thinking: there is a the exhaust pressure feeding the turbo and a little work done in the turbo and then pressure is split between the turbine and wastegate. So the wastegate pressure and turbine pressure vary inversely to one another. And the slight turbulence in the wastegate matters because the turbine side flows so well.

 

And finally adding a thicker gasket only moves the contact point further up the pipe since you aren't changing the distance between the pipe and flapper. If you, say, have an exhaust shop cut that pipe off and weld a perfectly sized one in place you may be much better off. Which is what is I am considering at this point.

 

Sent from my SAMSUNG-SGH-I337 using Tapatalk

[haruichi808]

Since I have emailed them about an exchange for midpipe or refund and had gotten the reply to adjust the dp toward the front of the car cause the holes were over drilled, but there in no room to move it. I'm very sad n dishearten cause it cost time n money plus wasted tune, that's why I had switched to an invidia already and now no problems, I haven't emailed back yet wanting a refund but I think that they should but don't expect it since I installed it but damn it don't work on my car and I have their axel backs n works great other than that just a tmic and was perfect b4 I installed that dp;(

[fahr_side]

The issue with your thinking: there is a the exhaust pressure feeding the turbo and a little work done in the turbo and then pressure is split between the turbine and wastegate. So the wastegate pressure and turbine pressure vary inversely to one another. And the slight turbulence in the wastegate matters because the turbine side flows so well.

I see where you're going but there's a small mistake or misapprehension in there. Let's mention here that drive pressure (AKA EGBP or exhaust gas back pressure) in the header is going to be in the range of 1.6 to 2 times the boost pressure at higher revs. Can't be more exact than that without measurements but that's the typical range for this turbo size range.

 

Note that gas enters the 'throat' of the exhaust housing, which is a bit like a venturi because it's reduced in the diameter from the sum of the two pipes coming out of the header. Yes the header is twin-scroll even though the turbo is single-scroll.

The bulk of the exhaust flow passes straight past the wastegate port and into the volute, at which point is starts impinging on the turbine, makes another (long) 90* turn across the turbine blades and heads out into the dump cavity in the exhaust housing twirling away like a merry little tornado.

 

In the process of driving the turbine and being turned around 90* this bulk of the exhaust gas has lost a lot of temperature and pressure as dropped to a few psi from being as high as 30psi.

 

The wastegate port is located at the throat has to make a sharp 90* turn to the flapper. By sharp I mean the inside of that turn is almost sharp enough to cut your finger with. The port is also smaller in diameter than the turbine housing throat. The aim of the wastegate is more to maintain a constant (or slowly increasing) drive pressure on the turbine wheel by bleeding some pressure off via this port. When you get to a point where constant pressure cannot be maintained even with the wastegate flapper held wide open, the wastegate is then choked, unable to flow any more gas, and this is where boost creep begins. Drive pressure rapidly increases at the turbine and shaft speed increases to drive the compressor past your target boost pressure.

 

In terms of remedies you have a few options.

 

1. Improve gas flow from the throat to the wastegate flapper by smoothing that out and increasing it's diameter if possible. AKA porting.

 

2. Let the gas escaping the port take the straightest, least restrictive path to a low pressure area, be that the midpipe or open air. Asking the gas to bounce off the flapper is already a restriction as every time you force a change in direction it's a loss of flow. The stock J-pipe has the gas jostling to get into the rapidly spinning and very turbulent flow out of the turbine. A divorced item like the Nameless has the gas flowing around all sides of the flapper, turning back slightly toward the pocket in the corner of the housing and then turning into their dump pipe. Asking the wastegate flow to join the flow from the turbine at or near 90* also creates turbulence which reduces flow.

 

3. Add restriction to the turbine dump flow to decrease total pressure drop across the turbine. Adding a cat, more muffler, or decreasing midpipe diameter would do this, for example.

[jackal8788]

....Add restriction to the turbine dump flow to decrease total pressure drop across the turbine. Adding a cat, more muffler, or decreasing midpipe diameter would do this, for example.

 

This little $2.00 champ did the trick for me In fact, I have since mailed it to another member who was having similar issues and he has reported that it remedied his overboost as well. I have the template as a .dxf if anyone is wants it.

[fahr_side]

This little $2.00 champ did the trick for me In fact, I have since mailed it to another member who was having similar issues and he has reported that it remedied his overboost as well. I have the template as a .dxf if anyone is wants it.

Technically speaking, that restricts the wastegate flow as well, but yes it works.

[FLlegacy]

http://uploads.tapatalk-cdn.com/20160525/be4a2340a60c2a0821f2bf9b2e9c39a8.jpgThis is a rough idea of what I am thinking of doing.

 

Sent from my SAMSUNG-SGH-I337 using Tapatalk

[jackal8788]

http://uploads.tapatalk-cdn.com/20160525/be4a2340a60c2a0821f2bf9b2e9c39a8.jpgThis is a rough idea of what I am thinking of doing.

 

Sent from my SAMSUNG-SGH-I337 using Tapatalk

 

That's an interesting idea that seems like it might have a few things working for it. It introduces a restriction in the flow path downstream from the turbine, thus adding backpressue and as a result of the reduction in flow area, you will create a region of higher velocity and lower pressure, which may further help scavenge gasses from the wastegate passage.

[ChrisCrash]

^^That does make a lot of sense. Are you thinking just a stright edge flapper or a "curved extension"? Im curious how much either design on their own would restrict airflow, possibly the curved restricting too much or creating unwanted pressure elsewhere.