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Vehicle Info NeededUNITED ENGINE MACHINEPART NUMBER: 648-KB251.040
Chrysler 450ci Hypereutectic Pistons Step Dome Top .260"
$45392
Ships on 09/11/2026
Lowest Price GuaranteeChrysler 450ciStep Dome Top Pistons Use with Chrysler 400ci Block
- Chrysler 450ci Hypereutectic Pistons
- Step Dome Top .260''
- 4.382'' Bore (+.040'')
- Use w/6.358'' Connecting Rod & 3.750'' Crank Stroke
- Comp. Ratio: 12.9/72cc; 11.8/80cc; 11.2/85cc; 10.7/90cc
- 8/pkg
Notes: - Made from Chrysler 400ci block
- Use only stock length (6.358') connecting rods
- Suggest checking quench dome with clay for clearance
- Closed chamber heads require the quench dome to be machined down
- Compression ratio will change with quench dome machiningTechnical Specs:
- Alloy: Hypereutectic 390
- Bore: 4.382'
- Crankshaft Stroke: 3.750'
- Connecting Rod Length: 6.358'
- Deck Height: 9.980'
- Compression Height: 1.722'
- Pin Size: 1.094'
- Pin Location: Centered
- Step Dome Top: .260' 4.4cc 2V Relief
- Intake Valve Relief: 0.264' Depth / 2.360' Diameter
- Exhaust Valve Relief: 0.264' Depth / 2.360' Diameter
- Top Landing Height: 0.221'
- Ring Grooves: 5/64' Top; 5/64' Middle; 3/16' Bottom
- Gram Weight: 705/190
- Compression Ratio: 12.9:1 w/72cc Heads; 11.8:1 w/80cc Heads; 11.2:1 w/85cc Heads; 10.7:1 w/90cc Heads
100% CNC Machined Pistons
New high silicon alloys and diamond tooling have give Keith Black designers the material and equipment for performance breakthroughs in engine design. KB piston are 100% CNC machined and T-6 heat treated from 16%-18% silcon Hypereutectic alloy. Features include drilled oil returns and pin oil supply, .072'' spiral wound retaining ring, 100% diamond turned, compensated high strength ring lands, high top ring location, 360° pressure pin oiling, diamond honed pin hole and lightweight rigid rib skirt design.
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Features:
- 390 Hypereutectic alloy with 16% Silicon
- Fully machined crowns and valve reliefs
- Drilled oil drain backs
- Full floating wrist pins
- Triple wound spiral locks
- Reflective alloy allows 2% power increase
- Quench dome technology minimizes deterioration
- Zero deck quench designs
- Sold in Sets (except when noted as 1 piston per package)
Part TypePiston
Product LineUEM Pistons KB Signature Series Hypereutectic Chrysler Pistons
BrandUNITED ENGINE MACHINE
Part CategoryPerformance Parts
Vendor Part NumberKB251.040
Package Qty1
Package TypeEA
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Some parts are not legal for use in California or other states with similar laws / regulations
