Nameless Downpipe: Official 5th Gen GT Install Thread

I can't remember the username(s) at the moment, but it's been noticed in the past that the wastegate actuator bumps into the edge of the turbine housing flange, so they could potentially trim a little material off there to get some more travel.

So to be clear: Your car is at the same tuner shop that Nameless just did their test at, and they found a mechanical reason with the dp that was preventing adequate boost control?

So to be clear: Your car is at the same tuner shop that Nameless just did their test at, and they found a mechanical reason with the dp that was preventing adequate boost control?

 

Yes, but that's only with an aftermarket BPV and after I expressed concern with tuning for 20 PSI on an engine that's still stock. I was given the same initial options as Ryan: tune for that amount of boost, stick with the OEM BPV, or explore a different path. I chose option C.

 

I should point out: my car hasn't been on a dyno yet.

Edited February 21, 2017 by Ellesedil

Adequate boost control means (in my mind) being able to dial down to 18psi, even with an aftermarket bpv.

 

I'm frustrated. I bought this thinking that it would give better boost control than the other options, and this test only seems to show that it's not notably worse than the others. They seem to be on the ragged edge of boost control and calling it good. If I had known this I would have bought the Invidia catless and got my wastegate ported.

Still might do that.

Let me clear this up after talking with English about this. They found out that the factory actuator does not have enough physical throw in the rod to fully open the flapper valve.

 

It has nothing to do with the downpipe or any downpipe for that matter. They are only seeing it open about 30%

 

English Racing

 

"The actuator doesnt have enough throw to allow the wastegate flapper to open 100% it opens maybe 30%"

 

"the DP has no affect one way or the other

if anything I think this is using a modified form of the Ford boost control strategy to open the blow off valve or engineer controlled boost leaks to limit the problem

no matter what its obvious that they engineered one mistake to fix another"

 

They are about to get going on Ellesedil car now.

Found the thread I was thinking of previously: http://legacygt.com/forums/showthread.php/5th-gen-gt-engine-re-build-257922.html

 

User WheelZ mentioned in post #14 that the little external tab that connects to the wastegate flapper interfered with the housing and/or the flange, and that whoever ported his exhaust housing also took a little meat out to address that situation. Maybe English could look into that if they can't get in there and port the internal passages? This seems like low-hanging fruit to me- it's external, and as long as whoever does the grinding keeps the transitions nice and smooth, there's no more risk of creating heat-related stress concentrations by trimming the outside than there would be on the inside.

So, my car is still boosting to 20 PSI. They're not seeing any knock. So I'm back to my 3 options: leave it as it is right now, return to the OEM BPV, or see if porting the waste gate housing makes a difference.

 

Mainly, this is the kind of concerns I have with this much boost:

 

4. Stock VF-54 turbo. I’m not comfortable pushing these past 10 or 11psi on pump gas at redline because the turbines just get choked anywhere beyond this kind of shaft speed. Note that this is not much more than what’s targeted in the stock mapping. Subaru basically fitted the smallest turbo they possibly could in this application to hit the power target they were looking for. Improvements in peak power on stage 2 cars come mostly from leaning out the very fat stock fuel curve, the reduction in EGBP from running catless or with high-flow metal cats, and then being able to run more timing because of the lower EGBP and EGT. Power limit is about 235whp on pump gas and torque is limited to about 330lbft on the stock headgaskets because pushing beyond 18psi is going to lift a head and pop the head gasket before very long.

The other issue with the stock turbo is the wastegate. As many have found out, the flapper is sized ‘just’ large enough for the job on the stock hardware and tune but for example fitting a high-flow exhaust lowers backpressure enough to allow boost creep. It’s especially obvious in colder weather and with catless J-pipes.

 

...

 

2. Stage 2. Blockage point here is the turbo itself. As above, but add a high-flow catted, or catless J-pipe. Now you can raise boost to 18psi peak on pump gas and run leaner AFR and more timing. Note boost still needs to taper at high revs due to the size of the turbo. Stock injectors are adequate for pump gas but I’d back them up with a better fuel pump like a DW200 or a 300 if you think you may go bigger later. On E85 you will want the bigger pump plus 750 or 850cc injectors and again you may go to 1000s to future-proof yourself. 235whp/330wtq is typical.

At this point I think a FMIC would definitely help. As mentioned above, the air flow to the stock TMIC is pretty limited and in longer sessions at WOT and high revs it’s going to get heatsoaked.

Oil cooler recommended for EDM models.

 

Modding cars is new territory for me. I'm going to sleep on this.

I would love to hear thoughts from other tuners on running 20 ish psi of boost on a stock motor, I am antsy myself about it sometimes. But I do understand the risk is always there and you have to keep that in the back of your mind at all times and don't do dumb things with your car: not letting it warm up properly before getting into boost, not allowing some cooling time between pulls, not changing all fluids on time, watching your knock and fuel ratio.

Found the thread I was thinking of previously: http://legacygt.com/forums/showthread.php/5th-gen-gt-engine-re-build-257922.html

 

User WheelZ mentioned in post #14 that the little external tab that connects to the wastegate flapper interfered with the housing and/or the flange, and that whoever ported his exhaust housing also took a little meat out to address that situation. Maybe English could look into that if they can't get in there and port the internal passages? This seems like low-hanging fruit to me- it's external, and as long as whoever does the grinding keeps the transitions nice and smooth, there's no more risk of creating heat-related stress concentrations by trimming the outside than there would be on the inside.

Wow!...That is nuts. Why? Just why?

 

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There's one boost cap method that got glossed over in the last few pages. Either refit the stock cans or make a restrictor plate as has been described earlier in this thread. Much better solution than bleeding boost via the BPV which:

1) works the turbo harder than necessary

2) heats charge air unnecessarily

3) makes AFR harder to control

 

On boost targets... I know people get away 20psi on E85 for years but gas makes higher cylinder pressures.

I've seen newer motors do 60k on 20psi before popping a gasket. I've seen stock cars with 120k suddenly tuned to 20psi pop them in a month. YMMV and all but the cars I see go a long time were at 18psi or less, at least on pump gas.

 

With 20/20 hindsight I'd have a tried a few different things with that downpipe. Maybe more of a bellmouth as English are trying to create. Maybe a 300 cell cat vs. 200. At the end of the day, would it do anything a simple bellmouth design (like Invidia's) doesn't? Probably not.

 

An actuator with a longer stroke is an interesting idea. I have bare turbos here but I need to look around for an actuator to check out how far the flapper opens. Someone could contact Turbosmart about this, as they have far more 5th gens in their home market. Doubt US makers would help. Ask if they are willing to engineer an LGT application for the list.

 

http://www.turbosmartdirect.com/Product-Categories/Subaru-Actuators/

Edited February 22, 2017 by fahr_side
teh grammarz

Damn, there really just aren't any good photos out there and the few videos on the topic are so awful they made me scream.

 

Here's a shot of the inside of an Evo 16G housing some kind Evo person chopped up in the name of science.

 

[ATTACH]236738[/ATTACH]

 

You can probably guess that the wastegate port is made by sticking a core through the wall of the housing to form a hole there when it's cast. It's basically a straight hole at roughly 90* to the flow of gas through the throat on it's way to the turbine.

 

Here's a really rough (sorry but no time to break out better tools) sketch of how that looks in cross-section.

 

[ATTACH]236735[/ATTACH]

 

Note the very sharp edge the gas must crab around. Remember that gas has inertia and although nature abhors a vacuum the gas cannot possibly stick to the wall while making that turn at the speed it's going. Instead, it detaches, like the air across the top of a wing in stall, and this causes turbulence and poor flow rate.

 

Here's an equally rough sketch of how this mess can be made better with porting.

 

[ATTACH]236736[/ATTACH]

 

Remove as much metal as you can from the sharp up-stream edge before the chuck of the die grinder crashes into the port opening from the outside. Grind away at the housing up-stream of the port to blend that as well as you can. Here's the first photo again with a red line on it showing about how far back you want to blend that up-stream.

 

[ATTACH]236734[/ATTACH]

 

Nothing needs to be mirror polished and there are reasons doing so doesn't even help things. Do not do any more than barely clean up the remaining port window. Do not open up the port window as it narrows the area the wastegate flapper needs to seal properly.

The sharp edge on the downstream side of the port actually helps direct more gas into the port. Rounding this off would actually help gas bypass the wastegate and head into the turbine, which is not what we want, so leave it alone.

 

All of this info needs to live in a sticky. It took me a couple of hours to find it, which is kind of ironic considering how much time I've spent reading through this thread today.

 

I think I'm going to have the turbo ported and try to target 18 PSI on peek boost. Another concern is that we've been around 45-50 degrees in the PNW lately. If I understand things correctly, I'd be concerned that we'd get closer to 21 PSI in the dead of winter as the car is right now.

 

Maybe after I own a house again, I'll contemplate taking a path to get more.

Edited February 22, 2017 by Ellesedil

This is just my two cents. If the WG flapper really does not open that much, you would think that BNR would have mentioned this. As far as I understand they have hybridized several vf54's. You would think they would mention to their customers that along with porting the wg you should also modify the flapper in some way. As I said just my thoughts.

This is just my two cents. If the WG flapper really does not open that much, you would think that BNR would have mentioned this. As far as I understand they have hybridized several vf54's. You would think they would mention to their customers that along with porting the wg you should also modify the flapper in some way. As I said just my thoughts.

I've also hybrid-ized a bunch of VF-54s, but the pile of stock turbos we have here for modding don't have actuators fitted and usually the cores I get from customers have them removed as well. I had only thought to test the actuator once, to confirm at what line pressure the actuator would crack at, and that was with the turbo on the car. Actuator travel was not measured but did not look shorter than usual, at least not so it stood out at the time.

I thought Kinugawa sold actuators for the VF54

I thought Kinugawa sold actuators for the VF54

http://shopping.kinugawaturbo.com/kinugawabilletadjustableturboactuatorihivf22vf23subarustirhf5hb-1-1-1-2.aspx

 

No idea if they actually fits since their other VF54 parts specify Legacy in some way.

But, it's not the actuator that's the issue, it's the arm operating the flapper that's contacting not allowing the flapper to fully open.

 

Or am I mistaken?

 

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Possibly a dumb question, but why would the ECU be reading WGDC as 0 if the wastegate is in fact not all the way open? Would it be because WGDC is only a measure of how often the wastegate is opening and closing? Not the actual amount? Edited February 22, 2017 by Apexofthevortex

Possibly a dumb question, but why would the ECU be reading WGDC as 0 if the wastegate is in fact not all the way open?

It doesn't measure the mechanical throw of the WG arm and flapper, it only measures the voltage going to the EBCS to allow pressure to actuate the WG, so it doesn't know if a WG is even attached to the system.

From a different thread...

 

I took some videos for fake internet points! and to contribute to the community. Mods - please link this stuff into threads that are appropriate. Additionally, Mods, please feel free to download the videos and upload them into a different video source than dropbox. In other words, I grant you full copyright license to do what you want with the videos.

 

Waste gate flapper and actuator

This is a Kinugawa 20G/TD05 but appears to utilize the OEM waste gate flapper and actuator. It does not appear to open beyond the plane defined by the exhaust flange/surface of the exhaust housing of the turbo (which I think is relatively standard). It does appear, however, to be pretty dang close (e.g., so as to not make contact with the flat surface of the OEM downpipe). As (I think) mentioned by fahr_side in another thread, I suppose there is nothing stopping folks with bellmouth downpipes (like me) in using an actuator rod that opens the waste gate flapper valve further for less restriction by flapper valve, less turbulence with turbine exit flow, etc. Some delicious food for thought.

 

https://www.dropbox.com/s/rscw2w5vdvqocz0/IMG_1489.MOV?dl=0

 

Waste gate porting

My waste gate was ported by the guy that previously performed the port and polish services for a widely respect Subaru aftermarket parts company based in Minnesota (before they stopped offering such services). It looks pretty.

 

https://www.dropbox.com/s/ytmhdommu9x9f5i/IMG_1490.MOV?dl=0

 

I have not run this turbo yet, so I don't know how effective the waste gate porting is.

 

Peace out,

mcg_

Wastegate duty cycle doesn't have anything to do with the actual position of the flapper, and there's no position sensor there that would give you that reading. The ECU controls the EBCS using a pulse-width modulated (PWM) signal, which is a square wave with the peak at whatever voltage the solenoid runs at, and the trough at zero (basically a really fast on/off). WGDC is an indicator of how hard the EBCS is trying to keep the wastegate flapper closed- 100% means it's putting full boost pressure into the actuator to keep it closed, 0% means it's venting the actuator to atmosphere (aka "spring pressure"), and anything in between tweaks the force on the actuator to try to maintain target boost pressure. There's actually a couple of newish Go Fast Brett videos on mcmtv2 about boost control which do a better job explaining than I can over text.

 

Another good example is the power level setting on your microwave, that's just a slow PWM. Power level 5 is going to be something like 10 seconds on, 10 off, 7 would be 14/6, etc.

 

An actuator with a longer stroke is an interesting idea. I have bare turbos here but I need to look around for an actuator to check out how far the flapper opens. Someone could contact Turbosmart about this, as they have far more 5th gens in their home market. Doubt US makers would help. Ask if they are willing to engineer an LGT application for the list.

 

http://www.turbosmartdirect.com/Product-Categories/Subaru-Actuators/

 

 

 

I emailed them got a response fairly quickly however they would need a turbo to be sent to them. If anyone has a spare turbo id be willing to pitch in for the shipping or buy the whole turbo to send. Heres the message

 

 

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I'd also be more than happy to help pay for shipping for someone to get a turbo out to them.

So are we thinking getting the flapper all the way open is going to eliminate the need for porting?

 

 

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So are we thinking getting the flapper all the way open is going to eliminate the need for porting?

 

 

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It's hard to say for sure but if what English racing and Nameless are saying is in fact true and the wastegate can open up to 70% more than it does, it definitely could help a lot. It's worth a shot if you ask me.

Seems to me that even if the door is open half way it should still be able to flow way more than the small wg passage is able to let through. The air flow may hit the flapper a bit, but the opening is still uncovered. I only have my experience to go on, using my 20g hybrid, but it has a nicely ported wg and my peak wg duty cycle at 21psi is only 52%. Unfortunately I think porting is the way to go.