B58 Racing

Buying guide · Gleb Blekher

B58 Charge Pipe Install: Gen 1 F-Chassis vs Gen 2 G-Chassis and the GR Supra

Short answer: The B58 charge pipe runs from the turbo outlet to the throttle body. Swapping it is a top-side job on most cars: pull the intake, unclip the pipe from the turbo, unbolt it from the throttle body, move the sensors and O-rings over, and fit the new pipe. Plan on 1.5 to 3 hours and no lift. Gen 1 and Gen 2 pipes don't swap, because Gen 1 uses a 3-bolt throttle body flange and Gen 2 uses 2 bolts. Gen 1 cars are the ones that most need an aluminum pipe. On a stock-turbo Gen 2 BMW or Supra, it's optional.

I'm Gleb Blekher. I run B58 Racing out of Dallas, TX. The charge pipe is a cheap part with a lot of bad installs behind it. Most of the boost leaks people blame on the pipe come from a clip, an O-ring or a coupler. This guide uses the makers' own install instructions and what owners report on the forums.

Do you actually need a B58 charge pipe?

Start here, because a lot of people buy one they don't need.

EngineCarsFactory pipeOur take
Gen 1 (B58B30M0)M140i, M240i, 340i, 440i, plus 2017–2019 540i/740i and 2018–2019 X3/X4 M40iPlastic, 3-bolt throttle body flangeRecommended before Stage 2
Gen 2 (B58TU)M340i, M440i, G42 M240i, Z4 M40i, LCI 540i/740i/X3 M40iPlastic, 2-bolt flangeOptional on the stock turbo
GR Supra 3.0A90/A91Plastic, multi-piece, 2-bolt flangeOptional on the stock turbo
B58N (2025+ M340i/M440i)G20, G22Plastic, its own part numberDifferent pipe; ask us

The sources disagree on how often the Gen 1 pipe fails, so here's both sides:

  • do88 says the Gen 1 plastic pipe is prone to failure as it ages or as boost goes up, and that a failure can put the car in limp mode or stop it running.
  • OneFastShop calls the Gen 1 pipe a known failure point that it has seen crack and puts it on the list before Stage 2.
  • BMWTuning.co says it has heard of only a handful of B58 pipes breaking, mostly on big-turbo cars, and that the stock pipe is strong enough for a tuned car.

For Gen 2 and the Supra, the record is better. Owners on SupraMKV say the stock pipe holds up unless you add a bigger turbo, more boost or water-methanol, and several say aftermarket pipes gave them boost leaks. OneFastShop reports a SupraMKV owner who ran a big turbo at about 30 psi on track on the factory pipe.

My take: on a Gen 1 car, fit an aluminum pipe when you go to Stage 2. On Gen 2 or a Supra, buy one when you add a bigger turbo, more boost or methanol, or if you want the bungs for a boost sensor. A charge pipe doesn't add power on its own.

Read B58 Gen 1 vs Gen 2 if you're not sure which engine you have. The quickest check is to count the bolts holding the pipe to the throttle body.

Difficulty, time and whether you need a lift

  • Difficulty: 2 out of 5. Mostly clips, sensors and a few bolts. The fiddly part is seating the pipe on the turbo outlet.
  • Time: 1.5 to 3 hours. Mishimoto lists 1.5 hours for its Supra kit. An F30 owner on Bimmerpost said a Gen 1 install took about four hours the first time.
  • Lift: not needed. The CTS Turbo guides for both generations are done from the top. You may want the car on stands to see the lower end of the pipe at the turbo.
  • xDrive vs RWD: CTS shot its Gen 1 guide on a 2016 340i xDrive and says other cars follow the same steps. We found nothing that adds xDrive-specific steps.

Tools

From the CTS Turbo and Mishimoto install guides:

  • T30 Torx for the throttle body bolts on Gen 2 and the Supra (CTS, Mishimoto). On Gen 1, CTS removes three screws at the throttle body but doesn't list the bit size, so check yours before you start.
  • T25 Torx (Mishimoto, Supra)
  • 10 mm socket for the auxiliary water pump bracket nut (Mishimoto, Supra)
  • 7 mm socket for hose clamps (CTS, Supra)
  • 17 mm 12-point wrench (Mishimoto lists it for the Supra kit)
  • 1/4" ratchet and extensions
  • Pick tool for connector tabs and the spring clip
  • Flat screwdriver
  • Torque wrench (small range, inch-pounds)
  • Thread sealant if you plug unused bungs (CTS lists it as optional)
  • O-ring lube or clean engine oil for the O-rings

Parts list

Every link below fits the cars listed with it.

Gen 1 F-chassis (M140i, M240i, 340i, 440i):

Gen 1 G-chassis combos (charge pipe plus turbo inlet): G30 540i and 2018–2020 X3/X4 M40i.

Gen 2 BMW (M340i, M440i, G42 M240i, Z4 M40i) and GR Supra:

GR Supra only:

2025+ M340i/M440i (B58N): FTP Motorsport B58N charge pipe. It's a different part from the earlier pipes.

Spare coupler for FTP B58 pipes: FTP reinforced silicone hose, 2.5" to 3".

Shop all B58 charge pipes.

Step-by-step: Gen 1 F-chassis charge pipe

This follows the CTS Turbo Gen 1 guide (CTS-IT-341), shot on a 2016 340i xDrive. Your pipe's own sheet wins where it differs.

Stage 1: prep

  1. Work on a cold engine and disconnect nothing you don't need to.
  2. Check the new pipe. Make sure the throttle body flange is flat around the bolt holes. A CTS reviewer reported a weld bead that stopped a bolt head from seating. Fit plugs to any bungs you won't use.

Stage 2: removal

  1. Remove the airbox and inlet duct.
  2. Free the turbo inlet pipe. Disconnect the vacuum line, unplug the connector on the PCV hose at the side of the inlet pipe, and unclip the harness from it.
  3. Remove the PCV hose at the top of the valve cover.
  4. Remove the turbo inlet pipe. Pull up the spring clip to release it from the turbo.
  5. Unplug the MAP and air temperature sensors on the charge pipe.
  6. Remove the three screws holding the charge pipe to the throttle body.
  7. Pry the plastic retainer free at the lower end of the pipe, then lift the old pipe out.

Stage 3: install

  1. Move the MAP and air temperature sensors to the new pipe.
  2. Move the O-ring from the lower end of the stock pipe into the lower end of the new one. Lube it lightly.
  3. Push the lower pipe onto the turbo outlet first, without the spring clip. Then insert the spring clip and make sure it's fully seated.
  4. Fit the upper pipe, silicone coupler and clamps loosely.
  5. Install the three throttle body bolts first, then tighten the coupler clamps. CTS's order keeps the joint from pulling the flange crooked. Torque the clamps and bolts to the value in the instructions supplied with your part.
  6. Plug the sensors back in and refit the inlet pipe, PCV hose, vacuum line and airbox in reverse order.

Step-by-step: Gen 2 BMW and GR Supra charge pipe

This follows the CTS Turbo Gen 2 guide (CTS-IT-349) and the Mishimoto Supra guide (MMICP-SUP-20). Both are shot on a GR Supra. The BMW Gen 2 cars share the 2-bolt throttle body and the same basic layout, but the parts around them differ. Check your kit's sheet for your chassis. do88 warns the gap between the throttle body and the slam panel is tight on the G-series, and that the slam panel edge may need a few millimeters ground off for its pipe.

Stage 1: prep

  1. Engine cold. Remove the engine cover.
  2. Remove the intake (airbox and tube) from the turbo inlet.

Stage 2: removal

  1. Unclip the turbo inlet pipe and remove it (CTS).
  2. Unplug three connectors: the MAP sensor, the air temperature sensor and the auxiliary electric water pump (Mishimoto).
  3. Move the auxiliary water pump out of the way. Mishimoto removes it from its bracket (one 10 mm nut). CTS also unclips a coolant hose from the charge pipe.
  4. Release the pipe from the turbo by removing the spring clip.
  5. Unbolt the pipe from the throttle body (two T30 Torx bolts) and lift it out.

Stage 3: install

  1. Move the MAP sensor, the air temperature sensor and the throttle-body-side O-ring to the new pipe. Mishimoto supplies a new bolt for the MAP sensor.
  2. Move the turbo-side O-ring and spring clip to the new lower pipe. CTS says to remove the factory rubber seal and reinstall it in its pipe.
  3. Plug unused bungs. CTS says if you won't use its extra ports, take out the threaded inserts and refit them with thread sealant.
  4. Fit the lower pipe to the turbo and push until the clip seats.
  5. Loosely fit the upper pipe with the silicone coupler and clamps, then bolt it to the throttle body.
  6. Refit the water pump to its bracket and plug it back in.
  7. Plug in the sensors, tighten the coupler clamps, then tighten the T30 bolts. Torque to the value in the instructions supplied with your part. Make sure each clamp sits behind the bead on the pipe.
  8. Refit the turbo inlet, intake and engine cover.

After the install (both generations)

  1. Check every connection by hand. Pull on the pipe at the turbo to confirm the clip is locked, and check the throttle body bolts, coupler clamps, bung plugs and sensor connectors.
  2. Start it and listen. A hiss or whistle under boost means a leak. A SupraMKV owner's checklist for chasing a leak: the middle coupler, the clip at the turbo outlet, the throttle body screws and the sensors on the pipe.
  3. Smoke test if in doubt. It finds leaks faster than driving around.
  4. Scan for codes. Boost-deviation or underboost codes after a charge pipe install usually mean a leak or an unplugged sensor.
  5. Tune. A charge pipe on its own doesn't need a tune change. If you add water-methanol or a boost sensor to the new bungs, your tune has to support it.
  6. Recheck clamps and plugs after a week of driving.

Common mistakes and how to avoid them

  • Dry O-rings. Pushing a dry O-ring onto the turbo outlet can roll or cut it. Lube it. One SupraMKV owner's advice was simply not to force it dry.
  • Trimming or removing O-rings because the pipe won't seat. Supra owners report the OEM turbo O-ring being too thick for some aftermarket pipes. Some trimmed it, some removed a small O-ring, and one spent a summer chasing boost leaks because of it. Don't modify seals unless your pipe's maker tells you to. Call them first.
  • Spring clip not seated or clocked wrong. Listen for the click, then pull test. A SupraMKV owner says the clip's orientation can cause leaks. Replace a stretched clip.
  • Reusing a tired O-ring. OneFastShop recommends a fresh OEM O-ring at the throttle body if the kit's looks thin. A Supra owner fixed a leak by going back to the OEM O-ring.
  • Clamps on the wrong side of the bead. The clamp has to sit behind the raised lip or the coupler can blow off under boost.
  • Over-tightening clamps. do88 says cranking clamps down to stop a hose popping off can deform the pipe ends. Use your kit's torque.
  • Unused bungs left loose. Seal and snug the plugs, then check them again after a week.
  • Wrong generation. Gen 1 is 3-bolt, Gen 2 is 2-bolt. Count before you buy.

FAQ

Do I need a charge pipe on a B58?

On a Gen 1 car going to Stage 2, it's cheap insurance. On a stock-turbo Gen 2 BMW or GR Supra, it's optional. Upgrade when you add a bigger turbo, more boost or methanol.

Do Gen 1 charge pipes fit Gen 2 B58s?

No. Gen 1 uses a 3-bolt throttle body flange and Gen 2 uses a 2-bolt flange. Buy the pipe for your engine.

How long does a B58 charge pipe install take?

Usually 1.5 to 3 hours. Mishimoto quotes 1.5 hours for its Supra kit. First-timers on Gen 1 cars report up to about four hours.

Does a charge pipe need a tune?

Not by itself. You only need tune support if you use the bungs for water-methanol injection or another sensor.

Why does my new charge pipe leak boost?

Usually it's the install: an O-ring that's missing, rolled or the wrong size, a clip that isn't seated, a coupler clamp off the bead or a loose bung plug. Check those before blaming the pipe.

Is the Supra charge pipe the same as the M340i's?

They're both Gen 2 B58 with a 2-bolt throttle body, and some pipes fit both, like the FTP Gen 2 pipe and the Active Autowerke pipe. Others are Supra-only or BMW-only. Check the fitment on the listing.

For the rest of the build, see the best B58 mods, in order and the B58 downpipe install guide. Supra owners should read our A90 Supra mods guide.

Sources