Well that's odd, my jumper says it's rated for 4 & 6 cylinder motors.. seems to the jumper mfgr. cylinder motors do make a difference.
It is a reference value. It is a value so that the “common” consumer has an idea “more or less”, if what he is about to buy…is going to work for him.
It is to be assumed that a common consumer will be driving a 4 or 6 cylinder car with between 1500 cm3 and 4000cm3...
An "industrial type" consumer, who is driving a 6 cylinder truck/machine... with 12000 or 14000cm3, that aforementioned bracket barely turned on the dash lights.
The size of the starter motor is proportional to the size of the motor that it has to start….the same happens with the starter clamps…the “copper inside” diameter should be in relation to the power of the starter motor.
A lithium jumper starter battery fulfills exactly the same function as a “capacitor” in an electric motor….it is the initial “kick”….But…everything is related to everything, so if the initial kick “permanently” is much greater than what the bushings/bearings of the electric motor were designed for…..there will be premature wear…(in electric motors, the greatest wear occurs during start-up)