440 crankshaft broke

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aaronk785

aaronk785

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Blew my engine this last race. Broke the crankshaft in half. It's a 440 factory steel crank in about a 650hp engine. Short block was about 9 years old and was at just under 600hp. Added new trickflow heads, dominator crb. And ported super victor and on the fifth run it blew at the top of 1st. My question is, will a factory crank live at 650hp and last or did I go to the well to many times.
 
Ouch! Have you torn it down yet to see if anything else let go? I could see it breaking the crank if the main saddled had cracked or there was A LOT of cap walk going on. Or unless said crank had a crack that hadn’t been spotted. 650 hp is getting close to the repeated power limit of most production blocks, but the stock forged cranks are known to be capable of much more than that. More than one has been used in a nitro Hemi before.
 
I hope I can tear it down this weekend and figure out how it all started. None of the plugs have been hit. I guess thats a good thing maybe the heads aren't hurt to bad. Thanks everyone.
 
Craigslist Florida > Treasure Coast > auto parts > 440 crank.

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I'd also recommend the ATI Super damper for your application. They have a high damping coefficient due to the frictional damping provided. 65'
Click to expand...
 
I went as quick as 9.82 but the stock 440 cranks are in my eyes junk at this ET. When I tore them apart after five years if they weren’t cracked in half they had cracks. If I tore the apart after three years they had cracks in them. If I tore them apart after two years which I never did they probably had cracks in them. I stopped even sending them out to have magnifluxed and just threw them on my scrap piles. We didn’t have cheap options back then but you do now.
 
I cracked the steel / forged Eagle 4 inch stroker crank in my 408 last year , luckily it didn't hurt anything else and the motor stayed together and it only wiped out one main bearing. I haven't fixed it yet with new cranks being in the $1,000 range .
 
My experience with them at higher HP levels is like PBR’s.

In the time period of about 20-30 years ago I built a number of bracket race 440’s in the 600 hp range.
Never had one break a crank, but when they came back for freshening(2-3 seasons), the cranks were always loaded with cracks.
One was cracked on the front and rear of every journal, and not tiny little cracks either.
 
I broke a crank in my 520 which destroyed the motor. We freshened it the year before and the main bearings were worn out. That was our sign but we didn't know it at the time. Now every time we freshen up a motor the crank gets crack checked. 150 dollars can save you a lot of parts.
 
We broke a 440 steel crank years back, but we found that the number 3 main web was cracked also. This could have led to breaking the crank, but we had no solid evidence. We bought a stroker crank , put it in a 440 HP block and went back to racing.
 
Once you get to that horsepower level you have exceeded what a factory crank is capable of sustaining. When you add up the money you have in parts that can be destroyed if something lets go it really makes.sense to upgrade to a 4340 crankshaft. I sell Molnar Technologies products and all big block Mopar crankshaft are priced at $997 plus $96 shipping for any stroke they offer. Really cheap insurance compared to the total investment it cost to build an engine today. Also when building a BBM it is a good idea to use ARP BBC main bolts as you get an extra 3 threads worth screwed into the block.

Tom
 
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