I beam vs H beam
 

I'm being fed all sorts of misinformation & now I'm totally confused. I need some CC forum counseling. What are the advantages of one over the other?
Ultimately, what made you go for one over the other & are H-beams worth the extra $?

Many thanks,

It's simple really
 

Dimis How much power are you looking to make in the motor? The same applys for what pistons you use, cast? forged? Hyper? Titanium?
For the cost different of a couple hundred doolars and the amount of money it's costing you to build your motor, "H" rods are easy to choice. What motor is this going in?? Over biuld the motor and you should get many years out of it to drive without failures. Rick L.

Some time back I did some research on this matter and found that the H beam rods are supposedly easier (cheaper) to make, so the manufacturers like to push them. While holding the rod to do the boring of the big and small end holes, the CNC equipment can easily run a cutter up the sides of the rod.

There was some laboratory test data from back some time ago that showed that H beam rod bearing oil layer thickness was a bit more uniform across the journal with the greater stiffness of the H beam in that direction, but I don't know whether the I beam they tested was the same weight or the same relative stiffnesses (you can make an I beam the same stiffness in the out of plane direction as an H beam, if so chosen). The rod manufacturers use this to justify their cheaper to make parts. The problem is the dominant loading is typically in the direction of rotation and H beams will buckle much easier in that mode, ref this example:
http://www.clubcobra.com/photopost/d...od_failure.jpg
In the real world, the crank and block will be flexing also, which the I beam would tend to more readily accomodate, keeping the bearing from coming in contact with the journal at the edges. Anyway, I couldn't find any examples of Formula 1 engines using H beam, so the net outcome is they are not likely really beneficial. I've also heard comments that some of the better quality rods just happen to be H beam, so the quality aspect is why people are buying them, not because they are H beam.

The H beam is a lot harder to make than the I beam. I have a customer than manufactures both. The time on an I beam is probably 1/3 less than the H beam, and you can use somewhat generic tooling. The chances of a mistake on the I beam are a lot less also due to chip evacuation and trying to hold wall thickness on the H beam.

Are they worth the extra money? From a machining aspect alone, yes. They do cost a lot more to manufacture. From a performance standpoint? Like everything else, it depends on what you are using them for.

When I build an engine, a lot of my $$ goes into "longevity".

Given the same, or even similar costs, I always go with the product that offers greater lifespan.

Could the H-beam con-rod design offer greater durability in this respect?

Just curious...

Thanks!

Dugly :cool:

Con rod
 

Formula 1 rod: Worlds largest online auction of auto art, (l'art et l'automobile)
While this rod is from several seasons ago, it's still in the rhelm of the modern age. In the cost is no object world of F1 for them to use H beam certainly says a lot.
The reality, however, is either design (executed correctly) is going to be good enough for most Cobra applicable engines, with other quality aspects being the determining factors.

I have ran both in my Cobras with no problems. But they were all basically hand made as were the rest of the engine components. My engines never turned in the 7K plus range so that may have also helped make them seem indestructible. But one the engine is balanced, blue printed and such, I think either type wold stand up well for most applications.

Ron ;)

I recently posted an artical on the sister site ClubHotrod that uou can go over and read--some very detailed stuff from Race Engine Technology issue Nov 2011--
Post titled "Connecting rod tech" and posted on Mar 3 2012--

I might have time to load it here over the week end if anyone is interested and can't access it over there--think its about 8 pages of text and pics

That Ferrari rod is Aluminum, which just necessitates more metal to get the same strength. I have never seen an Aluminum rod in an H beam design. I have H beams in my motor now, but to ne honest I did notice that even by hand one can get a little twist going on. Interesting subject............

Trying the tech artical
Don't know why they came up as thumbnails--same method I used to upload on the other site

the rest of the 10 pages

This is one of those agruments that will never have an end.

From a pure architectural perspective the I beam seems to be the emerging choice for professional racing. So if you're looking at higher end Callies, Carillo, Oliver type stuff you'll be looking at I beams forged from 300M or similar. In the other realms of racing such as late model oval track the H beam is still highly regarded - with specialty suppliers such as Dyer or R&R. I all of these the material, engineeering and machining aspects are as important as the beam design if not more so.

In the land of less expensive rods such as Scat or Eagle the "game" is different. The offshore H beams were initially designed to mimic the appearance of the at the time most desireable Carillo H beams. The I beams were designed as upgraded stock replacements. The evolution of the products has thus been to have the inexpensive H beams ending up with noticeably nicer machining and somewhat better cosmetics. The offshore I beams are normally designed to be as inexpensive as possible while retaining desired features. Its still a blurry line between the two.

Even at the brand X white box house brand levels where the rods are brought into the country by companies named RPMMaxx or Star Galaxy the I vs H discussion can be a blurry line. These parts are decidedly not the same parts sold by Scat or Eagle. You did not think these ebay vendors just decided to fire up a forging foundry and machining center in China did you?

For those of you that have emailed me or PMed , I have forwarded the 10 pages as an email--also sent it to myself to see if it was readable-- also it is on CLUBHOTROD as I previously posted---

I lost a side-oiler block because of the I-Beam (stock) rods. Whatever the real reason was (we fond a stress riser leading to failure), I can only advise: get the best rods you can afford.

What is the price difference these days?

Anth,

Generally speaking the four parts of your engine you want to be as good as possible are the pistons, rods, crank and block. The crank and block are the foundation you build everything else around. If they are weak it doesn't matter what you do elsewhere there is a strength of materials engine failure waiting in ambush for you somewhere down the road.

After those two the pistons and rods take the spotlight. Your pistons need to be optimized for the environment you intend them to operate in. Normally aspirated pistons have one success formula and blown motor pistons have another. Putting one in into the other's service environment will produce unhappy results an eventually broken parts.

The connecting rod and its fasteners not only transmit the power from combustion through the crank slider mechanism but may well be the second most highly stressed component in the engine after the crankshaft. Certainly true on a blown motor and probably also true on a high output n/a engine.

Fred Carrillo started making H-Beams in the early sixties. He was and is considered the pre-eminent connecting rod manufacturer in the world and the father of the H-Beam design as we know it today. He patented that design to protect his intellectual design properties and seventeen years later when the patent ran out he applied for a second seventeen year period of protection. When the extended protection period expired H-Beam connecting rods began to appear from a growing number of suppliers. Today the numbers are legion and from all over the world.

Designed correctly the H-Beam rod is extraordinarily strong and also light. Done as a knock off, low dollar copy without adequate engineering time to properly design the rod for the intended engine/application they are a minimally an untested and most probably a weak link in your engine that will eventually lead to an engine failure.

When Ford built the supercharged 03/04 Cobra engines they went out of Ford to Manley for their H-Beam connecting rods. This was a production first! In Frank Moriarity's book Iron Fist Lead Foot, about the genesis of the engine/vehicle combination, John Colletti, who headed up the internal team was confronted with OEM connecting rod failure during Ford's 300 hour cyclical endurance run on the dynamometer.

To get through the endurance tests they did something Ford had never done to that point - they went to the outside for Manley's rods. Colletti said of the rod failures, "We're going to get rid of that problem, put the gold plated part in there." Two Manley rods cost Ford more than a fully machined Cobra block ready for assembly. The Manley rod equipped engine sailed through the endurance tests multiple times.

Those rods have since been run day after day in street driven vehicles and raced at the track with over 700 ft/lbs of rear wheel torque. The rods continue to perform flawlessly.

Fred Carrillo's original design earned the reputation of simply being the best but not the least expensive. When everyone else could they copied the part. If you select a quality manufacturer for your rods today you will get an extraordinary rod - not at a bargain basement price. The rod will most probably outlast the rest of the engine.

In a word they are stunning. If you buy from reputable manufactures who do not cut corners in the design and manufacturing process - you will not be disappointed. When it comes to mission critical engine parts, I have known many racers who bought the best and were satisfied beyond their expectations. I have also known many who didn't and later wished they did.

Ed

Although not a professional builder, I think rod bolt failures account for the majority of supposed rod failures, at least outside of pro racing circles. Cheap bolts, old bolts, and especially improperly installed bolts. ARP bolts have stretch criterion for installation, and using a simple torque wrench just doesn't cut it in a stressed application. In fact, a race engine builder told me that he brings his rod bolts to spec stretch three times before he actually does the final install!

phil

Potato, Pahtahto

It makes no real difference at all. The best thing about an H-Beam rod is that they don't look like stock rods, and it's easy to sell a "racy".

If H-Beams were stronger, and cheaper to make why don't the OEM guys use them in everything they make? The factories will sacrifice their mothers for $1.20 and four Jelly Bellies......

That was my mistake. The H beam is a lot more expensive to make from a manufacturing standpoint than the I beam.

Turn an H-beam 90 degrees cross section and you have an I-beam. :JEKYLHYDE

To say "it makes no difference at all" is as much conjecture as picking one over the other without empirical evidence. But then again, seems like folks here like arguing about things they can't prove.

The notch effect from the oil is highly reduced using aftermarket H-Beam vs stock I-Beam.