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H and I beam rods

southy

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Hey just wanting to know the difference between H and I beam rods?and which one would be stronger?:thumbsup:
 

southy

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yea, im guessing tht it would be the cross section of the rods, and yea i wouldnt have a clue what ones stronger.
 

vyjess

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its no so much the i beam or h beam part of the rod that gives u trouble its the size and quality of the rod bolts and the strength of the area around them is the more inportant part! a standard i beam with good rod bolts and prepped properly will be alot stronger than a cheapo set of h beams!
 

dons vs

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if you grabbed a rod and cut the little end section off and looked straight down the rod you will see a H or an I, that is where they get there names from one is shapped like a H and the other shapped like an I.
generally the I beams can be much lighter and are normally used in factory casting rods and some aftermarket gear although normally with aftermarket I beams they will take them to an A which is similiar to an I only with a much more stout bottom section.
The H beams are normally for high horse power engines and normally only an aftermarket forged or billet rod.
cost is much the same really though for retail anyway in fact some times the I beams are more expensive.

But its not just the shape of the rod you need to know, little end and big end weights are a big factor plus the over all weights and thickness of the rods.
material used and the fasterners used.
most off the shelf aftermarket rods will handle 500+hp so you dont really need to get to picky with them if your in the market for a set.
Just pick a set thats at a good price, a descent name and comes with some arp2000 bolts.
not to sure about commodores but a good set of h beam rods for jap 4 bangers are around 500-600 with arp bolts and a U buet set with arp625's or something can be around 1k
generally commo stuff is much cheaper but thats to give you an idea.
 

southy

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thanks don im not lookin for any as of yet, but its jus been a question that i have wanted to ask just to clear things up. but cheers
 

SilverVH

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dons vs: I agree mostly with what you say apart from 1 thing, that being rods handling a specified amount of HP.

Revs is what will kill a rod, not outright HP. You could safely make 500+ on a set of A9L's if revs are kept to a minimum, its when you start revving a motor hard when rods will stretch and break. H-beams are a stronger rod due to their design and will allow for higher revs whilst stretching and not suffer from breakage or un-roundness of the journal. I've seen I-beam rods last in 550hp motors and when pulled down, they are like new. Preparation is the key to having it last, balancing of the drivetrain is what is paramount to keeping an engine alive.

Hope this helps.
 

dons vs

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your right revs do kill rods but out right hp can as well. All to do with the amount of force the rod can withstand, obviously with more hp your going to have a higher shock load on the charge which will put much more stress on the con rod.
 

greenfoam

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dons vs: I agree mostly with what you say apart from 1 thing, that being rods handling a specified amount of HP.

Revs is what will kill a rod, not outright HP. You could safely make 500+ on a set of A9L's if revs are kept to a minimum, its when you start revving a motor hard when rods will stretch and break. H-beams are a stronger rod due to their design and will allow for higher revs whilst stretching and not suffer from breakage or un-roundness of the journal. I've seen I-beam rods last in 550hp motors and when pulled down, they are like new. Preparation is the key to having it last, balancing of the drivetrain is what is paramount to keeping an engine alive.

Hope this helps.
Also L34/A9L rods were used at Bathurst for many years at 7500-8000 rpm with 500 hp :)
 

SilverVH

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Greenfoam, the state of the rods after a race wern't to healthy lol, engine failures wernt due to piston shattering either hehe.

The point I was getting across is there is no set HP limit on a set of rods :p They should be rated with revs in mind, even a perfectly balanced billet rod will still banana if you push it to hard, but no need to get into engineering lessons!
 
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