Has anyone snapped a stock crankshaft?

[Tooky]

This question keeps popping up for me over and over and I don't wanna steal someone else's thread or let it go unnoticed.. Has anyone done it? What were the circumstances? If I remember right, John Waller put a 300,000 mile stock 4.3 crank in his 128MPH Typhoon so it would seem he has some faith in them, to say the least. I'm slowwly building a motor and I found a free LB4 Z longblock with 190K miles that I was gonna use the crank out of (and the block). Don't wanna do anything foolish so let's discuss.

 

[E-Rue]

as long as i have been here, there is only one incident i can remember, and i believe he broke several of them, so that example might have had a specific cause.......... oh wait there was also that guy with the super nice truck from rockford racecraft that exploded at the nationals 3 years ago. larry brown? not sure, im bad with names. anyway..... my point is that they dont normaly break. hope that helps.

e

 

[TurboManiacal]

Yeah that was larry brown...E and I were standing right there when it happened.

 

[GM TURBO]

I have portions of Larry Brown's on tape. It was more of the aftermath as I was taping Gavic's truck in the staging lanes. It does have audio and the crowds reaction. It was a very very ugly sound.

I haven't ever heard of a stock crank snapping. I am sure the people who fear it have upgraded. There are few trucks spinning high RPM's also which is where I would think more failures would happen.

 

[bezerk]

Nightdiver broke a crank

 

[bigtime]

Does anyone know why these cranks broke?? was it because they were
weak or was it because of another problem. detonoation will break a crank
pretty quick! Bad harmonic damper, improperly balanced assembly, Out
of balance torque converter, spun bearing........
A properly tuned turbo engine is actually pretty easy on the crank, not like NOS. or a supercharged engine.
Just curious.

 

[ZMann]

I beleive Larry Brown's crank busted after his input/output shaft broke in the tranny??

 

[jwaller]

Re: Has anyone snapped a stock crankshaft?

John Waller put a 300,000 mile stock 4.3 crank in his 128MPH Typhoon so it would seem he has some faith in them, to say the least

yes thats exactly right. I did just that.

my belief is that if you don't deto the doo doo out of it, and you keep your tune close, you wont have any problems out of it.
I never have..

 

[myclone]

Syclonewillie broke a crank

 

[nightdiver]

My crank broke cause a journal was refilled , spanned bearing dont you call it ?
The crank was damaged and repaired in US (well he said so)
I didnt brake his face cause i might need something i cant find some time later

 

[GM TURBO]

I beleive Larry Brown's crank busted after his input/output shaft broke in the tranny??

Of course.

 

[Syclone#1992]

Was talking to the guy at Ramchargers that used to warrenty work on many Typhoons at the stealership. He said they had a handful come back with broken cranks. I said I was suprised because I always thought thought people bent the stock connecting rods. He said that they would cringe whenever they would see a Sy or Ty come in.

Don't know how much this is true, but that is what he said.

 

[Tooky]

I said I was suprised because I always thought thought people bent the stock push rods.

I thought it was the connecting rods?

 

[HotRodV6]

Well, from what ive been able to find out, is that if the rods and pistons are good and oil clearences are set right, and you dont try to spin 10K RPM's a stock cast crank will survive, at least for awhile. Dont spin it any faster than you have to to make the power.

Ive talked to people about having my stock crank nitraded or shot peened and then the Cryo treatment, and from most of the big time racers ive talked to hear in H-town they say the best thing to do for a stock crank is to have it shot peened and then reground and repolished if necessary, and then have it cryo treated, that will make it as strong as possible without spending alot of money on a billet crank that takes forever to get.

Thats wnhat im doing to my stock crank, and im running a NOS motor, it will be a fogger set to a 300 shot, ran thur a progressive controller, so it will not hit that hard, will only be around a 75 shot out of the hole than ramp up to a 150 shot total in the beggining, thna maybe a 225 if it still holds together, and if im not in the 10's yet ill go the full 300. Im told it "should hold" and my max RPM will be 6500 shift points with a 6800 or 7000 redline. Ill let you knoiw how it works out, and hopefully be at the NATS next year stroking the timers with 10.80's or better.

 

[100in6]

hot rod

thought i would throw a little extra in. i see you're gonna gas this motor outrageously. how much boost you planning to run. if you're gonna run reasonable boost levels it might work. with all that nitrous and if you run high boost levels you might be in too much for a stock crank. it's true that the stock cranks hold up very well if you 4 bolt splay the caps and have em reworked and checked, but i don't think anyone has run that much nitrous in a motor and i know that most guys i know with big turbos don't run much more than 24 or so pounds of boost with a stock crank. what size turbo you planning on using?

i realize the forged cranks cost a bunch (i have one), but bustin one and taking a bunch of stuff with it aint cheap.

just trying to help ya. that's a hell of a lot of nitrous your thinking of running in a turbocharged motor! i cringed at running a 25 shot in my intercooler to help me get to the 9's and i chickened out.

anxious to hear what you plan on doin before you do it

les

 

[10secTy]

If you keep the rpms down below 5500 and have no deto the stock crank will do what ever your 700R4 will handle. I have run up to 30psi boost with mine and its 20 under. I have more left in my truck once the boost control is sorted out and I am not worried about the crank but I watch the tune very closly.

Nolan

 

[bigtime]

If you are using NOS you better buy a billit crank. Nitrous is
harder on the crank than turbos.
Turbo=gradual power
Nitrous=Instant

BIG difference, especially 300hp on a v6

 

[HotRodV6]

Well my plans dont call for a turbo just yet, just a healthy motor and the gas. My Sonoma GT didnt come with a turbo so its going to stay that way at least for now, althouht i do want to to atleast a single turbo down the road, and maybe a twin, just have to see how the money goes.

I am using 15 degree potiac/brodix heads, custom made cunningham 6" connecting rods and wisco 4.130 bore 1.250 CH and .150 dome pistons, wil have around 11.2 CR, these heads easily flow over 300+ CFM, brodix says they have a 240cc intake runner, so my weak link will be the stock 4.3 CPI intake im using, until i can get the money to get a sheet metal intake made. cam specs will be around 286/294 ADV DUR and 232/240 @.050 112 LSA 107 ICL and with my 1.85/1.75 jesel rockers lift will be .647/.686. Im running a 10134388 bowtie iron block all billet caps, ARP main and head studs, rest of motor will be ARP bolts or studs. Looking to make at least 300 at the wheels on motor, would like closer to 350+ but ill be happy with 300, and then hit it with the gas. Will have a built 700R4, 3500 stall Yank converter, Chrysler 8 3/4 rear with 4.10's and a detroit locker. Flex-a-form leafs and caltracs, with a custom panhard bar out back, with DJM 3" drop lower a-arms, QAI Coilovers, bear 13" brakes on modified B-body spindles, with Hothckis upper G-body arms. over all the truck should sit at about a 4/4 drop, i have a set of 2001 S-10 ZQ8 16x8 wheels(yes the 13" brakes fit perfect-without grinding the wheel) but may end up being the wrong offset, so new wheels may have to be the choice. Anyways, im looking for 10.80's or better and would like to get there with only a 225 shot(75% of system capacity) and then maybe a low 10 with the full 300.

But to tell you the truth, im scared to hit it eith the full 300, becaue i dont know if it will hold, and your right a broken crank can and will take out alot of other expensive parts with it. So well just have to see when i finish the truck, hopefully early next year, and havetime to get the bugs worked out of it, so i can drive to the Nats, run a few times and drive it back home.

 

[bigtime]

Well my plans dont call for a turbo just yet, just a healthy motor and the gas. My Sonoma GT didnt come with a turbo so its going to stay that way at least for now, althouht i do want to to atleast a single turbo down the road, and maybe a twin, just have to see how the money goes.

I am using 15 degree potiac/brodix heads, custom made cunningham 6" connecting rods and wisco 4.130 bore 1.250 CH and .150 dome pistons, wil have around 11.2 CR, these heads easily flow over 300+ CFM, brodix says they have a 240cc intake runner, so my weak link will be the stock 4.3 CPI intake im using, until i can get the money to get a sheet metal intake made. cam specs will be around 286/294 ADV DUR and 232/240 @.050 112 LSA 107 ICL and with my 1.85/1.75 jesel rockers lift will be .647/.686. Im running a 10134388 bowtie iron block all billet caps, ARP main and head studs, rest of motor will be ARP bolts or studs. Looking to make at least 300 at the wheels on motor, would like closer to 350+ but ill be happy with 300, and then hit it with the gas. Will have a built 700R4, 3500 stall Yank converter, Chrysler 8 3/4 rear with 4.10's and a detroit locker. Flex-a-form leafs and caltracs, with a custom panhard bar out back, with DJM 3" drop lower a-arms, QAI Coilovers, bear 13" brakes on modified B-body spindles, with Hothckis upper G-body arms. over all the truck should sit at about a 4/4 drop, i have a set of 2001 S-10 ZQ8 16x8 wheels(yes the 13" brakes fit perfect-without grinding the wheel) but may end up being the wrong offset, so new wheels may have to be the choice. Anyways, im looking for 10.80's or better and would like to get there with only a 225 shot(75% of system capacity) and then maybe a low 10 with the full 300.

But to tell you the truth, im scared to hit it eith the full 300, becaue i dont know if it will hold, and your right a broken crank can and will take out alot of other expensive parts with it. So well just have to see when i finish the truck, hopefully early next year, and havetime to get the bugs worked out of it, so i can drive to the Nats, run a few times and drive it back home.

What??????????

 

[Tydriver]

Ive talked to people about having my stock crank nitraded or shot peened and then the Cryo treatment, and from most of the big time racers ive talked to hear in H-town they say the best thing to do for a stock crank is to have it shot peened and then reground and repolished if necessary, and then have it cryo treated, that will make it as strong as possible without spending alot of money on a billet crank that takes forever to get.

I agree with this 110% Also, I can add one other person to the list who's name will go unmentioned but his broke because of piss-poor machine work on the block.

Have the crank inspected, machined and frozen, should be OK. Try to stay away from nitriding and only use it of you cant get it cryo'd. For some reason however I am upto crank #4 at the machine shop and I cant manage to get one thats worth machining. Every one has been a POS so far. :banghead: :banghead: