Robbie Wilson

Does anyone else wonder why an lt1 can get away with running a larger cam and still pass emissions while the ls1 is limited to only -4 degrees of overlap as a rule of thumb to pass Ca smog?

For ex. Largest cam to pass ca somg (ussually) in an ls1

224/224 114 = -4 degree's of overlap.

Le2 emissions cam for lt1

224/230 112lsa = 3 degrees of overlap?

cc503 (widely known as the biggest smog friendly cam from the 'off the shelf')

224/230 112 (is it not weird that le2 and cc503 have the exact same specs???) = 3 degrees of overlap

If we look at the gm hotcams

ls1 hot cam

218/227 112 = -1.5 degree of overlap, and known to fail smog

lt4 hot cam

218/228 112 = -1 degrees of overlap, known to pass smog in lt1

Am I missing something??? Lt1's pass smog with bigger cams. So does cam lift effect smog? Also do the lobe profiles/aggressiveness have anything to do with it? Because I am not seeing how this is possible.

Isn't it weird that the more "efficient" engine pollutes more at X amount of overlap? or is it just lower emission standards for the lt1?

edcmat-l1

iTrader: (10)

I think you answered your own question. Take a look at the emissions specs for each year. If the LT engine had to conform to the same standards as the LS does, they wouldn't pass either.