What engines does the 72mm stroker crankshaft fit?
This crankshaft is designed for big-block Honda GX390-style engines and is particularly well suited to the Wildcat 460. It can also be used with Honda GX390, Predator 420, and other 88–92mm bore clone engines when the correct connecting rod, piston, and clearances are used.
What displacement does the 72mm stroke produce?
Displacement depends on the cylinder bore:
Bore | 72mm Stroke | Approx. Displacement |
88mm | 72mm | 437.91cc |
90mm | 72mm | 458.05cc |
92mm | 72mm | 478.63cc |
The 92mm bore Wildcat 460 with a 72mm stroke produces approximately 478.63cc.
Is this crankshaft recommended for the Wildcat 460?
Yes. The Wildcat 460 is our preferred platform for this crankshaft because its taller deck height provides better piston and crankshaft clearance. When combined with the appropriate flat-top piston and EC 8273 connecting rod, the assembly can achieve approximately zero deck with minimal additional machining.
Can I use this crankshaft in a Predator 420?
Yes, but it is not necessarily a drop-in installation. The Predator 420 may require a different connecting rod, piston combination, and/or machining to achieve the correct deck height and clearances.
Can I use this crankshaft in a Honda GX390?
Yes. The 72mm stroke can be used with an 88mm bore GX390 to produce approximately 437.91cc, provided the piston, connecting rod, deck height, and crankshaft clearances are properly matched.
Can I use this crankshaft with a 90mm bore?
Yes. A 90mm bore combined with a 72mm stroke produces approximately 458.05cc.
Can I use this crankshaft with a 92mm bore?
Yes. A 92mm bore and 72mm stroke produces approximately 478.63cc. This combination is particularly well suited to the Wildcat 460 platform.
What connecting rod should I use with the Wildcat 460?
For the Wildcat 460, we recommend using the EC 8273 connecting rod with the appropriate Wildcat flat-top piston. This combination is designed to provide favorable piston-to-deck geometry with the 72mm crankshaft.
Will the 72mm crankshaft give me more horsepower?
Increasing stroke increases engine displacement and crankshaft leverage. It can also increase piston speed and compression depending on the piston and rotating-assembly combination. The actual power increase depends on the complete engine combination, including the cylinder head, camshaft, compression ratio, carburetion, exhaust, ignition, and RPM range.
Will I need to modify my engine block?
Possibly. This crankshaft should not be considered a universal drop-in replacement. Depending on the engine and rotating assembly, clearance may be required around the crankshaft counterweights, connecting rod, cylinder, camshaft, or other components.
The Wildcat 460 generally provides better clearance because of its taller deck design.
Can I use the stock connecting rod?
Do not assume the stock connecting rod will provide the correct geometry. A 72mm stroke changes piston position and rotating-assembly geometry. The connecting rod must be selected based on crankpin diameter, rod length, piston compression height, deck height, and required clearances.
What should I check before assembling a 72mm stroker engine?
Always verify:
- Crankshaft journal and crankpin dimensions
- Connecting-rod compatibility
- Piston compression height
- Cylinder deck height
- Piston-to-deck clearance
- Crankshaft counterweight clearance
- Connecting-rod-to-block clearance
- Connecting-rod-to-cam clearance
- Piston-to-valve clearance
- Piston-to-head clearance
- Camshaft and compression-release clearance
Is this crankshaft suitable for racing engines?
Yes. The 72mm stroke is intended for performance and racing big-block clone applications, including high-output Wildcat, Honda GX390, and Predator-based builds. Proper balancing, clearancing, and rotating-assembly measurements are strongly recommended for high-RPM applications.
Does increasing the stroke increase piston speed?
Yes. A longer stroke increases mean and peak piston speed at the same RPM. This should be considered when selecting the connecting rod, piston, rings, camshaft, valve train, and intended operating RPM.
Is the 72mm crankshaft a direct replacement for a stock GX390 or Predator 420 crankshaft?
No. Although it is designed for GX390/420-style big-block applications, the longer stroke changes the engine's rotating geometry. Proper piston and connecting-rod selection and clearance verification are required.
What is the best engine platform for this crankshaft?
For the easiest and most practical combination, we recommend starting with the Wildcat 460 block. Its taller deck height and compatible 92mm flat-top piston make it particularly well suited to the 72mm stroke configuration.
Do I need to have the engine professionally assembled?
For a 72mm stroker combination, professional engine-building experience is strongly recommended. This is a performance rotating-assembly component, and incorrect clearances or component selection can result in serious engine damage.
