Does the kilowatt rating of a starter indicate anything about the torque or quality of the starter?

Question

I have been shopping for a starter for a John Deere Gator. The OEM starter is 0.9KW. There are several aftermarket starters that replace the OEM part number. The advertised kilowatts vary from 1 KW to 1.4 KW. This is about the only data that I have to compare the starters, although some of them also specify weight. All of these starters appear to be direct drive rather than gear reduction, so I think they all work the same way.

Answer 1

Torque? Probably.

Quality? Anybody's guess.

Power demand? Definitely.

I think you'll want to stay close to 0.9KW when you choose a new starter, and 1KW is close. Manufacturers don't spend money on parts that are more robust than necessary to get the job done with a defined safety margin. Your Gator's battery, battery cables and starter relay are designed to work well and have a reasonable life with a 0.9KW starter, which likewise performs well enough to start the engine.

If you replaced your starter with one that consumes 2-3 KW, it would no doubt start the engine like gangbusters, but it would shorten the life of the battery, overheat the cables and potentially ruin the contact points on the starter relay in short order. The undervoltage from a too-weak battery pushing too many amps through too-skinny cables could also shorten the life of the unnecessarily big starter.

A 1.4KW starter probably won't have an immediate negative impact, but it will wear out the battery and starter relay quicker than a 1KW. If your OEM starter has always been good enough to start the engine reliably, there's no reason to go much bigger.