Eagle broke crank

Thought I'd share. Now that the new motor is done, finally got around to pulling the 514 out tonight. This is the engine that broke on the last race of the year. I couldn't stand it, I had to pop off the pan to see what happened. This engine didn't have alot of power. Moved the car a best of 6.60's at 3200 lbs and didn't turn over 6000 RPM. I was told when I bought the car that it was a 514 with eagle crank and rods. When the crank broke, I was skeptical. I couldn't imagine an after market crank breaking on such a mild engine. Turns out, it is an eagle crank. Just out of curiostiy, any ideas what would have caused this? The break happened between the counter weight and the #1 journal. Notice in the second pic I am holding a 1/4" extension to show how thin the crank is in this area.

You weren't by chance running a Fluiddampner were you ? I broke 2 with a Fluiddampner on them
Frank

Frank Merkl wrote:You weren't by chance running a Fluiddampner were you ? I broke 2 with a Fluiddampner on them
Frank

No but it was a cheap Summit SFI deal

And now that I have popped the pan off and pulled part numbers, turns out it was a 512". 4.14 Eagle stroke crank p/n 46041402200-c (apparently good for 1500hp) 6.8 Eagle rods p/n crs 6800-s and JE pistons 4.440 p/n 150728

Frank Merkl wrote:You weren't by chance running a Fluiddampner were you ? I broke 2 with a Fluiddampner on them
Frank

I wonder if that was it. It was a p/n SUM-C4272 Summit brand balancer that claims works with external OR internal balance. Still, the crank looked awfully thinish in the area it broke. IDK

On the run that that happened, we discovered the battery was shot when we were called to the lanes. Had to crank it with a jump box to fire the car in the lane. Didn't even have enough battery juice to hold the trans brake solenoid. As soon as I hit the throttle, it pushed through the beams. I was pissed and just held it down. It all went down hill from there. Would it be possible a bunch of fuel built up in that cylinder that maybe wasn't firing and once if fired it was too much? The car noticeably changed in power at about the 100 ft mark. Then just started skipping like hell.

all 460 balancers will work with internal or external balalnce, as the weight is actually on the spacer behind it when external.

If you got a decent 60 ft. then i say you was making 550 hp max at that weight . how did the bearings look on the longer part? that should tell if it was flexing enough to crack one. Summit owns trickflow and summit one is the exact same trickflow balancer.

ED502 wrote:If you got a decent 60 ft. then i say you was making 550 hp max at that weight . how did the bearings look on the longer part? that should tell if it was flexing enough to crack one. Summit owns trickflow and summit one is the exact same trickflow balancer.

Bout right. 60' was low 1.40's. Haven't pulled any mains yet.

Soup the Fluid Dampner myth is BS Not one single soul has any proof they are bad, I ran one for 15 years with no problems and know others that have run them years and years....I wish I still had my Fluid Dampner at least I could see the timing numbers...

Low battery........ im sure the ign wasnt happy and the pissed off tuneup as a result finished it off.

Check valves and pushrods on #1 and or #5. With it not fireing well, sounds like it could have hydraulic locked a cylinder. A load of fuel and it couldnt compress it.

Remove the rod and see if it broke at the fillet radius.

From the looks of the size of that "lightening" hole in the rod journal, It reminds me of that "flexy flyer" crank Blake had some years ago...

QtrWarrior wrote:From the looks of the size of that "lightening" hole in the rod journal, It reminds me of that "flexy flyer" crank Blake had some years ago...

It damn sure don't leave much material for strength.

Until it is examined further it is anyone's guess what caused it. But,I think it's NEVER wise to make a pass W/low voltage battery or ignition that is acting up. Cylinder hydralic's can and WILL occur. jmo

Lem Evans wrote:Remove the rod and see if it broke at the fillet radius.

enough of the ......

1] dampner
2] low battery
3] hydraulic

Did it break at the fillet radius?

Lem Evans wrote:

Lem Evans wrote:Remove the rod and see if it broke at the fillet radius.

enough of the ......

1] dampner
2] low battery
3] hydraulic

Did it break at the fillet radius?

I haven't popped the caps off yet. What exactly do you mean by fillet radius? Did you see the pics?

soupbean wrote:

Lem Evans wrote:

Lem Evans wrote:Remove the rod and see if it broke at the fillet radius.

enough of the ......

1] dampner
2] low battery
3] hydraulic

Did it break at the fillet radius?

I haven't popped the caps off yet. What exactly do you mean by fillet radius? Did you see the pics?

Never mind. I looked it up. It appears it may have. I'll check tomorrow.

Lem Evans wrote:

Lem Evans wrote:Remove the rod and see if it broke at the fillet radius.

enough of the ......

1] dampner
2] low battery
3] hydraulic

Did it break at the fillet radius?

b
Lem,
Is that like the filet that the Texas Roadhouse has?
I got filled on one of those, but my crank was ok.

fillet up, start it, then do a burnout.............

Wheelie58 wrote:

Lem Evans wrote:

Lem Evans wrote:Remove the rod and see if it broke at the fillet radius.

enough of the ......

1] dampner
2] low battery
3] hydraulic

Did it break at the fillet radius?

b
Lem,
Is that like the filet that the Texas Roadhouse has?
I got filled on one of those, but my crank was ok.

http://www.google.com/search?q=fillet+radius&hl=en&tbo=u&rls=com.microsoft:en-us&tbm=isch&source=univ&sa=X&ei=f5PvUJrsI9GF0QHo_YDYCg&ved=0CDQQsAQ&biw=1024&bih=630

http://www.google.com/search?hl=en&tbo=d&rls=com.microsoft%3Aen-us&biw=1024&bih=660&tbm=isch&sa=1&q=start+it+and+do+a+burnout&oq=start+it+and+do+a+burnout&gs_l=img.12...11333.21837.0.23032.31.17.0.14.0.1.387.2259.0j11j0j1.12.0...0.0...1ac.1.Eu4gevEldzM

Wheelie58 wrote:

Lem Evans wrote:

Lem Evans wrote:Remove the rod and see if it broke at the fillet radius.

enough of the ......

1] dampner
2] low battery
3] hydraulic

Did it break at the fillet radius?

b
Lem,
Is that like the filet that the Texas Roadhouse has?
I got filled on one of those, but my crank was ok.

The filiet radius beef at texas road house is the only thing my wife orders....so it must be okay.

I know nothing about your crank.

Getting back to the broken crankshaft issue.........I've seen Bryant crankshafts break in the same place. The common themes are that the journals were turned .010" under. My first though was about the lose of surfice heat treatment. After talking to informed crankshaft professionals.....best answers were...local grinder srewed the radius up.

If soup's crankshaft broke at the radius:

1] Poorly done radius.
2] Flexing in that area.
3] Both.