some engine that they didn't have knock limit?

Can you give some engine that you didn't find a knock limit? So to have it on our mind?

One with low compression, or using high octane fuel. You can optimize the timing (for maximum torque) without regard to a knock limit.

Whether an engine is knock limited will depend greatly on the fuel you have access to so it's not really that easy to just produce a list for you. An engine that's not knock limited here in NZ on our local 98 octane fuel may well be knock limited on a lower grade fuel.