making engine work with no chassis harness possible?
 

i was just curious
can i use just engine harness/trans harness
in a shell and wire up a relay for fuel pump
ignition and power for ecu?
and just run a power to the battery from alt for charge?

no grounds?

providing you know what wire on the engine harness need powering up.

yes grounds.
just to pinout grounds on ecu

Yes. You will also likely need to wire in a dummy light for the alternator to work depending on what motor you are using.

Just curious to why you need to wire a dummy light for the alternator? Is it to see if the alternator is charging the battery? I'm currently doing electrical on my track car so just making sure I'm not missing any important info.

Would you happen to have a link of a thread that's covers what you need to power on your engine harness/ECU? I did a lot of research but I want to make sure I wired the ECU correctly before I fire up my SR.

In the dash there is usually a bulb on older cars like pre-02 ish. One side of the bulb gets 12v switched power. the other side goes to the alternator plug. When the alternator is turning making a/c power the bulb stays off because the diode trio prevents a/c current from entering that wire that leads to the bulb. When the diodes in the alternator go bad, the bulb will light because a/c current looks like a ground to 12v, thus completing the 12v circuit.

In many applications this wire acts to 'sense' the voltage supplied to the bulb, in order to determine charging voltage. Without a 12v source with a resistor as a bulb provides (or just a resistor I guess) the alternator may not charge correctly. Some computers directly control alternator voltage through this wire, so a 'dummy bulb' can be used in those applications to bypass using the computer to control alternator voltage. Maybe someone could elaborate on the field wire now...