Gorilla Girdle
- Thread starter durallymax
- Start date
Last season one of MPL s customers with a built motor,480 over 366
I tuned his truck and ran a 2200 PW on 30 over inj, Mild tuned truckCC/SB
Broken crank
same spot as everyone else.He had Robs tuning at first and wanted something more custom and less HP because of his previous bad luck.
it was internal balanced with ARP main studs.
He had probaly 12000 miles on the motor
Last season one of MPL s customers with a built motor,480 over 366
I tuned his truck and ran a 2200 PW on 30 over inj, Mild tuned truckCC/SB
Broken crank
He had Robs tuning at first and wanted something more custom and less HP because of his previous bad luck.
it was internal balanced with ARP main studs.
He had probaly 12000 miles on the motor
it must have been your tuning :hug: :joker: that must been an awful feeling Simon
Honestly, I would say if I thought it was tuning.
I dont see how tuning can wreck a crank though?There is only so much you can do with tuning
Trans and getiing it to run is one thing,But being hard on parts?
Honestly, I would say if I thought it was tuning.
I dont see how tuning can wreck a crank though?There is only so much you can do with tuning
Trans and getiing it to run is one thing,But being hard on parts?
Simon I was just giving you a hard time
i know your tuning is just fine on hard parts 
Simon I was just giving you a hard time
I know Nick, I was just trying fig0ure out how bad tuning would effect the crank?
You can have some pretty crappy tuning and the truck will still run good times.
I know this, because i tune my own truck
Were the mains set with extra clearance?Last season one of MPL s customers with a built motor,480 over 366
I tuned his truck and ran a 2200 PW on 30 over inj, Mild tuned truckCC/SB
Broken crank
He had Robs tuning at first and wanted something more custom and less HP because of his previous bad luck.
it was internal balanced with ARP main studs.
He had probaly 12000 miles on the motor
Not 100% but think so.
The guy had a reputable dmax builder do the work
But sadly has worse luck then I do!
Cough, cough. Tuning has a lot to do with the crank failures. It is at minimum one of the major variables.
I can tell you >40° of total timing won't bust a LLY crank at 5250 rpm and 800+ rwhp. This was a GT45 single that made peak HP at 4800.
And I can tell you that 300rwhp with <20° timing can bust an LLY crank. This was a Predator tow tune on an otherwise stock LiLLY.
So I doubt it's timing.
Lots of folk claim to have a solution for crank breakage. I can tell you I don't have a solution. Until I break a crank, I won't know anything.
And I can tell you that 300rwhp with <20° timing can bust an LLY crank. This was a Predator tow tune on an otherwise stock LiLLY.
So I doubt it's timing.
Lots of folk claim to have a solution for crank breakage. I can tell you I don't have a solution. Until I break a crank, I won't know anything.
you arent comparing the same rotating assembly, one could've been manufactured differently, balanced differently, etc. therefore i don't believe that by the above test you can rule out timing...JMHO
I've always run as much timing as the engine wanted, and that's a lot. I stage into the beams at ~30° and it goes up from there.
It might be I'm not making enough power to break a crank, dunno.
The curious thing is, the number of <500rwhp trucks that have broken cranks, and the number of 750+ trucks that haven't.
If timing was the trigger, I should snapped my first one in 2004. The Triple Stack of Doom was probably 45°+ on kill. It would actually 'burst' it had so much timing, you'd have to turn it down. People were breaking cranks back then too. The TTS Extreme had 28 deg peak, and a few broken cranks were observed back then. I don't remember anyone breaking a crank with a triple stack.
As soon as there aren't any broken cranks at <26° then I'll be a believer. So far, that's not the case.
It might be I'm not making enough power to break a crank, dunno.
The curious thing is, the number of <500rwhp trucks that have broken cranks, and the number of 750+ trucks that haven't.
If timing was the trigger, I should snapped my first one in 2004. The Triple Stack of Doom was probably 45°+ on kill. It would actually 'burst' it had so much timing, you'd have to turn it down. People were breaking cranks back then too. The TTS Extreme had 28 deg peak, and a few broken cranks were observed back then. I don't remember anyone breaking a crank with a triple stack.
As soon as there aren't any broken cranks at <26° then I'll be a believer. So far, that's not the case.
im not saying its a cause of failure, im just saying that by the analysis Pat posted it cant be ruled out. thats bad science. Im no scientist, but i listened in 7th grade.
Yes, it is bad science.
But not worse than, 'it must be timing' without proof that it's even related to peak cylinder pressure.
There are many theories:
A) Shock on the crankshaft. (Solid engine mounts, wheel hop, etc)
B) Timing.
C) Harmonics. (balancers, balancing, etc)
D) Factory defect.
I know "D" is some of it. Otherwise you wouldn't see stock engines or lightly tuned engines breaking cranks.
I know "A" breaks things. Anything made of hardened steel hates impact loads.
As far as "B" goes? Go to dyno and watch how gradually the power falls as you get near optimum timing. This isn't a sudden shock. It's not 'pinging' or detonating.
Harmonics? That is plausible. Dunno though.
Like I said, I don't have any answers. I just know that wild amounts of timing won't break a good factory crank. You can advance it till it bursts, and it isn't going to break the crank.
I realize that not putting something in the equation is Being ignorant.
However, there is only so much you can do with tuning.
I am curious to hear about fingers answer to this issue.?