Well the 9280efr was for the 20B (which I think was undersized high rpm). But I sold the 20b, otherwise would have gone with the G47 as you mentioned. So G50 is for the replacement to 20B.

I found it really challenging to decide on the turbo as the new motor is sideport only, and I don’t have crazy power goals due to wanting to run on pumpgas (e85 is not prevalent where I live). That’s why I picked the smaller compressor option on the G50. And unfortunately Garret left out the vband turbine option on the G50 (they offer it on most others), which is why I went with the Tial. And I picked the middle option on the AR size. Thinking being I’m going with the smallest compressor option and the G50 turbine will flow as much as the older GTX55, so assuming it will spool quickly but also not run out of steam up top. There are not many real life examples to compare to for this configuration out there, so just did my best to triangulate across 3 and 4 rotors with relative turbo sizing, compressor maps, turbine maps, etc to avoid undersizing the turbo but without going too large for top end I’ll never use. I also looked at the more publicly known cars, Rob Dahm has the G55 on the 4 rotor but I will never be able to attempt the big power he is doing, his 3 rotor has the G47 and that becomes emap constrained at the top RPMs (again, higher than I will go), and David Mazzei’s had the GTX55, but that car was p port. I feel like G50 kind of fit right in for what I’d like relative to all that. Spoke with a few shops for input as well. Also did the whole compressor and turbine area estimating from the old Howard Coleman threads. Most of those turbos are older tech, but scaling those for double the engine I figured was helpful for ballparking.

it’s too late to send back now so we’ll see how it works eventually haha. Always happy to hear people’s thoughts on it though.

 

Also, here is a G47/G50 compare from Garrett.

https://www.garrettmotion.com/knowle...turbochargers/

unfortunately, it was not really helpful for me when picking between the two. I gravitated toward the larger turbine of the G50. Then when looking at the compressors I felt like I wouldn’t need the larger 88/120 wheel. So that left me with the 80/109.

but the G47 series has the same exact compressor wheels. So going back to look at the G47 turbine chart not being that much less than the G50, I started thinking about the larger compressor wheel to get the wider islands at the lower pressure ratio section. But then I was like, well if I’m doing the bigger comp wheel, might as well do that with the G50 to get the benefit of the larger turbine. But then I flopped on that because I was already ok with the limitation of the smaller comp wheel. So ended up with the large turbine with smaller comp wheel.

at the end of the day, it would be cool to test both as well as a G55, but like all the other turbo comparison threads, it will just never happen haha. I’m sure I will enjoy this if I ever finish it. I just won’t know if I could have done something that spooled better but had essentially no top end downside. But I’m ok with it.

Long rambling explanation, but that was my train of thought on the whole thing in case you are curious.

 

in terms of compressor flow vs boost pressure along with efficiency, the G47 seemed more applicable for a 20B. Tial has a 1.45 A/R G47 housing as well.

was just curious …
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Yeah no worries. I really don't understand why the G47 and G50 both exist given they have the same compressor wheel options and the turbine side does not seem to be all that much better flowing on the G50

 

because the exact same compressor will output a different map result based on the turbine assembly it’s paired with. It’s not just the compressor, but the two working together.

generally speaking, when I see a tall, narrow compressor map result I’m generally thinking really high boost piston engine application is all. Mostly because super high boost rotary applications are rare.

none of this is criticism though. I was genuinely interested in the thought process and given your goal the results should be readily achievable.
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Started on the intake manifold. Have a ways to go still but slowly shaping up.

Once the LIM is welded together, elbows will be welded to the top of the runners to curve over the engine and go into a plenum similar to a plazmaman/hypertune style 2jz plenum with a DbW throttle body coming to the front of the car.


LIMs from Xcessive who made this possible, instead of re-melting their defected pieces they were kind enough to cut me a deal on some pieces with only the block face machined. I was originally going to use stock LIMs but got lucky here. The top flanges will be cut off, and the injectors will be machined later so that they will all be in the same plane. Luckily, because I’m using pieces, I was able to cut off the parts that had major flaws. There are still some issues, like if you look at the intermediate port the casting didn’t fully form , but easily weldable and can grind it down.

Mocking up the layout using a gasket. Luckily once you drill out the rivets holding the gasket together, you get 3 metal gaskets ready for cutting and taping. Then transferred it to my heat sync manifold welding block so I can bolt the pieces down when welding them together.

Used my trusty sawzall for the rough cuts. Still need to do some trimming and will grind it down on the belt sander to get the ports lined up perfect between the 3 pieces before welding.

Rough cuts done. Left everything a little long, as it’s easier to grind away a little material vs add it back if you go too short.

Example of trimming needed.

It’s long. Will be resurfaced flat after welding it.


Will cut the flange off to make it lower, then elbows like this will be added on.

Example of how much will get cut off the top of the LIM and where the elbow will go. Just enough clearance for the secondary fuel rail.

Drilling the holes, trying to keep it straight on the deeper ones. Worked better than I expected.

Finished drilling the holes on each piece. Tested them against the gasket and a block with studs in it. Came out pretty good.

Example of plenum. Hoping I can find a place that will sell me one before they finish welding runners on. But if not, a cheap one from eBay will do and I’ll cut them off. I measured the head of a 2jz, and it’s actually about the same length as a 4 rotor, so it will work out well, just 8 smaller runners instead of the 6.

 

I was planning on a similar UIM for a 13B. My thought was to cut an elbow in half on the centerline for the inner and outer radius end pieces, with the same size pipe or tube also cut in half to go from the TB plate to the far end split elbow piece, and then use that as the pattern for the top and bottom pieces in sheet metal.

I could probably sketch it out if the explanation isn’t clear.
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I think you mean like this? I’m not opposed to it but just thinking with the work required to make it look nice, likely makes sense to get one already done and then add to it (assuming dimensions are what I need).





what I’d love is something like this, dual plenum for cosworth engines, but I can’t find anything similar that is as long as a 4 rotor needs to be. I tossed around the idea of doing 2, one for primaries and one for secondaries (with longer runners), but then tuning and running 2 throttle bodies is more complex than I’d like. And space is a big issue already.

 

I love this thread as I never really know exactly what is going on, yet it is always something awesome.

Super entertaining, nice work!

 

Thanks. I think you framed it up nicely, I often don't know what's going on myself. Just having fun and learning new stuff. Too many projects leads to nothing getting finished is the downside though haha.

 

I knew about the Jenvey turbo plenum, but the initial inlet section has to be above or below the main plenum rather than straight in. That’s generally a fitment issue.

So I found this pic to demonstrate how to fabricate it, except we want it with a single TB inlet rather than the dual inlet shown



.


so I was looking at starting with 3” Sch 40 Aluminum pipe & elbows, which is 3.5” OD x 0.216” wall thickness (78mm ID). You might need 4” Sch 40 though, which is 4.5” OD (102mm ID)

So with a single inlet you have the inside radius half-pipe of the elbow at the TB plate, with the straight half-pipe outer piece starting at the TB plate matched up to the inner elbow half pipe piece, and then the taper/length required establishes the TB plate angle, with the outer radius elbow half pipe piece trimmed to fit the taper of the straight half pipe piece at the far end. Then the open center area can be traced out for the flat sheet pattern for cutting the top and bottom pieces.

if it were me, I’d bevel all the joint edges for laying near flat welds with full penetration, then grind it all down smooth and uniform, then either polish or bead blast it to look like it was cast. Some people might prefer the welded look though.

the thing to consider is the typical plazmaman plenum is going to be $1200+ USD, against what it takes to fab & weld your own. Even those Jenvey plenums are going to be near $1000 once finished out.

There are easier ways to do it if you don’t object to having curved but flat end pieces rather than rounded half pipe style. It likely has no real influence on how the plenum functions, but is more an appearance factor.
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Yeah. That is really nice. Agree with you on grinding the welds and then blasting it for the finish. I can't weld good enough to make it pretty anyway. Now let's get into plenum volume and runner length, I feel like packaging/space will dictate most of it in my case though.

 

Turbo arrived. Unfortunately the compressor housing is larger than I anticipated… will see where to fit this thing.

 

Wow I love the fabrication work and being able to repurpose stuff that is so cool man I respect that so much.

 

back to the SSM BNR twins car. Some parts came in so I figured I’d keep getting the long block assembled so I can finally get the engine out of the middle of the garage. The work below due to the Xcessive LIM not allowing the OEM twins oil and coolant feed lines to work. You can heat and bend them, but I was worried about them cracking. So hardlines it is. CNF / cunifer tubing (corrosion resistant but easy to bend vs stainless), and stainless fittings.







Turbosmart oil filter. Did this because the pressure is better from the rear and maybe makes front bearing oiling better. Downside is the filter block has ports that are pre-filter, so needed to add the filter in. RaceOnly is coming out with a filter block that has a post filter port, but it’s not out yet.

I’m out of practice, but getting the hang of it back. Has been 10 years since I did hardlines.



Of course I didn’t think to remove the nipples until after it was all assembled, at the time of putting on the water pump and housing, I didn’t realize I’d be doing my own lines.

Came out without much trouble. Need to get some 1/4”NPT to -6AN fittings.

 

Also got turbo mounts for the EFR twins car and 4 rotor car. These bolt to the oil drain flange of the turbo. The turbo drain then connects to this. These have flanges on the ends to weld a pipe/tube brace to and then attach the brace to the engine block (or tube frame of the car if engine is rigid mounted but mine is not). This will relieve some of the stress on the manifold and prevent cracking.



Every part should come wrapped in a beer coozie

O-ring groove for sealing to turbo side oil drain

 

the one advantage of V-band turbine fitting is the clearance provided over a square/rectangular flange

cunifer tubing is awesome for pretty much anything; brakes, coolant, fuel, etc.

so much win here.
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Thanks. I love the vbands, really a key part of what makes the efr twins possible. I don't think I'd ever go back to normal flanges unless there was a real sizing availability issue.

I really love working with the cunifer tube. I used stainless and aluminum previously, this is just so nice to work with. This is good practice for the efr twin plumbing, those turbos sit in a much more visible position, so hopefully the coolant and oil lines turn out nice on it.

 

Got the last coolant line done. I don’t love it, but it’ll do. Will need to do some adjusting to the heat shields, but I think the hard part is done. Will need to give the block a flush before hooking up the lines permanently though.


Tapped the top and bottom coolant ports. Ended up using the lower.

 

now pull all those cunifer lines off and buff polish them out.
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Sequential twin turbo manifold is now complete. Cross over pipe, EGT, and emap bungs all welded in.

it’s a bit of a tight fit. There is a little interference on the wastegate arm of the primary turbo and the secondary turbos inlet pipe. I can rotate the secondary turbo toward the fender to create space , but then the housing inlet vband hits the strut tower. I think I can get away with shaving some material off of the wastegate actuator connector. For now this is good and I can start on the cold side piping.

can’t start on the downpipe yet as I’m waiting for the turblown LIM to come out which has more clearance on the front runner where I need it.


Final welding.

First install after welding. Still fits.





OEM LIM, I was going to use xcessive but the font runner sits forward and out, which leaves no room for the primary downpipe

Turblown LIM which is getting pretty close to production. Will give me plenty of room for the downpipe. 1/2” really counts here.


Here you can see the interference point I need to address. I think there is enough material to just shave the little arm that holds the actuator bar. And it shows where the vband clamp hits the strut tower. So need to rotate it toward the engine after I clearance the actuator.

 

This is really cool!
What's the plan to pre-spool the second turbo prior to transition? Slowly open the valve in the manifold while venting the secondary compressor? The OEM system feeds the secondary turbo with the exhaust gasses that bypass the primary wheel during precontrol.

 

Its quite fun to think about all the different ways that could be controlled. My head was spinning when I first saw the mockup!

Looks like that straight gate could serve a few functions (including prespool/precontrol), but I'm looking forward to the cold side plumbing myself.

I've been wondering if an OEM strategy is best or if some sort of compound setup would be feasible. Primary turbo with a small air/water cooler feeding secondary could be pretty simple and effective, but there are lots of options. I'm sure TC has put a bit more thought into it than myself though. I'm watching eagerly

 

Thanks. For the controls and valves, the electronic valve allows me to reduce the 4 OEM controls to 3. Since the e-gate is variable, it can be turbo control and pre spool all in one. I'll start with doing a PID table which opens at RPM x boost. Could also to emap or turbo speed. This will be a bit of trial and error. For example, open 10% then ramp it up to fully open quickly.

On the cold side, there is charge relief and charge control. I have a small Bosch DBW throttle body which will go right after the secondary compressor outlet. Then a Y pipe where the 2 compressor pipes join. This will also be variable based on a PID table.

Charge relief is something I'm still guessing at. Turbosmart makes an electronic blow off valve that runs on PWM. They said as long as I'm not constantly taxing it, it can probably vent enough air during the brief secondary transition. I'd actually like to simplify and see if the charge control valve can control two functions. e.g. if the secondary turbo is in pre-spool and primary is already ramped up, can I crack the charge control valve open a bit to let the charge releif into the main cold side piping. Or, will this result in air from the primary turbo rushing in against the pre spooling secondary and cause issues. I think the exhaust side would have more energy than the cold side and avoid spinning backwards, but idk if this tension could result in turbo seal issues.

Would sure be nice to only need 2 valves in total.

 

I think compounding would actually work well. It seems like it's a little more common these days, but I've really found it difficult to find resources on the specifics related to sizing the turbos properly, which turbo goes first and why, etc. every time I see a picture of a compound setup I try to trace where all the pipes are going haha.