AMTuned will be closed for holiday Dec 20th - Jan 3rd. Orders placed during this time will ship out after our holiday closure.

Audi S4 B6 B7 4.2L 40V BHF BBK Engine Rebuild Program

Regular price $10,499.95

The original and most trusted 4.2L 40V Chain Driven engine rebuild on the market. With nearly 100 successful rebuilds as of late 2023, we can confidently say we are a master at our craft! All of our rebuilds come with a final build sheet and many pictures of the process to keep for your records. 

As this model engine starts aging more, we have noticed that cylinder bore spec's are too often out of rebuildable range to justify a stock bore rebuild. Even bores that still have in-spec measurements (Within 0.0010" variance within a bore) are having excessive prolonged periods for ring seating due to oval bores causing multiple systems issues. Because of this, All of our stage rebuilds now include a sleeved engine block! We no longer service stock Alusil bore rebuilds. 

Customers must establish contact prior to shipping and purchase the desired engine rebuild stage in full before work begins. Shipping to or from our facility is not included. Local drop off and pick-up is available free of charge. Never shipped an engine? Let us help guide you through the process! We typically see shipping rates between $175-$500 one way within the continental United States. We do offer a 3% discount on all stage build options if customers desire to pay by check or bank-bank transfer options.

Long blocks are to be delivered to us without accessories. Accessories include: Oil Filter Housing, Water Pump & Pump Shaft, Power Steering Pump, A/C Compressor, Alternator & Bracket, Oil Cooler, Exhaust Manifolds, Engine Mounts, Knock Sensors, Intake Manifold, Coil Packs, and Cam Sensors. Spark plugs can be left in the engine, but rebuilds will not include spark plugs.

Engines must be shipped directly to our facility at the following address. Purchase and tracking needs to be completed and sent to AMTuned prior to engine arrival.


541 S Flagler Ave. Unit # A-West

Pompano Beach, FL 33060

AMTuned Engine STAGE 0:
Refreshed BHF / BBK 4.2L Long Block with 20k mile warranty on Stage 0 engine option only. TURN AROUND TIME IS ABOUT 8-12 WEEKS AFTER PASSED INSPECTION. 

  • Complete timing service utilizing the AMTuned ultimate timing kit.
  • Hydraulic roller rocket tappets are fully disassembled to free seized tappets, cleaned, and reassembled.  
  • Cylinder head refresh including cleaning and inspection. Replacement items include AMTuned upgraded solid core valve set, new guides, upgraded valve guide seals, and gaskets. Cylinder head mating surface will be skimmed to ensure optimal sealing during install. Valve seats will be cut, and assembled heads are pressure tested. 
  • Engine block refresh including cleaning & cylinder bore sleeving. Replacement items include main bearings, connecting rod bearings, piston rings, lower engine o-rings, valley pan gasket, valley pan check valves and cylinder head gaskets. Blocks with severe bore damage which cannot be reconditioned, will not pass our inspection process.


AMTuned Engine STAGE 1: Rated for up to 600whp & 7200 rpm. Turn around time is about 5 - 6 weeks. Turn around time is about 8-12 weeks after inspection. All items in Stage 0 package with the addition of:

  • AMTuned 4340 forged H-Beam with tapered end connecting rod package.


AMTuned Engine Stage 1+: Rated for up to 600whp & 8000 rpm for those looking to push higher boost. Turn around time is about 8-12 weeks after inspection. All items in Stage 0 package with the addition of:

  • AMTuned 4340 forged H-Beam with tapered end connecting rod package.
  • AMTuned Upgraded HD Valve spring package.


AMTuned Engine STAGE 2: Rated for 1000+whp & 8000rpm. Turn around time is about 10-14 weeks. All items in Stage 0 package with the addition of:

  • Sleeved engine block
  • Balanced rotating assembly
  • AMTuned design JE Pistons w/93 series pins
  • AMTuned 4340 Saenz Performance Connecting Rods
  • Supertech 1mm Oversize Upgraded Valves
  • Supertech valve spring kit with titanium retainers.
  • ARP head studs

We are the only company in the world utilizing our proprietary block prep service prior to machining the block. This in-house developed service allows us to run a factory bore size and not cheat by using a smaller OD sleeve and a tiny piston. This results in engines that are more powerful with factory displacement over the competition. Our service removes the risk of the vapor ports between the bores cracking behind the sleeves and leaking coolant down into the crankcase. Below is a picture of a block that did not have our block prep service. We removed the sleeves to find cracked coolant passages between the bores and visible signs of coolant entering the crankcase.