ACF Twin Scroll Bottom Mount kit hits the dyno

doublespaces

General of the Army
Oct 18, 2016
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2009 E93 335i
The previous thread on this kit is here: https://bmw.spoolstreet.com/threads/acf-fabrication-t4-twinscroll-manifold.2181/

Here is a clip from n54tech:
Hi guys, Payam finally got his car back together last week and sorted out the usual various gremlins that come from an eBay motor swap. So we took the opportunity today to do a little dyno testing with it. The setup is: 1) Stock junker motor 2) ACF twin scroll bottom mount kit, running a relatively small EFR turbo. Payam tells me its roughly equivalent to a PTE 6266. They put an 8psi WG spring on it as a starting point. 3) Fuel IT Stage4 fuel system, 100% E85, random China intake manifold. 4) All the rest of the usual suspects for bolt ons. 5) Tuned via JB4 using off the shelf software, settings, and back end flash map. Surprisingly virtually no actual tuning work was needed to get this thing up and running pretty well. Default port injection settings too. JB4 is doing all the work on that front in the back end as you toggle through different boost profiles. 6) No antilag used, 4th gear runs, ~75f temps, etc. Anyway we took the car through it's paces on the dyno. I found the lowest and highest maps the most interesting. On the WG spring at around 8psi it made ~400whp. Then on the other end with the WG spring completely maxed out (WGDC close to 100%), it put down an impressive ~740whp. Anthony and Payam were both at the dyno with me and there was some debate between us as to whether the spring is maxed or the turbo itself. Hopefully we settle that soon. Under real world load the car spools and drives really nicely, and no doubt if someone cared to optimize the tuning to the more aggressive side of things there is power and spool to be had. Personally I'm just finally glad this car is done so Anthony can start working on our white car's bottom mount turbo kit. :lol

Its good to see the car is up and running, I'm a big fan of the bottom mount. Space was really the main issue but it looks like they've figured it out.

The turbo kit is made by ACFabrication and equiped with the EFR 8374 1.05 Divided housing T4 Bottom mount. I have an 8psi spring as I plan on tracking this car as well on the circuit. It made a nice linear power band with a flat torque curve on that setting. Turned up to max the torque wow, just pushes you so far down into your seat. I got the best of both worlds with this setup.
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doublespaces

General of the Army
Oct 18, 2016
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AZ
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2009 E93 335i
Here was a post by @[email protected]
Got Payam's car back on the dyno today with a 12psi WG spring and a new version of the EOS intake manifold. We were hoping to eek a little more power out up top and did but at the slightly higher boost levels we had a lot more timing instability.

We also accidentally did a 35psi midrange run (duty bias wasn't adjusted for tighter spring)... Hello 800wtq+ on a stock motor!

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LoBoost

Corporal
Dec 22, 2017
242
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2008 135i, 2014 GTR
Anyone have pics of a completed manifold? Curious about the wastegate and dump tube positioning. In the thread linked in the first post I didn’t see an external wastegate or dump tube. I can kinda see it a little bit on the blue car, but it’s hard to make out.