aFe 51-81012-B is the Magnum FORCE Stage-2 Si Pro DRY S intake with a black ABS cover for qualified BMW N52 naturally aspirated 3.0L applications. One 21-91054 filter uses three oil-free synthetic layers. Its current replacement listing gives a five-inch height and six-inch flange; the main description calls it a six-inch conical filter without separately defining that dimension. The molded tube and housing retain the original MAF and factory duct, with explicit N51/SULEV engine-test-group exclusions.
The current manufacturer identifies N52 128i E82/E88 2008-2013 and E9x 3-Series 2006-2013. The exact manual lists 2006 325i, 2006 330i, 2007-2013 328i and 2008-2013 128i; original supported xi/xDrive named bounds remain. Exact selected dry-part retailer tables positively list 2006 330Ci Base, but that entry conflicts with the manufacturer N52/E9x scope and the M54/E46 engine/chassis evidence. That one legacy group is withheld pending exact manufacturer housing reconciliation, not represented as a physical installation test. Other original bounds remain unchanged. For 328i, the manual excludes engine test groups 7BMXV03.0N51, 8BMXV03.0N51, 9BMXV03.0N51, ABMXV03.051R, BBMXV03.051R, CBMXV03.0N51R and DBMXV03.051R. The 128i exclusions are the same list starting at 8BMXV03.0N51. Match the actual emissions label; do not invent a pseudo-trim or extend to turbocharged or diesel 3-Series models.
| Years | Make | Model | Named trim; actual engine and hood requirements apply |
|---|---|---|---|
| 2008-2013 | BMW | 128i | Base |
| 2006 | BMW | 325i | Base |
| 2006 | BMW | 325xi | Base |
| 2007-2013 | BMW | 328i | Base |
| 2009-2013 | BMW | 328i xDrive | Base |
| 2007-2008 | BMW | 328xi | Base |
| 2006 | BMW | 330i | Base |
| 2006 | BMW | 330xi | Base |
Verify 51-81012-B against the actual engine, sensor and vent connections, mounting locations and applicable emissions requirements before ordering.
| Brand | aFe POWER |
| Manufacturer Part Number | 51-81012-B |
| Selected filter | 21-91054; three oil-free synthetic layers; five-inch height / six-inch flange |
| Tube / housing | 05-81012B5 / 05-81012B2; molded plastic |
| Selected cover | 05-81012B3; black ABS plastic |
| Bellows | 05-01542; 3.1-inch ID x 3-inch length |
| Coupling clamps | Two #048 03-50007; separate filter-flange clamp |
| CCV alternatives | 03-50191 brass 1/8-NPT fitting or 03-50410 brass 1/8-NPT plug |
| Fasteners | Two M4, four M6 hex and seven 5/16-inch button-head screws; lengths not specified |
| Washers / grommets | Two M6 lock, four M6 flat washers and two supplied grommets |
| Battery / torque / recheck | No battery step or numeric torque in exact manual; inspect after 100-200 miles |
| Current filter dimensions | 7.5-inch base, 5.5-inch inverted top; five-inch height |
| Quantity | Manufacturer service part | Component |
|---|---|---|
| 1 | 21-91054 | Selected oil-free Pro DRY S filter |
| 1 | 05-81012B5 | Intake tube |
| 1 | 05-81012B2 | Housing |
| 1 | 05-81012B3 | Selected black ABS cover |
| 1 | 05-01542 | Silicone bellows |
| 2 | 03-50007 | SAE #048 coupling clamps |
| 1 | 03-50191 | Brass 1/8-NPT CCV fitting |
| 1 | 03-50410 | Brass 1/8-NPT closure plug |
| 2 | 03-50490 | M4 screws; no stated length |
| 2 | 03-50071 | M6 lock washers |
| 4 | 03-50070 | M6 flat washers |
| 4 | 03-50052 | M6 hex screws; no stated length |
| 2 | 03-50033 | Housing grommets |
| 7 | 03-50259 | 5/16-inch button-head cover screws; no stated length |
Only the selected dry filter and black ABS cover are supplied; the shared oiled filter and patterned cover are alternative configurations. Retain the original dome grommet below the airbox, separately from the two supplied housing grommets. Retain the original steering-reservoir nuts and restore its bracket air line. A small gap at the NPT fitting/plug hex is normal; do not force it flush. No new MAF, steering pump, reservoir or CCV hose is itemized. The two numbered #048 clamps serve the bellows; the filter has its separately illustrated flange clamp. No carbon-fiber cover is supplied with this selected black version.
aFe Power develops application-specific intake, filtration, exhaust, cooling, tuning, suspension, drivetrain, and truck-performance components supported by product testing and documented installation requirements.
One 21-91054 Pro DRY S element with three oil-free synthetic layers, five-inch height and six-inch flange. The shared oiled filter is an alternative; do not oil the dry element.
What is the cover made from?The selected cover is vacuum-formed black ABS plastic. The patterned ABS cover belongs to the separate appearance option.
Can N51/SULEV coverage be inferred from the 328i name?No. The exact manual excludes listed N51/SULEV engine test groups. Compare the actual emissions label.
What happens to the steering reservoir?Move it for access where required, then restore it with its two original nuts and reseat the air line on its bracket.
Which grommets are retained or supplied?Retain the original dome grommet under the housing. Two separate new housing grommets are supplied.
Should the NPT fitting be forced flush?No. The exact manual identifies a normal small gap between the threaded fitting hex and tube. Use the fitting or plug appropriate to the actual CCV connection.
Why is the legacy 330Ci record withheld?Exact retailer positives conflict with the manufacturer N52/E9x scope and independent M54/E46 engine evidence. It remains a source conflict pending exact housing reconciliation, not a physical installation-test conclusion.
What torque, battery and inspection instructions apply?The exact manual gives no battery-disconnection step or numeric torque. Check bolts, clamps and connectors after 100-200 miles.
Verify aFe 51-81012-B. Read all sixteen pages and figures A-I on a cool engine. Save the two original airbox bolts, unplug MAF, release the airbox clamp and original air duct, then lift out the original airbox without losing the dome grommet. If the steering reservoir sits above the intake tube, save its two nuts, release the air line from its bracket and move the reservoir for access as illustrated. Loosen the throttle-body clamp, release any original CCV hose and remove the tube. Transfer MAF with the supplied M4 screws. Fit the 1/8-NPT CCV fitting on vehicles with that hose, or the NPT plug where absent; a small hex-to-tube gap is normal. Seat the bellows internal bead in the throttle-body groove, check it can rotate when seated, and tighten the throttle-side clamp at the external locating bead; leave the other clamp loose. Move the reservoir for clearance without fastening it yet. Fit the two supplied housing grommets, seat the housing over the original dome grommet, reconnect the air duct and secure the housing with two M6 screws and flat washers. Pass the tube through the housing top and into the bellows. Reconnect CCV where fitted and MAF. Secure the tube with the remaining two M6 screws, flat washers and lock washers, then secure the bellows clamp. Install the selected filter and flange clamp. Restore the reservoir using its two original nuts and reseat the air line on its bracket. Secure the selected cover with all seven button-head screws. No battery-disconnection step or numeric torque is given. Check bolts, clamps and connectors after 100-200 miles.
The exact current black dry primary and its shared sixteen-page manual were inspected. The newly downloaded manual and dyno image are byte-identical to the current patterned dry version already read and viewed in full, including all four contact sheets, full bill, assembly diagram and figures A-I. The selected bill explicitly identifies the black cover. This page links no airflow chart; the related patterned-cover chart actually labels oiled 54-81012-B at 241 versus stock 154 CFM, 1.5 inches H2O, approximately 56.5%, and is not a selected dry test certification. The linked dyno names earlier oiled 54-81012 with a six-inch inverted-filter note, printed July 26, 2011, comparing July 26 versus April 29 acquisitions. Both identify original exhaust and third gear. Table maxima differ by eight hp and nine lb-ft; the advertised 12 hp and 15 lb-ft maximum-point claims have no corresponding marked points or full weather/correction conditions. The earlier filter note and unspecific current six-inch conical description do not override the explicit five-inch-height/six-inch-flange service dimensions. Exact selected black dry retailer positives for 330Ci conflict with manufacturer N52/E9x scope and independent M54/E46 engine/chassis evidence. That one group and native selection are withheld pending exact housing reconciliation, not a physically tested incompatibility claim. D-550-38 is cited for some applications, but full conditions remain held after the earlier official access challenge; explicit N51/SULEV exclusions apply and blanket 50-state approval is not certified.
California Proposition 65 warning: this product can expose you to chemicals known to the State of California to cause cancer and reproductive harm.
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