Stainless has a lower tensile strength than regular bolts. At least that's what I read in a stainless steel bolt catalog I have. The catalog is several years old, so maybe they have come up with newer better alloys by now. For high strength applications, I would tend to use what the manufacturer used or better. I wouldn't use any Chinese crapola. I bought a grinder stand from sears, and had to replace every fastener with American made bolts. The bolts that came with it were so bad that the head wasn't even centered with the bolt shank! YIKES! They broke like soft butter when you tried to tighten them. Same thing on an engine stand, same thing on my cherry picker, etc... Maybe see what ARP offers. Motor mounts, i'd be iffy and very careful about what you put in. Fastnal has a good selection, if you have one near you - but they sell Chinese stuff also.
