Nameless Downpipe: Official 5th Gen GT Install Thread

[ripstik]

math.

 

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.

 

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...

 

hahahaha i know, I concentrated on fluid dynamics in school, tho since i have only used it to generate theories rather actually doing calculations. still blows me away, the amount of time and effort spent must have been tremendous. They made some machines that worked pretty damn well with hand calculations and hand drafted drawings, manually operated lathes and mills. now i can model something, not even make drawings and have a laser sintered part made out of damn near anything at my door in a week.... shit's cray.

[fahr_side]

This is a rough idea of what I am thinking of doing.

 

Nice idea. Not sure how you'd fab that in there except by removing the wastegate dump pipe temporarily, but it would improve things I'm sure. Very clean way to merge the two flows.

 

 

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[fahr_side]

This is a rough idea of what I am thinking of doing.

 

 

Nice idea. Not sure how you'd fab that in there except by removing the wastegate dump pipe temporarily, but it would improve things I'm sure. Very clean way to merge the two flows.

 

 

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[FLlegacy]

I am thinking of making a larger plate and curving it over the wastegate pipe. I think I could have it welded in from the outlet. First, I need to find someone that can tig weld it in.

 

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[fahr_side]

You might also just cut away some of the dump pipe and weld in a 'U' shaped part of sheet metal like this:

 

http://i464.photobucket.com/albums/rr5/fahr_side/20160420_175515_zpsltdxthxs.jpg

 

Opening up and extending the merge like this would reduce turbulence and improve flow without you having to tack things into the inside of J-pipe.

[Sm00veM00ve]

Showed my Tuner that when I was up there to pick up the leggy today :] I'm going to try and have him right a short little excerpt of his opinions on the tuning process, design etc. He's just really busy right now so I don't have any set timeline for when he can write something but I'll make sure I get something eventually. He was not a fan of how the design was implemented at all, but I'll leave it at that until I can get him to do a write up on the experience.

 

So the car is "done" but still has a slight overboost issue (can be weather, gear, etc. dependent) On a hot humid day like it is today in CT, I probably won't run into any issues, but on a colder day with less humidity= denser air which raises the likely hood of overboosting, So I can go WOT but I'm gunna take it easy until we try a solution he was thinking of to solve the overboost issue: In a nut shell, loosening the WG actuator spring. I'm not gunna go super into detail because honestly I don't want to say anything wrong or misleading, but thats essentially what we talked about doing. Lower spring press should solve overboosting by not letting it boost as high...then he can go in the tune and revise it and finalize it. Again sorry that it's going to be dissapointing but I really don't want to just fake words. When he was walking me through I understood what he was saying but I don't think I can properly put it into words if that makes sense, but cutting that piece off the downpipe seemed to have solved the actuator hitting and not being able to open fully so thats good, and took care of the huge spikes to 25/26 I was seeing.

 

So on a mustang dyno, I made I believe 294whp, didn't pick up much over all due to running out of octane and the small turbo, and toilet cams, so I'm planning on getting flexfuel whenever that happens. But she made huge torque, 407wtrq. Damn rocket now and I haven't really banged through any gears, just short pulls. Intake sounds good, exhaust is suppppeeer loud which I love (muffler deletes from nameless) but just a warning for anyone else who was looking at getting the full almost straightpipe set up. I'll be getting some videos eventually :]

[ripstik]

i can't wait to hear this thing at WBM in a few weeks

[Starks]

So he wants to reduce preload on the waste gate spring essentially? Meaning the waste gate is going to be opening sooner under lower boost thresholds.

 

I'm pretty interested in what he has to say.

 

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[BBPeik]

^^^I was thinking the same thing. Interesting way to combat the problem.

[Sm00veM00ve]

I believe so, we just talked about so much in little time that just because how I am, I can't remember everything right away haha. Yeah I'll be trying to get him to write something up, and I'll post it for him on here.

 

Yeah can't wait to see everyone at wicked, He actually invited me to show for his shop at WBM so naturally I said yes haha so that's going to be pretty cool for me, never done anything like that before so definitely come say whats good, and I'll bump that WBM thread from the dead to try and get another meet up to happen after if anyone is down :]

[FLlegacy]

I was wondering if preemptively opening the flapper might help control over boost. I suspect the wastegate will get over whelmed eventually. But sounds like for shorter gears it will work.

 

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[fahr_side]

Once the wastegate is wide open, it's wide open. We've seen from other logs that even with WGDC reduced to zero, boost just keeps rising. A softer WG actuator helps reduce spiking but does nothing to help with creep at high revs.

 

 

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[FLlegacy]

So from a tuning standpoint is lowering the spring tension going to cost some low end power or boost for the sake of controlling overboost in the top end?

 

And since we are discussing boost/overboost couldn't a small amount of high boost in the top end help push a little more power where the stock tune starts to fall off. Would this also make the engine more prone to high rpm knock/detonation and possible turbo failure? Or is it a matter of having enough fueling to keep the engine happy and in one piece?

[fahr_side]

So from a tuning standpoint is lowering the spring tension going to cost some low end power or boost for the sake of controlling overboost in the top end?

No. Spool will slightly slower / later in return for less tendency to overshoot target and spike high around 3k2 to 3k6rpm. Creep at high revs won't be affected.

And since we are discussing boost/overboost couldn't a small amount of high boost in the top end help push a little more power where the stock tune starts to fall off. Would this also make the engine more prone to high rpm knock/detonation and possible turbo failure? Or is it a matter of having enough fueling to keep the engine happy and in one piece?

 

 

We can push boost higher at peak revs as it is by increasing WGDC. What I find with the stock turbo is that efficiency is so poor we have to pull so much timing as to offset any gains from pushing more air. Another 1psi is worth a few more g/s which in theory is worth more power, but then you have to pull 1 or 2 degrees timing to avoid knock and give up your gains. You might gain something if you had a FMIC but as you mention you're wringing the turbo's neck and such high shaft rpm will shorten it's life.

 

 

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[GTEASER]

She made it safely. Comparison pics and measurements will come this weekend.

 

http://uploads.tapatalk-cdn.com/20160526/69e511e85032afa8c3dafb9609a8b612.jpg

 

Note the soot pattern between the wastegate dump pipe and the extended turbine pipe, this is the area that fahr_side mentioned that the wastegate flow needs to turn multiple times to exit the housing. It is almost wiped clean from what is probably high velocity flow.

 

http://uploads.tapatalk-cdn.com/20160526/19f6377d56eea0ac4e1c39131e5f20de.jpg

[fahr_side]

Either that, or the flapper is so close with the gate open there's no room for flow there and thus no deposits.

 

 

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[ripstik]

god i need to get a job designing these things. I've put more thought into how to improve/solve this DP than i ever have put into designing a seal.

[FLlegacy]

god i need to get a job designing these things. I've put more thought into how to improve/solve this DP than i ever have put into designing a seal.

I was shopping for a tig welder last night...lol.

 

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[ripstik]

I was shopping for a tig welder last night...lol.

 

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I've been looking into taking classes. i used to be good at MIG and ARC welding and was alright at brazing when i was in HS but haven't done it since and never got a shot at a TIG welder. there is an awesome welding institute here but for some reason they don't have a single night class

[FLlegacy]

^^^youtube if you can mig/arc weld tig is not much different from what I have seen. It is mostly about patience and a steady hand.

[FLlegacy]

Susppose I smooth the edges I painted yellow, how much would that help?

I think it might help as well if the turbine dump was welded on the inside of the flange as well to keep the wastegate flow from getting caught in the crease there as well.

[ripstik]

Susppose I smooth the edges I painted yellow, how much would that help?

I think it might help as well if the turbine dump was welded on the inside of the flange as well to keep the wastegate flow from getting caught in the crease there as well.

 

are you talking about just smoothing the edges or actually creating a sort of bell mouth for the dump pipe? smoothing the dges will have some effect but obviously it matters how far you go with it. making a bell mouth for the waste gate flow would likely fix over boosting if the flapper is free to move, but it would be some difficult fab work that's for sure

[GTEASER]

That small gap (crease) betweent he flange and turbine dump pipe is not going to affect anything negatively, if anything it will help flow by creating a stagnant zone at the hard angle.

[FLlegacy]

are you talking about just smoothing the edges or actually creating a sort of bell mouth for the dump pipe? smoothing the dges will have some effect but obviously it matters how far you go with it. making a bell mouth for the waste gate flow would likely fix over boosting if the flapper is free to move, but it would be some difficult fab work that's for sure

 

I am thinking of just smoothing the sharp edges to keep the gases from having to make those sharp turns. Since I will need to buy a porting bit for the turbo might as well get some use out of it.

[ripstik]

That small gap (crease) between the flange and turbine dump pipe is not going to affect anything negatively, if anything it will help flow by creating a stagnant zone at the hard angle.

 

eh... stagnant zones in most cases are no bueno. a crease like that can definitely have a negative effect on flow. you have to remember "stagnant zones" are considered that because the average of flow has no velocity but there are still particles moving every which direction in them. and in this case the only way those particles can escape that area is in the opposite direction that we want. so it will hinder flow worse than a hard corner which can at least release particles only perpendicular to the direction we want.