Forged Crank

Mr.Spool

Well-Known Member
Joined
Nov 6, 2006
How many other cars have you had 900hp success with? T
actually ive been at this a long time and have set up several turbo buicks with multiple motors and cars making over 150hp per hole.i tuned a pretty nasty 109 tonight that is making big power as well.
 

Mr.Spool

Well-Known Member
Joined
Nov 6, 2006
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.
not of this matters a lick to racer or someone that wants to go fast,speed costs.there is no race warranty,no engine builder will give you one.
 

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.
no worries,thank you!the truth of it is alot of blind faith was given to those back in the day.then guys started testing and pushing things but the turbos and computers in reality just sucked compared to what is out there today.the auto correction and the data that can be obtained is just awesome.the cars are tuned better and the shocks and tire tech and drivetrain teck(driveshaft speed sensors,converters),with alcohol based fuels is incredible,thats how we are going faster, we know more ,can control more, and can apply more.i feel alot of guys on this board just dont understand about the new tech.
 

Mr.Spool

Well-Known Member
Joined
Nov 6, 2006
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.
its pretty neat and is alot of fun.
 

Mr.Spool

Well-Known Member
Joined
Nov 6, 2006
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.
remember no one is saying a forged crank is not stronger than a cast crank.what i am saying is that when the motor is built correctly for those components /tuned correctly,the op will be able to run his 10 sec passes without to much worry of hard parts failure.i really dont care which crank he uses,but people who think the stock cranks are weak are quite wrong ;)
 

TexasT

Texas, Where are you from
Joined
Sep 10, 2002
I think the reason I started the thread was to get some real world experience. The stock cranks aren't cheap and are getting long in the tooth. With the advent of the internal balanced chicom units it becomes much less of a spread in cost difference. The stock balancers and flex plates aren't new anymore either so if a guy was going to buy these things anyway , I think the forged stuff should get to the conversation.
The forged is stronger than stock. I don't think anyone will argue that( maybe they will, who knows) . But it is also more rigid and that to me is the thing I want to Include as that wiggling stock unit is what takes out the webs in the block in my opinion.
I do like all the discussion. I hope it helps more than just me. More thought is in order on my end. An engine will get assembled eventually or if one comes up that can be bought I would go that route. Time will tell.
 

Mr.Spool

Well-Known Member
Joined
Nov 6, 2006
But it is also more rigid and that to me is the thing I want to Include as that wiggling stock unit is what takes out the webs in the block in my opinion.
I don't hurt the webs in a stock block with a stock crank,you haven't been paying attention.put the summit 4140 in it like in your post,if the motor is built right and tuned correctly you wont have a problem for a long time,especially in the 10 sec range.
 

TexasT

Texas, Where are you from
Joined
Sep 10, 2002
I've read and reread this thread and others several times. I am paying attention. Bottom line is if I'm going to go hunting a crank and other parts, and it doesn't cost too much more, why wouldn't a guy upgrade? I have the rolled fillet main crank out of a 4.1L and another 4.1L that may or may not have that crank. The crank that may have both is in my og T and it is a running engine and not be taken apart to get the crank.
This leads me to aquiring a stock crank at $300 plus shipping or so from what I've observed in the market . This doesn't get a perfect crank and gets one of unknown history. This is the crossroad I'm at. If I already had the stock crank that would clean up at 10/10 or even 20 on either or both I could see dropping it in and running it. But I don't, so that is my conundrum at this point.
I appreciate all(yes, you too MrSpool) input.
And I encourage any and all additional experiences from all.
 

TexasT

Texas, Where are you from
Joined
Sep 10, 2002
I have the two 4.1 blocks. I have two cranks. I steady hunt for used stuff ( think 84-85 turbo blocks and cranks) but I like to think I'm frugal. So I don't pick up every last thing I come across as I don't have a place to put it or the time horizon to use it.
As we know those 4.1 blocks aren't as strong as the 3.8L production block. This is where the wiggling crank theory of mine come from. I don't think tuning is it will be my problem. If it is I'll learn. Possibly the hard way.
I'm not building a no time car that gets trailered and sees short stints of run time. It might get on a trailer but I don't have garage art. Mine will be driven.
Next over the top activity might be a half fill of the block to strengthen the webs on that 4.1. does it need it? Again , LOTS of opinions. I've been reading up and the decision hasn't been made yet. A lot of my stuff goes along with how much help I can get out of my son. I can't do all the things I used to. Even though I want to. So more equipment and such to make things easier. No more man handling stuff like I did. Body just can't take it.

I do like that this got to four pages of replies without boiling over. Good stuff!
 

Mr.Spool

Well-Known Member
Joined
Nov 6, 2006
Bottom line is if I'm going to go hunting a crank and other parts, and it doesn't cost too much more, why wouldn't a guy upgrade?
nothing wrong with any type of upgrade if you want it and can pay for it and want to wait for it,its still kind of america ;)
 

ronviper

Member
Joined
May 3, 2005
It's funny 30 plus years, the DFI compare to the FAST or HOLLEY etc which would you choose.
Thirty years plus cast crank, rods and hyper pistons compared to forged crank, rods and pistons which you choose.
The products produced today are better, you have to know how to tune with either choice, are tv's the same thirty years later, just food for thought.
 

ronviper

Member
Joined
May 3, 2005
Mr Spool technology moves forward with or without us, the stand alone computers are far superior to the eighties ecm.
We adapt or become dinosaurs, that is the world we live in.
 

Mr.Spool

Well-Known Member
Joined
Nov 6, 2006
Mr Spool technology moves forward with or without us, the stand alone computers are far superior to the eighties ecm.
We adapt or become dinosaurs, that is the world we live in.
im knee deep in all of it,but for a 10 sec buick you dont need much of it ;)
 

750H.P.V6

Brutal 6 Racing
Joined
Sep 4, 2001
Actually I would choose an axis extreme and a stock ecm.works awesome and will do 768 grams/sec off a maf.for 9/10 second passes it's a no brainer.
Sounds like I need to get rid of my XFI and go back to burning chips on my 386 25 like I did 20+ years ago.

Neal
 

Mr.Spool

Well-Known Member
Joined
Nov 6, 2006
Sounds like I need to get rid of my XFI and go back to burning chips on my 386 25 like I did 20+ years ago.

Neal
i gotta say im impressed with what eric has done with the chips.to be honest ive never really liked xfi,that may not make some people happy but one could argue xfi is old teck like those that feel about the stock ecm,i do really like the holley ive been spending alot of time with that system lately and its impressive,i dont have any experience with the gnecu so i will not comment,but there is lots of good stuff out there and it doesnt smack the wallet like a fuelteck.guys go fast on alot of different systems,better nowadays is how many inputs you have for data ;)
 
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