The rule supposedly is that you want a friction hitch to be 3mm smaller than the diameter of rope you are trying to grab and to use 3 wraps. We did a bunch of tests and here are the numbers:

4MM PARACORD:
*Prusik 3.74kN
*Klemheist 3.34kN
*Auto Block 3 wraps slips at 1.34kN, 4 wraps slips at 5.32kn
*Paracord doubled twice 8.90kN
*Paracord in a loop 4.06kN

5MM ACCESSORY CORD:
*Prusik 8.16kN and 5.36kn
*Klemheist 7kNish Slips and locked off and broke at 11.62kN
*Auto Block: 3 wraps 0.36kN Slips / 4 wraps 3.62kn Slips

7MM ACCESSORY CORD:
*Prusik 7.9kN and 5.18kN
*Klemheist 3.3kN Slips
*Auto Block: 4 wraps 0.8kN Slips

HOLLOW BLOCK 14KN MBS:
*Prusik 5.84kn
*Auto Block: 3 wraps 0.42kN Slips / 4 wraps 1.38kn Slips

Learn and SHOP at https://www.hownot2.com/shop
Best EMAILS on Earth: https://www.hownot2.com/signup
SUPPORT US and get gear discounts https://hownot2.com/support
10% off ROCKY TALKIE by clicking https://www.hownot2.com/rocky

00:00 What are friction Hitches
03:37 4MM Tests
05:08 5MM Tests
07:29 7MM Tests
08:53 10mm on 10mm Test
09:50 Hollow Block
10:53 Conclusion