Be sure to get the correct engine parts for your classic VW with this engine size calculator.

If you're looking to find what deck height you would need for a 1776cc engine and you want the compression ratio to be 8:1, and you know your cylinder heads have a combustion chamber volume of 58cc, enter the following numbers into the appropriate box: Cylinder Bore= 90.5 mm, Crankshaft Stroke= 69 mm, Combustion Chamber volume in CCs= 58 and the compression ratio you want= 8.

Then click on the Deck Height button below and the deck height you would want will be calculated - 0.033". You'll then know where you can set your deck height to achieve your desired compression ratio.

Engine Calculator

MM / Inches
Measurement
Cylinder Bore
   
Crankshaft Stroke
   
Deck Height
   
Combustion Chamber CC's
Engine Compression Ratio:
Cylinders
Engine Displacement:

Solve for which:


Note: VW would round engines up to the nearest 100cc. Example: 1192cc 36hp Engine would be refered to as a 1200cc engine.


Unit Converter:

Enter Values in MM or Inches box below to convert values.

MM
Inches
Fraction

Definitions:

Cylinder Bore

The cylinder bore measurement is the distance across the inside diameter of the cylinder. A 1600cc engine has an 85.5mm cylinder. A 1776cc engine has a 90.5mm cylinder, and 1835cc engine has a 92mm cylinder and a 1915cc engine has a 94mm cylinder.

VW Cylinder Bore Diameter

Crankshaft Stroke

The crankshaft stroke is the distance from the centerline of the crankshaft to the centerline of the rod journals, then multiplied by 2. A 1600cc engine has a 69mm stroke crankshaft. We offer the stock 69mm crank as well as 74, 76, 78, 82 & 84mm crankshafts.

VW Crankshaft Stroke

Deck Height

Deck Height is the measurement from the top of the piston to the top of the cylinder. Aircooled VW engines must have zero deck height or more. The piston can't stick out past the edge of the cylinder, otherwise the piston will hit the cylinder head. Cylinder shims can be used to increase the deck height to raise or lower the compression. We offer cylinder shims for 85.5, 90.5, 92 and 94mm cylinders.

VW Deck Height

Combustion Chamber CC's

The combustion chamber CC volume is a key figure needed to correctly set the compression ratio. We offer a head CC measuring kit which makes measuring the volume of the combustion chamber easier.

VW Combustion Chamber CC's

Engine Compression Ratio

The compression ratio is the calculation of how much volume is in the cylinder when the piston is at BDC (bottom dead center) compared to the volume in the cylinder when the piston is at TDC (top dead center). Type 1 engines from the factory typically had 7.5:1, Type 2 engines normally dished pistons to increase the volume and lower the compression to 7.2:1. For more performance oriented engines, we aim for about 8.5 to 1. Keep in mind, higher the compression ratios mean more heat along with the performance gains. High octane fuel is recommended for all air cooled VWs regardless of the compression ratio.

VW Compression Ratio Example

Engine Displacement

The engine displacement is the combined total of the volume of all the volume that all the pistons in the engine move in their respective cylinders. Both the bore and the stroke make up this volume. A stock 1600cc engine actually displaces 1585ccs, VW rounded up. A 4 cylinder engine with 88mm pistons and a 74mm crankshaft would displace 1800ccs.

DECK VOLUME TABLE

Deck Height Piston Size Deck Height in CC's
85.5mm 87mm 88mm 90.5mm 92mm 94mm
.030" 4.36 4.51 4.62 4.88 5.04 5.27
.035" 5.16 5.34 5.47 5.78 5.97 6.24
.040" 5.79 6 6.13 6.49 6.71 7
.045" 6.71 6.54 7.11 7.52 7.77 8.11
.050" 7.28 6.95 7.72 8.16 8.43 8.8
.055" 8.03 8.31 8.51 9 9.3 9.71
.060" 8.72 9.03 9.24 9.77 10.09 10.54
.065" 9.46 9.8 10.03 10.6 10.96 11.44
.070" 10.15 10.51 10.75 11.37 11.76 12.27
.075" 10.9 11.28 11.55 12.21 12.62 13.17
.080" 11.64 12.06 12.34 13.05 13.48 14.08
.085" 12.33 12.77 13.06 13.82 14.28 14.91