Crank and Block
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Actually the dealer was both right and wrong. The turbo cranks are discoontinued and when they look them up they will cross over to the N/A cranks. Thats why the dealer says they are the same part numbers.
Now while on this subject, has any one run a .040" over 109 block? Did it fail? If so would a .030" over block have done the same? I know it is not recomended but that is not my question. I can't see that taking .005" more out of the wall will cause ity to fail.
Now while on this subject, has any one run a .040" over 109 block? Did it fail? If so would a .030" over block have done the same? I know it is not recomended but that is not my question. I can't see that taking .005" more out of the wall will cause ity to fail.
Chris McDade
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Power source book
Guys,
Go look in the Buick Power source book. It clearly states that the cranks with the rolled fillets are stronger than the cranks without the rolled fillets. Buick has been running this crank with the rolled fillets on there race cars since the early 80's. Im sure that buick tested both of these cranks and thats way they stated what they did. Im sure that the NA crank is good , but how much stronger is the crank with the fooled fillets? I wonder if anyone has ever done a test on these crank besides Buick on the identical motors with identical tunning to see which one would last longer.
Just my 02 worth.
Later
Guys,
Go look in the Buick Power source book. It clearly states that the cranks with the rolled fillets are stronger than the cranks without the rolled fillets. Buick has been running this crank with the rolled fillets on there race cars since the early 80's. Im sure that buick tested both of these cranks and thats way they stated what they did. Im sure that the NA crank is good , but how much stronger is the crank with the fooled fillets? I wonder if anyone has ever done a test on these crank besides Buick on the identical motors with identical tunning to see which one would last longer.
Just my 02 worth.
Later
I don't think anybody here is trying to say the N/A cranks are stronger than the Rolled Fillet cranks. That trhe rolled fillets provide an added degree of security is for sure.
Personally, I guess what I really want to know is where the cranks that have failed actually failed.
Personally, I guess what I really want to know is where the cranks that have failed actually failed.
Why? Are you going to use a flux capacitor to "build-up" the crank in the weak spot? Are you going to turn off the fuel to the cylinders that are on the weak spot?
As many of us have stated, the NA cranks are weaker than the turbo cranks. There's nothing you can do to the crank to make it last longer (you can't cut the fillets, they are pressed in).
The rolled fillets are where the journals meet the counterweights. Putting two and two together, I'd say the fillets were probably added there because that is where the cranks were failing. I'm no engineer, I'm just applying common sense. Which in my case has been known to commonly be wrong
Originally posted by Scott231
Why? Are you going to use a flux capacitor to "build-up" the crank in the weak spot? Are you going to turn off the fuel to the cylinders that are on the weak spot?
As many of us have stated, the NA cranks are weaker than the turbo cranks. There's nothing you can do to the crank to make it last longer (you can't cut the fillets, they are pressed in).
The rolled fillets are where the journals meet the counterweights. Putting two and two together, I'd say the fillets were probably added there because that is where the cranks were failing. I'm no engineer, I'm just applying common sense. Which in my case has been known to commonly be wrong
You know, this is the third negative response to a post in this thread you've made. But you still haven't been able to answer anything. If you've broken a crank, please tell me how it broke. If you have not broken a crank, or you have nothing to contribute, then maybe you'd do well to keep your opinion to yourself. That you aren't an engineer is painfully apparent. I'm just looking for some real experiences, not your opinion on what you have heard.
Thanks.
Ummm...Ellis, I think you better settle down a little...Scott has been around these cars for a long time and I believe he is a founding member of the gnttype list(over 10 yrs now, if memory serves)...
There should be pics on www.gnttype.org of a broken crank...maybe do a search of DOTCC and see what comes up...DOTCC = Drive Over The Crank Club...
Scott has probably forgotten more about these cars than you can even begin to know about them...
There have been people that have ticked off very knowledgeable Turbo Buick gurus who won't even post answers to questions anymore, just for the very reason of the comments you just made about Scott...he is just telling you what he knows and has experienced/seen before...
Do a little research here on this BB(search feature) and on the gnttype site(READ IT!!!) before you ask a questions...Chances are real good that it has been answered before...
Flame suit on...
There should be pics on www.gnttype.org of a broken crank...maybe do a search of DOTCC and see what comes up...DOTCC = Drive Over The Crank Club...
Scott has probably forgotten more about these cars than you can even begin to know about them...
There have been people that have ticked off very knowledgeable Turbo Buick gurus who won't even post answers to questions anymore, just for the very reason of the comments you just made about Scott...he is just telling you what he knows and has experienced/seen before...
Do a little research here on this BB(search feature) and on the gnttype site(READ IT!!!) before you ask a questions...Chances are real good that it has been answered before...
Flame suit on...
- Joined
- May 26, 2001
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- 9,208
Scott, like everyone else is entitled to an opinion. His, like mine and others, is use the proper crank for a performance application.
Usually these "opinions" are based upon knowledge gained by personal experience and sharing from others. Right or wrong, I would like to know Scott's [and others] opinions as we do learn lots from them.
Do not know how experienced you are in motors and especially these turbo motors, but most of the time the crank does NOT break. It flexes, it distortes, it acts like a snake and does wierd things that are not explained in an analytical form. This results in damaged bearing and/or worse.
If you want an experienced answer, put in your non-turbo crank, run it in the 10's, and then we will all know what happens good or bad!
OK, EVERYONE TO YOUR NEUTRAL CORNERS!
Well, I am going to do that. I have a NA crank, that I am going to try to hit the 11s with. And, I am going to do it with rear tires that are skinnier than most of you have for front tires, which means that I am going to have to push a ton of weight alot harder near the end of the track, and alot less at the beginning. If I drive over something, I will let everybody in on it.
One question though. Will a girdle help out in areas that the crank is lacking? What I mean is:Will putting a girdle on the engine help to keep the crank from flexing? Any honest attempts to answer the question are welcome. Anyone that is going to get frustrated typing one up can turn off their set now. Thank you, and happy motoring!
Brian the unconventional kid.
Well, I am going to do that. I have a NA crank, that I am going to try to hit the 11s with. And, I am going to do it with rear tires that are skinnier than most of you have for front tires, which means that I am going to have to push a ton of weight alot harder near the end of the track, and alot less at the beginning. If I drive over something, I will let everybody in on it.
One question though. Will a girdle help out in areas that the crank is lacking? What I mean is:Will putting a girdle on the engine help to keep the crank from flexing? Any honest attempts to answer the question are welcome. Anyone that is going to get frustrated typing one up can turn off their set now. Thank you, and happy motoring!
Brian the unconventional kid.
Well, I'm not trying to get anybody PO'd. I'm just asking a question. Really, I have no desire to upset anybody. While Scott231 may be a long standing member, and have a lot to contribute, I have only really noticed his input on this thread. So the only thing I know about him is what I have seen here in the last 2 days. It's a first impression. Be that as it may, I'm not looking for a fight, just an honest opinion. I'm kinda like a 2 year old. "Because" has never satiated me.
I looked at the photos on the DOTCC on ttype.org, and while the pictures are pretty fascinating, it is hard to tell exactly how the crank failed. There are ways to describe a failure.
Let me take a minute to try to explain why I keep asking what appears to be such a pig-headed question:
The reason my curiosity is piqued on this is that the general consensus is that the rolled fillet cranks are stronger. However, cold rolled fillets are a means of introducing stress into a surface, which helps to minimize cracks forming and is a means of increasing fatigue life. Fatigue life is a duration thing, and relates to how long a part is expected to last (number of cycles) under a given load.
I asked a mechanical systems professor (he is also a PE) how the fillets increase ultimate strength. He thinks it has little to do with the ultimate strength of the part, and much more to do with the fatigue life. In fact, he thought the slightly smaller diameter of the rod throws on the crank may have an adverse effect on the ultimate strength of the part, but that would have to be measured to really know. He also said that the greatest stresses on a crankshaft will be concentrated on the main journal between the rod and the crank throws.
Anyway, if such is the case, it might be a much wiser allocation of funds to go for a girdle and/or billet main caps to prevent crank flex at the mains. Of course, this is only an idea. But everything starts somewhere. So, I asked about it.
Anyway, sorry for any ruffling of the feathers, but I don't really think it right to insult someone for asking something. I am a student, I am in my mid 20s, and I do have a lot to learn. But, I'm also very mechanically incliuned, I have built a couple of engines, and I have fixed a lot of problems on a lot of different systems, both mechanical and electric. I'm here to learn as I build up my GN drivetrain. I just like quantifiable information.
I looked at the photos on the DOTCC on ttype.org, and while the pictures are pretty fascinating, it is hard to tell exactly how the crank failed. There are ways to describe a failure.
Let me take a minute to try to explain why I keep asking what appears to be such a pig-headed question:
The reason my curiosity is piqued on this is that the general consensus is that the rolled fillet cranks are stronger. However, cold rolled fillets are a means of introducing stress into a surface, which helps to minimize cracks forming and is a means of increasing fatigue life. Fatigue life is a duration thing, and relates to how long a part is expected to last (number of cycles) under a given load.
I asked a mechanical systems professor (he is also a PE) how the fillets increase ultimate strength. He thinks it has little to do with the ultimate strength of the part, and much more to do with the fatigue life. In fact, he thought the slightly smaller diameter of the rod throws on the crank may have an adverse effect on the ultimate strength of the part, but that would have to be measured to really know. He also said that the greatest stresses on a crankshaft will be concentrated on the main journal between the rod and the crank throws.
Anyway, if such is the case, it might be a much wiser allocation of funds to go for a girdle and/or billet main caps to prevent crank flex at the mains. Of course, this is only an idea. But everything starts somewhere. So, I asked about it.
Anyway, sorry for any ruffling of the feathers, but I don't really think it right to insult someone for asking something. I am a student, I am in my mid 20s, and I do have a lot to learn. But, I'm also very mechanically incliuned, I have built a couple of engines, and I have fixed a lot of problems on a lot of different systems, both mechanical and electric. I'm here to learn as I build up my GN drivetrain. I just like quantifiable information.
you can draw your own conclusions, but until you have built a turbo motor and raced it, all your scientific conclusions are 100% worthless....
you are getting the benefit of many years actual racing experience here...not some classroom bench racer
quantify what you want, but do it in the real world...build your motor and run it fast and see what happens...then I guess you'll know? (and you won't have to ask us)
you are getting the benefit of many years actual racing experience here...not some classroom bench racer
quantify what you want, but do it in the real world...build your motor and run it fast and see what happens...then I guess you'll know? (and you won't have to ask us)
Fair enough Ellis...
To answer one of your questions...The rolled fillets are a "type" of forging process that is done to the cranks...It compresses the grain of the material and makes it more dense and stronger in that area...The crank is only as strong as the radius on a non-rolled fillet crank and the rolled fillet on the turbo cranks is what gives it it's strength...I have a lot of hands on practical experience with this area since I am a machinist and machining huge printing press rollers that have small journals need a radius in the corners to give the bearing journal strength to keep it from bending...
Now to get a non-turbo crank to be as strong as a turbo crank, you would have to increase the size of the radius that is ground into the corner of the journal, but doing that would decrease your bearing width which is not the best thing to do on a high horse/high torque motor...The only way to increase the strength of the non-turbo crank, but yet keep the bearing width wide enough to take the loads is to pressure roll(tons and tons of pressure) the fillets at the corners of the journals...
Now keep in mind that ALL production crankshafts are a nodular cast iron material, not a forging...The only kinds of cranks that are stronger than the production turbo crank, are an aftermarket forged crank(if there even are any for the 3.8L V6) and an aftermarket billet steel crank...Since the mains were already being pressure rolled, it is only just another setup to have the rod journals pressure rolled...
In my opinion, but never having seen a non-turbo crank broken in half, other than the DOTCC pics, I would think that the non-turbo crank would break at a rod journal, since it doesn't have the pressure rolled fillets AND the rod journals are a smaller diameter than the mains, which makes it weaker at that point anyway...Also, if it does break, it will almost always break at the corner of the journal and not in the middle of the journal unless there is already some type of stress crack, fracture, or an imperfection in the casting elsewhere...
Hopefully this answers some of your questions...
To answer one of your questions...The rolled fillets are a "type" of forging process that is done to the cranks...It compresses the grain of the material and makes it more dense and stronger in that area...The crank is only as strong as the radius on a non-rolled fillet crank and the rolled fillet on the turbo cranks is what gives it it's strength...I have a lot of hands on practical experience with this area since I am a machinist and machining huge printing press rollers that have small journals need a radius in the corners to give the bearing journal strength to keep it from bending...
Now to get a non-turbo crank to be as strong as a turbo crank, you would have to increase the size of the radius that is ground into the corner of the journal, but doing that would decrease your bearing width which is not the best thing to do on a high horse/high torque motor...The only way to increase the strength of the non-turbo crank, but yet keep the bearing width wide enough to take the loads is to pressure roll(tons and tons of pressure) the fillets at the corners of the journals...
Now keep in mind that ALL production crankshafts are a nodular cast iron material, not a forging...The only kinds of cranks that are stronger than the production turbo crank, are an aftermarket forged crank(if there even are any for the 3.8L V6) and an aftermarket billet steel crank...Since the mains were already being pressure rolled, it is only just another setup to have the rod journals pressure rolled...
In my opinion, but never having seen a non-turbo crank broken in half, other than the DOTCC pics, I would think that the non-turbo crank would break at a rod journal, since it doesn't have the pressure rolled fillets AND the rod journals are a smaller diameter than the mains, which makes it weaker at that point anyway...Also, if it does break, it will almost always break at the corner of the journal and not in the middle of the journal unless there is already some type of stress crack, fracture, or an imperfection in the casting elsewhere...
Hopefully this answers some of your questions...
Steve Wood
Active Member
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- Jul 18, 2001
- Messages
- 2,338
The Power Manual says that a cast crank with filets is good for up to 400 hp with excellent reliability. I believe they meant for near continuous duty such as road racing and higher rpms.
Our experience over the years would suggest to me that in our applications, they are pretty reliable to somewhere around 530-540 hp as long as the rpms stay in the lower 5000's. Beyond that, a girdle is required due to the walking, wiggling of the crank. Steel mains probably add to the equation but I think the girdle is the primary benefit.
Altho the Buick engineers that designed these engines may not have been the best, they were the guys who were pulling more hp per cubic inch than all the v8s of the period so they musta known a little bit about what they were working with.
I find the economics strange in that someone is willing to try to go tens on a crank that is known to be lesser in strength. The last time I blew an engine, it cost several thousand dollars to replace. I don't see the point in saving two hundred dollars on a crankshaft. I guess each generation has to learn on its on but I will follow the experience of those that laid the trail before me in this case.
Our experience over the years would suggest to me that in our applications, they are pretty reliable to somewhere around 530-540 hp as long as the rpms stay in the lower 5000's. Beyond that, a girdle is required due to the walking, wiggling of the crank. Steel mains probably add to the equation but I think the girdle is the primary benefit.
Altho the Buick engineers that designed these engines may not have been the best, they were the guys who were pulling more hp per cubic inch than all the v8s of the period so they musta known a little bit about what they were working with.
I find the economics strange in that someone is willing to try to go tens on a crank that is known to be lesser in strength. The last time I blew an engine, it cost several thousand dollars to replace. I don't see the point in saving two hundred dollars on a crankshaft. I guess each generation has to learn on its on but I will follow the experience of those that laid the trail before me in this case.
Yes, that is the primary benefit of a girdle (secondary benefit is to strengthen the block itself). A girdle can be installed with stock main caps, that are in good condition and will be almost as strong as the same setup with steel caps.
I went to the steels because 2 of my 3 front main caps were horseshoe-shaped.
Not to be a smart a$$ but if you can't afford the better crank, you cannot afford to be racing.
If it decreases the risk of catastrophic failure, then why wouldn't you buy the better piece? Cheap insurance.
I have run 11.62 @119 with a NA crank and only had a thrust bearing failure. We did not know it was a NA crank as I bought the engine complete and the seller was unaware that it was rebuilt.
.030 girdled stock block ported irons steel caps #2 and 3
Ran 10.37 @ 128.3 MPH yesterday with a 1.38 60' on the trans brake.
I would agree with your opinion on the .005 not making much difference. I would do it before I threw the block away, but wouldn't spend the $$ to put the girdle on a .040 block.
I will be at Norwalk
Intercooler
New Member
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- May 24, 2001
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- 3,534
Was this for me?
Well if it was, the NA crank was "the only" thing I could find at the time, period! The .010"/.030" was in my old motor when I bought the car. Like I said, no problems with any of them! There is no gurantee that a std./std., .010"/.010" or any combo will be a cut above any of the other combos. If you run it properly and it has been checked I don't think it matters one way or the other. The NA crank is definately not my choice but if that was the only thing I had to run I probably would and hope for the best but I was only talking a 12.8 car anyways. As far as not buying the better piece, where is your forged unit? That would make a much better "race" piece-eeeeh? Racing is racing and you takes your chances!Similar threads
