Keep in mind shafts don't break at a given HP level. They break at a given point of stress. How that stress is applied will determine it's limits.
I run a billet input shaft (thanks Joe). Until this transmission, I had none. I also have never broken a shaft. (Now watch, I will today)
Depending on how you race/use your truck and how much you try to get out of each hp to the track IMO answers the question. Heavier trucks are harder on them. A 4wd launch is harder on them. Locking the converter early is harder on them. Tighter converters can be harder on them too but in some cases, easier on them.
I run a 7000 lb 2500 4x4 with 33" tires. I run 4wd, usually launch with no less than 20psi. I don't lock my converter until I reach 3rd gear, I run a stall of about 1900 rpm and it has lived so far at 550hp and high 12 second passes. With stock shafts I ran 13's, same set-up and routine except for 265's and 430-450hp. I have launched many times at 30 psi on stock shafts and not had to pay the price. Would I recommend it? No.
I bet if I started locking in 2nd gear I break one of my non billet shafts in 3 passes. If I run a tighter converter and build the same boost I'll break it too. In other words, I have decided to give up some ET for this HP level to maintain reliability.
Just something to think about.
I run a billet input shaft (thanks Joe). Until this transmission, I had none. I also have never broken a shaft. (Now watch, I will today)
Depending on how you race/use your truck and how much you try to get out of each hp to the track IMO answers the question. Heavier trucks are harder on them. A 4wd launch is harder on them. Locking the converter early is harder on them. Tighter converters can be harder on them too but in some cases, easier on them.
I run a 7000 lb 2500 4x4 with 33" tires. I run 4wd, usually launch with no less than 20psi. I don't lock my converter until I reach 3rd gear, I run a stall of about 1900 rpm and it has lived so far at 550hp and high 12 second passes. With stock shafts I ran 13's, same set-up and routine except for 265's and 430-450hp. I have launched many times at 30 psi on stock shafts and not had to pay the price. Would I recommend it? No.
I bet if I started locking in 2nd gear I break one of my non billet shafts in 3 passes. If I run a tighter converter and build the same boost I'll break it too. In other words, I have decided to give up some ET for this HP level to maintain reliability.
Just something to think about.