Monty’s Single Turbo -> Back to Twins (Compound)

[VMCB5S4]

Thank you for the detailed response. I'm tracking so far and looking forward to what you find after testing.


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[Monty23]

I planned the intercooler piping last night and should have it all built this weekend. I think it's going to work great. Due to packaging constraints, I can't use all 3" IC piping like I wanted to. So, I will need to use 2.5" (BW372SXE compressor outlet is 2.5" anyways) from the big to the small turbo. Then I'll run 3" piping from the small turbo to the IC and the TB. I am also going back to blow thru MAF since I just am not going to have the room on the inlet of the big guy.

Stay tuned

[Monty23]

New intercooler piping done. Using my old treadstone tr1035 intercooler for now to get the new hardware sorted.

[Monty23]

Hot parts have been dropped off to be ceramic coated locally. I hope to have them back in ~2 weeks and we can get the first start!
During this time, I need to adjust the fuel line routing, make some new oil feed/return lines for the turbos, and update the engine harness.

We are getting close now

[Monty23]

Here is a system diagram I created to help with understanding how this all should work. LMK if you have questions.



Edit, updated this diagram to show how this wastegate plumbing will allow for additive boost, rather than multiplying the PRs. This will help me push the big turbo into a more favorable location on the compressor map at higher boost.

This post explains the boost control scheme: https://www.yellowbullet.com/threads...1/post-3681284

[VMCB5S4]

I see the direction air will flow. I'm uncertain of how the large turbo pushing air through the small turbo inlet will be efficient?


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[Monty23]

Good question. This is where most people go "that dog ain't gonna hunt".

Turbo compressor efficiency is calculated base on differential pressure (which simply means outlet pressure - inlet pressure = differential pressure). As you saw in my previous posts, I am running the PT6062 @ PR=2. PTE does not have compressor maps for their turbos, but the Garrett GT3582r compressor/turbine inducer/exducer dimensions are very similar and people in the past swore PTE stole Garrett's design so hopefully, this compressor map is in the ballpark. Look at the efficiency zone at PR=2 (my starting point -> I'll test up to 3.0 for experimental purposes). The mass flow (LBS/min) is not going to be correct on that map because the air is going to be much denser at 15psig inlet/ 30psig outlet vs. 0psig inlet/ 15psig outlet (this is what the map would have been created for). So I can't tell exactly where I will be efficiency-wise, but I do know from my research that both turbos will only need about half to 2/3s the shaft speed to make 1000whp vs. just the big guy on his own which would need to be completely strung out. Also, since the small turbo is effectively making my engine larger displacement, the big turbo will spool up much faster in this configuration vs. the big guy alone. I will be testing all these assumptions soon enough, this is a giant experiment

Check you this old thread: https://www.yellowbullet.com/threads.../216811?page=1



Looks like I'll need a PR of 3.0 to make the 1000whp I am targeting with the s372sxe as the LP turbo.
So I will probably need to step up to a much larger turbo like an S480 that can flow much more at a lower PR so my intake manifold pressure doesn't end up at 80psi... but that's way down the road.



Check out this video for some real results (pay attention to the 3:30 mark):

[VMCB5S4]

I'm actually understanding this for the most part. The video was very helpful as well. Thank you for explaining too. This is great for reliability as you run both turbos at less speed and create less back pressure in the process. Looking at the charts, the S480 does make sense. I couldn't imagine our intake manifolds being able to withstand anywhere near 80psi. I guess you would need a custom manifold like seen in the video for higher than 40-50psi. I have no clue though.

I did notice they mentioned having a turbine speed sensor is critical so you can bounce that speed off of the compressor map in order to run both turbos efficiently and using boost is difficult for accurate settings. Do you have plans to add sensors in the future or will wastegate settings and psi readings be fine for your setup?

This whole build is awesome btw. Keep up the great work!


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[Monty23]

I'm planning to monitor egts, intake temps (both inlet and outlet of the small turbo) and exhaust back pressure in the up pipe to the small turbo.

[mikeb17]

Not to be the downer, but I did the whole welded block and compound thing and it lasted around 100 miles. The compound worked amazing, the welded block actually did more harm than good. I’m pretty sure it made things worse…

[Monty23]

How much power/torque was it at?

I'm in this deep, so I'll just see what happens. And if it doesn't work out, I'll resize everything for k03 spool and a measly 800whp

[e30bum]

It’s nice to see people doing different things with the turbo configurations. I followed your lead with installing a two post lift, now it looks like I’ll be learning welding too haha.

[Monty23]

It’s nice to see people doing different things with the turbo configurations. I followed your lead with installing a two post lift, now it looks like I’ll be learning welding too haha.

A lift and welding skills are a complete game changer. They unlock so many possibilities. If you want to fab, do yourself a favor and get a Bauer (harbor freight) deep cut portaband and a SWAG benchtop table for it. Then you can make perfect cuts on tubing and such. Also, pick up a medium-sized belt sander so you can make all your joints have a perfect fit-up. Any gaps in your joints make welding 1000x harder until you have expert control over your weld pool and filler. Good luck man.

[e30bum]

Thanks for the tips! I’ll check those out. Hopefully we see some records broken with your car 👍

[mikeb17]

How much power/torque was it at?

I'm in this deep, so I'll just see what happens. And if it doesn't work out, I'll resize everything for k03 spool and a measly 800whp

Hard to say because it before I owned my dyno. There’s also windage issues when you weld the ports shut. I was squeezing 20 psi out of the g42-1450 totaling 38 psi. This was with two GTX2860s as the high pressure turbos. Not sure what your tuning with, but I got my setup working decently well. I’m happy to share any information. If you tune it on a dyno, just try and keep torque at 700 or below. Any more than that and you’re risking things regardless of welded block / girdle.

[Imho]

i was just thinking the same how the block will handle such setup... I recently found crack on my block (supported by girdle) it made 7k km with ~1000nm of torque (2xgtx2867r g2)

[Monty23]

i was just thinking the same how the block will handle such setup... I recently found crack on my block (supported by girdle) it made 7k km with ~1000nm of torque (2xgtx2867r g2)

The assumption was the welded block and girdle would be enough. Still TBD...

Sorry for your loss. Which girdle?

[Imho]

yeah I am a bit sorry too but luckily i spotted before final catastrophe so I can save internals, girdle was something custom.. made locally - now i will move to THE-tuner plate + billet mains hopefully it can hold

[q_dubz]

shhheeesssh!

[Silverex]

Not to be the downer, but I did the whole welded block and compound thing and it lasted around 100 miles. The compound worked amazing, the welded block actually did more harm than good. I’m pretty sure it made things worse…

Can you explain why you think it made matters worse?

[CELison]

I would imagine there needs to be a very small amount ductility in the block. Maybe welding the windows moves that flex point to somewhere more likely to cause catastrophic damage.

[Monty23]

I used a high nickel rod to ensure the weld area remains "more flexible" than the grey cast iron. We'll see if it works.

[Silverex]

My main concern would be making sure the mainline is still true. So a line bore would need to be done which isn’t the most common or easiest operation to do well.
I’ve thought about having the hole machined for threads so a plug could be screwed in which could have holes in it to help with the windage issues.

[Monty23]

No line of sight for a drill or tap. The holes that need to be plugged aren't very round either.

[CELison]

We racing in the spring? I need the hit lol.

[Monty23]

We racing in the spring? I need the hit lol.

I just picked up my coated exhaust parts today, so I'm trying to get her running this weekend
And I am still using my old bottom end (just rods), so I won't be making any crazy power just yet.

[CELison]

I'm trying to have Blake finish tuning in the next couple weeks. The only thing that can throw a wrench in it is the local station switching to winter blend E.

[Monty23]

I'm trying to have Blake finish tuning in the next couple weeks. The only thing that can throw a wrench in it is the local station switching to winter blend E.

You should really have winter blend E70 tune too, just a slight tweak to fueling is all that's needed between e70 and e85 IMO. These cars are just too much fun in 40-degree weather.

[CELison]

Yeah, I just don't really drive it in the winter. But it is fun on summer tires when it's that cold doing 2nd gear rolling burnouts. NT05s on RPF1s currently on the car.

[Monty23]

Added some Heat Shield Armor to the important areas.

[Silverex]

No line of sight for a drill or tap. The holes that need to be plugged aren't very round either.

Yea it would have to be done a CNC with the right tooling to machine the hole to size and threaded. It would not be an easy tap/die deal.

Exhaust looks great!!

[Monty23]

Downpipe and wastegate plumbing is ready, so I can finally put her back in where she belongs!
When I drop it back in I just need to tie the downpipe into my 3.5" exhaust and recirc the wastegate.
Getting really close now boys and girls...

[Monty23]

Just sitting there waiting... I think this will be the weekend.

[Monty23]

Looks like I can fit an intake!





Hope to have the car on the road in the next few days so I can make the All Audi GTG meet this Saturday.

[CELison]

What's this sat? The Europaparts thing?

[Monty23]

After fighting with no fuel on the passenger side bank, I finally figured out that #1 and #2 fuel injectors weren't spraying any fuel at idle/startup. Little cleaning and she runs. Now to put her back together for a maiden voyage!

https://youtube.com/shorts/roTcNpDoS7w

[oasis]

Awesome!

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[Monty23]

[Monty23]

Ok so I made a little goof up with installing this B6 A4 3.0 trans in my car. I saw it had a plastic plug instead of the VSS sensor, so I just swapped my VSS over to this trans. When I went to drive it I wasn't getting a speed signal. Then I discovered Audi didn't put the VSS tone ring in these trans, so I had to get the car in the air, pull pass axle and diff flange on the trans to swap it in. Not a huge deal though.

The VSS pickup (tone ring) is this ring below, item #16 in the diagram.



B6 3.0 has no tone ring



And the b5 s4 VSS tone ring that went in. The Bentley recommends pulling the seal and digging the tone ring out of the axle cup hole in the diff flange. I was worried about marring sealing surfaces and pulling the diff flange was simple. And since it is o ring sealed, no need to replacec any gaskets (just gear oil).







And, here's how she is sitting. I am getting a little oil in my IC piping from my BW S372sxe, so I ordered a turbosmart oil pressure regulator to keep constant oil pressure at 40 psi. I have read it helps on other platforms and I saw Levi used this reg when running his S372 as well.
One of the issues is that I could only fit a -10an oil drain easily without pulling and modifying my upper oil pan, so hopefully, this will let me get by. If not, -12an return line it will be...

[CELison]

Guessing you don't want to run a scavenge pump?