[mayasonata]

hyundai boasts that the yf comes with cracked connecting rods found in upper class cars such as the benz SL.

is this all hype ?

 

[Mike Eckman]

Connecting rods are installed in two pieces. The small end is connected to the piston, and the large end is connected to a bearing on the crankshaft.

Connecting rods come in two pieces, with the large end separating in two so that it can be installed on the crankshaft. Normally, a connecting rod is forged from a single piece of metal, and then "cut" down the center line of the large hole for installation and then two bolts are installed to "clamp" it together.

Take a look at the following pic of a connecting rod and its separation where the crankshaft would go.

With a traditional connecting rod, this split is in a straight line and very smooth. With a cracked rod, this separation is "cracked" intentionally by design. A crack is not perfectly straight and will have some variations in the metal which can help keep the two pieces of the connecting rod together.

Imagine a cookie. Take one cookie and cut it down the middle with a knife. Then take another cookie and break it in half with your hands. Envision the one thats cut as having a very straight and smooth edge. The one you cracked in half wouldn't have a smooth line.

Inside your engine, the connecting rod is exposed to extremely high amounts of stress. Cracking the connecting rod and having uneven marks actually helps side to side force from separating the connecting rod inside your engine.

Whether or not, this technique will have any measurable improvement in reliability in a car like the Sonata remains to be seen, but high end cars with extremely high RPMs (or motorcycles) can benefit from this technique.

 

[Second2011]

Hmmmm, I had to look that one up:


High strength cracked connecting rods are used that minimize weight and size, while also increasing connecting rod rigidity and long term durability. A "cracked" connecting means that the rod and cap are forged as a complete unit during the manufacturing process, and then cracked apart to create a custom fit between the two matching surfaces. The use of high strength steel contributes to the connecting rod's slender shape and results in a 50 percent increase in fatigue resistance for a long lasting engine.

The design allows for the elimination of connecting rod bolt pins, since the connecting rod bolts can be precision machined to fit the cap to the rod. The end result is a connecting rod that is 13 percent lighter and has a 20 percent smaller cross section, resulting in less rotating mass inside the engine and less space occupied by the connecting rod - a significant component to creating a powerful, efficient and compact engine.

 

[Mike Eckman]

QUOTE (CCltd @ Jul 12 2010, 11:34 AM) index.php?act=findpost&pid=341046

Hmmmm, I had to look that one up:

High strength cracked connecting rods are used that minimize weight and size, while also increasing connecting rod rigidity and long term durability. A "cracked" connecting means that the rod and cap are forged as a complete unit during the manufacturing process, and then cracked apart to create a custom fit between the two matching surfaces. The use of high strength steel contributes to the connecting rod's slender shape and results in a 50 percent increase in fatigue resistance for a long lasting engine.

The design allows for the elimination of connecting rod bolt pins, since the connecting rod bolts can be precision machined to fit the cap to the rod. The end result is a connecting rod that is 13 percent lighter and has a 20 percent smaller cross section, resulting in less rotating mass inside the engine and less space occupied by the connecting rod - a significant component to creating a powerful, efficient and compact engine.

I like your explanation too. Its much less wordy than mine!

 

[elp_jc]

Crap. Ford has been using that method since the early '90s, and it's widely used today. And there's nothing 'fancy' about that; it's just a cheaper way to build connecting rods that happen to be better too, that's all. For those who don't know what that is, picture a one-piece connecting rod. Rather than cutting the large (crankshaft) end in two right at the middle, it's cracked, meaning it can only be put back together one way, which fits perfectly and avoids any kind of side/lateral motion, for better durability. So yes, cracked conrod caps are not interchangeable; each one is unique, and only mates its 'paired' conrod. Hope this helps.

 

[mayasonata]

so why is hyundai making a big deal out of it ? I'm getting sick of hyundai's attempts to boast gimmicks....it's very misleading.


QUOTE (elp_jc @ Jul 12 2010, 12:41 PM) index.php?act=findpost&pid=341051

Crap. Ford has been using that method since the early '90s, and it's widely used today. And there's nothing 'fancy' about that; it's just a cheaper way to build connecting rods that happen to be better too, that's all. For those who don't know what that is, picture a one-piece connecting rod. Rather than cutting the large (crankshaft) end in two right at the middle, it's cracked, meaning it can only be put back together one way, which fits perfectly and avoids any kind of side/lateral motion, for better durability. So yes, cracked conrod caps are not interchangeable; each one is unique, and only mates its 'paired' conrod. Hope this helps.

 

[Bearcats]

QUOTE (mayasonata @ Jul 12 2010, 12:46 PM) index.php?act=findpost&pid=341052

so why is hyundai making a big deal out of it ? I'm getting sick of hyundai's attempts to boast gimmicks....it's very misleading.

And Ford, and GM and BMW and Mercedes...its just not one manufacturer...

 

[Klooks Kleek]

QUOTE (mayasonata @ Jul 12 2010, 11:46 AM) index.php?act=findpost&pid=341052

so why is hyundai making a big deal out of it ? I'm getting sick of hyundai's attempts to boast gimmicks....it's very misleading.

If I ran a shop or produced a product, I would not hold back on trumpeting a special procedure that was beneficial simply because my competitors chose NOT to publicize it. In fact, shame on them for not talking it up.

I certainly would not in good conscience claim I was the ONLY one to do something if that were not the case, but I would not be shy about marketing it if I knew it to be something good.

 

[Mike Eckman]

QUOTE (Klooks Kleek @ Jul 12 2010, 01:08 PM) index.php?act=findpost&pid=341083

If I ran a shop or produced a product, I would not hold back on trumpeting a special procedure that was beneficial simply because my competitors chose NOT to publicize it. In fact, shame on them for not talking it up.

I certainly would not in good conscience claim I was the ONLY one to do something if that were not the case, but I would not be shy about marketing it if I knew it to be something good.

This is a very common practice.

Allstate has commercials on television all the time talking about "Accident Forgiveness" wherein, if you havent had an accident in the last 5 years your rates wont go up if you file a claim.

This is something State Farm and other companies have been doing for years, but they dont have a national advertising campaign. So while, I think its good that Allstate offers it, its nothing thats special to them.