Cummins Rod & Piston Comparo

[ZRacer]

Found this interesting photo in this month's issue of "Mopar Muscle" on page 73. This is a revised comparison photo of the Cummins, D-Max and Folrd rods and pistons. I can't believe how much larger the wrist pin bore is on the Cummins! Looks like it's built for some serious Bombing Abuse!

 

[SRadke]

Chrysler is using that in their displays now. I saw it in a Dodge booth at a very large local rodeo.



-Scott

 

[turboost]

The longer the stroke the beefier the rod needs to be. The higher the cylinder pressure the beefier the piston needs to be. This pic really means nothing. Grand Nationals are making over 600hp on stock engines and there rods are not too big b/c a short stroke means less stress. Same way with a turbo'd 5. 0 mustang. Their rods are a little smaller than the dmax's. Cummins rods and pistons are bigger b/c they have to be and I'm glad they are.



On a side note it does make you feel better about putting twins on it

 

[DPelletier]

turboost,

You have a point as far as the rods go, but the increased bearing surfaces and strength of the piston as well as the rods all conspire to make the Cummins a stronger (and longer lasting) engine than the others. Having less rpm doesn't hurt, either. I wouldn't say the pic means nothing. Look at the piston again; it's like jewelry!



Dave

 

[ZRacer]

Last week the vendor who manufactur'es the pistons for Cummins was at the Tech Center showing off their stuff. They had a couple of diesal pistons on display and we got to talking about the different features. This photo doesn't show it, but the top ring land has a cast iron and nickel alloy "I" grove he called it which increases the wearability and strength compared to cutting the land in aluminum. They also pointed out the larger wrist pin bore as being able to withstand a higher load for a longer period. And for increased strength, they bush the pin bore and imrove strength even more. The pistons are extremely nice pieces when you see them out of the engine.



I'm assuming that the marketing folks at DCX love to point out the significant difference in strength the Cummins appears to have over the other 2. From what most folks have seen in terms of durability and longevity it would be hard to argue the Cummins doesn't live up to the task. Whether or not the Cummins design is actually stronger than the others isn't as important than the image of stregth that is portrayed. GM does it with the Allison, Mopar is doing it with the rods and pistons. It's all about postureing and image.