: Over-sized Northstar Pistons



AJxtcman
01-30-08, 09:18 PM
I have a few listings for pistons.
This is a stock replacement type piston manufacturers listing.
http://i224.photobucket.com/albums/dd25/AJxtcman/Northstar/96to99.jpg

http://i224.photobucket.com/albums/dd25/AJxtcman/Northstar/00to02.jpg

Submariner409
01-30-08, 09:39 PM
Very curious. The oil rings are different widths on the two pistons, but the same p/n applies. The older pistons also have a larger wrist pin diameter, making it necessary to change rods if you want to go up 0.22 in compression points, and they are .006" taller (compression difference) which might lead to quench interference, and the older specs for oversize infer that you can bore the liner, or is that factory sizing specs? Strange, because a .050 oversize is a few c.i. in a 280 base displacement.

The two are really not interchangeable.....and the specs mean that there's no oversize for '00-'03.

med
01-31-08, 01:05 PM
Are those oversize numbers over in mm or inches? I assume mm. My FSM says something like overbore 0.050mm to a max diameter of 87.5mm:cookoo:<--which makes no sense to me. Can someone clarify as I' m sure I'm mistaken. Didn't someone overbore on a Fiero N* with Ross custom pistons like 1mm or something? <--What came of it.

AJxtcman
01-31-08, 03:00 PM
Didn't someone overbore on a Fiero N* with Ross custom pistons like 1mm or something? <--What came of it.


Not running yet

93.5mm is the max bore listed in the original training manual from 1993. I will have to look in the 99 information.

AJxtcman
01-31-08, 03:09 PM
3.66" stock = 4565 CC's or 278 C.I.:histeric:
3.6811" max = 4614 CC's or 281 C.I.:hmm: