crank support

At what level of boost,blower size, ect. do I need a crankshaft support on my alky BBC?

 

Just buy it. Well worth it in my opinion. We use one on our bbc alky topolino, (kobelco 14/71) 42-48lbs boost

But I will also probably make one for my lower powered alky bbc (8/71 at 20-25%) probably about 18-25lbs boost

 

If you are not concerned about every last ounce, why wouldn't you run one? Your #1 main will appreciate it.

 

I have one motor with a support on it and several without. I have run this way for years and cannot tell the difference in crank or bearing life. Maybe its the way I run them or ???

BBC's
8-71
tractorpulling
8000 RPM is the norm

 

I have just heard that the front mains like the help. I work on one car with it, and another without it. Of course, one is a 11,000 RPM AJ motor, and one is a brad, so they are apples & oranges. I like having them on there, except when the belt leaves.