Butler Performance • Pontiac Tech
389 Compression Calculator
Static compression ratio & displacement for the Pontiac 389 block. Enter your build below — results update instantly.
Static Compression Ratio
10.2 : 1
Total Displacement
389 ci
Per-Cylinder Volume Breakdown
Swept volume796.3 cc
Chamber volume72.0 cc
Deck volume0.0 cc
Gasket volume8.5 cc
Piston volume+6.0 cc
Total clearance volume86.5 cc
8-cylinder Pontiac V8. This is a static (geometric) compression ratio for build planning. cc your actual heads and confirm deck height after machining. Questions on your combo? Ask a Butler Tech ›
389 Block — Cubic Inch Reference
| Bore | 3.75 | 4.00 | 4.21 | 4.25 |
|---|---|---|---|---|
| Stock 4.062 | 389 | 415 | 436 | 441 |
| +.030 4.092 | 395 | 421 | 443 | 447 |
| +.040 4.102 | 396 | 423 | 445 | 449 |
| +.060 4.122 | 400 | 427 | 449 | 454 |
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Dial in your compression with the right pistons, gaskets, and a matched rotating assembly.
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389 Compression Calculator
| Bore: (diameter) | ||
| Stroke: | ||
| Cylinder Head Volume: | ||
| Effective Dome Volume: Butler Ross Flat Top -8cc |
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| Deck Clearance: | ||
| Compressed Gasket Thickness: .040 is standard thickness | ||
| Number of Cylinders: | ||
| Compression Ratio : | ||
| Total Displacement (in.3) : | ||
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| 389 Block | Stroke | |||||
| Bore | 3.75 | 4.00 | 4.21 | 4.25 | 4.50 | |
| Stock | 4.062 | 389 | 415 | 441 | 467 | |
| +.030 | 4.092 | 395 | 421 | 447 | 473 | |
| +.040 | 4.102 | 396 | 423 | 449 | 476 | |
| +.060 | 4.122 | 400 | 427 | 454 | 480 | |