OpenPipe: Straight-Piped Percheron 1.0

OpenPipe for the Percheron
OpenPipe swaps the Percheron's DPF/SCR box for a straight 90 mm pipe that runs from the turbo to a side exit under the left skirt. With nothing between the turbo and the open air, the 12.8L inline-six finally sounds like a big diesel.

It also adds two optional turbo sounds: a compressor surge and a Brazilian-style turbine comb whistle. Power, torque and boost are unchanged.

Sound showcase video:


Parts

• Side Exit Open Pipe (Intake > Exhaust Downpipe > Exhaust Filter): the open pipe, with its own sound and smoke.
• Modified Turbocharger (Intake): the stock turbo with two extra slots for the parts below.
• Surging Compressor (Modified Turbocharger > Compressor): a "stu-tu-tu" surge when you lift off from full boost.
• Turbine Comb (Modified Turbocharger > Turbine Outlet): a falling whistle on every lift-off and shift.

Each part works on its own, so you can run the surge or the comb with the stock exhaust. If both are fitted, only the comb plays.

Open pipe
BeamNG's engine sounds are fixed recordings, so OpenPipe retunes the stock exhaust sound instead of replacing it:

• No muffling (the stock box muffles 85%) and volume at the game's maximum
• Deeper firing pulses, straight-pipe drone, and more bark and rasp
• Stays raw at light throttle and on lift-off
• Louder engine brake, since it shares the exhaust sound
• 40% more turbo whine

Smoke follows engine load: clean at idle and cruise, smoking from about a third of full load, and heavy black smoke when you work it hard. Stab the throttle before the turbo spools and you get a thick puff. At highway speed it leaves a solid trail.

Surging Compressor
The stock turbo never surges or flutters on diesels, so this part adds it. Hold near full boost (at least 75% for over half a second), lift off, and the compressor surges in slow pulses that wind down with the turbo. The harder and longer the pull, the louder and longer the surge. It plays once per lift-off, stops when you get back on the throttle, and ignores the rev limiter.

Turbine Comb
The pente na turbina is a Brazilian truck mod: a slotted, comb-shaped plate welded into the turbo outlet that whistles as the turbo spins down. The whistle here is modelled on recordings of real trucks.

• Plays on every lift-off and shift, as long as there's some boost
• Hard pulls at high rpm give a higher, longer whistle (up to about 2.5 s); quick low-rpm shifts give a short, low one
• Pitch drops faster when revs fall quickly, like on a clutched upshift
• Works with the stock exhaust too, at about a third of the volume

Installation
Put OpenPipe.zip in %LocalAppData%\BeamNG\BeamNG.drive\current\mods without unzipping it, then fit the parts on a Percheron with the 12.8L diesel. Don't keep an unpacked copy in the mods folder as well, or the game loads it twice.


Notes

• Only for the Percheron's 12.8L inline-six diesel.
• Bug reports: open the console (~) and include any red errors, plus a list of your other enabled mods.
• This is a game mod. Removing a DPF or SCR from a real road vehicle is illegal in many countries.

Credits

• BeamNG: the surge sounds are rebuilt from the game's own turbo recordings.
• The comb whistle was measured from Melhores Roncos De Caminhões Com Pente Na Turbina #1. No audio from the video is included; the whistle is synthesized.