Replacing LS1 with 5.3
The spark in the trucks is very conservative because a truck engine needs to be able to pull the GVWR of the truck and trailer up a hill, possibly at full throttle, possibly for extended periods of time, whereas a car would almost never be at full throttle just to get up a hill...cars see far far far less sustained full throttle time...trucks get weighted down with heavy payloads and trailers and whatnot all the time.
I would NOT advocate running the car spark tables with the 5.3...I would re-tune the 5.3's spark tables...but I'd do so carefully after I had the engine running successfully using it's original tables. There will most certainly be more power and more mpg in the 5.3 with tuning work above and beyond it's stock tune.
The spark in the trucks is very conservative because a truck engine needs to be able to pull the GVWR of the truck and trailer up a hill, possibly at full throttle, possibly for extended periods of time, whereas a car would almost never be at full throttle just to get up a hill...cars see far far far less sustained full throttle time...trucks get weighted down with heavy payloads and trailers and whatnot all the time.
......
... trucks are calibrated for cheapo 87 octane and F-bods/Vettes/GTOs/etc are cal'd for premium fuel.




