eb02z06

iTrader: (18)

My understanding has been:

I-beam: N/A Hi-revving engines
H-beam: F/I , N2O

Zombie

iTrader: (2)

Why do people think stock rods are weak? I've been making about 700 hp on mine for 10k+ miles. My friends car has about 700 on his stock rods and another friends car has 600 on his. These are also all high milage motors 70k+. All of the mentioned cars are turbo cars and all have stock bottom ends.

The stock pieces are not weak. We will be pushing one of the cars as far as it will go this year. I'm thinking we can break 900 rwhp with just upgraded rod bolts.

eb02z06

iTrader: (18)

So if that's the case-if i were to build a budget 346 can i just use the stock rods-polish the beams and use some forged pistons? Would that be good for 650-700 rwhp?

2000_LS1

Budget motor IMO=

Stock Crank - $75 for polishing
Stock Rods - Free
ARP Bolts though - $100
Diamond or Mahle Pistons - $600
FM or Clevite Bearings - $100
ARP Head Bolts - $125
5.3L Heads and 918 springs- $500
Your choice of cam I like the voodoo cams for street use - $400
Pacesetter Coated LT's - $450
Cut-out - $75
Lid - $100
ls6 intake for pre 2001 ls1's - $350
ported tb - Free
de-screened MAF (? the effectiveness of this) - Free

Not too bad I don't think. Just a quick guess on the prices, heads may be off a little. And that should be good for 400-475 rwhp depending on tune from what I have seen in my own and other cars. And price isn't too bad either considering. One way to lower cost is to go with ls6 springs, buy a used cam, used headers, may already have an ls6 intake but do not skip this step, and that's about all I can think of right off the bat. Auto cars will need a stall and Man cars will eventually need clutches. Then both sooner or later will need a 12 bolt or 9" rear.

2000_LS1

Also honed walls to 3.905, that shouldn't be a whole lot.

Zombie

iTrader: (2)

The biggest reason to not use the stock rods is finding pistons that fit the stock rod and bore. The other down side is resizing them since they are a cracked rod.

My new motor is a 370 and I'm using eagle SBC I-beams ($270) with some used forged diamond pistsons I got for $200.

I just wanted to point out that stock parts are not weak. Parts don't break from power for the most part, they break from mistakes such as detonation and oiling issues.

2000_LS1

Well with more power the chance of a detonation or oiling issue is a whole lot more dramatic. More power will show you the weakest link in your motor. I would say the weakest link in the ls1 is either the rod bolts, or I believe the pistons. In the motor anyway, as far as drivetrain, I'd say clutch or rears. I had both go out at about the same time (2 weeks apart, clutch first). But my pistons went way before they did, actually a detonation issue with n2o, and floating valves, a whole other story.

DavidNJ

What Tony said is dead on. I would add something though.

In theory, an I-beam rod had bending stiffness in the direction where the pin and journal are rotating, not contributing bending forces. The H-beam has stiffness in this access. However, the strength is more complicated than just adding metal. So buying from a known vendor whose parts have been used and raced by people with combinations similar to or more abusive than yours is important. These manufacturers have developed their designs from experience, which may have included failures. For example, how many rods have you seen fail around the beam? How many around the rod bolt or pin?

Weight isn’t always a sign of designed in strength. Crower Maxi-Lights are sized for specific journal and pin sizes. Other rods frequently use one blank for different sizes. They end up with small journal/pin sizes weighing more than their large journal/pin cousins do.

The various sections of a rod can only be made so thin. H-beams have two sections along the rods longest dimension and can only take so much off the center. There are crossbeam rods that have a cross-shaped cross section. These rods claim the thicker material handles drilling an EDM pin oiling hole easer.

However, we live in the real world, and if you are spending $600 for a set, the Compstar, Eagle and SCATs are H-beam.

ODB

i didnt feel like reading everything but the majority of high end companies offer their 1000+ hp rods as i beams. and they are all %100 american made not some cheap overseas material machined here. crower, oliver, lentz, and even howards rods are offered as i beams. as far as what you should choose go for the lightest longest rod you can use depending on the hp requirements. if you can find a 550 gram rod that will hold up to 700hp as opposed to a 650 gram rod go for the 550 gram rod. usually the lighter rods tend to be i beams anyway....it all depends on your application. dont base anything on looks alone

blazerls1

iTrader: (23)

i'm using a set of i-beams because I got a killer deal on a set of olivers

2000_LS1

So...what we have learned here is....

no matter what the papers, sponsors, techies on the board, you or me say, it is still a matter of opinion. I'd say you're okay with either I or H beams, as long as they are a good quality material, and they fit your plans. Spend your money accordingly. Personally, I'd say H beam, just because I can, lol.

97F1R408

iTrader: (2)

I have oliver I beams in a 408 and eagle H beams in a 370 and a 346 which have never come apart 408 has big blower high boost 370 has turbo high boost and 346 has direct port n20 . After thinking about it I dont think Ive ever seen a thread that someone had one snaped in half ,I'm sure it happened but these arnt sbc or bbc engines the design and ridgedness is all playing its part. I'm guessing one of my engines will probably blow shortly after writing this !

2blue

Several years ago Hot Rod magazine had an engineer calculate the rod loads for the 4 cycles. The highest was on the exhaust stroke where there is a very small compression load when pushing the exhaust out that is overwhelmed by a huge inertia load from the piston mass, the pin knuckle and the pin when the crank reaches TDC and the aforementioned masses try to keep going straight up the cylinder bore. This puts tensile stress into the rod which can be handled by any shape crosssectional area and the rod material's yield (tensile) strength(psi). During the power stroke where maximum compressive loading occurs, the rod has to be analized as a column to prevent buckling, which is why the crosssection is either an "I" or an "H".

SSilverSSurfer

iTrader: (8)

compstars are great from what ive heard

fastbasser

iTrader: (1)

"I" beam Cariilo's in mine. (Did some say I beams are cheaper?) lol Should hold all the HP I ever try to make.

madmaxz

iTrader: (7)

anyone herd of Probe Industries? they have a 6.125 lightweight rod they say is good to 800-900hp weights 599grams $500. Probe is big in the mustang community

mastrdrver

An I-beam has more cross secion then a H, lighter then a H, and if that isn't enough for you what do the Top Fuel and Funny Cars use...I-beam and they are making a lot more power then anyone else.

2000_LS1

Well, I think you COULD spend more on H-Beams if you really wanted to...and you COULD spend twice as much on some I's. In the end, it's about user preference I would say. I like either...til one gives me a reason not to like it anymore.

Thanks for the input guys.

Boostaholic

iTrader: (4)

If you can break either of them your doing pretty good in my book, have not read about many forged rod failures on this board that were due to bad rod choice.

Red99C5

I would go with the I-beam and the lightest rod possible. The heavier the rod, the more stress is on it. At 6000-7000 rpm a rod can have the dynamic weight
(G-force) of about 8000 -10000 pounds. The lighter you can make the rod, the better.