What is the hot piston for a modified A14 street, canyon motor? Doesn't have to be a factory piston, I'm perfectly happy to spend a little more if an aftermarket piston will outperform. I'm building a replacement for my tired A14. I'm using an H89 head and I'm aiming for 10 to 10.5:1 Compression ratio. Any thoughts?

For 10.5:1 use a flat-top, which means after-market. Custom order from Arias.

Thanks DD,
What is the Bore Diameter of the A14 block and Piston? Also, how far out can the A14 be safely bored? Plus, will I need to pocket the pistons or the block? I suppose it depends on the cam and rocker ratio. What is the standard rocker ratio?

A14 bore: 76 mm
A14 limit: 79 mm. use sonic testing before boring

Do not need to cut pocket in the block, but need shallow reliefs in the pistons.

Stock rocker ratio is 1.44:1

Is sonic testing a common machine shop practice? What are we looking for in terms of results? At 78 or 79mm, what is the resulting displacement?

Yes. The Nissan competion manual says this about the orginal A12 block: "Cylinder wall thickness should be checked by sonic testing when increasing initial bore size in excess of 1 mm/.03937 in."

They only sold A14 pistons in 0.5 or 1mm oversize, so they didn't go in excess of 1 mm.

The A12A block I hear can usually go to 78mm with no problems.

1607 cc is commonly gotten from A15 blocks by a combination of 79mm (over)bore and the stock 82 mm stroke.

Quote:
This is surely basic high school maths.
Cylinder volume is calculated by using the following formula. Use millimeters as this is the standard that was used when the engine was designed.

R squared x Pi x L [x number of cylinders if you want whole of engine displacement] divided by 1000.

Use a scientific calculator to get the correct value of Pi.
R= Radius [Half of the diameter of the bore]
L= The length of the stroke of the crankshaft

This will give you the displacement in cubic millimetres, so divide by 1000 to get cubic centimetres.
Too easy.

Hey, I'm an artist not an engineer... Who needs math? Actually, I'm sure I can handle that formula, but I'm out of town and don't have access to a manual. What is the stroke for an A14 crank? Also, at 78 or 79mm what is done for a head gasket?

76mm Bore & 77mm stroke = 1397cc [Standard A14]
78mm bore & 77mm stroke = 1471cc
79mm bore & 77mm stroke = 1509cc