piston to bore clerance
#6
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My guy at Wiseco told me .0030-.0035 on my 85mm 2618 forgings for street/slight race turbo use. He said the big boost honda or roadrace guys run .0045".
My machinist f'ed up and my worst cylinder is .0047. Clankadee-clank! My engine isn't running yet but I'm sure it will be llloouudddddd. The skirts are coated and the pins are offset .030", hopefully that helps some. I plan to rebuild it next winter anyway.
My machinist f'ed up and my worst cylinder is .0047. Clankadee-clank! My engine isn't running yet but I'm sure it will be llloouudddddd. The skirts are coated and the pins are offset .030", hopefully that helps some. I plan to rebuild it next winter anyway.
#8
What the piston manufacture wants for skirt clearance is machined in the skirt.
Take your Std bore and add the over bore
Working with a 1.8l BP-ZE block 94-98
Std Bore is 3.268 or 83mm
3.268 + .040 (1mm)= 3.308
Now measure the skirt 90* from the wrist pin
You should be 3.3045-3.305
That will give you .003-.0035 piston to wall clearance.
Now some "fine" adjustment can be made from this spec, to better suit your needs in your build.
Going an extra .0005-.001 will not kill your engine, nor should you hear piston slap
Get the P2W a bit too much and your knock sensor may pick up some untill the engine warms and expantion of the piston starts.
Take your Std bore and add the over bore
Working with a 1.8l BP-ZE block 94-98
Std Bore is 3.268 or 83mm
3.268 + .040 (1mm)= 3.308
Now measure the skirt 90* from the wrist pin
You should be 3.3045-3.305
That will give you .003-.0035 piston to wall clearance.
Now some "fine" adjustment can be made from this spec, to better suit your needs in your build.
Going an extra .0005-.001 will not kill your engine, nor should you hear piston slap
Get the P2W a bit too much and your knock sensor may pick up some untill the engine warms and expantion of the piston starts.
#11
My guy at Wiseco told me .0030-.0035 on my 85mm 2618 forgings for street/slight race turbo use. He said the big boost honda or roadrace guys run .0045".
My machinist f'ed up and my worst cylinder is .0047. Clankadee-clank! My engine isn't running yet but I'm sure it will be llloouudddddd. The skirts are coated and the pins are offset .030", hopefully that helps some. I plan to rebuild it next winter anyway.
My machinist f'ed up and my worst cylinder is .0047. Clankadee-clank! My engine isn't running yet but I'm sure it will be llloouudddddd. The skirts are coated and the pins are offset .030", hopefully that helps some. I plan to rebuild it next winter anyway.
Doubt .0002 will give piston slap.
Keep in mind a sheet of note book paper is .003 thick, so .0002 is 1/15 the thickness of a sheet of nootebook paper.
Most rod or cramk tolerance from max to min is appox .0007 or about 1/4 the thickness of a sheet of notebook paper.
I have seen engines with .008-.010 wear in them and not slap.
#13
Last engine I heard run that had piston slap, was built by a first time guy.
When he brought it to me, and I tore it apart, I found a .030 over block with Std bore pistons and .030 rings. A new box of .030 pistons and a light hone and he was good to go.
There is no black magic to building an engine, some clearances are rather sloppy.
Now the ECU... thats all balck magic voodoo on the way it works.....
When he brought it to me, and I tore it apart, I found a .030 over block with Std bore pistons and .030 rings. A new box of .030 pistons and a light hone and he was good to go.
There is no black magic to building an engine, some clearances are rather sloppy.
Now the ECU... thats all balck magic voodoo on the way it works.....
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