This guide will touch on some of the specifics required when you build an B4x engine block.
(The B4x Platform shares around ~90-100% of its engine parts with the B58 & B38, S58 part cross compatibility to be confirmed).
Required Parts and/or Procedures for forging the B4x:
- The B4x engines are made in the factory with the following: (This is taken from the BMW Technical Documentation and applies to B46, B48, B46TU, B48TU and B48A20T1).
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¶ First we have the most common and cheapest Sleeve option the "Parallel" or "Repair" Sleeve:
- The "Parallel" or "Repair" Sleeve is good for those that need to repair the block close to factory specification if re-applying the arc spraying process is not available. The problem with these sleeves on the N2x platform lies in 3 areas:
- Using these sleeves with the Athena "Cut-Ring" Head Gasket, this gasket which incorporates a "Seal Wire"/ "Fire Ring" that is free floating from the rest of the gasket is quite thick and during the head torqueing process it places an immense amount of strain on the sleeve. If the sleeve is not installed correctly then the sleeve will begin to drop during the first engine heat cycle and you end up with a blown head gasket and loss of cylinder compression. The sleeve will continue to drop until it eventually bottoms out in the block, however finding out when this will occur is time consuming and costly (It only took me 6x to find out when my sleeve would stop dropping).
- Installation Error/Sleeve Mis-match, we've seen this too many times on this platform and it needs to be addressed. Most of the "Parallel"/"Repair" Sleeves we have seen are usually a "close enough" match from another engine application such as a diesel engine that is very similar but not identical to this engine. What we have seen is engine builders choose a sleeve that has either too large of an Outer Diameter or too small of an Outer Diameter. Those that use too large of an Outer Diameter results in the machinist carelessly machining into the coolant passages between cylinders which no matter the amount of sealant the engine builder may use will allow the coolant to leak down the cylinder between the aftermarket sleeve and the OEM aluminium cylinder wall resulting in coolant mixing with oil. Those that use too small of an Outer Diameter result in the cylinder wall thickness being too thin and under high horsepower or detonation can crack the sleeve, resulting in a failed motor.
- The last issue we have seen with these types of sleeves is when used under high performance applications, the sleeve drops as they're just not fit for purpose the immense cylinder pressures cause the block to warm up and the N2x uses quite a soft aluminium composition, which once warm combined with high power will see the sleeve drop, head gasket fail and another engine rebuild.
- You might think "what if I got a really good engine builder and a custom "Parallel"/"Repair" Sleeve made" if you did manage all of this, you could still experience the issue highlighted in point 3. which is why we only recommend such a sleeve for OEM style rebuilds where the engine power won't exceed standard stage 2 OTS levels. It is also recommended that if you do use this method you ensure the right type of material the sleeve is made of will be fit for the application it is being used for so it doesn't prematurely distort or crack. If you have access to re-applying the arc spray process then we would recommend you do that over a "parallel"/"repair" sleeve as its a lot less prone to the issues highlighted above.
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¶ Flanged Sleeve this is a sturdier option and is denoted by flanged top or "hat" on the sleeve:
- The "Flanged" sleeve is very common in the BMW engine building world mostly in the 6 and 8 cylinder engines. The flanged top of the sleeve has more surface area and helps the sleeve stay seated in the block and eliminates the sleeve from dropping. The 3 issues we have seen with these types of sleeves in the N2x platform are:
- Cracked sleeves in high performance built engines, this is bound to happen if you use a sleeve that has too thin of a cylinder wall thickness. Most of the "Flanged" Sleeves we have seen are usually a "close enough" match from another engine application such as a diesel engine that is very similar but not identical to this engine or use a material not designed to handle high boosted/nitrous applications. However should you elect to run a sleeve that is quite thick in wall thickness you then run into the likelihood of machining into the coolant passages between the cylinders and allow coolant and oil to mix. The best option we can suggest here to avoid this issue if you want to use this method is to have Darton Sleeves Inc, create custom "Flanged" sleeves that allow maximum wall thickness without causing the machinist to machine into the coolant passages between each cylinder.
- The last issue is sleeve material, you want to ensure the sleeve is constructed from a robust material so it doesn't distort or crack under high horsepower applications. Darton Sleeve's flanged sleeve material has so far been tested in other engines and is yielding great results over previous "generic" flanged sleeve solutions used.
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Required OEM Replacement Bolts & Gaskets.
- These parts must be replaced when rebuilding the B4x engine as they are either "Torque to Yield" or Gaskets that should be replaced (Torque to Yield "TTY" is a bolt or fastener that once tightened into place is stretched and can no longer be reused as it will never hold or regain the same amount of tightening torque). TBC list of parts that require replacing.
Connecting Rods, "Conrods", "Rods".
- Parts are listed from "Strongest" to "Weakest" (generally Stronger/Higher HP rated parts are more expensive):
- CP Carrillo Conrod with Carr Rod Bolts
- CP Carrillo Conrod with WMC Rod Bolts
- Max Speeding Rods with ARP L19 Rod Bolts
- Max Speeding Rods with ARP2000 Rod Bolts
Forged Pistons.
- Parts are listed from "Strongest" to "Weakest" (generally Stronger/Higher HP rated parts are more expensive):
- Piston Coatings are optional and can improve the durability of the piston, but I would only recommend using them when looking into a 600+HP.
- Default piston pins are a chromoly material, however for additional cost you can upgrade these to heavy duty/steel piston pins. I recommend upgrading the pins if your goal is for the 800+HP range.
- Pistons come in 2x off the shelf sizes 82mm and 82.5mm.
- Pistons come in 3 standard compression ratios: 9.5:1, 10.0:1, 10.2:1, 10.5:1 and 11.0:1. Depending on your turbo setup I would recommend a 9.5:1 or 10.2:1 compression piston just due to the cylinder head design using 11.0:1 Compression piston will end up limiting your achievable power on gasoline. Just remember Head Gasket thickness and "decking" or resurfacing the engine block or cylinder head will increase or decrease total engine compression (thicker gasket usually = lower compression).
- Piston options (2618 forging is material used normally in top fuel engines, its an extremely robust and strong material compared to 4032 forgings):
- CP Carrillo 2618 Forging Piston.
- JE Pistons 2618 Forging.
Head Gasket Options.
- BMW OE Head Gasket (OE 11128654273) 1.0mm thick.
- OEM MLS Gasket, requires a fresh engine block and cylinder head resurface to seal correctly, with a surface finish greater than 60RA.
- BMW OE Head Gasket (OE 11128654272) 0.7mm thick.
- OEM MLS Gasket, requires a fresh engine block and cylinder head resurface to seal correctly, with a surface finish greater than 60RA.
Connecting Rod Bearings.
- Due to the different sizing's these bearings can come in, you should have your shop/builder source the correct sized bearings. However the recommended and only upgraded bearings are ACL Tri-Metal Racing Bearings whilst King Bearings offer products for the B4x, they are either OEM replacement or ACL rebranded bearings. You can get the bearings coated with a low friction coating such as a Calico Coating. If you want to have your bearings coated, it would be best to reach out to Calico separately.
Crankshaft Bearings.
- At this stage the only offerings are OEM or King Bearings, given the vast array of sizes the main bearings can come in, it is best to let your shop/builder order the correct size for your application. Again Calico Coatings can be applied to these bearings if you reach out separately to Calico. The Calico Coating is a low friction coating/film applied to the bearing.
Head Studs (Including TQ procedure).
- Currently the B58 ARP2000 and ARP CustomAge 625+ Head Studs are the go to aftermarket head stud.
- Torque procedure, follow the ARP TQ specs for your appropriate studs, however the sequence of Torque is as per the below BMW documentation.
- Once the initial head stud TQ procedure has been complete, recheck TQ after to ensure that any air pockets in the ARP lube has released - for added security if you want, rechecking the head stud TQ after a 500km break in will ensure the head studs are maintaining their final TQ spec.
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Main Studs.
- Currently BMW B58 ARP2000 can be used in the B4x.
- Torque procedure for the Main Studs is as follows:
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Auxiliary Mods/Information:
- If building a motor especially the N2x series engine, ensure you have all the correct supporting mods for your engine/turbo setup (This is more a checklist of what you may also want to consider, it is not required for building a motor):
- Upgraded Charge-pipes.
- Upgraded FMIC.
- Upgraded Intake.
- Upgraded Turbo Inlet.
- Upgraded Performance Exhaust.
- Upgraded DV Module.
- Oil Catch Can.
- Upgraded Coil Packs (If Necessary).
- Meth Injection (If Necessary).
- Upgraded HPFP Solution.
- Port Injection (If required).
- Upgraded DI Injectors to S63TU DI Injectors (OE 13647599876).
- Appropriate Spark Plugs and Gap.
- External/Aftermarket Oil Cooler Setup (look at N55 solutions) ensure you use an oil thermostat! so your engine doesn't take forever to warm up and you damage your bearings/internals etc cold oil is less vicious, meaning its more thick and can take longer to coat surfaces.
- Upgraded LPFP If Required (Not needed for anything under 450WHP based on DynoJet).
- Rotating Assembly Balancing
- Crankshaft Polishing
- Cylinder Head Porting
Cylinder Head Valve Train Specific Upgrades:
- B48/B58 Ferrea upgraded valve kit.
- B48/B58 Ferrea upgraded valve spring kit.
- B48/B58 Supertech upgraded valve kit.
- B48/B58 Supertech upgraded spring kit.
- Vac Motorsports Hardened Valvelocks