Brian Crower

Honda K20A3/K24A

A USDM only production engine, the K20A3 and similar cylinder head configurations were developed for a performance, yet economical mindset. Although VTEC, it is only featured on the intake camshaft. The K20A3 is found in the 01-03 Civic Si while the K24A1 is in the 01-03 CR-V. The K24A4 is the most popular of them all due to the fact that was used to service the 03-up Accord as well as the 02-03 Element. Because of it's tall deck height (9.114"), the trend will be to take these blocks and use the K20A/K20Z head found in the 06-up Civic, 01-06 RSX-S for more rpm potential and added tuning ability. However there will be plenty of tuners wanting to stay true and run the original K20A3 head.

Stage	Description	Cam #	Adv. Dur.	Dur @ .050	Lift (in)	Lift (mm)	Kit #
	Forced Induction/NA Street Specification Short duration profile builds cylinder pressure by reducing overlap, high lift for more air intake. Requires kit BC0050.	BC0051	284°/284°	193°/193°	.410"/.410"	10.41/10.41	BC0050 or BC0040
	Normally Aspirated Specification Hot street/strip or road race specification. Use with CAI, H, E, ECU, A/F mods. Excellent street manners. Requires kit BC0050.	BC0052	296°/284°	206°/193°	.429"/.410"	10.89/10.41	BC0050 or BC0040
	USDM K20A3 (Base RSX/Civic)	Stock	270°/276°	181°/173°	.372"/.383"	9.45/9.73
	USDM K24A (Accord/CR-V)	Stock	270°/276°	181°/173°	.372"/.383"	9.45/9.73

Rocker Ratio: 1.75:1 mid, 1.7:1 sec, 1.7:1 pri
No valve timing events due to variable intake cam.

VALVE SPRING/RETAINER KIT
Designed for high rpm, BC valve springs are wound from only the highest grade, super clean, chrome silicone alloy and feature proprietary processing procedures for consistent pressures. BC retainers and spring seats are CNC machined from 6AL4V titanium to exacting tolerances. Use steel retainer for high mileage applications.

Kit #	Spring #	Retainer #	Seat #	Description
BC0050	BC1050	BC2050	No Seat	Single spring, titanium retainer
BC0040	BC1040	BC2010	BC2904	Dual spring, titanium retainer/seat
BC0040S	BC1040	BC2011	BC2904	Dual spring, steel retainer/seat

Spring Pressure:
BC1050 Seat: 1.567" @ 78 lbs / Open: 1.100" @ 206 lbs / Coil Bind: 0.972" (no machine work required)
BC1040 Seat: 1.580" @ 84 lbs / Open: 1.100" @ 250 lbs / Coil Bind: 1.030" (no machine work required)

STAINLESS STEEL VALVES
BC valves are made from premium stainless steel, fully machined and swirl polished for ultimate air flow. Dished head for added weight savings and increased valve control at high rpm. Standard and oversize head.

Part #	Description #
BC3040	35.0mm Intake (standard head diameter)
BC3041	30.0mm Exhaust (standard head diameter)
BC3042	35.5mm Intake (+.5mm head diameter)
BC3043	30.5mm Exhaust (+.5mm head diameter)
BC3044	36.0mm Intake (+1mm head diameter)
BC3045	31.0mm Exhaust (+1mm head diameter)

K20A3 2.35L/K24A 2.60L STROKER KIT

• BC 4340 billet steel crankshaft (102mm stroke K24 / 92mm stroke K20).
• BC 4340 Pro Series custom steel billet rods w/ARP2000 bolts (.935" BE width).
• CP aluminum forged pistons (any bore size, any compression ratio).
• 5100 Series carbon steel alloy wrist pins. 9310 pin upgrade available.
• Ductile iron plasma top rings, tapered second ring, low tension oil rings.
• High strength ACL Race Series bearings included.
• Fully system balanced and ready to install.

Kit #	Crank #	Rod #	Piston #	Bearing #	Desc.
BC0044	BC5048	BC6058	BC7048	BC4020	92mm w/LW rods
BC0045	BC5048	BC6048	BC7048	BC4020	92mm w/heavy duty rods
BC0048	BC5049	BC6059	BC7049	BC4020	102mm w/LW rod
BC0049	BC5049	BC6049	BC7049	BC4020	102mm w/heavy duty rods

The BC stroker kit for the Honda/Acura K Series engine platform incorporates the wider B16A bearing (.935" width) that offers more surface area than the .740" width bearing found in the OEM K Series crank and rod combination. The added surface area increases bearing life, especially at extended rpm. Note: This kit requires custom rods (BE bore and BE width).

Stock Specifications:
K20A3 86mm Bore x 86mm Stroke - 8.350" Block Height
K24A 87mm Bore x 99mm Stroke - 9.114" Block Height

 

 

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