Great, I am glad someone else is doing the bigger diesels now. I did the 160 around 7 years ago and was running the st 2500s 3250s and a 4500 having a blast! If you search way back you should find some info, I remember running a 26-8 off my 3W 85cc twin.it was way more then it could take but if I remember i think around 4000 rpm. A 24 would be her max even a 23", but still you cannot beat the torque. Brian ps I also did a asp 80 4 stroke and flew the plane for a couple of years on the same diesel fuel as the rest. Testing is most rewarding- sometimes-