A20A3 Diamond Pistons Order Specs

These specs were posted by "bobafett" of the 3geez.com forums. These specs are for custom low compression pistons for the A20 engine. The pistons ran one guy about $660 with rings.

These specs are for reference only for a future boost build up.

Custom Piston Specs: Job # 22507
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Bore: 3.307" (remember, this is +.050 overbore)
Compression Height: 1.167
Effective Volume: -11.9
Intake Valve Depth: .125
Exhaust Valve Depth: .077
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Top Ring: 1.2M
2nd Ring: 1.2M
Oil Ring: 2.8M
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Lock Ring Decription: SPIROLOX DBL
Lock Ring Part Number: #01-5000
Wrist Pin Diameter: .827"
Wrist Pin Length: 2.500"
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Piston Weight: 328 Grams
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Note: Install these pistons with .0040 clearance measured 90 degrees to the pin hole @ .850"

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Custom Piston Information: (These are the numbers that were sent to Diamond for them to make my pistons)
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Finished Bore Size: 3.307" (big)
Stroke: 3.583"
Rod Length: 5.394"
Compression Distance: 1.167"
Block Deck Height: 8.352"
Desired Piston to Deck: 0
Piston Type: Dish
Ring Groove Info:
Top: 1.2mm
2nd: 1.2mm
Oil: 2.8mm
Radial Widths:
Top: .125"
2nd: .144"
Oil: .105"
Support Rail: Yes - 019012276
Rings With Order: Yes
Part Number: CR-3794 (STD)
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Wrist Pin Info:
Diameter: .827"
Length: 2.500"
Pins With Order: 4130 (std)
Wall Thickness of Pin: .145
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Pin Lock Type:
Double Spiral: .042"
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Other Order Info:
Quantity: 4
Engine Type: Honda
Application: Street/Strip
Desired Compression Ratio: 8.5:1
Cylinder Head: 12v A20A
Casting #: PJ0 / HF7
Chamber Volume: 47.6cc
Comp. Gasket: .050"
Gasket Bore Dia.: 3.340"
Known Gasket Volume: 7.1cc
Rod Info:
Material: Steel
Small End Width: .785"
Thickness Above Pin: .203"
Piston Material: 2618
Skirt Shape: Ribbed Side Relief
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Misc Engine Information:
Approx Engine Only HP: 150
Combined HP: 350
Power Adder Information:
Type: Turbo
Pressure Max: 20 psi
Fuel Type: Gasoline
Octane Rating: 91 Minimum
Notes: .180 Crown Min. Brushed Rod.
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Compression Ratio Calculator Results:
Number of Cylinders: 4
Bore: 3.3070"
Stroke: 3.5830"
Rod Length: 5.3940"
Gasket Bore: 3.340"
Comp. Gasket: .050"
Block Deck Height: 8.3520"
Top Ring Down: 0.210" ------ 20PSI Boost
Chamber Volume: 47.6
Dome(-) Dish(+): 12.00"
Piston / Deck: 0.000"
Calculated Values:
Total Volume: 571.78
Cylinder Volume: 504.32
Clearance Volume: 67.45
Gasket Volume: 7.18
Top Ring Volume: 0.68
Deck Volume: 0.00
Piston Top Land: 3.269
1/2 Stroke: 1.792
Comp Height: 1.167
Cubic Inches: 123.10
Compression Ratio: 8.48:1
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Base Engine Inputs:
Bore: 3.3073"
Stroke: 3.583"
Cylinders: 4
Rod Length: 5.394"
Deck Height: 8.3582"

Chamber / Piston Inputs:
Chamber CC's In Head: 47.6
Piston Design: Flat Top w/valve relief (i have dished pistons, they probably don't need this for their calculations to work)
Valve Reliefs: 12cc's
Gasket Thickness: .050"
Gasket Bore Diameter: 3.340"
Deck Height Clearance: 0.00"
Piston Ring Depth: 0.21"
Piston Top OD: 3.236"
Compression Height: 1.173"

Calculated Results:
Cylinder Size: 30.78 cubic inches / 504.5 cc's / 0.505 liters
Engine Size: 123.12 cubic inches / 2018 cc's / 2.018 liters
Chamber Size: 4.15 cubic inches / 68 cc's / 0.068 liters
Compression Ratio: 8:41
Bore/Stroke Ratio: .923
Rod/Stroke Ratio: 1.505

Volume Contributions:
Head Chamber: 2.904 cubic inches / 47.6 cc's / 70% of total
Gasket: 0.438 cubic inches / 7.18 cc's / 10.6% of total
Deck: 0 / 0 / 0
Valve Reliefs: 0.732 cubic inches / 12 cc's / 17.6% of total
Piston OD: 0.077 cubic inches / 1.26 cc's / 1.9% of total