Monty23
Member
Hi all,
My name is Justin. This is my first post in this forum and I plan to have many related to my Goblin project that will be quite unique from the standard powertrain perspective. I am a gearhead-racer-adrenaline junkie at heart and a family guy and mechanical engineer by day. I have owned this 2001 Audi S4 (AKA B5 S4 by the Audi Community) for the past 11 years and it has gone through a few different transformations. The most wild was the compound turbo kit that I built and installed last fall/winter and that is what I am planning to share here. For those of you not familiar, these cars are AWD and about 3600 lbs.
If interested, the complete build thread is here and page 1 has a nice index:
Monty’s Single Turbo -> Back to Twins (Compound)
Videos:
Tuning/Logging -
Friends reaction -
Racemotive Pocono Event -
Performance:
Racemotive Pocono PA - 148mph in the 1/3 mile race event
Draggy result:
Highlights of the build:
1) Planning the compound setup
My goal was to make more power than my existing 700whp setup without losing any response.
I chose a PTE PT5858 BB with a .64AR hotside as my high-pressure turbo and a BW S372SXE as my low-pressure turbo.
Total manifold boost pressure = pressure ratio of turbo 1 multiplied by pressure ratio of turbo 2. See https://takemebeyondthehorizon.wordp...ressure-ratio/ to learn more about pressure ratios if you are interested.
So, with the small turbo at 16psi and big turbo at 6 psi:
Small turbo PR = (16psig + 14.7psia) / (14.7psia) = 2.09
Big turbo PR = (6psig + 14.7psia) / (14.7psia) = 1.41
Total manifold boost = 2.09 * 1.41 = 2.95 * 14.7 = 43.4psia - 14.7 = 28.7 pisg
And with the small turbo at 16psi and big turbo at 16 psi:
Small turbo PR = (16psig + 14.7psia) / (14.7psia) = 2.09
Big turbo PR = (16psig + 14.7psia) / (14.7psia) = 2.09
Total manifold boost = 2.09 * 2.09 = 4.368 * 14.7 = 64.2psia - 14.7 = 49.5 pisg
2) Packaging - Cutting and Welding
I taught myself how to TIG weld during this process. I used a Chinese AHP201 tig welder and 304 stainless tubing for the hotside. I used standard intercooler tubing kits from ebay for the coldside plumbing.
This story will mostly be told with photos
Old engine out:
Removing the secondary firewall to make "so much room for activities"
Spare Engine/Trans to build the new setup
Turbo(s) mounted in the best possible location to minimize hotside dead volume.
Building the hotside and making it all fit and not rub anything it should was fun
Back-purged all my welds
1st Test fit
Doesn't quite clear my steering rack
Cut and fixed - sharpie line was where the flex joint was when hitting my steering rack
My name is Justin. This is my first post in this forum and I plan to have many related to my Goblin project that will be quite unique from the standard powertrain perspective. I am a gearhead-racer-adrenaline junkie at heart and a family guy and mechanical engineer by day. I have owned this 2001 Audi S4 (AKA B5 S4 by the Audi Community) for the past 11 years and it has gone through a few different transformations. The most wild was the compound turbo kit that I built and installed last fall/winter and that is what I am planning to share here. For those of you not familiar, these cars are AWD and about 3600 lbs.
If interested, the complete build thread is here and page 1 has a nice index:
Monty’s Single Turbo -> Back to Twins (Compound)
Videos:
Tuning/Logging -
Performance:
Racemotive Pocono PA - 148mph in the 1/3 mile race event
Draggy result:
Highlights of the build:
1) Planning the compound setup
My goal was to make more power than my existing 700whp setup without losing any response.
I chose a PTE PT5858 BB with a .64AR hotside as my high-pressure turbo and a BW S372SXE as my low-pressure turbo.
Total manifold boost pressure = pressure ratio of turbo 1 multiplied by pressure ratio of turbo 2. See https://takemebeyondthehorizon.wordp...ressure-ratio/ to learn more about pressure ratios if you are interested.
So, with the small turbo at 16psi and big turbo at 6 psi:
Small turbo PR = (16psig + 14.7psia) / (14.7psia) = 2.09
Big turbo PR = (6psig + 14.7psia) / (14.7psia) = 1.41
Total manifold boost = 2.09 * 1.41 = 2.95 * 14.7 = 43.4psia - 14.7 = 28.7 pisg
And with the small turbo at 16psi and big turbo at 16 psi:
Small turbo PR = (16psig + 14.7psia) / (14.7psia) = 2.09
Big turbo PR = (16psig + 14.7psia) / (14.7psia) = 2.09
Total manifold boost = 2.09 * 2.09 = 4.368 * 14.7 = 64.2psia - 14.7 = 49.5 pisg
2) Packaging - Cutting and Welding
I taught myself how to TIG weld during this process. I used a Chinese AHP201 tig welder and 304 stainless tubing for the hotside. I used standard intercooler tubing kits from ebay for the coldside plumbing.
This story will mostly be told with photos
Old engine out:
Removing the secondary firewall to make "so much room for activities"
Spare Engine/Trans to build the new setup
Turbo(s) mounted in the best possible location to minimize hotside dead volume.
Building the hotside and making it all fit and not rub anything it should was fun
Back-purged all my welds
1st Test fit
Doesn't quite clear my steering rack
Cut and fixed - sharpie line was where the flex joint was when hitting my steering rack
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