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Nein. I-beam configuration will always be stiffer in bending for the same weight than H-beam. That's just how it is. Axially if they are the same weight then they are equal in stiffness. If an H-beam is stiffer than I-beam then it weighs more, and you could have made a stiffer I-beam.
Did you see what I wrote? With all metallurgy, length and finish equal..... Not weight.
Google rod manufacturers that manufacturer both.
Google distributors that sell both.
The reason why there are different designs is because there are different applications. Let's throw Tri-Beam into the mix.
The strongest rods available for the Ecotec that I have found are all I-Beam type made by Manley.
Did you see what I wrote? With all metallurgy, length and finish equal..... Not weight.
Google rod manufacturers that manufacturer both.
Google distributors that sell both.
If you don't account for weight then just make the stupid thing solid. Then it's the stiffest you can get.
I have seen that video before. "All things being equal, the H-beam is stiffer but the I-beam is lighter" makes zero sense. Weight is HUGE (see my comment above) and should absolutely be factored. If weight isn't equal when comparing, then what geometric design constraint is? If you include weight (which you really should) there is absolutely no advantage to H-beam.
Bending stiffness: adv. I beam
Axial stiffness: equal
Buckling: adv. I beam
Crippling (unlikely): equal
I also asked a seller of rods at SEMA. The best he could do was "it doesn't matter because they usually fail in tension." Since I have seen plenty of pictures of bent rods, I just left.
Last edit: Looks like the first comment on Summit's youtube video nailed it.
Taking a quick look at those tri-beam: the reason that they did that is in bending, the further away from the neutral axis the stiffer in bending it is. That is why I-beam is better than H-beam. They moved some material further out so it becomes stiffer in bending. If the cross-sectional area is the same then it is the same stiffness axially, regardless of configuration.
H-beam rods are not better than I-beams, its the other way around. At least for Subaru engines. Not sure about Cobalt.
our blocks rated to 650 HP use H-beam rods, but our 1000 HP blocks use forged I-beams.
I wasn't being Cobalt specific, I was being general and what is available to the public to purchase. Still with all things for an application being equal, there is more weight and strength in the H design due to the mass being in what we know as the ends (H) than the center where as the I has the mass in the center (I)and not the sides. Per application, it is just more alloy.
Reciprocating weight is always a concern for high revving gas burners. Not so much for 3000 HP Diesels running H-beam 4032 billet steel rods.
I wasn't being Cobalt specific, I was being general and what is available to the public to purchase. Still with all things for an application being equal, there is more weight and strength in the H design due to the higher mass.
Reciprocating weight is always a concern for high revving gas burners. Not so much for 3000 HP Diesels running H-beam 4032 billet steel rods.
fify. It has nothing to do with where the mass is in that plane.
I haven't researched this much but the main difference that nobody seems to be mentioning is the orientation of the beams. Both stiffness structures are really similar profiles just the ratios are different and oriented 90 degrees to each other. I-beam has a narrower thicker flange and H-beam has a wider thinner flange as you can see by the letters and H is just a squished down I. From a column standpoint like has been said either orientation could have the same resistance to buckling. However, looking at pictures it looks like rods tend to bend in the same plane as radially around the crank shaft. This would give the I-beam rod more stiffness or resistance to bending to correctly combat the way your rod will typically bend.
If you have ever seen and I-beam in a structure (with gravity) you will see the flanges run horizontally because they need to resist bending vertically. An analogy to using an H-beam in a typical structure would be like taking a wide-flange I-beam and putting it on its side so the flanges are now on a vertical plane. With my practically non-existent understanding of con-rod design the H-beam design does not seem to be optimized to combat bending in the typical direction a rod will bend.
Found this picture that is a good visual comparison of H-beam vs. I-beam rod orientation
Excellent find jdbaugh1. Obviously I haven't researched enough to know just what dimensions the rods are using, but based on the "H-beams are stiffer but heavier" statement my guess is that they are making H-beam rods like the 3rd from left configuration. They're not as efficient in bending but they have more material so they resist axial (tensile or compressive) loading better than a lighter I-beam rod. My point was that you can design an I-beam rod that would have a better moment of inertia (I) than the same-weight H-beam rod but resist axial loading equally. On top of it, an I-beam would be much easier to forge so I'm still left wondering why people started doing H-beams in the first place. They couldn't have been an engineer.
Found 3 like this... Cyl 1,2 & 4. All toward the intake side. Still contemplating what's going on here. Top Rings are all free and as clean as can be. Surprised how nice the cylinders and skirts look for 126k.
Maybe in 08 they stopped coating them. Mine were all 06-07. Is the small end of that rod stretched, looks like the bushing isnt touching all the way around...
the problem isnt the pistons being weak, its the ring gaps are too tight for boost. what happens is with the extra heat the rings will expand more and when the end gaps butt together the ring has to go somewhere so it pushes up breaking the piston. the ecotecs have the top ring so close to the top of the piston it breaks so easily. other engines with the top ring lower down the piston will take a little more before it breaks the piston, however in the meantime it will scuff the hell out of the cylinder wall.
i think the stock pistons would last a lot longer in the 2.2 and 2.4 under boost if you opened the ring gap up. factory top ring gap is between .008-.014", if they were opened up around .018-.022" for the top ring they would be a lot happier.
After getting in my custom Diamond pistons, I thought I would share what comes with the Total Seal ring pack and what OEM shows. I would recommend you always follow what the ring manufacturer suggests for your application.
So first are the OEM specs for the 2.4 LE5. I will just compare the top compression ring for the sake of simplicity.
6-12 thousandths
Then the SAE recommended ring end gap.
10-20 thousandths
Now, file to fit your application. In this case, my application.
08-02-2017, 04:46 PM
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