Downflow outlet on a 16G

[pneumo]

I'm in the middle of converting my 16G to a downflow outlet. It's going to eliminate the standard J-pipe with it's tight 180 degree bend. This should reduce pressure drop, save a little weight, and clear up some extra room.

I removed the wastegate, drilled out the locating dowel on the compressor housing, and rotated the compressor housing so it points down. Then I started making an outlet pipe that works with standard FMIC piping. Here's a pic;

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I'm glad I learned to weld recently, it's fun! It's hard to see in the pic, but I formed a taper in the elbow where it meets the flange. I also ported the compressor outlet while the bare flange was bolted on so the outlet and flange match perfectly. I made the weld a little thick inside the pipe so I could use a porting bit and sanding wheel to smooth the transition inside the pipe. Now air has a smooth path and gradual transition from compressor to LICP. The pipe isn't done yet, I'm going to add a section that expands from 2" to 2.5" so it matches the LICP size.
I also need to fab a wastegate actuator of some sort.
I'll post more pics when it's finished.

 

[NOSLO2PT0]

Looks good. How did you taper the piping where it meets the flange?

 

[turboglenn]

Looks good bud! isn't it nice to be able to do things like this yourself? I will never get rid of my metal working equipment because there's nothing quite like saying "yea, i made that a few nights ago at home" when people are gathered around admiring your setup

 

[pneumo]

Yeah I definitely like making stuff! I made the taper by cutting a cross slice in the end of the elbow, then I carefully bent all the edges inward. It wasn't perfectly circular, so the extra thick welds gave me some material to port and shape.

 

[asrdave]

for the wastegate just run one off the o2 if you have the money for it, i alwasy found it easier to control boost that way too, looks good!

 

[KeelesKustome]

i wounder why someone hasn't designed a kit for this? it looks much more simple.

 

[AlphaVision]

Yeah, me too. Are there any donsides of this other than the need of external wastegate?

 

[pneumo]

I don't see any downsides to this mod at all! I'm doing this mod to improve flow and clean up the engine bay. If anyone wants to push their 16G a little farther like I am, then adding this mod with an external wastegate are 2 steps in the right direction.

Here's a closeup of my weld that joins the 2 pieces of pipe.

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[tstkl]

nice dave! I bet your going to be super jealous of my LICP and UICP when I'm done. RWD = super short intercooler pipes.

 

[manny correa]

it looks good man! but there is no way to keep the internal wastgate actuator on their? either bolted to the backside if the compressor cover some sort of way, or some kind of bracket coming off of the stock wastegate mounting holes? that would make it even easier. well from not having to go external that is... good work bud.

 

[pneumo]

nice dave! I bet your going to be super jealous of my LICP and UICP when I'm done. RWD = super short intercooler pipes.

Hi Brian, whassup!
Yeah, a 4G63 RWD setup has nice short IC pipe routing. We had a Datsun 510 with the evo engine at the shop a few weeks ago, very cool car!

BTW thanks for letting me use the J pipe. Need it back? LMK.

it looks good man! but there is no way to keep the internal wastgate actuator on their? either bolted to the backside if the compressor cover some sort of way, or some kind of bracket coming off of the stock wastegate mounting holes? that would make it even easier. well from not having to go external that is... good work bud.

I thought about that, too. There's a few ways to keep the internal gate. I was thinking of welding a couple threaded bungs on the comp housing and attach a bracket. This page has plenty of options, I like the 18psi actuator. Wastegates : atpturbo.com

 

[AlphaVision]

Hm. Can't the stock wastegate holes be used along with the one on the compressor outlet? If a proper bracket can be made - cut round to go around the compressor inlet and going to that third hole for stability. Maybe there will be some wastegate rod bending as well..

Here it is

 

[pneumo]

I finished the downflow outlet today! I took the time to sand down the welds inside the tube so air has a smooth path the whole way through. I welded a bead on the end of the pipe instead of rolling a bead, that weld doesn't look as nice, but it keep things smooth inside. I also cleaned up the discoloration from welding with a wire wheel. I just hope it flows as good as it looks! Here's a pic

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[1997_GSX]

How did you keep that thin flange from warping while welding?

 

[pneumo]

How did you keep that thin flange from warping while welding?

I didn't! It warped a little, so I put it on a sanding table and flattened it. I wasn't worried about the flange since I have used several Dejon uicp's in the past, I just seal them with a little bead of RTV.

 

[GDNF2ET]

This is also going to get that J-pipe away from the exhaust manifold..Might be a good time to put a vacuum source on there too...Nice work !! I'd be interested in one if you decide to make a couple...

 

[99gst_racer]

Very nice. Downfiring is definitely the way to go. I'm surprised I didn't see this thread until just now.


I did a downfiring on mine as well, but I wanted to completely eliminate the potential leak at the flange.

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Also, TRE used to modify 14b and 16g turbos back in the day to better fit 2G cars, and they had provisions to keep the internal wastegate. Pics:

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[pneumo]

Thanks for the pics, those are nice alternatives. I'm probably going to mod the internal wastegate mount like TRE did when I'm ready to swap this 16G onto my daily driven Laser. For now I'm using it on my Talon, so I'm taking a radical approach for boost control. Here's my 'boost controller'

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The pic doesn't show how I mounted it to the turbo. It consists of 3 parts: an adjustable wastegate rod end, a threaded rod with locknuts, and an old valve spring! I did it this way because the stock wastegate blows open too easily with a 34mm flapper. I tried adding a few washers under the stock wastegate mount, but boost still fell to 21psi by 6k rpm. I was thinking of using an 18psi wastegate, but it might not be enough for my goals. I'm trying to hit some good times on this car so I'm pushing high boost. A side effect of high boost on a small turbo is high backpressure at roughly 2:1 backpressure to boost ratio. So adding 5psi to the wastegate spring would give me roughly 2 or 3 psi more boost. I want more!

I read about a few guys in Texas who had good results from welding the wastegate shut on their 16G's. That sounded like a bad idea, I might try it! Except the backpressure to boost ratio quickly becomes unfavorable, so I wanted a wastegate spring somewhere between stock pressure and welded. Since my calculator has a hard time finding the average between 18 and infinity, I did some SOTP engineering and used an old valvespring, which has a spring rate of 175 pounds per inch. Then I cut off 2 coils so it fits better and that gives it a rate of 225 pounds. The threaded rod gives me some leeway so I can adjust the backpressure. Yeah, it's a backpressure regulator, not a boost regulator. I just hope it works. We'll see.

 

[turbotalon1g]

Nice, i don't know if you thought of this, but what if you welded 2 nuts to the comp. cover for the internal gate to bolt to? then you could have it anywhere you wanted.

 

[TurboATM]

...i dont know too much about it, but there are factory made down firing 16g compressor covers out there...that i mite have 1 of!

 

[JusMX141]

The Hahn Super 16G cover is downfiring, but a little difficult to adapt to an internally-gated system (as would be expected). You'd also have to get this cover machined for anything larger than a Small 16G compressor.

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[99gst_racer]

Hey, I got one of those too.

Another good down-firing option is the Subaru 16g compressor cover (the red one). Three different downfiring 16Gs here.

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[Ghostcrafter]

I think this just became my new favorite thread ... and something I can work on while rebuilding the engine too.

Subscribed!

 

[viprez586]

Is this really going to increase flow that significant compared to going from the normal style to a J-pipe?

Props for creativity, but I think it's overkill for a 16G.

 

[99gst_racer]

Is this really going to increase flow that significant compared to going from the normal style to a J-pipe?

Props for creativity, but I think it's overkill for a 16G.

Probably not, but IMO it's cleaner looking and it takes up less space.