What are the pro and cons of the varying wrist pin materials?
9310?
4340?
300M?
H11 Tool Steel?
Did I forget something?
I also have seen alot of companies advertise their pins as being a Tool Steel, without saying which one. Are they using H11, or something else entirely. I have done a little research into some of these materials , with some of them sharing similar yeild, tensile strengths and hardness.
What have you used, what held up well, what failed?
Due to the odd sized pin I require, I have only been able to come up with a plated 4340 Taper wall pin to suit my application
I know there are alot of experienced engine builders on the board, so hopefully some of you can share your experiences here.
Thanks
AL...
Wrist pin Materials?
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OldSStroker
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Perhaps you don't have to get into all the nuances of the various materials, and the heat treating used with each one. It's a complex subject.
What pin size do you require? Does it have to be a certain weight? Does it need Casidium coating? Does it need to be "exotic"?
Unless you are building an engine in the power, rpm and durability levels of a Nextel Cup engine, or throwing lots of boost on it, you might be able to have a readily available pin modified to your size needs. Alternately, a pin manufacturer might build you a special.
As you said, "tool steel" is a buzz word. It can vary at least as much from "worst" to "best" as plain and alloy steels.
H11 is classified as a hot-work steel that works well at temps up to 1000 F which isn't really important to a wrist pin. However, is has great strength properties and is used extensively in aircraft strength applications. I's not perfect so you have to live with its few shortcomings, not the least of which is cost.
The higher-end tool steels , like H11, are very "clean" steels with almost no impurities in them. Part of their very high cost is the work and energy it takes to make the H11 billets. IOW, H11 pins are probably overkill for most engines.
What pin size do you require? Does it have to be a certain weight? Does it need Casidium coating? Does it need to be "exotic"?
Unless you are building an engine in the power, rpm and durability levels of a Nextel Cup engine, or throwing lots of boost on it, you might be able to have a readily available pin modified to your size needs. Alternately, a pin manufacturer might build you a special.
As you said, "tool steel" is a buzz word. It can vary at least as much from "worst" to "best" as plain and alloy steels.
H11 is classified as a hot-work steel that works well at temps up to 1000 F which isn't really important to a wrist pin. However, is has great strength properties and is used extensively in aircraft strength applications. I's not perfect so you have to live with its few shortcomings, not the least of which is cost.
The higher-end tool steels , like H11, are very "clean" steels with almost no impurities in them. Part of their very high cost is the work and energy it takes to make the H11 billets. IOW, H11 pins are probably overkill for most engines.
Last edited by OldSStroker on Sun Jun 12, 2005 12:30 pm, edited 1 time in total.
Yes. And the stuff machines beautifully at anything 50HRC or better.OldSStroker wrote: H11 is classified as a hot-work steel that works well at temps up to 1000 F which isn't really important to a wrist pin. However, is has great strength properties and is used extensively in aircraft strength applications. I's not perfect so you have to live with its few shortcomings, not the least of which is cost.
The higher-end tool steels , like H11, are very "clean" steels with almost no impurities in them. Part of their very high cost is the work and energy it takes to make the H11 billets. IOW, H11 pins are probably overkill for most engines.
Oldstroker is right on the overkill. If I had to swing a really heavy (relative) piston at higher RPM, I might want them.
Tell us more about this build.
Chuck
it's a 406 Chrysler, 4.02" bore, 4.0 stroke , has a 6.380" GRP rod to go into it, flat top Venolia piston that weighs 400 grams, W2 heads, roller camshaft, 13:1 comp etc etc. It won't see a whole stack of rpm (7-7200) , and will remain normally aspirated.
The reason I have asked about people's experiences with different pin materials is because I have had a few people on other boards tell me to stay away from 4340 and 9310 material pins, and that they preffered Tool steel pins. I found this to be odd, as H11 and 4340 in their raw state, have very similar material properties, similar tensile strengths etc. What happens to these materials once hardened, I would have to look into. 9310 doesn't really share alot of similarites, and posesses a high nickel content, so I don't know about that one, it's not a material I have had anything to do with really. I have mainly machined stuff like 4140 , K245 , S600 and alot of M200.
I am getting the GRP rods through Patterson Racing, and will get my pins through them also, but because of the odd size (0.928"-0.930" x2.850"), Todd has only been able to find a plated 4340 0.180" taperwall pin for me. The engine was a 360 incher, and was running a 0.090" wall pin, so realistically, I am probably over thinking the whole deal.
Thanks guys
AL...
The reason I have asked about people's experiences with different pin materials is because I have had a few people on other boards tell me to stay away from 4340 and 9310 material pins, and that they preffered Tool steel pins. I found this to be odd, as H11 and 4340 in their raw state, have very similar material properties, similar tensile strengths etc. What happens to these materials once hardened, I would have to look into. 9310 doesn't really share alot of similarites, and posesses a high nickel content, so I don't know about that one, it's not a material I have had anything to do with really. I have mainly machined stuff like 4140 , K245 , S600 and alot of M200.
I am getting the GRP rods through Patterson Racing, and will get my pins through them also, but because of the odd size (0.928"-0.930" x2.850"), Todd has only been able to find a plated 4340 0.180" taperwall pin for me. The engine was a 360 incher, and was running a 0.090" wall pin, so realistically, I am probably over thinking the whole deal.
Thanks guys
AL...
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OldSStroker
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I'd advise not overthinking this, but ask Venolia for a recommendation. Why not just use the pins Venolia usually supplies with their pistons? It's easier to fit the rods to the pins than to fit the pistons to the pins. Venolia will fit to a pin when you order the pistons. I'd send them the pins if that were the case.
You mentioned .928-.930 pin diameter. Which size is it? Pin tolerances aren't .002 but more like 1/10 of that.
Pins need to be heat treated, so mechanical properties in the material's raw state is really not relevant.
Basically 9310 is a carburizing grade (it doesn't harden much without adding a skin or case of carbon) that makes a good impact friendly part. It's used in drag race only rear end gears with a fairly soft case hardening so the teeth will deflect a llittle under sever shock loads at launch without shucking out a bunch of teeth. Life is very limited because of the relatively soft case or outer surface. This doesn't sound like what your application for piston pins requires.
4340 is a medium carbon nickel-chrome-molybdenum steel which in piston applications will be carburized or case hardened to get a hard wear surface on the outside. It heat treats to a very strong, extremely tough but not too flexible core. It's a bit stronger than plain "chrome-moly" or 4140 pins which are common. They are both heat treated to approximately the same hardenss on the surface and similar inside or core hardness.
300M is basically a slightly modified 4340. It makes good axle shafts for Indy cars and probably excellent piston pins, but I wouldn't use it on your application; it's too expensive for what you get.
One uses the exotics like H11 and 300M when you need extreme strength along with very light weight. Again, I don't see this with your 400 gm pistons and probably 600+ gm rods.
Good luck.
You mentioned .928-.930 pin diameter. Which size is it? Pin tolerances aren't .002 but more like 1/10 of that.
Pins need to be heat treated, so mechanical properties in the material's raw state is really not relevant.
Basically 9310 is a carburizing grade (it doesn't harden much without adding a skin or case of carbon) that makes a good impact friendly part. It's used in drag race only rear end gears with a fairly soft case hardening so the teeth will deflect a llittle under sever shock loads at launch without shucking out a bunch of teeth. Life is very limited because of the relatively soft case or outer surface. This doesn't sound like what your application for piston pins requires.
4340 is a medium carbon nickel-chrome-molybdenum steel which in piston applications will be carburized or case hardened to get a hard wear surface on the outside. It heat treats to a very strong, extremely tough but not too flexible core. It's a bit stronger than plain "chrome-moly" or 4140 pins which are common. They are both heat treated to approximately the same hardenss on the surface and similar inside or core hardness.
300M is basically a slightly modified 4340. It makes good axle shafts for Indy cars and probably excellent piston pins, but I wouldn't use it on your application; it's too expensive for what you get.
One uses the exotics like H11 and 300M when you need extreme strength along with very light weight. Again, I don't see this with your 400 gm pistons and probably 600+ gm rods.
Good luck.
The Venolia Pistons I have aren't new, the engine has done a season or racing already, and I am adding more cubes to it. The engine sat around in pieces for the last 20 years, before coming into my hands.
The reason I am looking at a 0.928"-0.930" pin is because the pin bores in a couple of the pistons are 0.0005" out of round, so a slightly larger pin give me some material to hone out. To top this off, I have misplaced one of the wrist pins with moving the parts around.
Thank for the replies, they've been most helpful
AL...
The reason I am looking at a 0.928"-0.930" pin is because the pin bores in a couple of the pistons are 0.0005" out of round, so a slightly larger pin give me some material to hone out. To top this off, I have misplaced one of the wrist pins with moving the parts around.
Thank for the replies, they've been most helpful
AL...
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OldSStroker
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Yep, get a .930 pin and shorten it. Have the pistons and rods honed to fit. Easiest solution. If they were .927 to start, go a couple .001 to assure the hone rounds up the holes accurately.la360 wrote:I know that companies like BME stock pins that are 2.950" long, it wouldn't take much for me to pop them into one of the Jones & Shipman cylindrical grinders at work and face 0.005" off each end too. I may give Todd a call in the morning regarding it.
Thanks again
AL...
Good luck!