I was under the impression that our engine was a 4-cylinder (left bank, right bank, left bank, right, etc.) batch fire system, but this diagram appears to show them as a 8-cylinder batch (bulk, all 8 at once) fire system. What gives?

 

TPI systems fire all 8 simultaneously. There are seperate fuses for the two banks, and two seperate wires going to the ECM, but they tie together inside the computer and run through a single transistor. The banks are wired seperately to keep the load on the wiring down, but the ECM fires both banks at once.

 

Yeah, I always thought it was 4 at a time, but now I learn than all 8 fire at once, so 7 of them are just puddling the fuel mixture on top of the intake valves until they open. So much for a good fuel/air mixture! No wonder our TPIs make (roughly)half the power, and use double the gas of LS1s!

 

The only time you'd see fuel puddling is at idle. Otherwise, the fuel and air stay in suspension in the intake tract until the valve opens. There's not enough time between firings for it to sit and puddle.
The LS1 makes more power and gets better gas mileage compared to a TPI because the LS1 is newer more modern technology with MUCH better heads, and a much better computer. Also, the length of the TPI runners limits its ability to flow air above 5000 rpms, right where the LS1 really shines. Shorten the length of the TPI runners, and you get cars like in our SoCal club, who make 400+ horsepower and get 20+ mpg like an LS1, and still pass CA emissions tests.