viprez586 said:

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.

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I already made 408 AWHP on a Mustang dyno with the stock Jpipe and an unported, cracked exhaust manifold, and a wastegate that blew open and only held 22psi at redline. I plan to push my setup a lot farther as soon as I get a clutch that works right. A mod like this can only help.

I was considering using the Subaru compressor housing. I looked at one and compared it with the stock cover. The Subaru housing is slightly smaller internally, so I scratched it off my wish list. Those other housings look interesting. The TDO6 cover is my next choice.

Me and my friend doing a downflow conversion on my FP68HTA with trying to keep the internal wastegate. We are practicing with a 14b. I'll post the results here.

I like what i see in here..

AlphaVision said:

Me and my friend doing a downflow conversion on my FP68HTA with trying to keep the internal wastegate.

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Probably would've been easier to just buy a 68HTA from a Subaru and swap the turbine housings, don't you think?




You could tweak the actuator arm as needed to fit the DSM turbine housing.

It would be easier, but there are a few factors that are against me.

1. I didn't know at that time that this can be done (I am still a learner)
2. I didn't have a good 14b turbine housing, and still don't have a nice one
3. I live in a country with less or around 10 turbo DSM's DSM flanged turbos, housings and parts are very hard to find and getting one from abroad costs too much

Also that way I can rotate the comp housing whenever I want back to stock position.

As for the actuator I may cut it in half and put an adjusting screw to solve any issues. I am still waiting for the mahcine shop to port it and will start experimenting more

Getting this J-pipe outa the way of the heat and being able to put my FP stainless cover back on would be nice..

pneumo said:

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.

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!

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Isn't boost pressure dropping off at high rpm a product of the mass flow of the turbo not being able to keep up with the mass flow of the engine?

I've also read about people welding the flapper closed on 14B and 16Gs and I'm pretty sure the boost is going to behave exactly the same way. Reach it's max flow/psi then drop as the mass flow of the engine catches up when RPMs get high.

It's also detrimental as the wastegate path is more area for your exhaust to escape and closing that off will raise pre manifold pressure higher than if you were to have a functioning wastegate.

Cutlassjim said:

Isn't boost pressure dropping off at high rpm a product of the mass flow of the turbo not being able to keep up with the mass flow of the engine?

I've also read about people welding the flapper closed on 14B and 16Gs and I'm pretty sure the boost is going to behave exactly the same way. Reach it's max flow/psi then drop as the mass flow of the engine catches up when RPMs get high.

It's also detrimental as the wastegate path is more area for your exhaust to escape and closing that off will raise pre manifold pressure higher than if you were to have a functioning wastegate.

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Good points. A small turbo will run out of flow at some point.
OTOH If the wastegate flapper is large, or the wastegate spring is too weak, then it may blow open at high boost since small turbos at high boost can produce high exhaust manifold pressure. I have a 34mm flapper on my turbo, which will blow open easier than the stock flapper.

I agree that sending some exhaust through the wastegate will reduce exhaust manifold pressure, but exhaust heat and pressure is what powers the turbo, so we need to send most of the exhaust through the turbine wheel in order to make boost. Yes, there is a point of diminishing returns where exhaust manifold pressure rises quicker than boost pressure, which is why I didn't want to weld my wastegate shut. My dyno chart and logs show that each psi of boost made 11 ft-lbs of torque. Between the downflow outlet and stiff wastegate spring I'm hoping to gain an extra psi or 2.

I'm sorry I don't have any results yet, I was hoping to have these mods tested on the track by now, but my car still has issues with the clutch.

Here it is installed. Still have to put the radiator, but I think it will clear just fine

Cool thread Dave! This would work for me easily as I have an 02 mounted wastegate. So how much you charging for the pipe? I tried welding once and was decent at it, but not good enough to put on my own car! Then I no longer had access to the equipment and that was that.

I wonder if you will pick up the gains you are looking for?

The points I'm interested in are:

-shorter route
-away from exhaust mani
-cleans up engine bay some by eliminating j-pipe

very interested in this thread. I have a friend who just picked up a 16g equipped 2g. we have a lot of inadequacies to address with the installed turbo/IC system.

how do you feel about the WG function on with the actuator being placed at that angle compared to its original mounting position.

Phil1320 said:

Cool thread Dave! This would work for me easily as I have an 02 mounted wastegate. So how much you charging for the pipe? I tried welding once and was decent at it, but not good enough to put on my own car! Then I no longer had access to the equipment and that was that.

I wonder if you will pick up the gains you are looking for?

The points I'm interested in are:

-shorter route
-away from exhaust mani
-cleans up engine bay some by eliminating j-pipe

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Hi Phil,
I'm not sure how much this pipe would cost. I just made one for myself to see how it worked. If enough people want one I could look into offering them after the holidays. I could make 2 versions of this outlet pipe; a basic outlet made of mild steel with either a 2.25" or 2.5" section to match your lower intercooler pipe, and a nice stainless steel version with a gradual cone tapering out to 2.5" at the LICP.
If anyone is interested send me a PM.

AlphaVision said:

Here it is installed. Still have to put the radiator, but I think it will clear just fine

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Im working on this myself. Did you do any modification to the wastegate arm to be able to do it like this?

No. Modification to the wastegate arm. Just welded the bolt bungs as seen in the picture

where can we find the subaru 16g cover at? will it work with a mhi big 16g?

If I ever go back to a 16g, I'll have to do that. Looks nice. Should keep the charge coming into the intercooler a little cooler.

m_0ney_pit said:

where can we find the subaru 16g cover at? will it work with a mhi big 16g?

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This looks like it should work, but you should contact the seller to be sure.
subaru 16g turbo housing items - Get great deals on Parts Accessories items on eBay Motors!

It looks like most of the aftermarket subaru 16g housings are for evo3 16g wheels...will the housing play nice with the b16g wheel or do I have to swap to the evo3 wheel?

Think you could plumb a boost activated sol. valve to a vacuum source and use vac to help pull the wastegate closed? You might be able to tap the brake accumulator. Or possibly need a vac canister. Would be a cheap solution to upping the pressure on the factory actuator. You could even use an electric boost controller to regulate the vac amount supplied.

Also instead of welding the flapper shut you could just saftey wire it closed on track days? I was told by Lucas English this made his cars run worse, even though some additional boost was possible. They are into porting the housing to creep. Thought about going that route?

Have you considered your crushed factory BOV may be leaking at 30+psi? I run one as well with the "dodge garage" mod. If I could get my ca ront eh dyno I could monitor the BOV pretty easily. I've heard they leak over 30psi. Hard to check this though.


I'm at roughly 39lb of cracking pressure on my actuator with the addition of 3 10lb springs (advertised 10lb anyway). Spike to 35 or so and hold 27psi up to 6k or so before I Start to fall. I was thinking of getting some 15-20lb springs, but I'm not sure keeping the gate closed is all that beneficial. I also used the garret adjustable rod end. This can limit the flapper full open position much more than a few washers.

I wish there were afordable 8-9cm direct bolt on housings. I feel I'd gain the most with a slightly larger housing.

Heres my setup. My welds sure aren't as pretty though! I blame the mig!

I know myself as well as quite a few others are running Jusmx141's style Holset WGA hybrid. Although I'm still on the stock cams, at boost pressure alone (no controller) my car instantly held 20 flat to redline. I then turned up the ebc a little and it holds 24.5 straight to redline which is good enough until I start running E85. Before the stock 16g actuator would only hold about 15-16 IIRC at wastegate pressures. I could tune it for 25 but it would drop off to about 20-21 by redline. The stock spring just isn't strong enough at higher PR ratios. BTW you can also increase boost pressure by preloading the WGA's spring after this mod if you wanted to. I just kept it tight for easier controllability.

My shimmed stock WGA holds 30+ up top. ECMlinks boost by gear helps keep it all in line.

Very cool thanks everyone I learned something.

I called Robert at FP today and asked about using JUST the Subby hta68 cover on my DSMhta68, he said the Subby hta68 wheel is different then the dsm hta68 wheel..He said the solution would be to send him a stock Subby cover, and he'll machine it with the dsm program..

Just run a 17c compressor cover.. Wheel is the same size.

Here's an update for how did my setup perform.

I broke in the engine on Sunday. The driving conditions were: RICH - AFR between 10-10.5 under boost. Throttle was around 70%, never got past 75%. And RPM never went over 6K.

The turbo was holding 10psi from around 4K to 5K. then started building boost rapidly and on 5.5K I was getting 18-20 psi.

What I think is that I will need to tighten the wastegate. The problem is that I think that I cannot move the actuator further away because it will interfere with the front engine mount. I will have either to trim the mount bu a couple of mm or bend the actuator a little more than the stock bending to be more tight.

So everyone: keep that in mind. I will update with my further progress