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Author Topic:   Rods ?
halffast4
Member
posted December 11, 2003 06:56 PM
i would say any aftermarket rod is better just because of the fact that they are new.
i like scats myself out of all of them. they seem to have decent quality.

luke

Sweek7
Member
posted December 11, 2003 07:41 PM
You would be amazed at how strong a stock GM 5.7" rod is(not the PM rods). If I were given the choices that you have , I'd hand pick 8 good stock rod's , have SPS bolts installed , shot peaned, sized correctly, and use them . They will last longer

Steve

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Hendren Racing Engines
Rutherfordton , NC
(828)286-0780


tilley88
Member
posted December 12, 2003 05:55 AM
Are we talkin "X" rods?


sdhnc29
Member
posted December 12, 2003 06:16 AM
I'm speaking about any good hand picked stock early model 350 rod. One with centered pin bore's and big end bore's , that has little or no balance pad on the cap or pin end.

Steve

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Hendren Racing Engines
Rutherfordton , NC
(828)286-0780


ss11
Member
posted December 12, 2003 08:05 AM
Hard to believe you posted that right next to Steve's post! I don't think you could convince him that Eagle parts would make decent paperweights!


4barrel
Member
posted December 14, 2003 07:24 PM
"well you can handpick rods, have them reconditioned and bolts installed, for the same price as chinese rods."

My point exactly ! Plus you end up with American steel rather than recycled wagon wheels........lol

Steve

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Hendren Racing Engines
Rutherfordton , NC
(828)286-0780


dirtrace
unregistered
posted December 15, 2003 09:24 AM           
your saying gm rods are and were allways made in the usa, with usa metal. If I were a betting man I would bet against that in a heartbeat.

A gm car is no more american than a toyota tundra truck.

Almost all makes use body, motor, tranny mounts etc from chile. Chile is into rubber for some reason, they make a lot of goodyears and other tires also.

tilley88
Member
posted December 15, 2003 01:27 PM
Nafta did'nt start until around '92. Most of these rods Steve is talkin about were made way before then. Plus, alot of internals are still made using USA steel in GM V-8 engines. I've used X-rods in many of my motors and I'm always impressed with the abuse they take. How many chinese rods are actually produced for passenger vehicles that go 200,000 plus miles, then are reconditioned for racing?


outlawstock17
Member
posted December 15, 2003 01:53 PM
the steel tariff is on the verge of being lifted. the economical chinese parts are about to become even more economical.

ford is now using scat cranks in their crate engines. i'm no metallurgist, but until i start breaking "chinese junk", i'll run it.

Raz_900
Member
posted December 15, 2003 03:03 PM
I used Eagle 6" rods in a 355 last year, it's turned upwards of 7000 rpm with a stock crank and stayed together. I've also run stock 5.7 rods reconditioned with ARP bolts to 6500 with no problems.

This year, I was looking for another set of 6" rods. I first bought a set of Cat rods 'cause of the price. After getting them, and seeing the quality of the casting and machine work, I set them on the self and bought another set of Eagle's. Personally, for a street stock type motor, I think the Eagle's are perfect for a 6" motor. If you can't use 6" rods, I'd just use stock 5.7's with ARP bolts.


And actually, the engine shop I worked at didn't use the 'X' or 'pink' or 'heavyweight' rods in many of our motors. There's 3 basic GM 5.7 rods. We called them 'lightweight', 'heavyweight' and 'light-heavy'. The LW is the most common rod using a 9/16" beam and has formed sides by the parting lines (where most people stamp the numbers). The HW has the 9/16" beam and a smooth, machined surface on the sides. The L-H has a weak 1/2" beam and heavy big end and was used mostly in 305's not suited to performance duty. We used the LW rods because with ARP bolts they proved more than strong enough and were a few grams (every bit counts) lighter than a HW/X/Pink rod.

Can't agrue with a 406 spinning 7200 rpm for 3 years on the same bearings.




sdhnc29
Member
posted December 15, 2003 11:18 PM
Hey no problem guy's! Run the Chicom junk all you want, it's no skin off my nose. Just don't complain when your running it over. Just trying to help halffast4 see the light before it's too late. I do feel good knowing that the Nukes the Chicoms have pointed at us are made from the same metal, and probably the same guy's.....lol

Steve

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Hendren Racing Engines
Rutherfordton , NC
(828)286-0780


rocket36
Member
posted December 16, 2003 04:21 AM
there is certainly nothing wrong with running a standard gm set of rods as long as they are prepaired properly for racing. personnally i would use an aftermarket rod if the choice was there. i would choose scat first. eagles are also quite good and reliable. i believe the cat rods to be the stuff that didn't meet the scat tolerances and are then sold off, remachined and packaged and packaged for sale as are alot of the other brands.
you can go and put a set of us made carrillos or uk made cosworth (the 2 most reputable brands in the world) in your engine and still have them break and smash your crank/block/sump/heads if you don't know what your doing. component preperation, engine assembly and tune up are what will let you down. $100,000 cup car engines still suffer from odd failures now and then and they can use the best us, uk, asia made componentry but lets face it, nothing is indestructable.
should make a point (i'm sure steve will agree) that piston weight should also come into the criteria for selecting a rod, be it standard, remanufactured, "chinese", or "holliwood" brands.
for the record, my "home garage" built 415cui (factory gm 400 block)sbc dirt late model engine turns 7000-8000 every night, is now a season and a half old and runs "chinese junk" scat 6" 4340 h-beam rods and a "chinese junk" scat 3.8" 4340 crank.
might be just plain lucky, but i'd rather be lucky than good any day. lol.


Raz_900
Member
posted December 16, 2003 01:29 PM
quote:
Originally posted by rocket36:
...i believe the cat rods to be the stuff that didn't meet the scat tolerances and are then sold off, remachined and packaged and packaged for sale as are alot of the other brands.
you can go and put a set of us made carrillos or uk made cosworth (the 2 most reputable brands in the world) in your engine and still have them break and smash your crank/block/sump/heads if you don't know what your doing. component preperation, engine assembly and tune up are what will let you down. $100,000 cup car engines still suffer from odd failures now and then and they can use the best us, uk, asia made componentry but lets face it, nothing is indestructable.
should make a point (i'm sure steve will agree) that piston weight should also come into the criteria for selecting a rod, be it standard, remanufactured, "chinese", or "holliwood" brands.

Gotta say I agree. The best rod improperly prepped/installed will still fail. Only takes a tiny little pice of crud to ruin a bearing. At 7000rpm, there isn't much time between spun bearing and snapped rod.

The reason I'm using the Eagle SIR 6" rods is they let me run a lighter piston and the rod is 8 grams lighter than a stock LW 5.7" rod. I'm not making over 500hp, so why buy a rod to handle 700+hp?

Here's some piston weights for reference. I use Keith Black's, so that's what I'm referencing since they offer all the types.

KB106 standard 5.7 flattop -7cc piston & pin = 680 grams
KB112 standard 6.0 flattop -7cc piston & pin = 605 grams
KB231 lightweight 5.7 flattop -6cc piston & pin = 587 grams
KB260 lightweight 6.0 flattop -6cc piston & pin = 537 grams

So, taking 143 grams off the end of a 'cheap' 6.0" rod will help it live a long healthy life. If running a 'standard' weight 5.7 piston it's just a law of physics that you'll have to have a stronger rod to keep it from breaking. 140+ grams at 6500 rpm is an astronomical difference.

Using weight of piston and max acceleration with each rod (shorter rods accelerate the piston faster too)

5.7 standard piston w/3.48" stroke = 131,314.1 lb-ft/sec^2
6.0 Std pist w/3.48" stroke = 115,464.8 lb-ft/sec^2
5.7 LW pist = 113,355.0 lb-ft/sec^2
6.0 LW pist = 102486.9 lb-ft/sec^2

Or, just from rotating forces, going to a 6" rod and LW piston lowers the centrifugal force on the rod by about 22%. So, ignoring the pressure from combustion, which is the same on each rod/piston combo and substantial in it's own right, theoretically, a rod made from 22% WEAKER material could survive in a 350 (really it's prolly half that when computed properly). At least comparing a 5.7 rod standard piston motor to a 6.0 rod LW piston motor.

Of course in a real calculation you need to include the angle the force is applied to the rod, the compression force, size of rod beam, length of rod.. etc etc. I just didn't feel like going that far into it. The numbers above show the general idea concerning a longer rod and lighter piston reducing the load on things like the rods, crank, rod bolts, bearings and block/mains.

Whew... I almost wish I had something to do at work this week.

dirtracer50
Member
posted December 16, 2003 08:04 PM
After reading your post raz I'm wondering if your an engineer when at work. Just kiddin with ya.


Raz_900
Member
posted December 18, 2003 08:34 AM
quote:
Originally posted by dirtracer50:
After reading your post raz I'm wondering if your an engineer when at work. Just kiddin with ya.

I wish!!

Actually, I'm a Computer R&D/project lead guy for Bayer Corp. (yes, the aspirin people). But, I do have a Bachelor degree in Mechanical Engineering and worked in an engine shop for 3 years through college (95-98). So, I do the PC thing at work 'cause it gives me the money to do what I really love, which is racing & building motors. Pretty much every vehicle I've ever owned has gotten a new motor in it as 100,000 mile maintenance. Working with numbers is a stress releaver after having everyone in the frickin' country complain about why this doesn't work, or why such a thing doesn't work for so and so but does for them.. blah blah blah. Is it springtime yet??

GO 24
Member
posted December 19, 2003 10:58 AM
I'm gonna agree with Steve on this one, I won't even put the Chinese junk in our "bomber" engine let alone my late model--no way, no how, not ever. If restricted go with GM stuff otherwise use brand name made in America parts ie...Callies, Crower, etc...

I argued with a friend of mine last winter over this same subject except for the fact we were not limited to what we could run. I run a Crower and caught alot of slack for what I paid for it, he put in one of the lightweight Scats and ran it over in less than 500 laps!!!

dirtrace
unregistered
posted December 19, 2003 09:23 PM           
At least with crower and callies both you get more for your money...

lots more metal, and lots more weight.

I bought a crower std wt, and it was for a 383 5.7 rod and weighed 62 lbs, lol, I saw that on the ups box, opened it weighed it again and sent it back.

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