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If you’re looking to up your engine size then this handy calculator will determine your engine displacement depending on the stroke of crankshaft and the bore of the barrels and pistons.
Engine total displacement is calculated by this calculation:
Bore x Bore x Stroke x 0.0031416
The bore of the engine is the size of the pistons. The larger the diameter the piston the more cubic capacity (cc’s) it has. A 1300cc to 1600cc crankcase can fit up to an 87mm Piston without the need for any machining. Any larger than this will require your crankcase to be machined.
1200cc – 77mm
1300cc – 77mm
1500cc – 83mm
1600cc – 85.5mm
If you want to install Big Bore Barrels and Pistons onto your engine then you will need to machine your crankcase and cylinder heads to a larger bore in order to install them.
If you have a 1300cc , 1500cc or 1600cc crankcase then you can install slip in Barrels and Pistons without any machining required to the crankcase.
87mm and 88mm Slip In – 90mm Bore in Crankcase – 93.8mm Bore in Cylinder Head
90.5mm and 92mm Machine In – 96mm Bore in Crankcase – 98mm Bore in Cylinder Head
94mm Machine In – 97.25mm Bore in Crankcase – 101.1mm Bore in Cylinder Head
The measurement of the centre of the crankshaft to the centre of the connecting rod is called the ‘throw’. Multiply this number by two and it will give you the stroke of the engine.
A 1200cc engine uses a 64mm stroke crankshaft. All other Type 1 engine sizes use a 69mm stroke crankshaft as standard.
Longer stroke crankshafts are used to increase the engine displacement. When the stroke is longer, more torque is developed at lower RPM but the issue with larger strokes is a reduction in top end RPM. Maximum stroke in an Aircooled VW crankcase is 84mm (any larger would not fit in the case) this does not cause an issue. So the larger the stroke the better!
Hopefully this information has helped you to calculate your engine displacement. If however you are still unsure then please do not hesitate to contact us. You can email us at firstname.lastname@example.org, Facebook Message us or call our shop on 01322 335050