Forged Crank

TexasT

Texas, Where are you from
Joined
Sep 10, 2002
No doubt. I don't want to stir up any, I just wanted to get opinions and some real world experience from people who have or haven't gone this route and if they wanted to elaborate that is great too.
I am a budget guy but I am not afraid to drop some coin if it is warranted. I have Snap on and other truck brands in my box, but there are a bunch of chicom tools too. I don't like to overspend just to have something. It has to provide value. And if this forged route is justified in my mind I'll do it. If not I'll go with stock.
 

434nova

Active Member
Joined
Sep 30, 2013
Makes me really reconsider the forged crank and just go with a couple billet center caps, have it align bored and go with the stock stuff. 30yrs old stuff is still plenty tough as evidenced by some of the numbers guys are putting down. I'm not on a over the top on he edge unit. I'm not in my twenties out on the street every weekend or at the track like I was back then . Mostly I just want to be able to drive it and have it be reliable . I'm not out coyote or hellcat hunting. Just want to cruise and be able to make some passes when I feel like it. But it will get some boost and the e85 to support it. Which means fuel system so there is that expense too.
I would at the very least put a forged piston and do 2 center billet caps. If your not on Facebook there are a lot of guys running low 10s and even 9s now with stock crank and rods. Some are even running little 62mm turbos. Spend your money on a good fuel system and get someone who can tune. That’s what’s gonna make it survive. Good luck.
 

dynoman

Well-Known Member
Joined
Nov 30, 2009
3700lbs , stock crank with 3 biilet caps , stock rods , Diamond pistons , on E85 and I've been low 10's for 4 years now . A properly clearanced build , a good tune and no detonation is what it takes to make your motor live .
 

Mr.Spool

Well-Known Member
Joined
Nov 6, 2006
I understand the lure of a $500 forged crank but as above that is just the starting point. Then comes the balancer and flex plate to balance that internal unit so we are closer to a grand than not with tax and shipping . Then comes the actual balance job. As the while we are there gets going with forged pistons and new rods. So there we get it to two grand or $2500 and we haven't bought any crank or rod bearings, had the block vatted and checked, and some cam bearings and freeze plugs installed.
Gasket set, hg, and a valley pan for another hunski or two. Then a cam. Roller you say? There is another grand. Where are we? Five large or so and we haven't even seen that the block has the thickness in the cylinder walls with a sonic check.
And it spirals on.
For 10s,you dont need anything special,small turbo,you could just do it on a stock shortblock and put the car on a diet and run a stock ecm.but I like compression/caps,re bearing it with the right clearances,mild cam good spring pressures and ported iron heads.fuel system and tune.suspension and a diet goes a long way.it still wont be cheap.in the end you will either have a more or less expensive 10 sec car.
 

Mr.Spool

Well-Known Member
Joined
Nov 6, 2006
M
No doubt. I don't want to stir up any, I just wanted to get opinions and some real world experience from people who have or haven't gone this route and if they wanted to elaborate that is great too.
I am a budget guy but I am not afraid to drop some coin if it is warranted. I have Snap on and other truck brands in my box, but there are a bunch of chicom tools too. I don't like to overspend just to have something. It has to provide value. And if this forged route is justified in my mind I'll do it. If not I'll go with stock.
Mag the stock crank and send it
 

SCOOBY DOO

I'M NOT A MONSTER, I'M JUST AHEAD OF THE CURVE!!!
Joined
Feb 18, 2007
Being an automotive machinist by trade and racing every weekend for 17 years, you can run into the 10's on a stock crank all day...if built correctly...and ZERO KR. Mag the crank and the rods and have a BUICK builder do the machining and short block build. Throw a couple of billet center caps on it. Grumpy ran bottom 10's for years and into the 9's on a 20/30 stock crank.
 

ttypewhite

Well-Known Member
Joined
Oct 1, 2001
To the OP's question. I ran 9.94 back in 2009 in a full weight T-type with my 109 block, stock crank, stock rods and a J&E piston with steel caps. The block imo is the strongest of the 3, the 3 being crank,rods and the block itself. Since you're already looking at a forged crank, I would put a forged rod and piston in it as well as Neal had mentioned. There is no downside of having it in there, and gives you more latitude moving forward if you plan to go faster. As I have said many times before, time isn't friendly to anything. Add 35 years on yourself and you will see what I mean. The dollar bill shouldn't always dictate your build. I don't care who you are, it takes money to go fast. Period. But it would cost more than $1000 if anything gives up the ghost too... Bragging rights are always fun until there not and you have to do it again.
 

TTipe

Snake Skinner
Joined
Jul 25, 2008
The Buick engine mentally has changed ( for the better??) over the years. No one in the Buick community can examine a crankshaft / block casting for inclusions. If money is the concern the forged crank comes 1st after a magnafluxed, sonic checked, pressure check block. Deck & bore wall thicknesses are not consistent across the bore walls (as an example). I like verification in the bore quadrants in the stroke zone of the bore wall. You will reduce / eliminate any flexural moments going forged in the crank vs cast. The performance endurance limit of a cast iron crank is finite ( high nodularity is better) vs forged steel crank being infinite. The oil circuit of the passenger car block & cast crank has always been a place to be cautious about . A well prepared block oil circuit is necessary to survive (break as many sharp edges as possible) for stable oil flow. If the bearing oil wedge is too thin, then failure. Engine front covers (oil pump) were qualified for LC2 use or not (volume / pressure). Those that did not meet the requirements were used in the NA engines. The energy trend from a combustion cycle in a turbocharged engine is round at the top vs a high compression NA engine which resembles a cusp. The round energy trend of the turbo is favorable (like a push vs a slap). Engine management has greatly improved so a knock retard signal to a current engine management system may save an engine from hard part destruction (provided calibration is sound). The saddle (where a lot of destruction takes place) has not been addressed. If people would put the time into support / fuel systems (gas /alchy) their engines would last longer. The reduction of unnecessary forces indirectly related to proper combustion (ie off center rod orientation, internal vs external balance, excessive valve spring pressures, balancer slippage etc.) will add to engine longevity. Is the pay back from the extra expense worth it? In some cases yes, others no. We don't know the absolute health (ie inclusions etc) of our engine blocks cranks other than maybe miles on the odo. How long will my mill live given the beatings I subject it to. Am I happy getting an 11 sec time slip or must I venture to the track every weekend to get that 9 sec timeslip while my guts rumble about getting my car home after a bad day. Then we go down the wallet hole. I'm not so confident about something so I spend more money to protect what I have previously spent considering my goals. This just repeats.
(1 Build the best engine for your budget and work with the engine builder. Assume nothing. Take your own measurements. The Buick Power Source Manual & some others { This Board} can be helpful.
(2 Fuel the car such that your supply is greater than demand.
(3 Calibration is critical. Pay for good help. Good help may cost 1k as opposed to 8k for a new engine.
(4 Pursue your goals slowly & document / data log. Greed will take you to the dark side.
(5 Seat time!
 

Mr.Spool

Well-Known Member
Joined
Nov 6, 2006
I would at the very least put a forged piston and do 2 center billet caps. If your not on Facebook there are a lot of guys running low 10s and even 9s now with stock crank and rods. Some are even running little 62mm turbos. Spend your money on a good fuel system and get someone who can tune. That’s what’s gonna make it survive. Good luck.
Exactly
 

Nigel

Well-Known Member
Joined
Jun 16, 2001
The Buick engine mentally has changed ( for the better??) over the years. No one in the Buick community can examine a crankshaft / block casting for inclusions. If money is the concern the forged crank comes 1st after a magnafluxed, sonic checked, pressure check block. Deck & bore wall thicknesses are not consistent across the bore walls (as an example). I like verification in the bore quadrants in the stroke zone of the bore wall. You will reduce / eliminate any flexural moments going forged in the crank vs cast. The performance endurance limit of a cast iron crank is finite ( high nodularity is better) vs forged steel crank being infinite. The oil circuit of the passenger car block & cast crank has always been a place to be cautious about . A well prepared block oil circuit is necessary to survive (break as many sharp edges as possible) for stable oil flow. If the bearing oil wedge is too thin, then failure. Engine front covers (oil pump) were qualified for LC2 use or not (volume / pressure). Those that did not meet the requirements were used in the NA engines. The energy trend from a combustion cycle in a turbocharged engine is round at the top vs a high compression NA engine which resembles a cusp. The round energy trend of the turbo is favorable (like a push vs a slap). Engine management has greatly improved so a knock retard signal to a current engine management system may save an engine from hard part destruction (provided calibration is sound). The saddle (where a lot of destruction takes place) has not been addressed. If people would put the time into support / fuel systems (gas /alchy) their engines would last longer. The reduction of unnecessary forces indirectly related to proper combustion (ie off center rod orientation, internal vs external balance, excessive valve spring pressures, balancer slippage etc.) will add to engine longevity. Is the pay back from the extra expense worth it? In some cases yes, others no. We don't know the absolute health (ie inclusions etc) of our engine blocks cranks other than maybe miles on the odo. How long will my mill live given the beatings I subject it to. Am I happy getting an 11 sec time slip or must I venture to the track every weekend to get that 9 sec timeslip while my guts rumble about getting my car home after a bad day. Then we go down the wallet hole. I'm not so confident about something so I spend more money to protect what I have previously spent considering my goals. This just repeats.
(1 Build the best engine for your budget and work with the engine builder. Assume nothing. Take your own measurements. The Buick Power Source Manual & some others { This Board} can be helpful.
(2 Fuel the car such that your supply is greater than demand.
(3 Calibration is critical. Pay for good help. Good help may cost 1k as opposed to 8k for a new engine.
(4 Pursue your goals slowly & document / data log. Greed will take you to the dark side.
(5 Seat time!
Some cool history with engineering justification. Thanks for posting!
 

TTipe

Snake Skinner
Joined
Jul 25, 2008
Please recall, both Duttweiller & Ruggles would support a 500 fwhp limit on the main & rod rolled fillet stock crank. That's a high 10 sec et in the average weight car. The impression I got from Ruggles was 500 fwhp at the high end Jim Ruggles would use parts sent from Powertrain engineering (new parts) not seasoned parts for dyno testing. The crank & rod pin cranks are the subject of this remark. The 4.1 rolled fillet main (no rolled fillet rods) will not perform the same job as the turbo specific crank ( main & rod rolled fillets). ARP rod bolts will out perform the SPS rod bolts (provided you don't get a butt welded bolt-inspect your parts!) . Beaming / bead blasting the rod beams will improve longevity by reducing stress risers. Break the sharp edges on the crank counterweights as well. Obviously a lighter piston, piston pin & a properly balanced rotating asm will reduce the forces exerted on the crank.
 

Mr.Spool

Well-Known Member
Joined
Nov 6, 2006
Please recall, both Duttweiller & Ruggles would support a 500 fwhp limit on the main & rod rolled fillet stock crank. That's a high 10 sec et in the average weight car. The impression I got from Ruggles was 500 fwhp at the high end Jim Ruggles would use parts sent from Powertrain engineering (new parts) not seasoned parts for dyno testing. The crank & rod pin cranks are the subject of this remark. The 4.1 rolled fillet main (no rolled fillet rods) will not perform the same job as the turbo specific crank ( main & rod rolled fillets). ARP rod bolts will out perform the SPS rod bolts (provided you don't get a butt welded bolt-inspect your parts!) . Beaming / bead blasting the rod beams will improve longevity by reducing stress risers. Break the sharp edges on the crank counterweights as well. Obviously a lighter piston, piston pin & a properly balanced rotating asm will reduce the forces exerted on the crank.
500hp for a stock crank?that's just not what I have done or seen,I have seen guys with forged everything crack cranks cause they dont tune correctly.i have posted many times how I have made 900+hp on a stock crank,and not just on 1 motor.the blocks crack before the stock crank does if its build a certain way with the right tune up.
 

1986 Buick GX1

GX1 #001 [The One and Only]
Joined
Apr 24, 2015
500hp for a stock crank?that's just not what I have done or seen,I have seen guys with forged everything crack cranks cause they dont tune correctly.i have posted many times how I have made 900+hp on a stock crank,and not just on 1 motor.the blocks crack before the stock crank does if its build a certain way with the right tune up.

I remember reading in the GS-XTRA news letter in the ‘90’s that 500 fwhp was the limit on the stock crank as well, although I don’t remember who the article was by.
I also remember when it was thought that anything over 23 psi boost was guaranteed head gasket replacement.
Maybe tuning knowledge wasn’t what it is today?

900+ fwhp on the stock crank seems outrageous to think, but like you say, with proper prep and tune you’re proving otherwise.
 

Mr.Spool

Well-Known Member
Joined
Nov 6, 2006
I remember reading in the GS-XTRA news letter in the ‘90’s that 500 fwhp was the limit on the stock crank as well, although I don’t remember who the article was by.
I also remember when it was thought that anything over 23 psi boost was guaranteed head gasket replacement.
Maybe tuning knowledge wasn’t what it is today?

900+ fwhp on the stock crank seems outrageous to think, but like you say, with proper prep and tune you’re proving otherwise.
I'm not going to get into what's involved in making 150hp+hp per hole,but tuning is just so critical.the data nowadays is key to making power and having the car live.
 

Nigel

Well-Known Member
Joined
Jun 16, 2001
500hp for a stock crank?that's just not what I have done or seen,I have seen guys with forged everything crack cranks cause they dont tune correctly.i have posted many times how I have made 900+hp on a stock crank,and not just on 1 motor.the blocks crack before the stock crank does if its build a certain way with the right tune up.
The thing is the factory would have used average material properties (or maybe a more conservative set or properties based on how many failures they would have thought acceptable), which accounts for defects like inclusion, porosity, variation in the casting process and machining process... And then depending on inspection methods and expected escaped defects, would try to develop something that supported making money with an acceptable risk of failures. So obviously we get a variation in factory parts (is probably quite large), and some parts will tolerate more abuse then others.

The other thing is, would cracks show up in the block at the same locations and at the same power levels if a forged crank was used instead of the cast crank all else being equal? Not something practical to test, just something that would be interesting see what various configurations can handle and where the weak spots are.

The one big benefit of a forged piece over a cast piece, so long as it is done correctly, because anything can be done cheap and be junk, is the forged steel is going to have better material properties and less material defects just because of the process used to make a forging over a casting. Chance of an inclusion is an order of magnitude smaller for forged vs cast, much better fatigue strength, yield strength, larger elastic strain range....

Hot rodding is about innovation and extracting what you want out the machine, so I don't think anyone is being critical of your work. That is pretty cool extracting that kind of power out of the stock stuff. Each individual has to evaluate their goals and decide on what the appropriate level of risk is for what they want to do. The engineering and the physics, along with the way the factory would have evaluated the stock parts, would point someone to use a forged crank for elevated power levels. For your goals, skill set, and risk tolerance, the factory stuff obviously is working. It is also a testament to the conservative nature (at least back then) that GM used to evaluate and rate the capability of their parts.
 

TTipe

Snake Skinner
Joined
Jul 25, 2008
500hp for a stock crank?that's just not what I have done or seen,I have seen guys with forged everything crack cranks cause they dont tune correctly.i have posted many times how I have made 900+hp on a stock crank,and not just on 1 motor.the blocks crack before the stock crank does if its build a certain way with the right tune up.
I don't wish to argue with anyone regarding the performance of critical parts which are not well documented. Tuning, machining & preparation of hard parts has come along way since 1986. I'm just relating what was said by by the best with documented proof (dyno testing) back in the day. Your comments are well taken & I applaud your efforts. The origins of the crank / block are not known & verified (characterized & documented against other typical samples). The first engine in my car failed due to an assembly / machining error from the engine plant (fact 36) at 37k miles. It was replaced by a known / documented engine. My failed engine was considered an "out lier" in terms of of a statistical study that compared other documented unopened engines on a bell curve. It had a stock calibration & ran 93 / 94 octane unleaded gas. Proper crank preparation & reciprocating asm re-think well beyond that of a stock crank is required. I believe lighter pistons / pins, ARP rod bolts, beaming / bead blasting conn rods & proper asm balancing gets measurable durability improvements. Knock detection / spark retard / attack rate changes were primitive years back. We had no means of separating white noise from true knock in days of yoar. Due to lack of mechanical / thermal efficiency we had to chase torque via excess spark advance / & race fuel. Major improvements in air distribution & controlled "booze shooting" gets people around the "well it was only 2 deg of knock" syndrome. I would be curious to understand how you prove the power of your engine/s to your observers (hand calculations, vehicle dyno / engine dyno) or the "i put him on the trailor" method. Is your recipe one that you might share with others? How many other cars have you had 900hp success with? The engine supporting conditions / hardware / software / fueling have improved over the last 30+ years eliminating unpredicted shock loads to the engine components. Those components ( blocks, cranks etc.) were not as well developed as today. I can't warranty vehicles running on 93 r+m/2 pump gas, meet emissions or afford credits running the stock crank (LC2) at 500 fwhp. Knowledge & capability grows with necessity & experimentation. Same thing with blocks. Some live longer than others at elevated power due to preparation / controls / or just a stone stock car. Bottom line , you can't sell cars to the public and tell them they are out of warranty because they made more than 200 passes in the 1st year of ownership.
 

TTipe

Snake Skinner
Joined
Jul 25, 2008
The thing is the factory would have used average material properties (or maybe a more conservative set or properties based on how many failures they would have thought acceptable), which accounts for defects like inclusion, porosity, variation in the casting process and machining process... And then depending on inspection methods and expected escaped defects, would try to develop something that supported making money with an acceptable risk of failures. So obviously we get a variation in factory parts (is probably quite large), and some parts will tolerate more abuse then others.

The other thing is, would cracks show up in the block at the same locations and at the same power levels if a forged crank was used instead of the cast crank all else being equal? Not something practical to test, just something that would be interesting see what various configurations can handle and where the weak spots are.

The one big benefit of a forged piece over a cast piece, so long as it is done correctly, because anything can be done cheap and be junk, is the forged steel is going to have better material properties and less material defects just because of the process used to make a forging over a casting. Chance of an inclusion is an order of magnitude smaller for forged vs cast, much better fatigue strength, yield strength, larger elastic strain range....

Hot rodding is about innovation and extracting what you want out the machine, so I don't think anyone is being critical of your work. That is pretty cool extracting that kind of power out of the stock stuff. Each individual has to evaluate their goals and decide on what the appropriate level of risk is for what they want to do. The engineering and the physics, along with the way the factory would have evaluated the stock parts, would point someone to use a forged crank for elevated power levels. For your goals, skill set, and risk tolerance, the factory stuff obviously is working. It is also a testament to the conservative nature (at least back then) that GM used to evaluate and rate the capability of their parts.
Nigel a high percentage of block failures occur at the #3 journal web. Oil wedge thickness / trash are a likely factors along with crank flex & torsion. In my opinion no knock, no damage. I don't believe we detect / react to all occurances of knock. I used to race in the early 90's at engineer shoot outs (GM, Ford, Chysler) & run cam 2 purplle (110??) at 36 deg and never had a failure. Very little work done to the car. My Regal went 12.01 @ 117.5 in 95 deg F without issue. Forgot to mention 2,12 60 ft. Calibration & supporting hardware, improvement of induction efficiency & torque converters have changed the playing field. Oil circuit relieving / pump clearancing obviously helps.
 

Mr.Spool

Well-Known Member
Joined
Nov 6, 2006
I don't wish to argue with anyone regarding the performance of critical parts which are not well documented. Tuning, machining & preparation of hard parts has come along way since 1986. I'm just relating what was said by by the best with documented proof (dyno testing) back in the day. Your comments are well taken & I applaud your efforts. The origins of the crank / block are not known & verified (characterized & documented against other typical samples). The first engine in my car failed due to an assembly / machining error from the engine plant (fact 36) at 37k miles. It was replaced by a known / documented engine. My failed engine was considered an "out lier" in terms of of a statistical study that compared other documented unopened engines on a bell curve. It had a stock calibration & ran 93 / 94 octane unleaded gas. Proper crank preparation & reciprocating asm re-think well beyond that of a stock crank is required. I believe lighter pistons / pins, ARP rod bolts, beaming / bead blasting conn rods & proper asm balancing gets measurable durability improvements. Knock detection / spark retard / attack rate changes were primitive years back. We had no means of separating white noise from true knock in days of yoar. Due to lack of mechanical / thermal efficiency we had to chase torque via excess spark advance / & race fuel. Major improvements in air distribution & controlled "booze shooting" gets people around the "well it was only 2 deg of knock" syndrome. I would be curious to understand how you prove the power of your engine/s to your observers (hand calculations, vehicle dyno / engine dyno) or the "i put him on the trailor" method. Is your recipe one that you might share with others? How many other cars have you had 900hp success with? The engine supporting conditions / hardware / software / fueling have improved over the last 30+ years eliminating unpredicted shock loads to the engine components. Those components ( blocks, cranks etc.) were not as well developed as today. I can't warranty vehicles running on 93 r+m/2 pump gas, meet emissions or afford credits running the stock crank (LC2) at 500 fwhp. Knowledge & capability grows with necessity & experimentation. Same thing with blocks. Some live longer than others at elevated power due to preparation / controls / or just a stone stock car. Bottom line , you can't sell cars to the public and tell them they are out of warranty because they made more than 200 passes in the 1st year of ownership.
I will elaborate to a certain point,because my car is a nt car,I spent the day at the racetrack,and we are headed to the streets later.i will get back to this thread when I can,just didnt want to leave you hanging.
 

Mr.Spool

Well-Known Member
Joined
Nov 6, 2006
I would be curious to understand how you prove the power of your engine/s to your observers (hand calculations, vehicle dyno / engine dyno) or the "i put him on the trailor" method.
some guys take there car to the track,some to the street,some to the dyno,in the end,elapsed time/ mph and the weight of the car is the best way to really prove a cars.as a racer who does his own tuning it takes x amount of fuel to support x amount of horespower,and im less of a fan of the dyno these days knowing how it truly works or shall i say doesnt work in giving a true read of power,although it does have its uses.as a racer/driver putting someone on the trailer is huge,power to weight ratio and balance of the car with the right suspension and travel in concert with engine power that can be moved around by boost controllers and co2 gates and the ability to move the timing around so much more makes for a faster car!street or track.
 

Mr.Spool

Well-Known Member
Joined
Nov 6, 2006
Is your recipe one that you might share with others?
not really,i run a nt car and i see no reason to release my combo.i will say data and testing are huge,this is where most fall short,they throw parts at the car and dont drive,race,or test to make a faster car.
 
Top