If you have two torque wrenches, you can check them against one another - set both to 20lb and see which one clicks first, then up the poundage a click at a time and see when the click changes to the other wrench.
One caution. Many of the cheap torque wrenches will fail and you won't know it until you've gone way past the normal click point. When I worked on a race team we used Craftsman wrenches at first, but they would keep failing - Although Craftsman would provide them for free, free is no good if they can't be relied on... So we ended up changing out to Snap-On.