Originally Posted By Stanton
I just thinned it and sprayed it without activator. It still dried rock hard and is holding up fine.

Hmmm, I tried that with Omni and a month later it was still tacky !!

I use PPG Omni single stage for all the parts you describe - engine, trans, suspension, etc.. I prime with epoxy primer. I do all this stuff with either of the two cheapo Harbor Freight guns. Cleanup is the worst part.

Parts that are not prone to seeing any damage are done with rattle cans, seat brackets, pedal mechanisms, etc.

you don't HAVE to use catalyst in ACRYLIC enamel. it will dry but it won't be as durable or hold a high gloss shine without catalyst.
you HAVE to use a catalyst in URETHANE enamel.
these are both single stage paints from PPG omni.
omni type MAE acrylic enamel you can get away without catalyst.
onmi MTK acrylic urethane enamel you HAVE to use catalyst.

I think its Omni MTX now. Anyway, it definitely wasn't MAE.

I personally don't care for powder coat at all. It serves no purpose on parts that see no wear and tear and on parts that do it can't be touched up or easily redone when the parts do get chipped, scratched or scuffed. And while color selection is broad, it isn't as broad as paint and many powder coaters carry a limited range - you want something they don't have and you buy the whole box of powder. And I can paint a ton of parts for a fraction of powder coat costs.