CRG Discussion Forum
Camaro Research Group Discussion => Garage Talk => Topic started by: crossboss on June 17, 2021, 05:39:06 PM
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An informal poll, what are you guys using and or prefer, 'I' beam or 'H' beam rods for your current builds? And why?
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No one?
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Hmmm, I guess no one builds a high performance small block Chevy anymore?
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Most guys will use stock GM pink rods if they can find them. Most guys are about restoration on this site.
Get some Callies H beams with high end bolts if you are going to run high RPMs for a sustained time.
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Callies, Lunati and Oliver rods are the top shelf rods I would choose for a all out race engine for maximum performance until I went to aluminum. With today’s technology your “average” I beam rod is good for 500ish hp so really no need to spend the money on ultra performance until you are concerned with weight. Perfect example is I have a 306 sbc I am building and I chose Eagle rods with upgraded rod bolts. 550hp is the max those rods are recommended for so they will be more than enough for what I wanna do even when I spin it to 8500. The more interesting conversation should be valvetrain.. That is “usually” the failure point area. But I’m sure others will have differing opinions but that is where a person needs to spend their money. Valves, shaft mounted rockers, lifters, & pushrods.
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Aluminum rods are fine for certain applications, but won’t last as long as steel.
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Molnar or K1 Technologies H beam rods are the choices for my current engine build. The quality differences between the off shore Chinese rods to Molnar and K1 is night and day...for a measly 200 dollar difference (for my application) its a no brainer.
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The billet aluminum rods are certainly better than they were 20-30 years ago. Maybe I am not up on what currently is best. But I prefer steel, and there is a set of H beams under my bed for my next BBC full build.
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Yeah I tend to stick with I beams for most of my builds, but I have not put together a serious race engine in awhile. I would run H beams for something I was going to be hammering on alot more.
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Always have run Carrillo H beams in sustained high rpm applications -circle tracks-. Along with Callies billet cranks and Crower solid rollers lift and duration tailored to the particular head flow numbers.
I used some eagle I beams full floating in a 302 - with a crower solid roller and the original crank we turned it 7k. IT ran like a scalded dog.
I still have to original rods, they need to be rubushed, they were sloppy. - I kept them because they had the beams polished and and all stress risers polished really nice then had been shot peened.
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I have Eagle SIR I beam rods in my 302 but it does not get hammered all that often. Other users have reported issues with Eagle SIR big ends getting out of spec after a tear down. I probably would not use them again.
I have been buying Scat I beams (and a crank) recently. They are very nice for what they cost and not much bad to say about them. I have a set bushed for floating pins with ARP cap screws that are clearanced for my 383 Vette project. Works for me.
It costs a lot more to go to H beams but I just don't have a need for that much rod. I agree with what was said above, more valve train next.
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Here is a response from a good friend who is a racer and engineer concerning I VS H beam rods:
In general the I beam design can live under higher compressive forces than an H beam design. I have seen H beam rods "collapse" under high boost situations and a replacement I beam survived. The H beam design is stronger in an "extension" condition than an I beam favoring higher RPM conditions.
Aftermarket H beam rods are WAY overkill compared to 90% of the OEM I beam rods out there today. Rarely do they fail "on their own". The two most common failures are spun bearings taking them out or rod bolt failure from too many "torques'' , OVER torque, or too many "hours" of use in a race only application. This is why Nascar engines most often get new rods every 1,000-1,200 miles of race use.
I try to describe the difference in terms of "plates" . Both designs have three "plates" that make up the beam of the rod. The H has two wide plates in parallel to the rod with the smaller third one connecting the two in the center , perpendicular to the rod. The I beam has two thin plates perpendicular to the rod and one wide one connecting them parallel to the rod. "Plates" perpendicular to the rod create "compressive" strength/resistance withe the parallel plates create strength / resistance to extension/ inertia forces. One H beam rod company has taken a more aggressive stance and "spread" the two parallel plates wider and improved the compressive strength significantly over offshore copycat rods.
Let me know if you need more