Moparts
Another Eagle cast crank broken (408 stroker)
Posted By: madmax2
Another Eagle cast crank broken (408 stroker) - 03/09/10 11:30 AM
Posted By: CJK440
Re: Another Eagle cast crank broken (408 stroker) - 03/09/10 02:07 PM
Thats the second one i saw that broke the snout. After examining the one I had, I thought the weak point was the rear arm/journal cross section especially with all 8 cylinders twisting it.
Posted By: Anonymous
Re: Another Eagle cast crank broken (408 stroker) - 03/09/10 02:11 PM
that's not unusual with a cast crank. they just aren't made to hold up to that much horsepower.
Posted By: lewtot184
Re: Another Eagle cast crank broken (408 stroker) - 03/09/10 02:42 PM
if it were me, i wouldn't race a manual trans behind a cast crank. some folks may get by with it but my luck wouldn't.
Posted By: HotRodDave
Re: Another Eagle cast crank broken (408 stroker) - 03/09/10 03:57 PM
I have seen an aweful lot of those eagle cranks break just like that on the front end.
Funny how SCAT cast cranks don't seem to be doing that
Posted By: SLOW67
Re: Another Eagle cast crank broken (408 stroker) - 03/09/10 04:19 PM
I have a friend that races a Nova (yuck) with a 383 with a Scat cast crank with a jerico 4spd. 508hp to the wheels and no breakage and its been together 2 years. I've seen numerous eagle rods fail in weird ways with no rime or reason...
Posted By: Otherlane
Re: Another Eagle cast crank broken (408 stroker) - 03/09/10 04:32 PM
Dram,tell me something new.Why does a stock 360 crank hold 450 hp and not this cast crank?I have never a stock crank breaking but I could be wrong.back to the topic I had one of the cast when they first came out and my block let go before the crank did.After twisting 2 h-beams the crank was still good.i was running
10.50@3400 pound car.if I was building a few motor I would do the steel crank.
Posted By: Thumperdart
Re: Another Eagle cast crank broken (408 stroker) - 03/09/10 04:41 PM
Quote:
that's not unusual with a cast crank. they just aren't made to hold up to that much horsepower.
That`s what I used to think too Dan till I saw Darrell Parks click off consistent low 9`s with his cast crank iron headed small block. Granted it`s a 2500 lb. car but I`m guessing he`s making more power than the poster. 
Posted By: madmax2
Re: Another Eagle cast crank broken (408 stroker) - 03/09/10 05:14 PM
I not find reason why the eagle cast cranks (mopar , chevy, etc) are broken in the same place.
The car are a 3550 lb A-body.
Posted By: HotRodDave
Re: Another Eagle cast crank broken (408 stroker) - 03/09/10 05:28 PM
That place does not have a lot of material, it is light right there to help with balancing. The eagle cranks I have seen break often have air bubbles in the casting. The air bubbles mean it is weak and it is light weight over all so they have to take even more weight off somewhere on the side where the throw is to lighten it enough to balance. It all adds up to a really flimsey crank.
Posted By: emarine01
Re: Another Eagle cast crank broken (408 stroker) - 03/09/10 05:34 PM
Its hard to tell from pics but it looks like there was a crack long before failure, shiny part in the brake, what balancer were you running?
Posted By: moper
Re: Another Eagle cast crank broken (408 stroker) - 03/09/10 05:52 PM
Internal balance or external? As was asked.. what balancer and how did it go on?
Posted By: madmax2
Re: Another Eagle cast crank broken (408 stroker) - 03/09/10 06:00 PM
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Internal balance or external? As was asked.. what balancer and how did it go on?
is the engine of a buddy, the damper it's a Mopar Performance. 
Posted By: moper
Re: Another Eagle cast crank broken (408 stroker) - 03/09/10 06:06 PM
Just me tossing out ideas here... This isnt the first I've seen in terms of web stuff of that particular break. I have a couple of these in service in the 460-480 level (and automatics) and I will admit I'm nervous enough to probably stop sourcing them. But it terms of the "whys"... It looks like it started at the fillet which "should" be a fairly strong area. But that's where the otrsional stress is and the rpm doesnt matter if the harmonis are bad for wahtever reason. External balancing lends itself to stressing the crank more forcing it to flex, and a loose balancer or one that was hammered on or honed to fit more loosely can all contribute to crank stress, as can detonation. Never mind the 4sp part.
Posted By: emarine01
Re: Another Eagle cast crank broken (408 stroker) - 03/09/10 06:27 PM
Another question comes to mind, Were there any oiling system mods to this build or bone stock?
Posted By: Anonymous
Re: Another Eagle cast crank broken (408 stroker) - 03/09/10 06:33 PM
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Dram,tell me something new.Why does a stock 360 crank hold 450 hp and not this cast crank?I have never a stock crank breaking but I could be wrong.back to the topic I had one of the cast when they first came out and my block let go before the crank did.After twisting 2 h-beams the crank was still good.i was running [Email]10.50@3400[/Email] pound car.if I was building a few motor I would do the steel crank.
i don't have a definitive answer for you. i've seen plenty of broken cast cranks over my 34+ years in this business. there are a lot of places the blame could be placed, so take your pic.
bad cranks/ castings
bad balance job, internal vs. external
bad damper
heavy bobweights
and the list goes on and on.
some cranks seem to survive, others don't.
i do recommend moving up to a forged crank when your plans exceed 450 hp. that 450 hp might be fine, but what happens when you start making other improvements and then your at 500, or 550 or even more. plan ahead. it's cheaper in the long run to buy the better crankshaft up front IMO unless it's just going to be a slightly warmed over stock type build. i understand about working within a budget, but you don't ask for temporary fillings (i.e. cheaper) when you go to the dentist, so don't ask for a temporary crankshaft when you build your bracket motor.
Posted By: moparacer
Re: Another Eagle cast crank broken (408 stroker) - 03/09/10 06:37 PM
Exact same failure I had except mine broke at the back.
Just too thin between the rod and main journals.
Posted By: dart_73_br
Re: Another Eagle cast crank broken (408 stroker) - 03/10/10 12:38 AM
Quote:
Dram,tell me something new.Why does a stock 360 crank hold 450 hp and not this cast crank?
Because old stock cranks was not made in China! 
Posted By: dart_73_br
Re: Another Eagle cast crank broken (408 stroker) - 03/10/10 12:38 AM
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Quote:
Dram,tell me something new.Why does a stock 360 crank hold 450 hp and not this cast crank?
Because old stock cranks were not made in China!
Posted By: MR_P_BODY
Re: Another Eagle cast crank broken (408 stroker) - 03/10/10 12:52 AM
JMO but I would believe that it was a balance issue,
got it balanced from the company and in a lot of cases
thats not even close.... again JMO without knowing facts
Posted By: BobR
Re: Another Eagle cast crank broken (408 stroker) - 03/10/10 01:50 AM
Cast cranks are for lawnmowers.
Posted By: dOrk !
Re: Another Eagle cast crank broken (408 stroker) - 03/10/10 02:40 AM
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Cast cranks are for .......
.... cars with TORQUE CONVERTERS ! 
Posted By: tubtar
Re: Another Eagle cast crank broken (408 stroker) - 03/10/10 04:15 AM
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Cast cranks are for .......
.... cars with TORQUE CONVERTERS !
And 48 inch mower decks.
Posted By: mr_340
Re: Another Eagle cast crank broken (408 stroker) - 03/10/10 03:04 PM
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Dram,tell me something new.Why does a stock 360 crank hold 450 hp and not this cast crank?
Because old stock cranks was not made in China!
Seems to me that the 4" stroke vs. the stock 3.58" stroke might have something to do with it. Less overlap between the mains and the rod journals. I bet a cast 4" crank with 340 mains would be really bad.
Posted By: cheapstreetdustr
Re: Another Eagle cast crank broken (408 stroker) - 03/10/10 03:08 PM
something very miniscule to consider..
but heat cycles makes a crank stonger.
so to a tiney degree..a used crank main gain
a tiny bit more strength from it having been heat cycled.
i aggree that crank was destined to fail.
when its mass produced youll have that percentage
airbubbles,metalergy,,ect...its gonna happen in a cast crank..to some degree..
fwiw..
cheapst.
Posted By: goldmember
Re: Another Eagle cast crank broken (408 stroker) - 03/10/10 03:12 PM
I don't understand how a person could put an Eagle 4" cast crank in any build. It only takes a few seconds to see what you have.LOL If you must use a cast crank there are better options.
Posted By: LAR_414
Re: Another Eagle cast crank broken (408 stroker) - 03/10/10 03:40 PM
Just throwing this out there,....I've got an estimated 500-525 hp with my 4" CAST crank (mopar performance) with a pretty heavy bob wieght. Car is heavy (3350lbs). Has been together for about 7 years now. Runs 11.0's with automatic, and I just put a stick in it last year (still tuning), but hoping to run low 11's with the stick.
One time, I spun a rod bearing. Had the crank cut and they said that it was slightly bent, very slightly. They tried to straighten it, and the machine shop said that they couldn't believe how STRONG this crank was. They said it was about as strong as some (other makes) forged cranks they has seen.
Never had a problem with the crank! (340 mains, too)
Posted By: goldmember
Re: Another Eagle cast crank broken (408 stroker) - 03/10/10 03:55 PM
Quote:
Just throwing this out there,....I've got an estimated 500-525 hp with my 4" CAST crank (mopar performance) with a pretty heavy bob wieght. Car is heavy (3350lbs). Has been together for about 7 years now. Runs 11.0's with automatic, and I just put a stick in it last year (still tuning), but hoping to run low 11's with the stick.
One time, I spun a rod bearing. Had the crank cut and they said that it was slightly bent, very slightly. They tried to straighten it, and the machine shop said that they couldn't believe how STRONG this crank was. They said it was about as strong as some (other makes) forged cranks they has seen.
Never had a problem with the crank! (340 mains, too)
I have seen the MP cast crank take some abuse. Mid 10's most weekends for 7 plus years(did break last year in dramatic fashion,LOL). The MP and the Eagle are far from similar.
Posted By: AndyF
Re: Another Eagle cast crank broken (408 stroker) - 03/10/10 04:01 PM
These days there is only a small difference in total engine cost to go forged. I suppose things were different years ago. At one time the cast stroker crank was the only thing available to people on a budget but that is no longer the case.
Posted By: madmax2
Re: Another Eagle cast crank broken (408 stroker) - 03/10/10 04:33 PM
Quote:
These days there is only a small difference in total engine cost to go forged. I suppose things were different years ago. At one time the cast stroker crank was the only thing available to people on a budget but that is no longer the case.
The crankshaft was purchased in 2007, forged crankshafts were much more expensive than today.
and we thought we would hold less than 500 HP without problems. 
Posted By: dart_73_br
Re: Another Eagle cast crank broken (408 stroker) - 03/10/10 04:44 PM
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and we thought we would hold less than 500 HP without problems.
Yeah, this cranks are supposed to handle 500hp with no problems... 
Posted By: cheapstreetdustr
Re: Another Eagle cast crank broken (408 stroker) - 03/10/10 09:11 PM
just like the saftey on your guns..
"Its a mechanical device made by man,,prone to
failure"
still remember that 26yrs ago from the test...
good for something...
cheapst
Posted By: emarine01
Re: Another Eagle cast crank broken (408 stroker) - 03/10/10 09:36 PM
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and we thought we would hold less than 500 HP without problems.
Yeah, this cranks are supposed to handle 500hp with no problems...
There are lots of reasons parts fail, The easy thing to do is blame the part After 20 or so years rebuilding and repairing diesels I have seen more parts fail from improper assembly or the wrong part used for the application than defective parts,Now I am not saying that cheep eagle cranks are good < looked like a pourous casting> from pics, but I do know a chevy builder that uses 4 inch arm cast cranks in 650 hp range with out failure and I think they are eagle made 
Posted By: goldmember
Re: Another Eagle cast crank broken (408 stroker) - 03/10/10 09:40 PM
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and we thought we would hold less than 500 HP without problems.
Yeah, this cranks are supposed to handle 500hp with no problems...
There are lots of reasons parts fail, The easy thing to do is blame the part After 20 or so years rebuilding and repairing diesels I have seen more parts fail from improper assembly or the wrong part used for the application than defective parts,Now I am not saying that cheep eagle cranks are good < looked like a pourous casting> from pics, but I do know a chevy builder that uses 4 inch arm cast cranks in 650 hp range with out failure and I think they are eagle made
The Eagle cranks for Chevys do seem to hold up better than the pieces they make for the Mopar guys.
Posted By: MR_P_BODY
Re: Another Eagle cast crank broken (408 stroker) - 03/10/10 09:42 PM
What was the balancer on it and did you have it
balanced or did you have the crank company balance it
Posted By: DconD100
Re: Another Eagle cast crank broken (408 stroker) - 03/11/10 01:52 AM
Do the engines spin the opposite direction down there in Argentina?
My eagle 4 inch arm is holding up at about 450 observed hp. It internally balanced with the I-beam rods, and I have an ATI balancer...sure hope it keeps on trucking! I only have about 5000 miles, and about 50 quartemile passes on it.
Posted By: dr.mopar
Re: Another Eagle cast crank broken (408 stroker) - 08/26/11 04:28 AM
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Do the engines spin the opposite direction down there in Argentina?
My eagle 4 inch arm is holding up at about 450 observed hp. It internally balanced with the I-beam rods, and I have an ATI balancer...sure hope it keeps on trucking! I only have about 5000 miles, and about 50 quartemile passes on it.
Nice, it should stay together for a long time, you are producing the Horepower range the crank was intended for and probably shifting below the 6000rpm range.
My personal experience, eagle cast crank is a thing of beauty, light, affordable, easy to internally balance with no mallory, and the I beam eagle rods are the best value in the the market.
Doc 
Posted By: 1Fast340
Re: Another Eagle cast crank broken (408 stroker) - 08/26/11 05:15 PM
to the original poster:
did you have any balancers breaking before this crank broke?
asking since i have observed a crazy behavior from a friends cast eagle crank and im afriad his crank is about to do what yours already did, at about the same powerlevel.
Posted By: dr.mopar
Re: Another Eagle cast crank broken (408 stroker) - 08/27/11 04:40 AM
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to the original poster:
did you have any balancers breaking before this crank broke?
asking since i have observed a crazy behavior from a friends cast eagle crank and im afriad his crank is about to do what yours already did, at about the same powerlevel.
I wonder how many of these failed cranks are due to other problems as Scat points out with their units.
First, have these units been balanced externally? Or balanced at all.
If so have they been balanced properly by a pro?
Second, assembly? Were the balancers installed correctly? Or pounded on with a hammer.
Bottom line is these engines are often assembled by backyard mechanics with backyard practices. Often leading to mechanical failures.
People suggesting they broke a crank in the burn out box is just silly. Simply that was the hair that broke the camels back. So what really lead to the crank failure? Over revving? Who knows, I am sure there are many reasons for the failures, however my experience has been if built properly, within the limits outlined by the manufacters both Scat and Eagle make good products.
Why more eagle failures? They probably out sell Scat two to one.
Posted By: Mike Swann
Re: Another Eagle cast crank broken (408 stroker) - 08/27/11 06:26 AM
Lack of nickel as an alloying agent in the Eagle casting, imo. You see cracking in a lot in sockets and wrenches(hand tools) as well. They will add a lot of carbon to get it strong, but without the nickel, no fatigue life or fracture toughness.
The price of nickel has skyrocketed over the years and has been disappearing in non quality controlled metals, like Eagle cranks.
Ask Eagle if you can see the assay report on the casting lot. Bwahahahahaha.
Posted By: Guitar Jones
Re: Another Eagle cast crank broken (408 stroker) - 08/27/11 11:06 AM
I've seen that too, in fact the guy that did machine work for me had one in a 11.00/10.90 A body with an automatic and it broke the same way.
Posted By: dr.mopar
Re: Another Eagle cast crank broken (408 stroker) - 08/29/11 02:25 AM
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I've seen that too, in fact the guy that did machine work for me had one in a 11.00/10.90 A body with an automatic and it broke the same way.
Just another example of people not following the recommended HP ratings for these cranks. A 3000lb A body with a 200lb drive will go 11.40 with a 500HP engine.
In other words, your machinist was making around 540-550HP to run 10.9's with the cast crank. Is it any wonder it failed? Clearly with that type of HP the motor should have had a forged crank.
Posted By: goldmember
Re: Another Eagle cast crank broken (408 stroker) - 08/29/11 03:07 AM
It doesn't take 500hp to run 10.90's @3200lbs. I tried to use an eagle cast crank in my daily driver truck,but in 10 minutes after it showed up I had in back in the box for return. I was not able to save my buddy as he used this crank for almost 2 seasons,running 11.00 @ 3200lbs then it came apart and destroyed a lot more than the crankshaft. Good luck.
Posted By: dr.mopar
Re: Another Eagle cast crank broken (408 stroker) - 08/29/11 04:30 AM
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It doesn't take 500hp to run 10.90's @3200lbs. I tried to use an eagle cast crank in my daily driver truck,but in 10 minutes after it showed up I had in back in the box for return. I was not able to save my buddy as he used this crank for almost 2 seasons,running 11.00 @ 3200lbs then it came apart and destroyed a lot more than the crankshaft. Good luck.
I will agree to disagree, in my opinion it takes all of 500+ horsepower to run 10.90's in a 3200lbs door car and the need for a forged crank is obvious in such a fast car. If the friend got two yrs. out of the deal I would say he did pretty good considering the crank is on the ragged edge of its recommeded range.
Posted By: moparacer
Re: Another Eagle cast crank broken (408 stroker) - 08/29/11 04:43 AM
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Thats the second one i saw that broke the snout. After examining the one I had, I thought the weak point was the rear arm/journal cross section especially with all 8 cylinders twisting it.
Thats were ours broke at 100 passes and no street miles.
Posted By: goldmember
Re: Another Eagle cast crank broken (408 stroker) - 08/29/11 04:54 AM
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It doesn't take 500hp to run 10.90's @3200lbs. I tried to use an eagle cast crank in my daily driver truck,but in 10 minutes after it showed up I had in back in the box for return. I was not able to save my buddy as he used this crank for almost 2 seasons,running 11.00 @ 3200lbs then it came apart and destroyed a lot more than the crankshaft. Good luck.
I will agree to disagree, in my opinion it takes all of 500+ horsepower to run 10.90's in a 3200lbs door car and the need for a forged crank is obvious in such a fast car. If the friend got two yrs. out of the deal I would say he did pretty good considering the crank is on the ragged edge of its recommeded range.
I will agree to disagree. It does not take a forged crank to withstand that output. Just a factory cast crank or a cast MP/Scat crank and you'll have far better odds of a reliable engine,rather than a potential disaster. The engine in the duster was less than 500 hp(yes, it was on the dyno),so give me some idea how long that crank might last @ 450hp,475hp,etc I'd love to know the answer.I'll just keep putting better cranks in my builds and sleep better. 
Posted By: dr.mopar
Re: Another Eagle cast crank broken (408 stroker) - 08/29/11 05:29 AM
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It doesn't take 500hp to run 10.90's @3200lbs. I tried to use an eagle cast crank in my daily driver truck,but in 10 minutes after it showed up I had in back in the box for return. I was not able to save my buddy as he used this crank for almost 2 seasons,running 11.00 @ 3200lbs then it came apart and destroyed a lot more than the crankshaft. Good luck.
I will agree to disagree, in my opinion it takes all of 500+ horsepower to run 10.90's in a 3200lbs door car and the need for a forged crank is obvious in such a fast car. If the friend got two yrs. out of the deal I would say he did pretty good considering the crank is on the ragged edge of its recommeded range.
I will agree to disagree. It does not take a forged crank to withstand that output. Just a factory cast crank or a cast MP/Scat crank and you'll have far better odds of a reliable engine,rather than a potential disaster. The engine in the duster was less than 500 hp(yes, it was on the dyno),so give me some idea how long that crank might last @ 450hp,475hp,etc I'd love to know the answer.I'll just keep putting better cranks in my builds and sleep better.
Not all dyno's are created equal, just ask Hughes. At 450HP the eagle cranks are lasting a very long time, 7+ yrs. which is a long time in the life of most street strip rides.
In fact I just got 7 yrs. out of a 360 which had two cylinders cracked. Was it the blocks falt these cyls cracked? Who knows, however it didn't help that I overheated it a yr. ago when it started leaking fluid. So which came first the crack, or the overheating which likely led to the cracks?
What did I put back in? Another 360 because they make great drag motors with or without a stroker crank..
Posted By: goldmember
Re: Another Eagle cast crank broken (408 stroker) - 08/29/11 05:36 AM
Yep, I'll call Hughes in the morning so that I can be truly informed.
Posted By: Stroker Scamp
Re: Another Eagle cast crank broken (408 stroker) - 08/29/11 05:39 AM
Quote:
It doesn't take 500hp to run 10.90's @3200lbs. I tried to use an eagle cast crank in my daily driver truck,but in 10 minutes after it showed up I had in back in the box for return. I was not able to save my buddy as he used this crank for almost 2 seasons,running 11.00 @ 3200lbs then it came apart and destroyed a lot more than the crankshaft. Good luck.
just love that duster 
Posted By: HardcoreB
Re: Another Eagle cast crank broken (408 stroker) - 08/29/11 04:13 PM
just love that duster
I agree..we need more pics and details please.
Posted By: dr.mopar
Re: Another Eagle cast crank broken (408 stroker) - 08/30/11 03:18 AM
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Yep, I'll call Hughes in the morning so that I can be truly informed.
I will agree with you on this, Hughes is not all they are "cracked" up to be..
Interesting to note Mancini racing sell three different brands of cranks including cast eagles.
Things that make you go hummm? If eagle cast cranks were such an issue why would one of the top Mopar houses carry this product?
When you call the Hemi hot line they have no ill feelings about anyone using cast eagle cranks and have no mass reports of eagle crank failures?
To me this whole post was likely started by a few ill informed Scat fans.
According to my local speed shop it is Scat that is having the quality control issues, not Eagle.
Posted By: dr.mopar
Re: Another Eagle cast crank broken (408 stroker) - 10/02/11 01:30 AM
Latest update, our 408 with the eagle cast crank went 11.93 @ 111.4 in our 3600lb b-body satellite today.
Boy am I happy..
Posted By: Guitar Jones
Re: Another Eagle cast crank broken (408 stroker) - 10/02/11 03:29 AM
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Latest update, our 408 with the eagle cast crank went 11.93 @ 111.4 in our 3600lb b-body satellite today.
Boy am I happy..
And of course when it breaks you'll update us on that as well right?
Posted By: goldmember
Re: Another Eagle cast crank broken (408 stroker) - 10/02/11 04:13 AM
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Quote:
Latest update, our 408 with the eagle cast crank went 11.93 @ 111.4 in our 3600lb b-body satellite today.
Boy am I happy..
And of course when it breaks you'll update us on that as well right?
We can hope he does. I'll make a deal with him,I'll report back when the stock 360 cast crank breaks,it's been 100,000 street miles and makes 10 second passes without a second thought @ 3600lbs. We have hundreds of passes on this junk so you better get busy. 
Posted By: Guitar Jones
Re: Another Eagle cast crank broken (408 stroker) - 10/02/11 05:00 AM
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Quote:
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Latest update, our 408 with the eagle cast crank went 11.93 @ 111.4 in our 3600lb b-body satellite today.
Boy am I happy..
And of course when it breaks you'll update us on that as well right?
We can hope he does. I'll make a deal with him,I'll report back when the stock 360 cast crank breaks,it's been 100,000 street miles and makes 10 second passes without a second thought @ 3600lbs. We have hundreds of passes on this junk so you better get busy.
You can see the numbers in my sig, that's 15 years of 7000 rpm shifts on a stock 360 crank. If he get's even a quarter of that I'll be surprised.
Posted By: dr.mopar
Re: Another Eagle cast crank broken (408 stroker) - 10/02/11 02:42 PM
Lets see, race car compared to street car, kind of an apple and oranges thing don't you think. W5's? It better run 10's.
If you want to compare apples to apples lets do it. I unbolted all the parts from my J headed 360 and installed them on a street 408. Installed in the same car and it picked up 6 tenths. Worth it? certainly.
Bottom line, no one said the 360 crank wasn't good, in fact it is awesome. I'm just saying to the anti eagle crowd there is nothing wrong with the 4" Eagle cast crank if used as recommended..
