Here's the questions I posed on the Skoggin Dickey board. Anyone care to offer an answer?
https://www.thirdgen.org/messageforu...ML/000240.html

I have ARP waveloc rod bolts to add to these rods. I want to guarantee that they hold up to 475 HP in the (unlikely) event I succeed in my engine design and overshoot my goals.

They are going into a 6500 RPM minirammed 383. 10.25:1 compression, forged pistons, magnafluxed 400 crank with 350 mains, ARP main studs, block line bored, etcetera.



------------------
Daniel Burk
http://www.isthq.com/~dan/fcar.html
'84 Trans Am WS6/L69
KB SFC, Moser axles, Torsen Diff. PST suspension, Braided stainless brake lines,
5-point racing harness, Koni struts, 11-inch rear disks,Spohn Adj. torque arm,
Ported 305 heads w/1.94"intake valves, Comp Cams XE262H, Griffen alum. radiator,
Speed-sensitive steering conversion, underdrive pulleys, Crane Hi-6 & more. 1.05g skidpad verified.
New best E/T! 14.400 at 98.6 MPH in 88 degree air at Stanton, Michigan.

 

Are these "cracked" rods also? Meaning, is the cap/rod parting line interface machined flat, like conventional rods, or is the surface cracked or fractured? Generally, powdered metal rods are married with a cracked cap. Reason? Low cost to manufacture. If these are cracked cap rods, you can't resize the rod using conventional techniques.
Give me a day or so to check out the other surface preparation techniques you asked about. I'm not sure about one thing & want to check it out.
Regards, FJK

[This message has been edited by FJK (edited September 19, 2000).]

 

Others may have some different suggestions but generally there isn't much you can do. Have them magnafluxed to reveal any non-visible cracks first just to make sure you have 8 good ones from the start. Then grind off all the casting flash esp. at the parting line- these little rough/sharp edges can lead to a "stress riser" that causes internal strain on the metal when you get them good and hot. You can also have them shot-peened for simialr reasons (not the bearing surfaces).

After that you can go REALLY REALLY high tech and get them run through a "metalax" proocess that shakes the crap out of the rods, just below their resonant frequency and helps relax the internal stresses in the grain of the metal. Not crazy enough for you? Then why not have them cryogenically processed, too? They take the rods down to near absolute zero with liquid nitrogen and it lets the molecues line up nice and straight and strengthen their molecular bonds. I'm not doing justice to describing either of these processes but the results (I'm told) are much improved strength and wear characteristics.

Obviously, I've never done either of the last two procedures to any of my rods cause I don't have the bucks or the patience (or the need!) for any of that but the other stuff is worth doing and is easy, too.


------------------
94 Firebird Formula M6- No options but Z rated tires. No mods over $10. 13.5@105.
79 Malibu "beater" w/junkyard 400 SBC, tweaked QJet 4bbl, finally a decent set of heads, a few other tricks. A maddening 13.000001 @ 108 on the motor with little traction. No nitrous runs with the new heads yet.

"One of the last remaining QJet tuners on Planet Earth!"

 

in cars there is no guarentee, but with good arp bolts and a good balance, you'd be fine with them rods. they will hold up under that stress and with you using a 400 crank, it'll be the week link anyway since they lose alot of stregnth after being cut down that much.

 

Damon,

I'm not sure true MagnaFlux testing will be successful on PM rods, due to the random nature of the metal structure. They are produced by (in simple terms) an enhanced die-casting process combined with forging. The forging process should align the grain structure to some extent, but I suspect that the random nature of the grain may preclude getting a magnetic field to pull the particles and dyes into any potential crevices. A straight ultaviolet dye soaking and inspection under the UV lamp may reveal some defects, but I suspect the PM rods may require a different inspection process, like ultrasonic testing. I'd be interested to read whatever you find out about this.

------------------
Later,
Vader
------------------
"Make Me Bad"
Adobe Acrobat Reader 4.0

 

I'm not familiar with your specific rods, so you'll need to do some homework (and maybe you did) on what applications these rods are recommended. Additionally, it would be helpful if you could find out the configuration of the rods as manufactured. Maybe they are already shotpeened & have high grade rod bolts.
To answer your questions about PM rods....
First, you'll find they should be very smooth already, without as much forging die flash as a conventional steel rod. They can be shotpeened, same as any other steel rod. If they have a cracked or fractured cap/rod interface, they can not be sized like conventional rods. The cracked surface provides the cap to rod alignment, not the rod bolt shanks as found with conventional rods. That's why you resize the big end of the rod when changing rod bolts. The concern is that the new rod bolts slightly reposition the cap. So, the cap & rod mating surfaces are machined down about .001-.002", the new bolts are installed, the rod & cap are reassembled,& the big end of the rod is remachined back to correct bore size (usually by honing). This causes the rod center to center length to get shorter by .003-.005". So, if you have cracked rods, the only thing that can be done is installed the rod bolts, bolt it up, & dial bore gauge the bore for roundness, closely checking that there is no cap/rod mismatch. If the bore is off slightly, it can be honed to the extent that max bore size is not excede. The larger the bore, the less the bearing crush & you don't want that. Bearing crush is what prevents the bearing from spinning. So, you have to stay in bore specifications.
Relative to balancing, since you are already building a new engine, everything has to be rebalanced, including the rods. Rod balance is something you can not do yourself because rods are balanced in a fixture to measure small end weight (reciprocating) & big end weight (rotating).
If you choose to get your rods shotpeened, so indicate, because there is a proper sequence of events you should following for shotpeening, bolt installation, balancing, etc.
BTW don't be left with the impression just because someone said the rods are good to 450 hp & you produce 480 hp the rods will instantly fail. However, if your background search indicates you might have made a wrong choice, explore the alternatives to other rods on the marketplace.
Regards, FJK

 

Vader
It seems you're replying while I'm typing. I can't get scientific with you at this point on the merits of mag'ing PM, so I'll just say I don't know of any reason for your concern. For the time being, consider this analogy...magnaglowing grey iron. It has the microstructure like a sponge & there is no problem mag'ing it. What da' think?
Regards, FJK

 

Thanks for the suggestions. Since these are brand new rods, in sealed GM boxes, witha bright pink swab of paint on each rod, I assume that GM has already done some form of screening on them?? The stock rod bolts are (from memory) 150KPSI whereas the Wavelocks are 220KPSI. The rods are smooth with virtually no casting flash. The rods are made by pressing grains of fine powder together into a "green" part, then heated in a furnace, then heat treated, and finally, ground. The caps to NOT appear to be of a fractured nature.

I've recently spoken to the engine builder who says the rods will easily handle 450 HP, and the ARP bolts should add a good measure of reliability. Supposedly they are used in 800+HP applications. Perhaps I'm dreaming to think I'll exceed 450 HP naturally aspirated anyway! I am, however, planning on a 6250 to 6500 RPM red-line on this motor, and wish to make the shortblock as bullet-resistant as I can.