On a stock Olds 455, how much HP can it take before a girdle and forged crank is required?

Is it true the 455 main webs can distort just from torquing down the main caps?

 

There is no magical number. It all depends upon what everything checks out too. You might get 550 or so if all the planet's align.

 

Yes, but it’s no different than the cyl bores distorting when you tq the head or tq plate.
BTR routinely does high 500hp builds without a halo and they seem to do just fine. I’ve done one that made 560, no halo, again no issues. But you can raise this ceiling if you’re using aluminum rods, internal balancing etc. less stress, less flex and less potential for failure.
Hope this helps.

 

HP from a normally aspirated gasoline only setup is easier on the block than using a big, sudden hit of nitrous to get the HP.

 

Is a factory nodular cast iron crank better or worse than an Eagle steel cast crank when it comes to strength?

Does the internal balancing help with reducing crank flex?

Once you get into the 575-600HP +levels, one has to upgrade to the billet bottom end girdle, right? That or get a Rocket Racing block.

 

So from my research, here is what I found:

Factory Nodular Iron Crank = 550HP level is safe but anything above 550HP and things start to get sketchy due to crank flex
Eagle Cast Steel Crank = 600HP - 650HP level is safe but levels above that things start to get sketchy due to flex
Factory Forged 425 Crank = 700-750HP level is safe but levels above that and possible crank failure is due to cracking
New 4340 Billet Crank = 1,000HP level is safe

Stock Olds 455 Block = 600HP level before the block can begin to cause problems
Olds 455 Block with one-piece full length bottom end girdle from BTR = 700-850HP
Rocket Racing 455 Block = 2,000HP+

The variances of the above is due to a lot of factors, including clearances, machining, assembly, types of use (street vs racing), etc.

 

So, mine should take a 200 shot, hmmmmm.

 

do it!

 

You spray, you pay! Keep a shovel in the trunk!

The stock Olds 455 is not the strongest engine design. A lot of engineering advancements have taken place in the past 50 years with engine designs. I've seen a lot of 455's die an early death from high HP. Once you start pushing north of 550HP, I personally believe a billet or forged crank is a must for longevity. Sure, there are some who run the stock nodular iron but they probably rebuild the engine every couple of years if they race it hard.