How good are oem steel 440 cranks?

How much power have you put through a stock steel 440 crank? For how long? Ive heard of breakage before, but only once or twice. I know they are an undercut crank.

Stock block, crank, six pack rods, 915 heads. 575 hp 15 years. Still didn't break, but failed magnaflux.

How much power are you thinking of putting to one.. I
know a few at 700 hp still living.. they tend to last
longer than the stock blocks.... but the rods
were turned down to chevy size

No real first hand info but Moparbilly's brother's Gremlin is over 800hp with all the kits on and has survived a few Dragweeks. That car has always impressed me since its a factory block and crank going 8.90 @ 150. Hopefully he'll chime in.

We used a stock one with mains cut down in Lenny Meltons KOS Dart--it finally made some mid-upper 8 runs all on big NOS--ran for years --suffered through a 727 explosion, bad tuning guessing and I don't know what all until finally getting a super tune up then it just ran and ran and ran The 400 stock block had two bolt stock main caps and is STILL running.
Good tune up--timing right, no detonation and never worry--I have always felt they were stronger than the block.

I had one in my world block for 440 passes. That was one season. I figured I better get it out of there before it broke and killed my block. Car went 8.68 at 154mph. Was in my Lebaron at 2450lbs. Around 750HP

440 steel crank off set ground to chevy 2.1 in a 467ci Hemi, mild street roller. 700 HP??? This was done a LONG time ago but still running strong.

CAST crank 440, indy sr heads, 150 shot of gas, 9.69@135, 200 passes in the 63 Plymouth below. I then spent a heap of cash on a stroker combo and only managed a 9.23@145. Was it worth it ?????

Factory 440 crank, turned down to 400 mains, chevy rods, 3.90 stroke. Tune up on the mark, turbos, pump gas, NO 2 STEP. Went low low nines at 3700 lbs for years. Upgraded turbos went 8.80 155 at 3700 lbs.

For the same power level, ranked by life expectancy (best = 1st)
1. turbo, supercharge
2. NA
3. nitrous

Major killers:
1. heavy piston
2. high rpm
Remember, inertial load @ TDC exhaust is what breaks rods, and it increases as the square of the rpm - 8,000 is not 14% more than 7,000 (8,000 ÷ 7,000) but 30% more (8,000^2 ÷ 7,000 ^ 2)

They are not undercut. The fillets are rolled in, "compressed"
Doug

The magnaflux every couple hundred presses is the thing to do if running more than 600 HP. They will crack, but not break right away. So you can catch it before it lets go... If you magnaflux.

The more power, the more often to magnaflux for cracks starting.

Every bracket 440 I built over the years that had a stock crank and made over 600hp, when they would come back for freshening, the cranks were always cracked in multiple places......and not tiny little cracks either.
One of the motors had every journal cracked at both ends(two cracks per journal).
They needed a new crank every freshen up.

Same here. I even stopped magnafluxing them when I took them apart for rebuilds. I would just throw it on the scrap pile and send another crank out to be checked and polished.

No two steps, lite pistons, NO detonation--perfect tune up and they will run until you retire
I have only had two broke 440 steels in 25 years of racing, building etc
They are amazing units--the customers that broke them could have broken an anvil I have bought piles of them and had about 1/2 dozen not mag good but who knows where or how they had been used before that point--they were really well made units compared to everything else Mopar made Those and 727's are Mopars claim to fame IMO

But those are unrealistic goals. A cast crank won't break if you never put it in a position where it could. The simple fact is, when you get to a certain power level, it IS hard on the crank, no matter how much you baby it

The old 451 B block stroker had the cutdown stock 440 crank, but light pistons and never reved over 7,000 RPM. I think only around 575 HP?

If you are racing, why push the limits of the stock crank? It's plain old 1053 carbon steel with undercut journals. For a few hundred more, you can have a 4340 alloy steel crank with radiused journals that is at least 50% stronger, maybe 100%. If you break a crank, you could wipe out the rest of the motor, you could dump oil under tires and wipe out your car, and maybe get injured or worse. It's one of the things that costs so little to upgrade, just like stock rods vs. aftermarket, I don't mess around with 50 year old production line time bombs.

Eh. I dunno. It was a legitimate question. With respect, not everything is a "time bomb". But Ill buy a bigger, new crank for it.
Thanks everyone for chiming in.

every stock steel crank I have taken out after 300-400 runs has been cracked. except the last one I did't beleive it had two shops check it both said it was ok ??

Here's what happens when it does fail. I am sure it was cracked in multiple places and I didn't catch it. I have run stock forged cranks for year and never a problem with them. I put a new Molnar 8 bolt crank in my new engine. Old eng was right at 600 horse power. Zero warning that anything was a miss until it exploded, tried to throw the #3 rod journal out of the block.

Brian

It's a 40-year old passenger car cranshaft desiged for an engine making under 400 HP. My last one still mag-checked OK in a 600 HP build when I pulled it apart the last time, but I replaced it with a new 4340 piece for piece of mind.

Wow that hurts to look at