Alright im new to these forums as im mostly active in some nissan forums. I'm building a (go ahead and laugh) 1993 nissan 240sx with a gen 1 355 swap in progress.

right now im modding the oil pan to fit with the stock crossmember. im just wondering how to determine the capacity of my new pan. i know the formulas for volume, but how far up in the oil pan does the oil accually sit when it is full?

thanks alot for any help,
chris  

Put in a 1" plug in the oil pan at crank level.  Just fill the engine up but make sure to keep the oil below crank travel.  The more oil the better.  I don't agree with this, but there are many racers running stock SBC pans with 7.5 qts in them.  Also, the 1" plug in the oil pan will give you a great inspection point to look in the engine.  Fill it up and drain it out.  Then you know what you put in.  It's crude, but it gets the job done.  

The more oil the better? Surely not! Depending on the application, the added oil volume may not be worth drastic losses in high-end power.  

If your oil level stays below the crank at all times, it doesen't matter if there is one qt in the pan or 3 or 6.  Every pan is different.  But if you keep it below the crank it has no affect whatsoever on performance.  This is not my opinion, it is fact.  When you loose performance because of oil, it is because the cam, crank, rods, ect are slinging the oil around creating falsely added rotating mass.  

In a wet-sump oil does not stay below the crank well at all regardless of if there is 1 or 3 quarts in the pan.  

The only time the oil will stay off the crank is when it is not running. Especially in an over filled oil pan. The rotating assembly creates alot of turbulance and splashes oil up into the crank. It is a fact that it does rob power, CHP proved this in one of their mag issues a couple months back. This is why they make windage trays. Also, where is this extra oil going to go when you launch? To the back of the oil pan and up into the crank.