I am building a 406 and wonder how good the lt1/4 pm rods are(5.7 inches). I am using afr 190 heads and 150 shot of n20. Should I look into forged rods? If so which ones??

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1991 Firebird
350 L98 (was a 305 TBI),T-5,Edelbrock TES and cat back,Accel manifold
NOS,subframes,jegster torque arm,MSD Digital 6
AFPR,Lakewood lcas
Hurst linelock,SLP cam (206 212 .480 .486),relocated battery,cold air,Hypertech chip,centerforce df,clutch
poly bushings and mounts
AFR 190s
Harland sharp 1.5 rockers
autopower rollbar

12.33 @ 114.83 juiced uncorrected

13.510 @ 102 non juiced uncorrected

 

I have a set in a 310 sbc but haven't fired it up yet. They're suppose to be stronger than pink rods.The reason I used them is because they were so much ligter than a after market set I had [was going to build a much more radical engine] by about 100 grams.Advertised as good up to 450hp.

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S-Blazer 310 sbc Q-jet weiand 8004 Mallory dist. Crane 272/454 gm alum.heads Trw ft. pm rods Street Fulid damper ARP'S

 

for a power adder i'd run forged rotating assembly

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ICON Motorsports
1st & 3rd
MM Black Diamond 538 F&AM

 

Sorry ede but you are correct except for the fact that they are forged rods. The powdered metal process just replaces the casting operation. They are still forged rods; just initially sintered instead of cast.

 

I'm with Ede. I have two sets of PM rods, and they are supposed to be good to 450 HP. Forged CrMo steel are good to 2,000+HP in blower applications - which would you go with?

The nice thing about the PM rods is that they are lighter and very well balanced compared to most other factory rods (and a lot of Chinese aftermarket sets as well).

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Later,
Vader
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If you want to beat the World, it might reach up and pull you down...
Adobe Acrobat Reader

 

I'm running a set of them... so far so good

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"So many Mustangs, so little time..."
ICON Motorsports

 

I am not running them, nor do I know of anyone who is running them. I think it may come down to the individual casting/forging process vs the sintering/forging process. The initial nature of casting promotes good filling but random orientation of molecules in the rough form, that is until the forging process where it develops a concrete grain orientation around the edges of that forging. The sintering process seems like it would allow for excessive porosity. Depending upon the final compressive stage of the PM process, though, they might offer increased strength. The benefits of the PM process fot the factory are less finishing operations which translates into better quality control. It is fairly easy to acieve a near net shape out of sintering. Benefits may include increased strength due to grain orientation and a lack of significant stress risers. I know that one of my professors at school had a great deal of faith in the PM process. In my dealings with PM, like the gears used for ABS applications in front wheel drive cars, PM seems to be fairly brittle. What is the most common failure mode for a connecting rod? Someone should check their process FMEA

 

Vader, price is an object. What are good rods for about 350 bucks??

 

A friend of mine has the PM rods in his 74 Chevy Pickup.His motor puts out 400HP and regularly sees 6500 RPMs,and the truck weighs 4200 lbs with him in it.Hasn't had any problems.
Still, I would want a good set of forged I-beam or H-beam rods if I was going to use Nitrous.Some are not much more per set than the PM rods, if you buy new.
Just my opinion.
-Rich-

 

I have a set I am running now. I have heard great things about them from almost everyone except the machine shop. They said they are soft, and real hard to resurface. They said it is way to easy to machine to much. THat is all the bad I have heard. Horsepower won't break these. Excesive RPM does. If you have 300 or 600hp, it doesn't matter. The most stress on a rod is when the cyl. fires, and the crank pulls the rod down. It does have help from combustion, but the moment when the rod stops moving up, and starts down, this is the most critical point. It is common practice to use forged, or aluminum rods in racing applications, but look at the rpm that is being run. For a street engine that sees maybe 6500rpm, the PM rods are good. If you plan on running at that level or higher, especialy for prolonged periods of time, I would use steel H or I beam rods. If others on the board don't agree with me, good. I would like to see other opinions. I really don't have personal experience to show what I have stated. This is what I have read in Smokey Yunics book, Lingenfelters book, as well as "How to build Horsepower", and "How to build SBCs" published by SA Publishing. Really it makes sense to me. But I would like to see what others have to say.

Thanks,


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Joshua Johnston
1991 Z-28
350, T-5, K&N, Ported Vortec heads, Edelbrock RPM, Holley 750 D.P., HEI, 11.07:1 CR, Comp Cams Roller-.510"/.520"-282*/288* dur., Shorty Headers, Dual 2.5 Exhaust, Dynomax Bullet Mufflers, T&R Motorsports custom air intake, Bald tires

 

Metallurgically incorrect. Forging produces grain flow that enhances strength. PM does not - the "forging" is part of the PM sintering process.

FWIW, factory oil pump gears have been PM for a couple of decades. Discovered that during a metallurgy lab project (used clear potting - gave the mount to my mom, she thought it was pretty).

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R4. 2.93 limited slip. 2-1/2" cat-back, ZZ4 intake, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (ported World 305 heads, Crane PowerMax cam, Hooker 2055 headers, 3" Catco cat & 3" catback w/Flowmaster, restalled TC, Spohn SFCs).
57 Bel Air, my 1st car. '66 396, 9.7 CR forged TRWs, Weiand Action+, Holley 750VS w/4150 conversion, GK 270 cam, Magnum rockers, Jacobs Omnipack, 1-3/4" Hedders & 3" Warlocks, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, MegaShifter, 3.08 8.2" 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Idles smooth @ 600 RPM in D. Best 15.02/95.06 @ 5800' Bandimere (corrected 13.93/102.4 @ sea level).

 

Hey, I hate to get all political sounding, but define forging.

Forging can happend with or without heat. The only requirement that I am aware of for forging is the presence of intense pressure Webster defines it as "to form (metal)by a mechanical or hydraulic press with or without heat"
So what you are saying is that conventional forging processes produces different grain structure that enhances strength while the strength and grain structure of PM remains the same both before and after the PM process.

 

http://www.herbertperformance.com/Ca...ctingrods.html

I'm looking 2 get 6" rods myself. Has any1 heard about Pro Tech Engineering? $400 doesn't sound bad 4 forged H beams that r bushed.

 

The powdered metal rods, I beleive, is a forged rod. It uses tremendous pressure to compact the powdered metal into a rod. I'm not sure if it uses heat or not.



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Joshua Johnston
1991 Z-28
350, T-5, K&N, Ported Vortec heads, Edelbrock RPM, Holley 750 D.P., HEI, 11.07:1 CR, Comp Cams Roller-.510"/.520"-282*/288* dur., Shorty Headers, Dual 2.5 Exhaust, Dynomax Bullet Mufflers, T&R Motorsports custom air intake, Bald tires

 

[QUOTE]Originally posted by RB83L69:
[B]I'm running a set of them... so far so good

What engine are you running them on, the 310?

 

57kid, I believe that the rods are initailly formed using the PM process; then are subjected to "intense pressure."