Re: How much HP/TQ will a GM Crank handle ?
 

Not a question of if but when Rob. Years ago I learned of what is referred to as an S harmonic. It will either happen on 1, 3, and 5 or on 2 and 4. The bearings on either combination will show signs of the crank flexing. GM cranks are brittle and will micro fracture. One of my customers that runs 470 CID truck pull engines magnaflux's his customers cranks every year when they come down. These engines see 9500 rpm some of them and make around 800HP. He has had 2 failures of GM cranks but both had Fluid's on them. He doesn't like fluids. He has out of 7 engines 2 left with GM steel cranks that he feels are on borrowed time after 6 years of torture.

Pulling the pans and checking the bearings will tell you the most. Having the cranks mag'd is a very good idea.

Re: How much HP/TQ will a GM Crank handle ?
 

Chris I tore them down from last years running . The bearings didn't show any signs of flexing from last years HP level. The bearings looked so good I reused them. I stepped it up a bit this time and plan on leaving it at that boost/HP level for this year.We made a few pulls at 11.5lbs and don't think it would last long there :eek:

Chris thanks for the hookup on the Balancers!!

Rob

Re: How much HP/TQ will a GM Crank handle ?
 

Your welcome....If I need a coffee table I'll be callin'

Re: How much HP/TQ will a GM Crank handle ?
 

I still like your belt tensioner better. My belt flaps pretty good .I figure Tickfaw and Royalpurple In Lousinia May and June

Emerald beach Poker run,Destin FLin August

I am waiting on the New B Max HT drives ..I have none now :( and we have a locall powerrun/party here that looks like I am going to miss.

Rob

Re: How much HP/TQ will a GM Crank handle ?
 

Rob,I don't personally know how much hp a stock 1053 gm crank will take BUT a few years ago I was at Baker Engineering in Nunica,Mi getting a circle track car chassis dynoed and they had at least 10 if not more gm bbc steel cranks lined up against the wall broken off clean on various rod journals. The shop manager told me that most of them were out of boat motors :eek: . What are you using for lifters,springs and rocker arms to crank your motor up to 6300? What kind of spring pressures? My motor is set to buzz to 6000 rpm's (limiter) but Tyler Crockett told me to try to stay below 5800 because Hyd roller cams didn't "like" the high rpm's. I have touched the rev limiter at 6000 when running a 30 pitch and it didn't seem any different than 5800,Smitty

Re: How much HP/TQ will a GM Crank handle ?
 

Chris,I have a friend who works on blown alcohol tractor pull motors,he was showing me how the 4340 steel cranks get little cracks in them (super high boost and rpm's). He claims they run them until they get a TON of little cracks in them then he claims they can still be used in a street motor or marine engine because the rpm's are lower and the harmonics are different but I can't imagine building a motor around a crank that is full of cracks,Smitty

Re: How much HP/TQ will a GM Crank handle ?
 

We use either Comp (I think 887x) or Crane 13532 lifters, Comp Pro Magnum or Crane gold rockers, Isky 8005A or Comp 929 springs, set up 150-160# on the seat. Have never seen valve float to 6500...but I think they are getting close there. Usually try to turn 61-6300 max. :drink: