sugarsn10

iTrader: (2)

I know this is not exactly the correct place to post this, but I feel it has a better chance here than the classifieds because of the particular scenario.

I am in college studying material science, and am currently taking a metallurgy class and have to do 1 large semester project. I want to analyze the different materials used in sbc crankshafts. I have a couple gm cast cranks covering a range of about 30 years which i plan on testing. I also have a forged Scat crankshaft that is cracked. This is going to be the least important piece to study since it is forged and all of the others will be cast, but if time permits it would be interesting to get tensile tests on all samples.

The point of this post is that I am looking for junk Scat and Eagle cast cranks. I've been looking around for a while and even contacted Scat to see if they were interested in getting me a defective part for testing, but said they couldn't. I really want to see how the composition and properties of the different manufacturer's materials differ. If anybody has, or knows someone that has a junk aftermarket crank from either company, I'd be willing to give some amount of compensation in addition to shipping in return for an unusable crankshaft. Since I can't seem to get any manufacturer support for samples, I am planning on publishing this to the public for everyone to see what these manufacturers are really doing and how they rank competitively.

86LG4Bird

iTrader: (1)

I like this. I'm going to link this post to a couple of other "SBC" forums.

cuisinartvette

Lots of builders over on speetalk. com
Mfrs too so be careful on your wording to stay outta trouble on your findings. Would be interesting to read anyway

Know more than just metallurgy can bust cranks.

Interesting project. Try some local rebuilders?

Love to see the same thing done on various aftermarket heads esp the cheap ebay junk out there.

OrangeBird

iTrader: (1)

The way this sentence reads , it sounds as if the manufacturers may have already read your ulterior motive , and want no part of you . This sounds more like those TV reporters who are just dying to expose the next big scam rather than some college student intent on studying , and possibly improving , a vital engine component . Loose the vengeful attitude ( "since they won't help me , I'll air their dirty laundry" ) and you may find more cooperation ....

Good Luck ...

sugarsn10

iTrader: (2)

I appreciate all of the comments and help in getting the word out about my project. I completely agree with the idea that my wording was a little off. The idea I was trying to get across is that I want to show what the true differences from a metallurgical standpoint are. I don't feel that any company is running a scam. I am interested to see what kind of alloy these cast steel crankshafts are since there seems to be no information on that. Scat just calls it their "space-age 9000 material", which sounds like a lot of marketing hype to me even though I respect their product and even have one in my own engine. I also agree that there are many other factors that go into why crankshafts fail, but the composition is a big factor along with type of processing and design.

I was planning on from the beginning to supplying my findings to anyone interested unless I received a sample from a company who didn't want the results of their products shown to the public. I even offered to provide them with the results of my study if it interested them. Since I didn't receive any samples from any companies, I'm not really concerned with how they feel about me supplying this information since I have no obligation to them.

1gary

The thing is those companies already know(I would hope they do)where their products rank.GM brand or for that matter any aftermarket company might challenge your test results and testing methods...........................in court!!!.$$$$

You can be sure you have my 150% support.I have carry this cross about low dollar companies and their cranks for a very long time.Eagle's machining practices have left many a consumer with some very hard realities once they tried to use their products and did/do have history of cracking/breaking behind number 2 main journal.This play on words of "cast steel" is at the very least irritating.I have devoted a better part of my whole life to hot rodding and engine building and hate the idea of consumers being taken a advantaged of.I believe from the top of my head to the tip of my toes one of the core values of hot rodding that built it to what it was,is honestly and hard work.

What has transpired in the hot rod industry is none of these low dollar companies producing their own foundation cores.Yeah,I know,that fact is well know,but worth saying.But you combine that with not even being involved at all with QC and just being wholesaler,orders and cash in,product out the door,it leaves end users in one hell of a bad place.

What's in a name or branding??. Nothing really. Time and again once a name gets a proven bad rep,it closes that name down and shows up with a different name.No consequences aside from the lost of marketing money. Changes to correct the problems,usually bare minimum if at all.

So I'll get off this rant.I suggest you try to ask around some of the oval track machine shops to see if they have any defective products.I too would like to see your slant on testings,but that said,I don't want to suggest you become the sacrificial lam for my entertainment in this sue fest times we live in and suggest before you post/state your results,contact a lawyer to talk about the liability those findings might have on you.


BTW-thanks for you efforts on this topic.

What often comes to mind when I think of these business practices is "strip mining" grabbing as much profit as possible and leaving a mess behind.

sugarsn10

iTrader: (2)

Thanks for the tips and support 1gary. I definitely want to make sure that if I do share this information that I do it without getting into trouble or stepping on anybody's toes too much.

I definitely agree that the outsourcing of casting and forging operations has resulted in poor QC. It doesn't matter how well you control the quality of your machining if the material is defective. You can get a brand new part that looks pretty and even has beautiful tolerances, but if the composition is defective to the point of premature failure the product is flawed.

As I stated before, I don't want want this study to take into account design or machining quality, but purely the quality of materials used. I want it to be as scientific and unbiased as possible. I don't want to make any conclusions other than what the composition is and what the properties of it are. If the companies have an issue with CONSUMERS knowing what material they are buying, then I guess I have to rethink my idea of consumer rights.

HINKSON AUTO

I have always wanted to do what your doing testing the Scat and Eagle against the OEM cast GM crank.

I did some research on the Chinese dart look alike block that PBM tried to scam everyone say it was a high nickel and high density block only to find out it was junk after my testing.

Here are some links may want to look over.

http://speedtalk.com/forum/viewtopic...er=asc&start=0

Material make up

http://speedtalk.com/forum/viewtopic.php?f=1&t=18750

Final probing

http://speedtalk.com/forum/viewtopic...er=asc&start=0

Keep us posted on your results

I build a lot of circle track engines and about 15 years ago I tried the Scat cast crank and had 5 of them fail every one broke in the same spot, Right in the middle. A shop right near me had the same results. The GM crank never broke but would show cranks after a couple of years if racing.

Went to forged cranks and so far no issues.

InfernalVortex

iTrader: (4)

Have you considered evaluating the high nickel block myth? Might be easier/cheaper than crankshafts if blocks werent so heavy.

sugarsn10

iTrader: (2)

Well, a quick update on the project. I don't want to say directly which company this sample came from since my study is nowhere near complete. My good buddy had a crankshaft he bought from a local guy on this forum. He bought it along with heads and a rotating assembly from a guy who tore down the engine because of some sort of failure that caused some spun bearings. He was told it was a forged crank from brand S, but needed the journals to be ground. So he takes it in and finds out it had a crack in the front fillet on the first rod journal. So he gave it to me for this project, even though I didn't have much use for it since I was planning on looking at cast crankshafts.

So I bring the crank into the lab and my professor and I start looking it over and were having a hard time really deciding if it was a casting or forging. It had a strange surface finish and the parting line was indecisive. Eventually I cut the snout off the crank, took some hardness tests and eventually ran some samples in our carbon-sulfur analyzer. What I can say so far; it's definitely not 4340 like a forging, nor is it any sort of steel whatsoever. The samples all came back with above 3.4% Carbon and very low (>0.010%) sulfur. I'm currently in the process of mounting and polishing samples right now to study the microstructure and will also be running a couple spectro samples to ensure there are no other major alloying elements. Its interesting to see the science pointing towards ductile iron when both of the two aftermarket companies being studied refer to their products as "cast steel".

PS: I'm still looking for one more aftermarket crankshaft sample. Specifically a cast Eagle crankshaft. From reading all the threads on multiple forums about issues with them, I would figure they'd be around. I appreciate any comments, insights, or help with resources.

bestracing

My friends experience with Eagle wasn't a very good one either. Got a 383 kit for a LS1 motor and basically had to throw away all the bearings except two rod bearings. He had to get +0.001 sized bearings to get the proper bearing clearance. Bischoff built the motor for him and gave him the blueprint sheet along with the build as well. I was surprised with Eagle's crank had most of the journals machined out of tolerance for standard bearings.

I have to agree here as well. Keep personal comments and opinions out of the report and let the results speak for itself.

I have done some cross sectioning and etching to expose grain structures in welds to see penetration depth and heat effected zones but I'm no metallurgist. It would be interesting to see some of this

sugarsn10

iTrader: (2)

I have been doing testing on the GM and Scat cranks, but have yet to find myself an Eagle crank. I've talked to a couple local shops and so far none of them have had junk Eagle cranks laying around. I'd really appreciate any more leads on finding one. I've looked around on forums a little bit concerning broken eagle cranks, but most of them are from a few years ago. I'm going to try a couple other machine shops, but am hoping someone on here has one. Even if it's a good used crank that someone just wants to get out of their garage, I'm willing to pay for it.

sugarsn10

iTrader: (2)

So it has been a long time since I first started this research project and seemed to forget I had started this thread. I completed this project a few months after beginning this thread, but never shared details of the results on here. I thought some of you might still be interested, so I'm going to give a couple quick main outcomes. If anybody is curious and wants to know more, they can PM and I'd be happy to talk more about it. I found the results very interesting and hope to get more samples some day so that I can do further testing to verify my results.

The best way to quickly discuss the results is to show the micro structures from the samples. I attached 4 images to this email.

The first two pictures are images of the graphite nodules for the samples. The first image is of the GM sample. There is an overall higher nodule count along with larger, more uniform nodules than the Aftermarket. The second image shows the Aftermarket sample. As you can see, the sample is indeed ductile iron, not cast steel. This sample has similar nodules, but they vary more widely in size and the nodularity (roundness) is not as great.

The next two images show the samples' microstructures. Again, the first image is that of the GM sample, while the second image is that of the Aftermarket sample. In short, the Aftermarket sample has much more pearlite (dark area) than the GM sample. This typically results in greater hardness and strength.

Tensile bar samples were taken from each of the crankshafts. The GM sample broke at an ultimate tensile strength of 80 KSI with an elongation of slightly over 6%, while the Aftermarket sample broke at an ultimate tensile strength of 90 KSI with an elongation of just under 3%. These numbers follow the expectations from the microstructures.

I concluded that while the Aftermarket sample did provide greater strength which is contributed to greater alloy additions, the GM sample was "higher quality" ductile iron. The Aftermarket sample tensile test specimen did not meet the minimum elongation for a ductile iron grade of that ultimate strength, while the GM sample met the minimum elongation requirement for that grade. This could be attributed to the nodule quality.

These tests show that while the material used in the Aftermarket crankshaft is not steel, it does have an ultimate strength greater than the GM crankshaft. On the other hand, it lacks the elongation of the GM crank, which could mean it may be more likely to suddenly fail catastrophically if stressed beyond its yield point. The last point to think about is that these tests do not take crankshaft design or machining quality into account at all. I am by no means a mechanical engineer and would not be able to make a judgment on overall crankshaft performance. This was purely a study of material characteristics.

rusty vango

excellent post !! im personally proud as hell of you for adding a metalurgically biased point of view to us back yard builders.

sugarsn10

iTrader: (2)

Thanks for the support! I'm glad to hear that people find a metallurgical point of view of some value. What spurred me to finally finish this thread was a terrible article on crankshafts from one of the hot rod magazines online. The article used representatives from multiple crankshaft manufacturers, and yet at least 90% of the information they provided about material characteristics were completely wrong. Either the companies' salesman were misinformed or the information was misinterpreted by the writer. Metallurgy is a topic many people in our community aren't experts on, which makes it very easy for manufacturers and marketing departments to mislead us.

TTOP350

iTrader: (8)

I tossed a cast egale 400 crank last yr and a cast 400 GM crank, both had cracked during use. They were sitting around forever.